The slip ratio control (SRC) of electrified vehicles has been widely studied for improved safety. The majority of studies on the SRC take an approach to control the slip ratios of the left and right wheels individually. However, this study proposes a new method for designing SRCs, which is to utilize a coordinate transformation from the left-right coordinate (LRC) to the average-differential coordinate (ADC). As a demonstration, a driving force control (DFC), which includes the SRC in its inner loop, is modified using the ADC transformation. The effectiveness of the ADC-based DFC is verified through an experiment of several maneuver tests on a slippery road using a real electric vehicle.

Electric vehicles (EVs) contribute to reducing environmental impact but still face challenges such as limited battery capacity, high costs, and long charging times. Dynamic Wireless Power Transfer (DWPT) is a promising technology that enables EVs to receive power while driving, addressing these issues. This study develops a simulator that reproduces realistic urban traffic conditions using publicly available road network and person-trip data from Kashiwa City, Japan. The simulator incorporates traffic signal control, road gradients, and a vehicle dynamics-based energy consumption model. The simulation results align with previous big data analyses, confirming the validity and effectiveness of the proposed method. Moreover, it is estimated that a battery capacity of 4.82 kWh would be sufficient for 99% of vehicles to operate solely on energy supplied by DWPT system.

Although driving force control (DFC) has been proven to be one of the most promising strategies for traction control, its integration with other motion control functions in electric vehicle (EV) remains an open research challenge. This is because DFC has traditionally been developed utilizing single-wheel-model without consideration for other motion control objectives. To address this limitation, this paper presents a preliminary investigation into a hierarchical decentralized motion control system for multi-motor EVs, based on the DFC. In this architecture, the upper layer is responsible for vehicle speed control, while the lower layer comprises multiple DFC units-treating speed and driving force control are as global and local objectives, respectively. Additionally, a middle layer is to allocate the driving forces to attain supplementary goals. To facilitate a systematic design methodology, a role-sharing mechanism between upper and lower layers is established via a concept of "global/local shared model set." This concept enables both layers to be designed using standard robust control techniques. Notably, the design complexity remains independent of the number of actuators. Using a real in-wheel-motor vehicle, this paper demonstrates-both theoretically and numerically-that the trade-off between global and local objectives can be analyzed through the size of the shared model set.

The rapid development of autonomous driving technology calls for efficient and reliable methods for performance evaluation and optimization. This paper proposes Autoware Toolbox 2, which is a benchmark suite for the autonomous driving system, Autoware, using the Model-Based Development (MBD) approach. By modeling and simulating ROS 2 nodes in MATLAB/Simulink, the benchmark suite enables systematic evaluation of Autoware. Compared to traditional code-based benchmarks, the MBD-based approach improves modularity, reusability, and visualization, streamlining the testing process and reducing development time. Experimental results demonstrate that the proposed benchmark suite is effective in evaluating Autoware, and validate the utility of the benchmark suite and its potential to enhance both development efficiency and functional performance of Autoware.

In recent years, autonomous vehicles have attracted attention as one of the solutions to various social problems. However, autonomous driving software requires real-time performance as it considers a variety of functions and complex environments. Therefore, this paper proposes a parallelization method for autonomous driving software using the Model-Based Development (MBD) process. The proposed method extends the existing Model-Based Parallelizer (MBP) method to facilitate the implementation of complex processing. As a result, execution time was reduced. The evaluation results demonstrate that the proposed method is suitable for the development of autonomous driving software, particularly in achieving real-time performance.

In recent years, the complexity and scale of embedded systems, especially in the rapidly developing field of autonomous driving systems, have increased significantly. This has led to the adoption of software and hardware approaches such as Robot Operating System (ROS) 2 and multi-core processors. Traditional manual program parallelization faces challenges, including maintaining data integrity and avoiding concurrency issues such as deadlocks. While model-based development (MBD) automates this process, it encounters difficulties with the integration of modern frameworks such as ROS 2 in multi-input scenarios. This paper proposes an MBD framework to overcome these issues, categorizing ROS 2-compatible Simulink models into event-driven and timer-driven types for targeted parallelization. As a result, it extends the conventional parallelization by MBD and supports parallelized code generation for ROS 2-based models with multiple inputs. The evaluation results show that after applying parallelization with the proposed framework, all patterns show a reduction in execution time, confirming the effectiveness of parallelization.

The descent phase of the multi-rotor Unmanned Aerial Vehicles (UAVs) is one of the situations when UAVs tend to lose control because of the Vortex Ring State (VRS). The VRS is one of the states of turbulence. The VRS is a well-known phenomenon in manned helicopters and can also occur during the descent of a UAV. It is difficult to escape from the VRS without taking the VRS recovery motion. Some previous studies have proposed to avoid the VRS condition. However, those methods do not consider the effect of the wind disturbance. It is important to know the real-time turbulence information and detect the VRS to be robust to unexpected wind. This paper proposes a novel VRS detection method using the counter torque of the propeller motor to obtain real-time turbulence information. The method is verified with the bench experiments in a wind tunnel. The results show the possibility of the proposed method to detect the airflow flows into a propeller from dangerous airflow angles.

Recently, wireless power transfer (WPT) for electric mobilities has much attention. The electromagnetic field radiated by the WPT current is limited by the international regulations. In order to reduce the electromagnetic field radiated by the third harmonic current (3rd-EMF) in an SS topology WPT system, the inverter is often operated using a phase shift control whose shifted phase is fixed at π/3 rad. However, an additional DCDC converter is needed to control the WPT power. This paper proposes the two-pulse width modulation method to achieve both the voltage regulation and the 3rd-EMF reduction. The switching timing is determined by calculating the Fourier transform of the inverter output voltage waveform. The proposed method is experimentally validated using a GaN inverter which is used to generate the precise voltage waveform. The results show that the proposed method can regulate the voltage and reduce the third harmonic current simultaneously. The inverter efficiency is more than 92% when the duty ratio is more than 50% even if hard switching is conducted.

To overcome the short flight duration of drones, research on in-flight inductive power transfer has been recognized as an essential solution. Thus, it is important to accurately estimate and control the attitude of the drones which operate close to the charging surface. To this end, this paper proposes an attitude estimation method based solely on the motor current for precision flight control in the ground effect region. The model for the estimation is derived based on the motor equation when it rotates at a constant rotational speed. The proposed method is verified on the simulations and experiments. It allows simultaneous estimation of altitude and pitch angle with the accuracy of 0.30 m and 0.04 rad, respectively. The minimum transmission efficiency of the in-flight power transfer system based on the proposed estimation is calculated as 95.3 %, which is sufficient for the efficient system.

Range extension via speed trajectory optimization is an important issue for battery electric vehicles (EVs), To this end, this paper contributes a practical approach to globally minimize the energy consumption of EVs passing through multiple signalized intersections. The energy consumption is estimated using a traffic flow Gaussian mixture model (GMM) obtained from floating car data. Then, the optimal speed trajectory is generated using dynamic programming (DP). The algorithm is solved distributedly for each segment between two adjacent intersections, thereby, alleviating the computational burden. Furthermore, the proposal does not require vehicle-to-vehicle (V2V) and vehicle-to-infrastructure (V2I) communication. Experimental results demonstrate that the proposed algorithm can successfully reduce energy consumption. The reductions are respectively 11.7% and 8.0% compared to the simple strategy with the constant speed and acceleration/deceleration, and the conventional method which independently minimizes the energy consumption in each road segment between two adjacent intersections.

This paper presents a two-degree-of-freedom control system for improving the attitude control performance under the existence of propeller's loss of effectiveness (LoE). To deal with the long sampling time of attitude measurements, a multirate observer is designed to estimate the attitudes at every control period of the propeller actuator. Using the estimated attitudes, the LoEs are identified via recursive least squares (RLS) algorithm. Using the identified LoEs, the propeller speed references are adjusted to compensate the fault effect on the system. Some physical parameters of the attitude dynamics are also identified to adaptively update the feedforward controller. In summary, the proposed system only consists of practical algorithms which can be implemented conveniently in real applications. Experiments using a dual-rotor testbench show that the proposed system can quickly identify the time-varying LoEs. In comparison with a conventional singlerate control system without fault tolerance, the proposed system can reduce the pitch angle and yaw angle tracking errors by 69.3 % and 39.6 %, respectively.

The short flight time is one of the problems hindering the development of industrial applications of drones. As a solution to this problem, in-flight wireless power transfer (WPT) has been attracting attention, especially in security and R&D operations. One of the challenges of in-flight WPT for drones is the received power control due to fluctuations of mutual inductance and the motor's required power. To control the received power, the active rectifier is usually used in WPT applications, which keeps the power by switching. However, that switching deteriorates the system efficiency. Conversely, if there is not enough power, a normal WPT system cannot control power only by receiving side. In this paper, we propose a unique received power control for in-flight drones that combines power control by the rectifier and altitude control. The performance improvements have been experimentally demonstrated on the bench system. As a result, the conversion efficiency of the rectifier improved by 4.10 % because of a reduction in the number of switching times of the rectifier. When received power was insufficient, the current increased by 1 A and exceeded the lower limit of the control target.

To maintain the safe and accurate traction of electric vehicles (EVs), driving force control (DFC) has been studied for years. However, the classical DFC requires the vehicle speed to calculate the reference of wheel speed. It increases the complexity and nonlinearity of the DFC system. Moreover, the saturation of the force controller's output challenges any attempt to design and analyze DFC systematically. To overcome these issues, this paper presents a novel DFC system in which the force controller directly outputs the wheel speed reference. It alleviates the system complexity, as the vehicle speed is only used to calculate the upper and lower bound of the wheel speed limiter. The proposed DFC configuration allows us to analyze system stability using the circle criterion to address the wheel speed saturation. The effectiveness of the proposed DFC and the stability analysis is verified by graphical tests, numerical simulations, and experiments using an in-wheel motor vehicle developed by our research group.

Autonomous vehicles have attracted increasing research attention as a solution to various contemporary social problems. Current code-based development methods require time to understand the processing of open-source, complex autonomous-driving systems, and parallelization is performed manually when verifying the operation of such systems. Thus, a method for parallelizing autonomous-driving software using the Model-based Development (MBD) process was proposed. The parallelized code for autonomous-driving software can be generated semi-automatically. The proposed method realizes the generation of code that assumes operation on real-world hardware and reduces execution time.

To improve the cornering performance of the vehicle, the two-motor-torque difference amplification-torque vectoring differential (TDA-TVD) has been proposed for the two-input-two-output motor drive system, since it enables to increase the maximum torque difference between left and right wheels. However, this mechanism has problems of torque coupling and vibration in left and right drive shafts. In the previous research conducted by the authors, the TDA-TVD model analysis and drive shaft vibration suppression control methods are provided, but only feedforward control is considered. In this paper, a drive shaft vibration suppression controller is designed with frequency domain analysis of the model. The proposed controller consists of a feedforward controller using the inverse model of TDA-TVD, and a feedback controller using the rotation speed of the motor. The experimental evaluation of the proposed controller is performed using a real vehicle with the TDA-TVD system.

Every year, embedded systems, such as self-driving systems, are becoming larger and more complex which requires high computing power yet low power consumption. To meet these requirements, there is an increase in the usage of many-core processors. However, thorough understanding of the concept of many-core processors is needed for these to be adopted. Therefore, Software-Hardware Interface for Multi-Many-Core (SHIM), a hardware abstraction description, was developed to reduce the burden on developers. However, SHIM cannot fully demonstrate communication overhead as it describes overhead in instruction units. For this reason, the communication overhead cannot be used to estimate execution time. With this, we propose a new schema that can describe the communication overhead in API units. In other words, the communication API overhead can be described without relying on communication libraries. To improve the usability of the existing schema, which is SHIM, we incorporated the proposed schema into SHIM. We set up what is required of the proposed schema, considered use cases, and actually created instance diagrams to evaluate the proposed schema. We also compared the proposed schema with SHIM and determined what needs to be modified when incorporating the schema. As a result, the proposed schema can express communication overhead that varies with the combination of cores and message size, while significantly reducing the amount of description.

Three-wheeled electric mobility is an effective means of transport in a small and narrow space. As this electric mobility is widely utilized, the request of safety and performance for this mobility has become important. And thus a fault tolerance function needs to be developed to minimize the user’s intervention and improve driving performance. Fault-tolerance technology is applied mainly to sensors, but a fault tolerance function is also required from the viewpoint of driving-related actuators.In this paper, a fault tolerance algorithm is proposed taking use of newly-proposed concept steering fault disturbance and Model Predictive Control (MPC).To this end, an index is proposed to represent the failure of the steering motor as an objective numerical value, and this index is used for the driving controller of electric mobility.In this driving controller, MPC is designed based on a dynamic model of three-wheeled electric mobility to regulate the input values of steering angle and yaw moment to maintain driving performance by referring to the proposed index.By using the proposed algorithm based on the MPC, electric mobility can drive along a given route without user’s intervention in the event of a breakdown. The proposed fault tolerance algorithm is verified through various driving scenarios using a simulation model that reflects three-wheeled electric mobility.

This paper discusses the start-up process for a dynamic wireless power transfer system to an electric vehicle passing a road-side coil. To transfer maximum energy in a short time, the process of detecting an approaching vehicle and transmitting power must be carried out quickly. In most of the previous studies, problems of vehicle detection and power transmission have been considered separately. In this paper, the power transmission control process is proposed that combines vehicle detection and current control. The detection process uses only vehicle-side voltage pulse which enables both road-side and vehicle-side coils to sense approaching of the vehicle-side coil. And the current control suppresses the current overshoot at the start of power transmission. The proposed method was verified by experiments. Both coils could detect another one at a sufficient distance from each other. Additionally, power transmission starts at a point of small coupling coefficient was achieved without current overshoot.

Embedded systems such as automotive systems require high computational power and low power consumption. To meet these requirements, many-core processors have attracted attention. Compared with single-core processors, many-core processors can execute multiple processes in parallel, allowing for improved power consumption and performance. Due to their performance, many-core processors can be used in automotive systems which have strict real-time requirements. Therefore, it is important to obtain accurate hardware and software information. In this paper, we propose a method for estimating the execution time of an application supported by MATLAB/Simulink on a many-core platform. The proposed method considers operating system (OS) overheads with a real-time OS and Kalray MPPA-256 cluster structure which contains many-core processors. The effectiveness, and the experimental results demonstrate that the proposed method is more accurate than existing methods.

Multi-/many-core processors are being increasingly used to reduce power consumption and improve performance. In addition, the use of Model-Based Development for embedded systems has been increasing. Relative to these trends, Model-Based Parallelizer (MBP) has an essential role in parallelizing applications (i.e., Simulink blocks) at the model level. MBP maps Simulink blocks to cores using various types of information such as block characteristics, a C code, and the multi-/many-core hardware implementation. However, MBP does not consider many-core hardware with cluster structures. This paper proposes an algorithm that decides on core allocations by considering cluster structures. The proposed algorithm combines two other algorithms: one algorithm uses the core allocation of MBP and path analysis at the cluster-level and considers the influence of communication contention to decide on cluster allocations, and the other algorithm uses the results of MBP and remaps cluster allocations. The proposed algorithm produces better results than its component algorithms could separately. Evaluations demonstrate that the proposed algorithm obtained the better results than the existing method in terms of execution time on random and real models.

This paper presents precise control of ball-screw-driven stages based on projection-based iterative learning control (ILC). Standard ILC has a problem that only one reference trajectory can be learned and once the reference trajectory is changed to other, relearning is required. To overcome this problem, projection-based ILC using basis functions has been studied. To apply projection-based ILC to position control of ball-screw-driven stages, a model of rolling friction is needed. An approximation of rolling friction is introduced in the previous study, but this deteriorates control performance. In this paper, therefore, projection-based ILC using basis functions and data-based friction model which needs no approximation is proposed. Simulations and experiments verify the effectiveness of our proposal.

Recently, the demand for servo-motors and automated control methods have been increasing because factory automation is rising. According to growth of demand, there has also been increasing requests from customers to an automatic adjustment method of controller. This paper explains the automatic adjustment method which can adjust both structure and parameters of position controller. In conventional methods, the parameters of the controller with fixed structure could be optimized based on frequency response data of the plant. However, it was not possible to optimize the structure of the controller. Our proposed method makes it possible to optimize the structure of the controller by repeatedly renewal of the structure and optimization of parameters. The parameters are optimized based on Structured H∞control. Effectiveness of the proposed method is illustrated in simulation and experiment.

Although extensive research has been conducted to design active steering controllers for self-driving vehicles, the cross comparison between those controllers has not been studied much yet. Thus, we developed a benchmark to compare yaw rate control methods by active front steering. Three yaw rate controllers, model predictive control, linear quadratic integral control and yaw moment observer-based control, were compared in terms of four evaluation indices: slew rate of actuator input, emergency performance, robustness against disturbance and stability performance of sideslip angle. The comparison was carried out in simulation environment with a 10 DoF vehicle dynamics model validated by an experiment.

Semi-dynamic wireless power transfer (SDWPT) system is one of the solutions to short driving distance in electric vehicle (EV). This system provides electric power to EVs on the point of stopping. A scheme of sensorless positioning system in SDWPT system via magnetic resonance coupling is proposed in this paper. High transmission efficiency and short vehicular gap position are selected as the final stop position which lead to energy conservation and traffic jam problem reduction. These proposed methods also show more practicality of positioning system for SDWPT system by using command value prediction (CVP) and reinforcement learning algorithm (RLA). Performance of these two proposed method is evaluated by simulations and experiments. The results pointed out that these two proposed methods are able to stop the vehicle at the high transmission efficiency position without any visual sensor.

Rapidly-exploring random trees(RRT) are popular algorithms in path planning, because they provide efficient solutions to singe-query problems and possess probabilistic completeness. Its modifications, such as RRT* and Informed RRT*, extend RRT to asymptotically find optimal solutions as the number of sampling approaches infinity. These algorithms, however, give no considerations to robot's poses and kinematic constraints, and therefore their results can be unfeasible for a nonholonomic robot with given initial pose and desired final pose. In this paper, we present another modification of RRT* for nonholonomic path-planning with not only kinematic constraints but also initial and final pose constraints. The proposed method constructs the search tree as a directed graph of which each node retains the position (x, y) plus the robot pose θ, and a segment of clothoid curve and line is used for connecting and evaluating the cost between two nodes. Furthermore, by building two trees from both initial and final poses and executing bidirectional search, this method can find a path containing crosscut point. We experimentally show that our approach calculates smoother, more feasible paths than RRT* and satisfy the given constraints on curvature.

The authors' research group invented a Wireless In-Wheel Motor (W-IWM) in order to overcome the low reliability of In-wheel motor's power and signal wires. This system uses Wireless Power Transfer (WPT) via magnetic resonant coupling. In order to control the WPT systems with variable power load such as motor, it is required to achieve high efficiency and transfer power corresponding to the load at any time are required. We have developed W-IWM‘s control methods to transfer desired power with high efficiency. However, the efficiency in the low power output range still has room for improvement. In this paper, novel control method using the intermittent synchronous rectification is proposed. This method improves the efficiency of the W-IWM system in low power output range by improved transient current. Experiments and simulations verify the effectiveness of the proposed method.

In the application of in-motion wireless power transfer (WPT) for electric vehicles (EVs), the transmitter coil on the road has to detect the vehicle before the power transmission starts. Search pulse method in a previous study can judge the existence of vehicles by measuring the transmitting-side current and comparing it with the threshold value. However, the design method of the threshold value in a theoretical way has yet to be shown. Here we show a novel calculation method of the threshold value by using the envelope model of the transient response of current. The preciseness of the proposed method was verified by the full-scale experiment and the effectiveness of the detection algorithm improved.

Requirement of large motor torque with limited mounting space for In-wheel-motors (IWMs) expects a geared drivetrain, but the vibration and noise caused by gear collision deteriorates ride comfort. In our previous study, our research group proposed to apply joint torque control using motor-side encoders and additional load-side encoders to geared IWMs and the effectiveness is validated. However, in point of space and costs, the effect of mounting load-side encoders should be investigated carefully. In this paper, joint torque control using both motor-side and load-side encoders is compared with joint torque control using only motor-side encoders. Simulations and experiments demonstrate that load-side encoders make it possible to design controller without vehicle parameters and to reduce the impact of collision sufficiently.

The longitudinal tire forces can be estimated with in-wheel-motored electric vehicles (IWM-EVs). By exploiting this advantage, the authors have realized human friendly EV based on force control but only the longitudinal motion was considered. The aim of this paper is to achieve the next step: to propose a lateral external force estimation method. External force vectors can be estimated if each of tire forces can be detected. Longitudinal tire forces can be easily obtained with a disturbance observer (DOB). One easiest way to get lateral tire force is using lateral force sensors (LFS). In addition, steering DOB-based method is also discussed here. The Extended Kalman Filter (EKF) is used to calculate a external force vector from each tire forces. A precise external force vector estimation is achieved in the simulations and the experiments. The results of this paper can be applied not only to disturbance compensation but also to hand operated parking control.

Electric vehicle (EV) has great advantages in vehicle maneuverability using electric motor. As one of EV's motion control methods, driving force controller with slip ratio limiter has been proposed. In the conventional methods, slip ratio saturation value was fixed so that the controller was only applicable for going on straight. To make it usable for cornering as well, this paper proposed a variable slip ratio saturation method considering tire slip angle. Its effectiveness was verified by simulations and experiments on acceleration cornering close to tire's limit. The result shows a reduction of overall tire slip, and required steering angle was reduced by 20% at most for the same vehicle trajectory.

In-motion charging technology can drastically improve electrical mileage of Eclectic Vehicles (EVs). Therefore, it is expected as a game-changing technology. In this paper, we investigated cost-effective arrangement design of in-motion charging facilities that can maximize supply energy in the shortest section length as possible. In order to simulate that, we analyzed the actual driving data on urban area in Japan. We focused on the staying time near crossroads with traffic light and found the appropriate in-motion charging section length. Finally we did an electrical mileage simulation using actual driving data and confirm the effectiveness of the in-motion charging facility for electrical mileage extension.

Wireless power transfer (WPT) via magnetic resonant coupling has been widely studied for many applications. In the control of WPT systems with variable power load such as motor, achieving high efficiency and desired power corresponding to the load at any time is important. Some methods which increases efficiency by secondary side power converters has been proposed. In these research, however margin between possible transmission power which is determined by the primary and secondary side voltage and received power is necessary because WPT systems with variable power load is unstable. This paper proposes a method for maximum efficiency operation by dynamic voltage control of the primary and secondary side DC-link. Margin in the transmission power is unnecessary in the system configuration which has supercapacitor and DC/DC converter on the secondary-side because supercapacitor compensates power fluctuation. Simulations and experiments demonstrated feasibility of the proposed method and effectiveness of the controllers.

A collaborative robot is a robot that can work with humans in a shared workspace. It is expected that collaborative robots improve productivity and compensate for the shortage of working population. To make safe contact with the external environment, back-drivability is necessary. For high back-drivability, a robot with a joint torque sensor or a load-side encoder has been developed. Control methods using sensors effectively and improving collaborative robots performance are needed. It is known that disturbance suppression performance can be enhanced by disturbance observer (DOB). Disturbance suppression can make back-drivability higher by eliminating the effect of the contact force. However, a simple DOB cannot improve the disturbance suppression performance for a two-mass system like a robot joint. In this paper, we propose a method to enhance back-drivability significantly by simple filter design considering the structure of a two-mass system. The performance of the proposed method is evaluated by simulation and experiment.

Multirate feedforward control is widely used for the control of precise systems such as the high-precision stages and the hard disk drives. In the multirate feedforward control, it is possible to obtain a control input that achieves perfect tracking for the state trajectory. Therefore, it is necessary to generate a state trajectory corresponding to the output trajectory in advance. In this paper, the authors propose a state trajectory generation from an output trajectory for a multi-input multi-output system using singular value decomposition. The effectiveness of this method is verified through simulation and experiments.

Four-wheel steering (4WS) vehicles have superior characteristics in motion performance to two wheel ones by controlling the yaw motion and the sideslip angle. Previous research revealed that electric vehicles (EVs) driven by in-wheel motors (IWMs) can steer without steering actuators (electric power steering, EPS) by utilizing their appropriate alignment, the difference of right and left driving forces and self-aligning torques. In this paper, the system to apply the rear EPS-Iess steering method to 4WS EVs is proposed and 2 ways to realize it are discussed. The one uses the estimation of lateral force, and the other uses a lateral force sensor to measure the precise value and enhance the robustness against the modeling error of the vehicle mass. The effectiveness of the methods are demonstrated by simulations and experiments in the situations of avoiding collisions and changing lanes with a 4WS and four-wheel driving IWMs-EV without a rear EPS.

To achieve perfect reference trajectory tracking, a plant with continuous time unstable zeros requires an infinite time preactuation. However, literal infinite preactuation is practically infeasible. Preactuation as short as possible is desirable for high-precision motion systems. This paper, thus, proposes an optimal state trajectory regeneration method without preactuation. The original state trajectory, which requires the infinite preactuation, is generated by preactuation perfect tracking control (PPTC) method. Then we regenerate the state trajectory between the start and end time of the reference motion trajectory. This method is an extension of the method of a finite preactuation perfect tracking control (FPPTC) method. In the FPPTC method, perfect tracking after preactuation is guaranteed by regenerating the state trajectory during preactuation, whereas the proposed method of this paper guarantees only after the end of the reference motion. The state trajectory during the reference motion is optimized with respect to the control input and plant output constraints. A multirate feedforward scheme, which is a stable inversion for unstable discretization zeros, is subsequently presented to obtain a discretized control input that perfectly tracks the designed optimal continuous state trajectory.

The most critical problem in high-precision stages for semiconductor and LCD manufacturing is cable disturbance, which can be caused by power cables and communication lines. In our previous study, we designed a novel single-axis high-precision stage using wireless power transfer technology, which avoids cable disturbance. Here, we further develop this concept and propose a multi-axis wireless high-precision. Experimental results demonstrate the effectiveness of the multi-axis wireless high-precision stage.

This paper proposes a new approach for optimal allocation of wireless power transfer system (WPTSys) from a viewpoint of optimal control problem (OCP) for autonomous driving electric vehicles (EVs). These EVs are assumed to accurately follow a pre-determined speed profile. By transformation of the nonlinear optimization problem for optimal allocation of WPTSys to an OCP, well-known methods guaranteeing the global optimality of solution for the OCP are applied, such as Pontryagin's maximum principle or dynamic programming. Therefore, the global optimal solution of the allocation problem of WPTSys can be obtained. In addition, we consider a practical situation of EV operation from a probability point of view, where many EVs are operated with different initial battery state-of-charge.

Chatter vibration highly limits the accuracy and the material removal rate of numerical control (NC) machining operations. In this paper, an adaptive spindle speed selection method, based on an analysis using the semi-discretization method, is proposed to avoid and minimize chatter vibration in high-precision NC machining. Moreover, the proposed method is robust to modeling uncertainty and changing process conditions. The experimental results confirm the effectiveness of the proposed method.

Precise force detection is required to realize precise force control, and a lot of research have been conducted for precise and robust force estimation. Based on the industrial trends that the number of load-side encoders is increasing in various industrial fields, a force observer using load-side encoder information has already been proposed to avoid the estimation performance deterioration in the plants with resonant modes. However, an analysis of the load-side external force observer using load-side encoder is insufficient. Therefore, in this paper, a load-side external force observer is realized as a minimal dimension observer for further analysis, and the relationships between the observer gains and the performance deterioration by modeling errors are revealed. A novel design method for the observer gains is proposed to reduce the influence of modeling errors. The new design method of the force observer extends the conventional transfer function based reaction force observer. The analyses are validated by simulation and experimental results.

Semiconductor and LCD manufacturing equipment, which needs to position the stage in high-speed and high-precision, has been developed on both the mechanism and control. The experimental results, however, is often different from theoretical results because of a cable disturbance caused by such power cables and communication lines. Therefore, in order to eliminate the high-voltage cable disturbance, this paper proposes a next generation high-precision stage with lightweight moving coil type linear motor powered by wireless power transfer via magnetic resonance coupling. The experimental results demonstrate effectiveness of the proposed high-precision stage.

Electric vehicles (EVs) have an advantage over internal combustion vehicles in that the forces applied to the wheel can be estimated from the wheel velocity and input torque. By exploiting this feature, the authors propose to apply force control, which is often used for industrial robots, to EVs in order to achieve much more human friendly EVs. Many applications of force control for EVs are possible. In this paper, the hand parking assist control is proposed. The position of the vehicle body is adjusted by the human hand outside vehicles. The high backdrivability is achieved by using impedance control and driving force control. External forces applied by human hands and driving forces are estimated by disturbance observer (DOB). Some assist control methods are proposed and the most appropriate one is discussed with simulations by considering road surface change and resolution of wheel resolver. Finally, the effectiveness of the proposed method is demonstrated by an experiment.

This paper presents a novel open-loop shaping approach for robust PID controller design, relying on polynomial spline parameterizations. The proposed approach exploits the generalized Kalman Yakubovic Popov (KYP) lemma to derive parameter-dependent linear matrix inequalities (LMIs) for robust PID synthesis. Multiple finite frequency domain specifications are taken into account to intuitively design practical controllers. By assuming piecewise polynomial parametrizations for the parameter-dependent optimization variables, and subsequently applying B-spline based relaxations, tractable conditions are derived that guarantee feasibility of the parameter-dependent LMIs for all uncertain parameter values. An elegant and effective approach results that solves the robust PID synthesis problem with limited conservatism. Numerical results demonstrate the potential of our approach.

A pneumatic actuator has several advantages such as low heat generation, high weight power ratio, and low cost. However, it has several disadvantages such as time delays and nonlinearities. Because pressure and position feedback band-widths are limited by the time delay problem, it is difficult to implement a pneumatic actuator for a scan stage. Therefore, this paper proposes a modified Smith predictor for it and implements for an experimental scan stage. The effectiveness of the proposed control system is validated by frequency and time domain experiments.

In-Wheel Motor (IWM) which is a driving system of Electric Vehicles (EVs) is effective for expanding driving range and reducing vehicle weight. However, IWM has not been put in practical use because of a possibility of power lines disconnection. Therefore, we have proposed Wireless In-Wheel Motor (W-IWM) in which Wireless Power Transfer (WPT) is used to remove these lines and to enhance practicability of IWM. Moreover, we have proposed the advanced system of W-IWM which has Lithium-ion Capacitor (LiC) and circuit on its wheel side for dynamic charging. In this paper, a State of Charge (SOC) control of LiC on the wheel side in the advanced system is proposed. By applying the proposed control, the SOC control of the LiC and power management on the wheel side are achieved simultaneously. The proposed control is verified by simulations and experiments.

Backdrivability is highly required in various robotic fields such as industrial, welfare, and wearable robots. To miniaturize the system, gear reducers are often used. In gear reducers, there are backlashes, which deteriorate control performance. However, only from the view point of backdrivability, backlash has an ideal characteristic because the load side idles within the backlash width (i.e. When someone put external force at the load side, the load side does not hit the motor side within the backlash width). This means that external forces from the load side only feel the load-side impedance without motor-side impedance. The proposed method uses this idling characteristic to enhance backdrivability. Moreover, in industry, there is a trend toward the expansion of the use of load-side encoders thanks to their cost reduction. Based on this industrial trend, the proposed method is realized using both the motor-side and load-side encoder information to improve backdrivability. Simulation and experimental results demonstrate proposed method's effectiveness.

The catapult stage is a high-precision dual stage with a new structure which, by allowing contact between fine and coarse parts, is compatible with increasing size and acceleration. Impact force occurs in acceleration and deceleration regions, and may degrade a stage. This paper thus proposes a control method to reduce the impact force that considers the thrust limitation by combining model prediction and final-state control. In the proposed method, the timing to activate the fine stage is automatically determined by solving an optimization problem. Simulation and experimental results demonstrate that the method can significantly reduce the impact force between the fine and coarse parts.

Atomic Force Microscopy (AFM) is a scanning probe microscope with nanoscale resolution as well as an indispensable device for nanotechnology. Since AFM probe physically touches the sample surface, expectations for sample dynamics measurement are raising. One common measurement mode is force curve measurement. In the force curve measurement, atomic force is detected by the spring constant of the cantilever. In high speed measurement, however, the cantilever oscillates with its resonance frequency and cannot detect the atomic force. This paper proposes novel methods to identify cantilever dynamics and to measure the force curve in high speed using atomic force observer (AFO) and the effectiveness of the proposed measurement method was demonstrated by simulations and experiments. Furthermore, the robustness of the AFO against modeling error is discussed.

Chatter vibration is well known as an undesirable phenomenon, so various methods for chatter suppression have been proposed. Spindle speed variation as a triangular trajectory in the cutting process is one of the methods for chatter suppression. However, this method cannot suppress chatter vibration completely. Moreover, the triangular spindle speed variation requires large torque and a good response of the spindle motor. To solve these problems, this paper proposes a cooperative control of spindle and stage motors. The proposed methods are evaluated by simulations and experiments.

Wireless Power Transfer (WPT) has been widely researched in many application fields. Typical application to vehicle field is wireless charging for electric vehicles while parking and driving. Some power conversion circuit structures and its control method have been proposed in previous researches, for example, transmitting power control and efficiency maximizing control using a secondary-side DC-DC converter. However, selection method of optimal circuit structure for desired control is not clear. In this research, we propose generalized power conversion circuit structure on Series-Series compensated WPT circuit. Load current and power transfer efficiency are analyzed using equivalent AC resistance model about WPT circuit with constant voltage load. Then, we formulate operation points for desired control with consideration for operating condition.

Recently, Intelligent Transport Systems (ITS) technology have been intensively studied to solve environmental and energy problems by improving traffic flow. Along with the development of ITS and autonomous driving technologies, vehicle velocity control has to be considered for energy efficiency. In this paper, a minimum time autonomous driving (MTAD) system, which minimizes the traveling time considering energy constraint for an electric vehicle (EV), is proposed. The proposed method minimizes the traveling time by optimizing the velocity profile and front and rear driving-braking force distribution. The effectiveness of the proposed method is verified by simulations and bench tests.

Image-based visual servo using coordinates of feature points has been well discussed and used in many applications. However, these methods rely on the perfect matching of feature points, which is often difficult in an actual situation. Recently, visual servoing methods based on region informations such as mutual information and an image transformation matrix are proposed. While these methods can achieve more robust visual servoing, there is still some difficulties in how to extract and apply such information. In this paper, region based approach using Phase-Only-Correlation (POC), which is known as a subpixel image matching algorithm, is proposed. Although POC can be applied only in 4 DOF (degree of freedom) without X and Y axis rotation, it accomplishes robust and accurate positioning. We also reveal that the image jacobian, which is often difficult to estimate in realtime, can be written as time invariant matrix in 4 DOF with proposed control scheme.

In the past 20 years, control methods for two-inertia systems have changed from semi-closed control to full-closed control in order to achieve higher precision positioning. Though there is a trend toward the expansion of the use of load-side encoders in the industry, we can hardly say that control methods using load-side information are sufficiently studied. Therefore, our research group has proposed control methods using a load-side encoder such as Self Resonance Cancellation Control (SRC). We have demonstrated the advantages of SRC, but it needs two encoders. In order to reduce the implementation cost and space, a novel form of SRC, which employs the load-side information only, is proposed using a high-resolution encoder at the load side. The proposed method inherits the main advantages of SRC even though it can remove a drive-side encoder. Simulation and experimental results demonstrate that the comparable performance can be obtained by the proposed method without using drive-side information.

Electric Vehicles (EVs) are deemed as an appealing and practical solution for environmental and energy problems. The mileage per charge of EVs, however, is shorter than the mileage of Internal Combustion Engine Vehicles (ICEVs). In this paper, Range Extension Autonomous Driving (READ) system considering road gradient information is proposed. The proposed system optimizes the velocity trajectory and the driving-braking force distribution ratio for autonomous driving. The authors carried out simulations and bench tests that prove the effectiveness of the proposal in terms of mileage per charge.

In the past 20 years, control methods for two-inertia systems have gradually changed from semi-closed control to full-closed control in order to achieve higher precision positioning. Though there is a trend toward the expansion of the use of load-side encoders in the industry, we can hardly say that control methods using load-side information are sufficiently studied. This paper proposes a novel joint torque control method for a two-inertia system using a high-resolution encoder on the load side. The proposed method enables us to control joint torque precisely considering nonlinear elements such as backlash, lost motion etc. Simulation and experimental results demonstrate that the good performance can be obtained by the proposed method.

The In-Wheel Motor (IWM) is the most preferable driving mechanism of electric vehicles for vehicle motion control, energy efficiency, and vehicle design flexibility. One technical issue of the IWM is the reliability of power and signal wires. Wireless power transfer technology is the best solution. In this paper, a bidirectional wireless power transfer circuit using a primary inverter and a secondary converter is proposed. We propose a control method of both the inverter and the converter to stabilize the secondary DC-link voltage. The proposed method is verified by simulation and experiments using simulated test equipment.

In the recent years, attention has been gathered in the research field of electric airplanes (EAs), which have electric motors as a power source. EAs have many advantages including low environmental impact and safety. The flight range per charge, however, is shorter than that of conventional airplanes. This paper proposes a range extention control system (RECS) which extends the flight range of EAs by control. It is shown that the power consumption can be minimized by optimizing thrust distribution on multiple propellers with different properties. The effectiveness of the proposed method is verified by simulations and experiments.

Electrical airplanes (EAs) have become practical in the recent years. Considering the increase of demand on smaller aircraft and the attention to environmental issues, the demand on small EAs is expected to grow in the coming decade. However, the accident rate of small aircrafts is higher than that of larger aircrafts, so ensuring higher safety of EA is very urgent. Modeling and thrust control of EAs have been proposed previously by the authors' research group. However, this model and control method is not suitable when the propeller revolution speed is near and below zero. In this paper, the improved thrust control method based on new EA propeller plant is proposed. This method is necessary for design of airspeed control method, which can be expected to improve the safety of EA. A towing test method which allows plane's dynamical experiment on ground is also proposed. Real flight experiment was the only conventional method test a plane's dynamics. However, the test piece needs to be a complete airplane to conduct a real flight. Moreover, it is impossible to observe the response a particular input without interferes from other factors. The proposed method allows component technology to be tested in dynamical situations. The effectiveness of the proposed methods is verified through simulations and experiments.

Boost converters are used for high voltage supplying, and they generally have to use large capacitors to suppress output voltage variations. However, this characteristic makes the converter system very large. In this paper, three load current feedforward control methods, which are considered an unstable zero, are proposed for the boost converter. The proposed methods suppress voltage variation compared to feedback control methods and enable the converter to reduce output filter capacitor. Simulations and experiments are conducted to show the effectiveness of the proposed methods.

For high-precision control of a two-inertia system, information of both the drive side and the load side is usually required for obtaining high control bandwidth. In order to reduce the implementation cost and space, a novel control method, which employs the load side information only, is proposed using a high-resolution encoder which is today widely used in various fields. Simulation and experimental results demonstrate that the proposed method is implementable and shows good control performance.

High-precision stages require high-speed and high-precision control to improve their production throughput and quality. However, it is expected that their motion speed and accuracy will reach a limit in the near future if the structure of the conventional high-precision stage is used. Therefore, the authors designed and fabricated a stage called the catapult stage which has a decouplable structure consisting of a fine stage and a coarse stage. This stage is different from conventional dual stages in which the fine stage would be disturbed by the coarse stage since they contact with each other. This paper proposes a novel control system design for the catapult stage, and a settling time shortening control method using final-state control (FSC). So far, FSC is mainly applied to the applications such as hard disk drives whose initial states are the zero. However, it is important to consider the initial states for the catapult stage since the initial position, velocity and acceleration of the catapult stage are not equal to zero. Simulations and experimental results demonstrate the effectiveness of the proposed methods.

High-precision current control is demanded for many mechatronic systems to improve the static and dynamic performances. However, current measurement error inherent in the measurement system degrade the control accuracy, since the motor currents are not guaranteed to follow the desired references. In this paper, quantization error caused by analog-to-digital converters is studied. The dithering techniques combined with Kalman filter are proposed to suppress the quantization effects. First, two dithered systems, including the subtractively dithered and nonsubtractively dithered systems, are designed to whiten the quantization error. In the design of nonsubtractively dithered system, the probability characteristic of the metering noise is utilized to minimize the measurement noise level. Then, Kalman filter is designed to estimate the real current signals from the dithered current measurements. Since the variance of the total measurement error is theoretically calculable according to the proposed dithering techniques, Kalman gain can be determined analytically. Finally, simulations and experiments are performed to verify the effectiveness of the proposed approaches using a high-precision positioning system.

Direct yaw-moment control (DYC) is an effective method for achieving stable vehicle motion. In the DYC systems of vehicles with in-wheel motors and active front and rear steering systems, some control inputs are generally redundant. This means that input variables cannot be decided uniquely to control each longitudinal, lateral, and yawing motion. The equalization of workloads of each wheel based on longitudinal and lateral force distributions enhances the cornering performance of vehicles. Therefore, we propose a method for obtaining longitudinal-and lateral-force distributions based on least-squares solutions of the equations of longitudinal, lateral, and yawing motions. Furthermore, we propose a lateral-force control method using tire lateral force sensors, active front and rear steering systems, and a DYC method for enhancing the yaw-rate control performance. In this study, through simulations and experiments, we show that the equalization of the workload on each wheel and quick yaw-rate response are achieved by adopting the proposed methods.

In order to extend electric mileage per charge of Electric Vehicles (EVs), the powertrain efficiency should be further improved. A possible solution is employing transmission which is properly optimized for EV. Continuously variable transmission (CVT) is especially suitable, because it maintains the operating condition of electric motor being closer to the most efficient region even while vehicle speed is changing. In this paper, a toroidal CVT and a single ratio transmission are compared by numerical simulations regarding the overall efficiency. Toroidal CVT has an advantage for high torque-low speed region and low torque-high speed region. However, regarding the rest, the efficiency degrades in contrast. In order to improve the overall efficiency, the best implementation approach is introduced.

Electric vehicles (EVs) have become a world-widely recognized solution for future green transportation. However, the mileage per charge of EVs is short compared with that of internal combustion engine vehicles. Considering slip ratio, copper loss and iron loss, the authors propose a model-based range extension control system for acceleration and deceleration mode. Total driving-braking force is distributed based on vehicle acceleration and velocity. The effectiveness of the proposed method is verified by simulations and experiments.

This paper proposes a method which enables wheeled robot to climb a step that is higher than the radius of the wheel. In conventional method, this is impossible, because driving force of front wheel is not enough. This paper proposes a method utilizing the moment of impact between the wheel and the step to maximize the normal force, and hence the driving force of the front wheel. Effectiveness of the proposed method is verified by simulations and experiments.

This paper proposes a force sensorless control of cutting resistance for numerical control (NC) machine tools by spindle motor. In conventional NC machine tools, speed of spindle motor is set to a constant value during machining, and the spindle speed is determined according to operator's experience. The proposed method estimates cutting resistance by disturbance observer, and the spindle speed is determined by controlling the cutting resistance to follow the reference value. In addition, a novel method for velocity calculation which is referred as variable pulse number T-method is proposed to reduce the velocity measurement noise and to improve the robustness of disturbance observer.

To achieve fast and accurate positioning control, a controller based on a visual servo employing a multi-rate Kalman filter was implemented and experimentally evaluated. Although a visual servo is expected to achieve robust positioning control by eliminating positional errors due to operation environments, applying visual information to positioning control faces three challenges, namely, lower sampling speed, longer delay, and lower positional accuracy than those possible by using a conventional position encoder. To overcome these problems, a multi-rate Kalman filter with a time-delay compensation technique is employed to combine visual information with encoder-based positional information. Two models describing a positioning-control experimental system using a one-axis linear stage with a camera were investigated to determine the optimum structure of the Kalman filter. Evaluation of the experimental system showed that the designed controller achieves high-precision (±10 µm) positioning control within approximately 10-ms settling time while simultaneously adjusting the environmental positional errors.

High-precision stages are used for the fabrication of integrated circuits, liquid crystal displays and so on. Since higher integration density and product quality are continuously required for the development of industry and informatics, not only the stage position but also the stage attitude needs to be controlled rapidly and precisely. The attitude is determined by roll, pitch and yaw motions which are affected by nonlinearity and coupling caused by Euler's equation and rotational kinematics. These effects deteriorate the attitude control performance. This paper proposes a MIMO nonlinear feedforward attitude controller which compensates such effect. The effectiveness of the proposed approach is verified by simulations and experiments.

High-precision stages are industrial equipment for micro-fabrications. Fast and precise positioning control is very important technology related to the improvement of the throughput and the product quality. Especially, a large-scale stage has a low resonance mode which disturbs fast and precise positioning because of the structures of the stage. In this paper, a novel feedback system is proposed in a SIMO system using multiple position sensors which are located at an actuator side and a load side. The proposed feedback system has two remarkable features. One is that the effect of the vibration suppression and the phase stabilization of the resonance mode can be tuned simultaneously only by two parameters. The other is that the tuning of the resonance mode does not affect the rigid mode at all. Finally, simulations and experiments with a XY -gantry-stage are performed to show the advantages of the proposed feedback control system.

Atomic Force Microscope (AFM) is a device which can be applied to measure the surface topography of sample in nano-scale. Because cantilever holds its physical contact with the sample, it is also possible to measure the elasticity of samples in principle. However, in comparison with the improvement of scanning performance, the technologies for viscosity and elasticity measurement are still underdeveloped. In this paper, we propose a method which can measure both the surface topography and the elasticity of samples. Recursive least-square approach is applied to estimate the elasticity of samples using the information of the previous surface topography.

This paper presents a heuristic friction compensation approach for handling the springlike friction behaviors of a ball-screw-driven stage in zero-speed region. The friction compensation for the motion that the stage is decelerated to stop and then accelerated in the same direction, which is also referred to as non-velocity-reversal motion, is discussed in detail. As the elastic energy stored in mechanical components may not be completely released during non-velocity-reversal motion, the conventional compensation approaches may not work well. Therefore, some other sophisticated friction compensation approaches become necessary for this kind of motion. In this study, a velocity pattern recognition algorithm is presented as the first step to classify the velocity patterns in zero-speed crossing region. Then, sinc function is exploited to model the nonlinear springlike friction of the ball-screw-driven stage. It is proved that the friction can be properly compensated for both the reversal motion and non-reversal motion. Experiments are performed to verify the proposed approach and it is demonstrated that the control performance is significantly improved.

In order to control the motion of electric vehicles (EVs), it is important to control the driving force. Author's research group had proposed the driving force control method which uses wheel speed control. However, this control method has a limitation on the achievable control bandwidth due to multiple control loops. In this paper, a new driving force control method for EVs based on driving stiffness estimation is proposed. This method can achieve direct and quick driving force control. The effectiveness of the proposed control method is verified through simulations and experiments.

Electric vehicles have a disadvantage in that the cruising distance per charge is short. This paper proposes a range extension control system based on a searching algorithm of front and rear driving force distribution with total efficiency optimization. The proposed method maximizes the total efficiency considering the slip ratio and the losses in the motors and inverters. The effectiveness of the proposed method is verified by experiments using a plug-in hybrid electric vehicle. The mileage per charge can be extended by 18% by using the proposed method in a constant-speed test.

There are many types of wheelchairs. Users are able to choose suitable wheelchair for their purposes. Power-assisted wheelchairs are one type of wheelchairs, which use both propelling torque from human and output torque from motors for their driving force. To improve assist performance, many assist control systems were proposed. One of conventional assist control, proposed by Seki et al., is designed for motion of traveling in straight line. However, it is difficult for wheelchair users to rotate using conventional assist control. In this paper, a novel two-dimensional assist control for power-assisted wheelchairs is proposed. The proposed assist control system is designed for both straight and rotational motion of wheelchair, therefore, power assist performance in rotating motion is improved compared to conventional system.

Advanced control concepts for electric vehicles assume the correct functioning of sensors. In this contribution the problem of sensor failure detection and isolation in the case of lateral vehicle dynamics of EVs is tackled. The method depends on only basic vehicle parameters and assumes only a single failure in the vehicle system. A single sensor failure can be detected and the false alarm rate is minimized. The approach is based on the parity space method implemented with residual observers. Noise of sensors is taken into account and appropriate bounds in the feature space are derived in order to get a robust fault detection indicator. Simulation results and an experimental setup show the validness of the approach.

Among many vehicle states, body slip angle is one of the most important information for vehicle motion control. Due to the high costs to measure body slip angle with specific devices, it is necessary to investigate estimation methods using existing cheap sensors. From the viewpoint of sensor configuration, gyroscope, steering angle sensor, etc. are often employed for body slip angle estimation; in this research, two pieces of information provided by vision system are also utilized as additional measurements. Nevertheless, the sampling rate of normal camera is much slower compared to the other kinds of onboard sensors; for electric vehicles (EVs), motors' control period is shorter than the sampling time of cameras, which also brings multi-rate issue. Moreover, the time delay caused by image processing is usually too long to be neglected. In this paper, single-rate and multi-rate Kalman filters considering measurement delay are designed for body slip angle estimation, and a body slip angle controller is designed with the estimated result as feedback. First of all, vehicle model and visual model as well as the multi-rate and delay issues are explained; then, single-rate and multi-rate Kalman filters are designed for body slip angle estimation; and then, body slip angle controllers with single-rate and multi-rate estimators are compared followed with simulations and experimental results; finally, conclusion and future works are presented.

Accurate current signals are required for precise current control of AC motor drives. However, current measurement error including the metering error and the quantization error is unavoidable due to the inaccuracy of current sensors and the quantizing feature of analog-to-digital converters. In this paper, the combination of dithering techniques and Kalman filter is presented to suppress the current quantization effects caused by A/D converters. Firstly, the dithering system is designed to whiten the total current measurement error. Then, Kalman filter is exploited to estimate the real current signals from the whitened noise. The effectiveness of the proposed approach is verified via simulations and experiments using a high-precision stage.

A tactile map is an assistive tool for visually impaired persons to obtain special information. As new barrier-free laws were recently enacted in Japan, many Braille signs and tactile guide maps have been installed in various facilities. Several production methods are available for tactile guide maps. Screen prints have become increasingly popular in Japan because they offer several advantages, including the fact that they can be printed together with visual characters. However, users have one major complaint: screen printing does not create lines and dots on tactile maps, thus necessitating improvement in screen printing performance. In this study, we developed a new tactile map production device as an alternative to screen printing devices. Also, a tactile map created by our method included a vocal guidance function based on users' needs. We found that the finished-print performance and convenience of tactile maps improved considerably. This study will be useful in providing a new style for future tactile maps.

In this study, grasp positions of human hands are measured for planar objects for development of a reasonable grasp criterion for a two-soft-fingered robotic hand. We first propose a grasp criterion that yields the best grasping position for a robot hand with two soft fingers. To examine the properties of this criterion with respect to some weighting coefficients included in the criterion, a grasping experiment is performed by humans for planar objects with various sizes and shapes. Results show that many observed grasping positions used by humans correspond to a set of weighting coefficients that equally weigh all the factors in the criterion. A grasping experiment using a robot has also been conducted using a set of coefficients corresponding to the equal weight; the effectiveness of the criterion was confirmed.

Changing system requirements, especially for context awareness (CA) systems, often cause modifications in the software systems in order to adapt to dynamic environments. Since the requirements may become temporarily obsolete or contrary to human intentions, the CA systems need to be tuned to resolve the conflict. On the other hand, most CA design methods rely on pre-defined requirements and reasoning engine, thus, fail to address all the possible situations. Consequently, services provided by such a CA system are limited to accommodate some situations and unable to react as expected. Therefore, it is critical for CA systems to capture exceptions at runtime, infer changed human intentions, and adapt to these changes. This study focuses on inference of ever-changing human intentions and monitoring human intentions to handle system evolution. In this paper, we present an inference mechanism of human intentions via the human-machine dimensional inference ontology (HDIO). This ontology gives inference rules based on the BDI logic to deduce human intentions from contexts. Furthermore, the inference exercises of a healthcare system example shows how user intentions relate to system requirements and how they help improve self-adaptability of CA systems.

User intentions to obtain services evolve over time. Since the changes of intention may occur at any time, some system requirements may become temporarily obsolete or contrary to a user intention. However, user intentions often indicate potential, valuable goals for upgrading the system to a new version or engaging new development. Our research tackles requirements analysis issues via feedback from context awareness systems to identify user intentions and capture instant definitions of goal in a robust manner. This paper presents a context-aware goal elicitation process by exploring the aspects of data, information, knowledge and wisdom. Furthermore, captured user intentions and goals are shown in a case study of healthcare system, and issues for the goal elicitation are explored.

The purpose of this paper is to establish a method of shape recognition and grasping of unknown objects using a robotic hand with two soft fingers and one omnidirectional camera. For shape recognition, we propose to use a simple 2D version of the visual volume intersection method which takes advantage of a special feature of the omnidiretional camera attached to the hand. For grasping we propose a simple grasp quality criterion to obtain the best grasping position for the two soft fingers based on a visual hull in a horizontal grasp plane. We conducted several experiments and the results show the validity of the proposed method.

In large-scale, real-time systems, the software design process is still highly dependent on the skills of the developers. To enable the efficient, speedy design of reliable software products, we require a means of conveying design decisions from experts to other engineers. Our approach involves the development of the "causality of problem-issue-solution" (CAPIS) model which can be used to represent experts' thought processes. The CAPIS model divides a thought process that includes complexity and diversity into problems, issues, and solutions (PIS), and then describes conceptual models based on the knowledge hierarchy of data, information, knowledge, and wisdom. The PIS ontology is used to describe items in the conceptual models. This paper describes a software design method that is based on this CAPIS model. As an example, we consider the thought processes involved in building reliability into a UML class diagram

Scenarios that describe concrete situations of software operation play an important role in software development, and in particular in requirements engineering. Scenario details should vary in content and detail when described from different viewpoints (e.g. types of user or external interface), but this presents a difficulty, because informal scenarios cannot easily be translated from one viewpoint to another with consistency and assurance. This paper describes (1) a language for describing scenarios in which simple action traces are embellished to include typed frames based on a simple case grammar of actions, and (2) a procedure for translating a frame-based scenario from one viewpoint into another and (3) integration method of scenarios described from different viewpoints. We illustrate them with examples of program chair's job.

In this paper, novel multirate controllers are proposed for digital control systems, where it is restricted that the sampling period of plant output is longer than the control period of plant input. The proposed controllers can assure perfect disturbance rejection at M intersample points in the steady state. Moreover, the novel scheme of repetitive control is proposed based on the open-loop estimation and switching function, which enables to reject periodical disturbance without any sacrifice of the feedback characteristics. The proposed methods are applied to the visual servo system, and the advantages of these approaches are demonstrated by simulations.

No abstract available.