Automated handling of agricultural products with soft surfaces is a difficult task because they are easily damaged. In addition, small farmers, which are majority in Japanese agricultural industries, prefer inexpensive support systems that satisfy their limited investment abilities. This work-in-progress paper presents a support system to estimate the weight of a strawberry by using smart grasses for its weight sorting process. The weight is estimated by multiple images of the strawberry while it is picked by a worker. Experimental results show the effectiveness of the proposed approach.

Optimal trajectory generation of the large rotary cranes under a variety of constraints to suppress the two-dimensional load sway is generally a complex problem. In this paper, the cubic B-spline is used for smooth parameterizing the trajectory, and the time-optimal control problem is formulated for the three-dimensional point-to-point movement of the crane, satisfying the discrete kinematic and dynamic constraints along the trajectory. Practical applications require the real-time change in load positions, although recomputing the entire optimal trajectory requires high computational time. In this study, two methods are used to modify the optimized trajectory: a scaling factor and proposed reduced degree-of-freedom modification method. Simulation results compare total motion time, computation time, and constraint satisfaction, and the effectiveness of the proposed method is demonstrated.

It is important for robots to learn the usage of tools and support humans in aging societies. It is expected for robots possible to imitate human skills of tool manipulation properly using a deep neural network, although a huge amount of training data may be required. In this paper, a target human-like task of cleaning dust using several types of brooms with a robot arm is considered. A learning system that can reduce the amount of training data is proposed. The novelty of the proposed system is the ability to estimate the initial parameters of a deep neural network based on the shape of the broom and data stored from previous experience. Furthermore, the system changes the number of learning layers in the deep neural network depending on the broom shape. Results of experiences show the effectiveness in reducing the amount of training data.

In this paper, a model reference input shaping (MRIS) control will be formulated for a luffing dynamics of a rotary crane system with a time-varying rope length. The newly established technique is able to completely suppress the residual vibration for a highly nonlinear time-varying system. The basic idea of the proposed approach is to obtain a reference oscillation from a second-order time-invariant linear system, on which the standard input shaping control is applied. The MRIS control law is then designed to exactly match the real vibration of the system with the reference oscillation. By such a means, an exact zero vibration suppression can be achieved for the actual system. The reference (or unshaped) command is parameterized to cope with control objectives other than the vibration suppression. Simulation results are provided to verify the superiority of the MRIS controller over the standard robust input shaping control method.

Throwing and catching are fundamental motions for human beings, and may be applied for advanced human and robot collaborative tasks. Since catching motion is more difficult than throwing for a robot, this study deals with reduced impact catching of a flying object by a planar manipulator. The estimation of the object's trajectory is improved by the Kalman filter and the least squares fitting is proposed to accurately predict the catching time, position and velocity of the manipulator. To achieve reduced impact catching, the minimization of the total impact force in x and y-directions is proposed as an optimization problem. The fifth degree non-periodic B-spline curve is implemented to achieve smooth and continuous trajectories in the joint space. The effectiveness of the proposed approaches are demonstrated by simulation and experiment.

Contour error in machine tools is a crucial element for enhancing precision in manufacturing and production systems. The error should be as minimum as possible to ensure the quality of products. Despite the achievements of some previous studies, it is indispensable to further enhance control performance by minimizing contour errors. This study proposes a novel contouring controller comprising of a classical proportional-derivative controller, a nonlinear friction compensator, a disturbance observer, and a variable gain iterative learning controller to improve the control performance of machine tool feed drive systems. The control input of each drive axis is iteratively modified to enhance the overall tracking performance. The proposed method was simulated on a typical sharp-corner trajectory, and compared with conventional controllers for performance evaluation. Results revealed that the maximum contour error can be reduced by 75.2 %.

This article proposes a new approach for high speed and precision motion control of feed drive systems by considering both tracking and contour errors. Iterative learning control is used whereby the tracking error is considered in the feedback controller and the contour error in the feedforward controller. Without changing the original trajectory assigned by NC code, the proposed controller improves the tracking performance under sharp corner motion. The combination of errors and the use of iterative learning control lead to fast convergence within a few iterations. To analyse the performance, the conventional approach that uses only the tracking error has been considered for comparison. Simulation results show that the designed controller can significantly improve the performance of feed drive systems. The proposed method has demonstrated that the maximum contour error can be reduced by 46.3 %.

This paper presents a new type of crane system that can be employed in a narrow space in an ordinary house for supporting nursing and housework. The crane consists of straight and curved rails that can be assembled/disassembled so that an operator is able to assemble them according to the room/corridor structure of a house. Because an operator may not hold the transported person or object (load) in touch during the transportation in a narrow space, automatic load sway suppression is required. This study presents a motion trajectory design for load sway suppression by using a simple trapezoidal velocity motion that is widely used in industry without measuring the load sway for reducing the controller implementation cost. Simulation results demonstrate the effectiveness of the proposed design.

Although there exist devices that support an object transportation task such as a handcart, most devices are based on a wheel-type mobile mechanism, and hence it is difficult to move an object on a floor with high steps. Because a walking-type mobile mechanism enables to move up and down steps, it is expected to support an object transportation task in an environment with stairs or high steps. This paper presents a biped robot that supports an object transportation task up stairs for a human operator based on a prescribed path. First, we present a design of a biped robot with four actuators for a hip and knee joints of each leg. Next, we derive dynamics of the biped robot for simulation in which force applied by a human operator and reaction force from the ground are considered. Experimental results demonstrate that the developed system successfully climb the stairs under the human operation.

This paper deals with design and control of a standing-operator mobile robot. Because the human operator stands on the robot, the required area for the operator is relatively smaller than that for the wheel chair (seated-operator) robot, and freed-up area can be used for passengers and/or transporting objects. In addition, the position sensor used for monitoring the center of gravity of the operator can be used as a man-machine interface controller that enables hands-free operation of the robot as opposed to a joy-stick controller. However, with the proposed standing-operator system, the acceleration of the robot needs to be controlled to prevent the standing operator from toppling over. In addition, collision-avoidance control is indispensable because it is difficult to precisely control motion only by sensing the position of the operator's center of gravity. This paper describes the designs for collision avoidance and the acceleration controller for a standing-operator mobile robot. A general-purpose differential-wheeled structure with casters is employed in this study. Experimental results by several human operations in a corridor with corners demonstrate the effectiveness of the proposed acceleration and collision avoidance controller.

This paper describes a robot-mediated information guide system that introduces audio-visual information to users interactively. The developed information guide system is composed of a touch panel interface, a mediator robot and backyard control systems. The touch panel interface functions to display audio-visual contents, while the mediator robot attracts people to this guide system and help user's operation. Many robots in literature are equipped with interactive audio-visual interface, however in most cases the audio-visual interface is a front end of the robot for presentation. We propose a new communication framework in which the robot behaves as a mediator to make a bridge between users and audio-visual interface by generating speeches and gestures. We hypothesize that entrainment of the mediator robot with users and contents could promote user's immersion in the contents. We conducted experiments with the proposed information guide system to examine the effect of robot mediation in a realistic interaction scenario that actually guides city sites for visitors. The developed information guide system was demonstrated in the science museum of the city in May 2014 and will be used for public events in future.

Many industrial machines are operated along a simple motion trajectory such as a trapezoidal or S-curve acceleration/deceleration trajectory. This paper presents a motion trajectory generation method that suppresses the residual vibrations of such machines. First, we consider a residual vibration problem for a gantry-type crane that is widely used in industrial factories. The dynamics of the crane system is represented by a simple set of differential equations. Assuming that only a simple motion trajectory can be applied to an industrial controller, we propose a motion trajectory generation method that suppresses the residual vibration, which increases the production takt time. Simulation and experimental results demonstrate the effectiveness of the proposed method.

This study presents a simple S-curve trajectory generation method for rotary crane motion that can suppress residual load sway using only horizontal boom motion without load sway sensing. If load sway can be suppressed without measuring it, reduction in sensor cost can be achieved. Furthermore, employing simple velocity trajectory patterns such as trapezoidal and S-curve patterns, which are widely used in industrial automation systems, may provide cost effective controller implementation. Simulation results demonstrate the effectiveness of the proposed method.

Vietnam is one of the world's largest countries in terms of exportingers of cashews nuts in kernel (edible portion) form. Currently, more than 200,000 labors are engaged in the cashew processing industry. Although most cashew processing operations have been automated, the shelling operation is still conducted manually. Consequently, the shelling rate is very low compared to other operations, and the labor conditions are strenuous and unsafe. This paper introduces a cashew-shelling machine design to improve the production efficiency and working conditions. The proposed design includes shell milling operation and wedge splitting process designs. In addition, a conveyor system design to transport cashews is included to increase the production efficiency. Because cashews come in different sizes, we propose a force controller for the milling system that cuts the cashew shell without deteriorating the cashew kernel. Experimental results demonstrate the effectiveness of the proposed force controller.

Robotic systems provide support for many areas of human activities such as industry, welfare, nursing, housework, and office work. Human-robot soft physical interaction is crucial for realizing safe support in human living environments. This study considers the soft physical interaction between a robot and an object by presenting a control method of a robotic manipulator that catches a falling raw egg. First, we consider a nonlinear decoupling control of a robotic manipulator. Next, a controller design is presented for catching a falling object with a small impact force. This controller consists of two parts: a position tracking controller that tracks a desired trajectory before contact between the object and the end-effector, and a force controller that is triggered after the contact. We employ a position-based impedance controller so that the entire control system can be constructed as a position-based controller. To achieve good tracking performance and reduce the impact force, a discrete-time adaptive two-degree of freedom controller is employed, which considers disturbances such as friction. Experimental results demonstrate the effectiveness of the proposed approach.

Time-optimal trajectory planning for mechanical systems has been widely studied thus far because of its effectiveness to reduce the time required for many industrial tasks. However, in general, because the time-optimal trajectory is generated based on ideal dynamics of controlled systems, it may be difficult to implement the obtained trajectory to actual systems with vibration modes that are neglected in the trajectory generation. In other words, high-speed motion based on the time-optimal trajectory may cause the vibration of mechanical systems. We propose to employ the contouring control, which enables to reduce controller gain magnitudes while contouring performance are maintained, for the presents a method of generating the time-optimal trajectory for machine tool feed drive systems. Next, the contouring controller is applied to implement the optimal trajectory to the actual machine tool system. The effectiveness of the contouring controller for implementation of the optimal trajectory is demonstrated by comparative experiments with the conventional method.

Sound source tracking is an important function for autonomous robots, because sound is omni-directional and independent of light. This paper presents a new approach to sound source tracking for mobile robots using auditory sensors. We consider a general type of two-wheeled mobile robot that has wide industrial applications. Because obstacle avoidance is also an indispensable function for autonomous mobile robots, the robot is equipped with distance sensors to detect obstacles in real time. To deal with the nonholonomic constraint of the robot and combine information from the auditory and distance sensors, we propose a model reference control approach in which the robot follows a desired trajectory generated by a reference model. The effectiveness of the proposed method is confirmed by experiments in which the robot is expected to approach a sound source while avoiding the obstacles.

Because of the difficulty in realizing fully automated robotic systems from the viewpoint of cost efficiency and available current technologies, human-robot cooperative system has been widely studied to date. This paper deals with a human-operated robotic manipulator that supports the object-transportation task in houseworks and factories. A new controller design that provides two fundamental functions is developed; obstacle avoidance and stable transportation of object, even when the human operator makes mistakes in operation. A general type of three-degree-of-freedom robotic manipulator is considered, which moves in a horizontal plane and can be operated by a joy-stick controller. To achieve both the obstacle avoidance and the stable transportation of object with providing a function that incorporates the human-operatorpsilas command, we propose a model reference control approach in which the robot follows a desired trajectory generated by a reference model. The effectiveness of the proposed method is confirmed by experiments where several unskilled operators operate the manipulator for transporting a object in a narrow space.

In machine tool control, it is known that using the contour errors which are defined as tracking error component orthogonal to desired contour curves, as feedback signals is effective for precision contouring. Since the exact feed drive dynamics must be known in the conventional contouring controller design, we propose a design of robust contouring control system in this paper. We firstly introduce a controller design by which we can assign the controller gain for reducing the contour error independent of tangential error component to the desired contour curves. A robust contouring controller is then designed based on the variable structure control. The effectiveness of the robust controller is demonstrated by experimental results.