Hip assistance with cable-driven devices has been proven to help decrease the metabolic cost of gait. However, most existing devices use heavy actuating modules or provide assistance in only one direction, limiting the effectiveness. Cable-driven devices are also difficult to accurately estimate the hip position using only motor encoders, therefore utilizing various auxiliary sensors. This paper introduces a 1.5 kg cable-driven soft wearable hip assist device that can provide assistance in both flexion and extension, using a velocity-dependent delayed output feedback controller (v-DOFC). The device is designed with the consideration of ergonomics and pressure distribution of wearable parts, to increase the anchoring performance and comfort. The controller uses time-delayed feedback proportional to the velocity output state, allowing control without requiring accurate position estimation. Additionally, directional weighting is used to provide different assistance forces for extension and flexion to match different optimal assistance values. Experimental results show that the device can reduce metabolic cost by 13.8 % compared to walking without the device. The soft wearable hip assist device can be applied to help the elderly with weaker muscles to walk longer distances.

A convenient situation can be realized if home robots replace housework. However, tasks in an actual home environment are challenging for robots. Particularly, cleaning the table after eating is challenging because of the cluttered environments and various tableware shapes. This study presents a new type of gripper appropriate for picking and placing various tableware in narrow and cluttered environments. The gripper comprises a 1-DOF gripper and 2-DOF distal joints. The rotatable distal joints enable reducing the effective workspace when reorientating tableware and accessing tableware in narrow spaces. In addition, the gripper can transform into three types of grasping modes by actively rotating the distal joints for handling three types of tableware, namely cutlery, cups, and dishes. The gripper is experimentally demonstrated to handle various tableware and the tables can be cleaned after eating in real-world environments.

This paper proposes a novel approach to address the technical challenges of stable object grasping, particularly in the context of handling tableware in a home environment. Handling tableware is particularly important, yet challenging, due to the flat nature of most tableware objects and the need to maintain a stable posture to prevent spills. To address these challenges, we present three key contributions: 1) a large-scale tableware dataset, not commonly found in the previous datasets; 2) a novel sampling method for stable grasp pose generation; and 3) a multi-modal fusion grasp network that effectively learns 6- DoF grasp pose, including flat objects. Our dataset contains over 45 million grasp poses and 1 million RGBD images captured in 800 scenes, which include randomly selected 10–18 tableware objects under 4 different lighting conditions. The grasp poses in the dataset are generated using a novel sampling method that incorporates geometric analysis to ensure stable grasping with minimal object movement. Furthermore, we design an RGBD fusion grasp network (RGBD-FGN) that can combine information from RGB and depth images considering each characteristic. Our experimental results demonstrate the superior performance of our approach over existing techniques, which is a significant contribution towards developing a multitasking home robot. Our dataset and source code can be accessed at https://github.com/SamsungLabs/RGBD-FGN.

Pose estimation is a key challenge in robot manipulation and grasping task. Current object pose estimation approaches based on 3D models and depth sensor information have difficulties to handle transparent objects because of the limitation to capture the accurate depth information. To address these issues, we present a 6DoF pose estimation approach, called GhostPose, which utilizes a novel 3D bounding box prediction network and multi-view geometry with cameras on manipulator robot. Our 3D bounding box prediction network is simple and light-weight by adding a small branch to a one-stage object detector. The network detects 2D projections of 3D bounding box vertices. Then, 3D points are reconstructed from the 2D results of the multiple viewpoints with camera motion information, i.e. extrinsic parameters, calculated from the robot joint angles. We also present generalized pose definition to address pose ambiguity of symmetric objects and keep consistency of geometric properties around feature points across both of the symmetric and asymmetric objects. Comparing with the previous pose estimation approaches, GhostPose is more generalized to environments and object types, because it does not require 3D models, object specific key points, predefined stereo settings and depth map. In experiments, it outperforms a state-of-the-art approach and shows generalized properties by applying to a real manipulator robot grasping system.

We present a transformable catheter head structure for endoscopic catheter allowing the simultaneous use of a camera module and a large tool channel introduced through a small incision. At the site of interest, the head with a camera can be expanded from the initial straight configuration, which opens a window for advancing a tool that is located behind the camera. Two different designs were proposed and prototyped. One option has flexure joints directly fabricated at the distal end of a polymer catheter by laser micro-machining, while another design employs a hinged metal head assembled at the tip of the same type of catheter. The kinematic behavior of each head was evaluated during the head-up and tip steering motions, and compared with each other to draw a selection guideline between them. Experimental results prove the feasibility of the proposed head structure for smarter endoscopic catheters.

The papers in this special section examine robotic technologies of the fourth industrial revolution or Industry 4.0 that will impact manufacturing industries. The concept of the fourth industrial revolution has drawn attention throughout the world and many efforts to define the concept in diverse fields have continued. Generally, the concept can be summarized as the technology convergence through hyper-intelligence and hyper-connectivity. The core technologies providing the thrust of the fourth industrial revolution, especially in the industrial informatics field, are Internet of Things, robotics, virtual reality, and artificial intelligence. As one of the most critical characteristics of the fourth industrial revolution technology is that the boundary between cyber space and physical space becomes unclear, innovations in industry and business initiate through the fusion of these two spaces. It is the robotic system that plays the key role as a physical medium linking cyber and physical spaces and even changing the physical space through direct interactions. In this sense, robotic system should be recognized as a crucial platform in performing tasks in the cyber-physical space.

In this study, a vibrotactile pedestal with multiple actuators is developed and applied to smartphones to create a sense of information according to location and direction. As the main goal is to create a detailed sensation with a limited number of actuators, well-known sensory illusion effects are utilized to modulate vibrotactile stimuli to create an appropriate sensation. The monolithic design concept is utilized to the touch surface of the pedestal for a smooth grip so that there is no interference with screen interaction of the smartphone. Two experiments were conducted to validate whether the developed device could successfully reproduce directional and locational information according to given visual data. The results show that vibrotactile stimulation from the pedestal was useful in intuitively displaying information such as position and direction for smartphone applications. The implications of the work presented in this paper can serve as a stepping stone toward the development of smartphone applications with affluent sensory information through vibrotactile stimulation.

Variable stiffness enables the safe and effective operation of the minimally invasive surgical instruments. In this article, we propose a continuously variable stiffness mechanism of the scalable tubular structure. The mechanism consists of multiple coaxial nitinol tubes, and each tube has an anisotropic distribution of flexural stiffness created by nonuniform through-hole patterning. The stiffness of the mechanism is varied by relative rotation and translation among the tubes, resulting in flexural stiffness difference up to 7.2 times in the direction of load. Its flexural stiffnesses along principal axes are independently controlled by the suggested counterrotation algorithm. The stiffness change is validated through analytical modeling, FEM simulation, and the experiments. Thanks to its physically embodied intelligence, the mechanism has a simple scalable structure and the response time is immediate. We applied this mechanism to control the stiffness of the steerable needle. Varying the stiffness grants the additional degree of freedom to control the needle's trajectory, which can expand the workspace of the steerable needle.

Anthropomorphic arm manipulators usually consist of as a series of revolute joints and links. In this paper, serial-chain manipulators are described by a novel kinematic representation using a series of type R or T joints, which are classified according to relation between a rotational axis and two adjacent links. It provides an easy intuition to describe general types among existing manipulators and also to get intuitive ideas before designing of joint and link modules of modular manipulators. From these intuitive idea about joint configurations using two types of joints, a new concept of joint module with two input and one output connections is presented. This joint module enables to couple directly between two joint modules. In addition, practical solutions of mechanical and electrical connections between joint or link modules is introduced. The connection can be established between two modules via eight types of relative positions of 45 degree intervals. Using joint and link modules, 3-DoF(Degrees-of-Freedom) modular manipulators of three kinds of joint configurations are shown representatively. After assembly, the standard D-H(Denavit-Hartenberg) parameters of three examples are obtained utilizing information of joint and link modules.

Design optimization and fabrication of concentric tube robots are time consuming because of the complexity of their workspaces and the characteristics of the superelastic materials used to make them. This paper presents a procedure for the expeditious design and fabrication of a concentric tube robot for applications that require rapid tube preparation but have less complex design constraints. This procedure reduces a 3D workspace optimization problem to a 2D problem. The continuum robot includes a heat-shrink tube to reduce fabrication time and to give it a small radius of curvature. Experimental results illustrate the feasibility of the proposed procedure.

Shape tracking using a fiber Bragg grating sensor is a promising tool due to its thin, flexible, and weightless nature. Conventional investigations attached optical fibers with a metal rod which limited the curvature due to its stiffness and increased distance between the center of the fiber and that of the sensor. We fabricated ultrathin flexible shape sensor with 110 mm length and 560 μm diameter. Its low Young's modulus and small diameter makes it suitable for application in minimally invasive surgical robot such as active cannula. The sensor causes only miniscule resistance when the cannula rotates or moves, and allows extra spaces for other surgical tools thanks to its small diameter. After the calibration, the sensor was integrated to the active cannula and overall position of the sensor was tracked. It showed an average error of 3.17 ± 1.21 % of the lengths of the measured nodes from the fixed starting point. The error was comparable to the outer diameter of the cannula, 2.8mm.

This paper proposes a position and stiffness bounding approach (PSBA) for improving “geometry transparency” in time-delayed teleoperations. The proposed method can rapidly update the local model location in master site to the contact location in the slave site. The proposed PSBA can therefore avoid instability problem due to both discrete force controller and sudden contact location changes (so called “model jump effect”). Effectiveness of the proposed approach is shown by 1-DOF simple contact experiment in 500ms round trip time delayed virtual environment.

As a steerable needle or robotic manipulator, the concentric-tube robot shows good potential for use in minimally invasive medical procedures. However, the torsional deformation of the precurved tubes comes at the price of instability, which not only limits the workspace and tool path but also potentially creates danger of tissue rupture when external load is applied. In this paper, we propose anisotropic patterning of tubes to solve the instability problem. Hole-patterning can tune the mechanical properties of the tubes so that the ratio of the torsional rigidity to the bending rigidity becomes higher. This study investigates the effect of pattern design parameters by building a lumped analytical model and examining it with finite-element analysis. The pattern is engraved via laser machining and we experimentally verify that material anisotropy reduces instability.

The concentric-tube continuum robot generates distal end motions by translating and rotating the proximal ends of pre-curved tubes that overlap concentrically. This robot does not require additional actuators along the tubes because the overall curvature and distal end position are determined solely by interactions between the inner and outer tubes. However, under certain conditions, the rotation of the distal end is hindered as the actuation energy accumulates into torsional energy of the tubes. As the distal ends are rotated further, the accumulated energy from the twisting is suddenly released, which makes the tubes snap to a remote position. This is called the snapping problem, and it considerably limits the performance of the robot. In this paper, we propose a novel design for the concentric tubes to eliminate the snapping problem. The new design creates groove patterns on superelastic nitinol tubes to make the tubes more flexible to bending than twisting. Simulations and experiments were performed to verify that the tubes with our groove patterns had anisotropic structural characteristics, and video image analysis verified that this structural property can eliminate the snapping problem. A concentric-tube robot with this new tube design can have a larger workspace area because tubes with greater curvatures can be used without the snapping problem.

Multi-DoFs (Degrees of Freedom) manipulators with more than 6-DoF can perform complex and diverse tasks. To make these serial-chain manipulators safer, a variety of safety components were researched. If there is a crash at the end-effector of the serial-chain manipulators, components mounted on joints of the upper and lower arm can absorb the impact. Unfortunately, physical human-robot interaction does not occur only at the end-effector, a collision can happen anywhere from the base to the end-effector. If a collision occurs in the upper arm of relatively low DoFs, safety components attached to each joint may not work properly. Therefore, a study for joint configurations of serial manipulators is necessary with respect to the placement of safety components at the shoulder joint. Through various case studies, this paper verifies the appropriate joint configurations that place safety components at each revolute joint for physical human-robot safety.

A variable release torque-based compliant Spring-clutch (VCSC) and torque estimation by using distance sensor is presented. VCSC is composed of an output plate, compliance plate, compensate plate, and fixed plate. Due to these four plates, it has some functions in compliant movement, release mechanism, and gravity compensation during its work. Through these abilities, VCSC plays a role as a safe joint, reducing the impact of collisions between humans and robots. Also, it estimates the torque applied to a joint from a compressed length of a spring, using a distance sensor.

In this study, we developed and evaluated a tactile stimulation device for upper extremity motion guidance. The developed device stimulates skin pressing directly using “tapping.” A minimal number of actuators are used in the tactile stimulation device that is worn on the wrist. The device consists of six Tiny Ultrasonic Linear Actuator (TULA) modules, a control circuit, an upper case, and a lower case. We estimated motions through kinematic analysis of the upper extremities for motion guidance and our driving algorithm applied a tactile illusion to generate directional information cues and tapped one point using a tactile stimulation device to guide upper extremity motion. To evaluate the developed device, an experiment was conducted to test whether directional information can be successfully displayed by the device. As a result, it was found that the directional information cues could be reliably conveyed through the wrist with tactile stimulation using a “tapping” method that is based on tactile illusion, though the number of actuators that display continuous tactile stimulation is limited.

We propose a design method for a gravity compensator using unit spring balancers for multi-degree-of-freedom (DOF) and multilink manipulators. Existing spring balancers can be applied to a new design of a gravity compensator. When applying spring balancers to a new gravity compensator, it is necessary to determine how many spring balancers are required and where they should be placed. Our proposed design method can determine the number of spring balancers and their locations. In this study, the design of a spring balancer for multi-DOF and multilink manipulators is considered as a mapping between two spaces (i.e., the joint space for gravitational torques and the spring balancer space to compensate torques). The mapping matrix is obtained through eigenvalue analyses of the potential energy function. The number of rows of the mapping matrix represents the number of unit gravity compensators. The row vector of the mapping matrix also indicates the locations of the unit gravity compensators. Examples are presented to validate the effectiveness of the proposed method.

In this paper, we propose a SPAM (Simultaneous Planning and Mapping) technique for a manipulator type robot working in an uncertain environment via a Best Next Move algorithm. Demands for a smart decision to move a manipulator such as humanoid arms in uncertain or crowded environments call for a simultaneous planning and mapping technique. We assume no a priori knowledge of either the obstacles or the rest of the environment exits. For rapid map building and path planning, we use a skin type setup based on 3D depth camera sensors that completely encompass the entire body of a manipulator. The 3D sensors capture the point clouds used to create an instantaneous c-space map whereby a Best Next Move algorithm directs the motion of the manipulator. The Best Next Move algorithm utilizes the gradient of the density distribution of the k-nearest-neighborhood sets in c-space. It has tendency to travel along the direction by which the point clouds spread in space, thus rendering faster mapping of c-space obstacles. The proposed algorithm is compared with several sensor based algorithms for performance measurement such as map completion rate, distribution of samples, total nodes, etc. Some improved performances are reported for the proposed algorithm. Several possible applications include semi-autonomous tele-robotics planning, humanoid arm path planning, among others.

This paper proposes an algorithm to estimate external forces exerted on the end-effector of a robot manipulator using information from joint torque sensors (JTS). The algorithm is combination of Time Delay Estimation (TDE) and input estimation technique where the external force is considered as an unknown input to the robot manipulator. Based on TDE's idea, the estimator which does not require an accurate dynamics model of the robot manipulator is developed. The simultaneous input and state estimation is used to reject not only nonlinear uncertainties of the robot dynamics but also the noise of measurements. The performance of the proposed estimation algorithm is evaluated through simulation of a two degree-of-freedom manipulator and it demonstrates the stability in estimating the external forces. The estimation results show that this approach allows inexpensive sensors as joint torque sensors to be used instead of expensive ones as F/T sensors in robot application.

Realtime 3D depth sensor technologies, as manifested in several consumers' electronics products, have potential for a technological breakthrough in various robotic applications. Depth sensing of human body motions can promote intuitive gesture inputs for natural HMI (Human Machine Interface) as well as HRI (Human Robot Interaction) for various applications. In today's industry, the dominant trends in 3D depth sensing are shifting from the traditional laser based scanning or TOF (Time of Flight) depth sensing to the intensity based Infrared 3D depth sensing mechanism. However, the majority of 3D depth sensors does not function properly in a short range due to the limit of shutter speed or light speculation resolution. In this paper, we investigate currently available mono-vision based 3D sensor technologies followed by the results of a novel short range 3D depth sensing technology via multiple intensity differentiation. Our approach is to simultaneously calculate the 3D depth and the surface angle of an object to generate high quality 3D surfaces with an illumination intensity matrix from multiply adjacent light sources.

In this paper, we applied famous sensory illusions to generate spatial and directional vibrotactile cues using a vibrotactile cradle for the smart cell-phone. A grooved and slim design is applied to the contact side of the cradle for comfortable gripping, and the contact part consists of twelve vibrotactile areas which can operate independently. To maintain isolation among vibrotactile actuators, the surface of the cover is specially designed to absorb propagating vibration over the surface. The cradle's backside consists of twelve linear resonant actuators, a soft covering intersections and supporting area for actuators. For an evaluation of the developed device, two experiments were conducted to test whether directional information and spatial information according to visual data can be successfully displayed by the developed device. As a result, spatial and directional information is useful for displaying intuitive information for smart cell-phone application with the cradle.

The primary purpose of this research is to determine which is more effective, kinesthetic or vibrotactile cues, when presenting spatial information with haptic devices. Recent studies have explored the use of tactile cues; however, they were confined to a unilateral display device. Although many kinesthetic bilateral haptic devices have been developed to provide force feedback on an input handle, a vibrotactile stimulus has not been utilized when presenting directional information on the input handle. This paper attempts to adopt vibrotactile cues to design a bilateral device. In addition, a new six degrees of freedom bilateral haptic device, which provides a spatial sensation on the handle, is proposed. The sphere-shaped handle is, especially, designed to be covered by several vibrating panels. When a specific panel is activated, the user perceives the spatial location of the vibrotactile stimulus from that panel during the input operation. Control schemes that are based on the phantom sensation, one of haptic illusory phenomena, are proposed to achieve fine resolution with a limited number of tactors. Two experiments were conducted, in an effort to compare performance between a kinesthetic and a vibrotactile haptic device. The results showed that the vibrotactile cue provides a better method of perceiving the directional information as compared with kinesthetic feedback.

This paper proposes a design method of a static balancing mechanism using unit gravity compensators (e.g., 1-dof gravity compensator). In the design of a multi-dofs static balancing mechanism it is necessary to determine how many springs (or unit gravity compensators) are required and where they should be placed. This problem can be overcome by computing the mapping matrix between the joint space and gravity compensator space. The mapping matrix is obtained by analyses of the potential energy function. The number of rows of the mapping matrix indicates the amount of unit gravity compensators and linear joint constraints representing locations of unit gravity compensators. Example studies are presented to verify the effectiveness of the proposed method. Simulations are performed in that static balancing mechanisms designed by the proposed method can counterbalance the gravitational torques completely.

Interaction with humans is inevitable for service robots, which results in safety being one of the most important factors in designing the robots. Compliant component is an answer to the safety issue at the cost of performance degradation. In order to reduce the performance degradation, manipulators equipped with variable stiffness have been studied by many researchers. This paper presents a variable stiffness joint (VSJ) designed for a robot manipulator, as well as a control scheme to control the stiffness and position of the VSJ. Compliance is generated by leaf springs and two actuators are used to control the position and stiffness of the joint using four-bar linkages. Two actuators in parallel configuration are connected to the spring. Changing the effective length of the spring results in a change in stiffness. The position of the joint is controlled via two actuators rotating at the same speed in the same direction. A nonlinear controller is used to control the VSJ, and a singular perturbation model is adopted to prove the stability of the closed-loop system. Experiments are conducted to show that the position and stiffness are controlled independent of each other, and having less stiffness at the joint helps in making an unexpected collision with an object safer.

In today's industry, intuitive gesture recognition, as manifested in numerous consumer electronics devices, becomes a main issue of HMI device research. Although finger-tip touch based user interface has paved a main stream in mobile electronics, we envision touch-less HMI as a promising technology in futuristic applications with higher potential in areas where sanity or outdoor operation become of importance. In this paper, we introduce a novel HMI device for non-contact gesture input for intuitive HMI experiences. The enabling technology of the proposed device is the IPA (infrared Proximity Array) sensor by which realtime 3 dimensional depth information can be captured and realized for machine control. For the usability study, two different operating modes are adopted for hand motion inputs: one is a finger tip control mode and the other is a palm control mode. Throughput of the proposed device has been studied and compared to a traditional mouse device for usability evaluation. During the human subject test, the proposed device is found to be useful for PC mouse pointer control. The experimental results are shared in the paper as well.

In this paper, we have applied phantom sensation and sensory saltation to generate spatial and directional information using a vibrotactile display pad providing vibrotactile cues, T-mobile. A grooved and slim design is applied to the contact side of the T-mobile for comfortable gripping, and the contact part consists of 12 vibrotactile panels which can operate independently and separately. To maintain isolation among vibrotactile actuators, the surface of the cover is divided into several pieces. Each vibrating module consists of a linear resonant vibrational motor, a section of covering surface, and a vibration isolator. As an evaluation of the developed device, two experiments were conducted to test whether directional information and spatial information can be successfully displayed by the device. As a result, spatial and directional information is useful for displaying intuitive information for hand-held navigation with vibrotactile feedback.

We propose an algorithm of reliable detection of line for unmanned navigation of mobile robots using sensor fusion. To detect the distance and the angle between the robot and the line, we use a vision sensor system and a laser range finder (LRF). Each sensor system runs its own extended Kalman filter (EKF) to estimate the distance and orientation of the line. The vision system processes images being captured using well-known edge detection algorithms, and the LRF detects the line using the measurement of the intensity of the laser beam reflected. However, depending on the condition of the road and ambient light, each sensor gives us wrong measurement of the line or sometimes completely fails to detect it. To resolve such uncertainty, we develop a simple and easy-to-implement sensor fusion algorithm that uses weighted sum of the output of each EKF, and it gives us more reliable estimate of the distance and orientation of the line than each measurement/estimator system.

Compared with their robotic counterparts, humans excel at various tasks by using their ability to adaptively modulate arm impedance parameters. This ability allows us to successfully perform contact tasks even in uncertain environments. This paper considers a learning strategy of motor skill for robotic contact tasks based on a human motor control theory and machine learning schemes. Our robot learning method employs impedance control based on the equilibrium point control theory and reinforcement learning to determine the impedance parameters for contact tasks. A recursive least-square filter-based episodic natural actor-critic algorithm is used to find the optimal impedance parameters. The effectiveness of the proposed method was tested through dynamic simulations of various contact tasks. The simulation results demonstrated that the proposed method optimizes the performance of the contact tasks in uncertain conditions of the environment.

Safety of a manipulator designed to be used at home requires different approach than industrial robots, where safety is achieved mainly by decreasing the interaction with humans. Robots for applications at home, however, require frequent interaction with humans. Introducing compliant component gives the answer to the safety issue at the cost of performance degradation. In order to reduce the performance degradation, manipulators equipped with variable stiffness have been studied by many researchers. This paper presents a variable stiffness joint(VSJ) designed for a robot manipulator. The stiffness is generated by leaf springs and two actuators are used to control the position and stiffness of the joint. Changing the effective length of the spring results in change in stiffness. The position of the joint is controlled via rotating two actuators at the same speed in the same direction. The stiffness is controlled when the two actuators rotate in the different speed. Experiments are conducted to show that the position and stiffness are controlled independent with each other and having less stiffness at the joint helps in making unexpected collision with object safer.

Many studies have explored the use of tactile cues, however they were confined to the unilateral display device. Although lots of bilateral haptic devices have been developed to provide a guiding force on an input handle, however, a vibrotactile stimuli has not been tried to present directional information on the handle. This research introduces an attempt to combine a tactile display with an input device. A new 6DOF bilateral haptic device, which provides a spatial sensation on the handle using vibrotactile display, is proposed in this research. The sphere-shape handle is specially designed to be covered with several pieces of vibrating panels. When a specific panel is activated, the user perceives the spatial location of the vibrotactile stimulus during an input operation. This paper introduces the design of the proposed device, including the selection guide of the dimension, location, and number of vibrotactile panels. The method for combination of vibrotactile stimulus and the way to achieve fine resolution with small number of tactors are discussed. Experimental results show that the users can reliably perceive the directional information using the proposed device. An application for teleoperation of a robot proves the effectiveness and the usefulness of the proposed bilateral device.

Service robots are anticipated to be used in unstructured areas such as homes, hospitals, and public areas in the near future. However, safety issues need to be addressed before this can occur. In particular, robot manipulators that handle objects by physical contact run the risk of colliding with people or objects. Thus, it is important to prevent collisions that could injure people and damage robot manipulators. In this study, a safe joint mechanism is developed to ensure the safe use of a manipulator. This mechanism, termed `Spring-Clutch,' is a simple passive mechanism that consists of a coil spring and a CAM mechanism. When a torque is applied that is less than a threshold value, Spring-Clutch functions as a rigid joint between the input and the output. However, when an applied torque exceeds the threshold, angular displacement occurs between the input and output to reduce the collision force. If the applied torque is removed, Spring-Clutch immediately returns to its nominal position without the need for additional operations. This paper describes the design principles and performance of Spring-Clutch, and discusses the possibility of its practical use as a joint mechanism for safe manipulation.

A robot joint with a variable stiffness unit is presented. The variable stiffness unit (VSU) is composed of a motor, two rings that consist of arc-shaped magnets separated by spacers, and a linear guide to change the cross-sectional area of the two rings. Angular displacement between two rings causes the magnets to generate torque, which acts as a nonlinear spring. The stiffness of the joint is varied via changing the overlapping area of the magnets. The VS J exhibits nearly zero stiffness, which enables robot manipulator to be harmless to humans at a wide range of operating speed. Connected to a joint motor in series, the stiffness by the VSU and the position of the joint are controlled independently by two motors. The torque generated by the magnets is analyzed. Using dynamics of the joint, feedback linearization method is adopted to control the VSJ. In addition to feedback linearization, an integral controller is augmented in order to reduce the effect of model uncertainty and disturbances.

This paper introduces a novel motor learning strategy for robotic contact task based on a human motor control theory and machine learning schemes. Humans modulate their arm joint impedance parameters during contact tasks, and such aspect suggests a key feature how human successfully executes various contact tasks in variable environments. Our strategy for successful contact tasks is to find appropriate impedance parameters for optimal task execution by Reinforcement Learning (RL). In this study Recursive Least-Square (RLS) filter based episodic Natural Actor-Critic is employed to determine the optimal impedance parameters. Through dynamic simulations of contact tasks, this paper demonstrates the effectiveness of the proposed strategy. The simulation results show that the proposed method successfully optimizes the performance of the contact task and adapts to uncertain conditions of the environment.

Over the past few decades, various haptic gloves have been developed for use in virtual environments. The actuating systems for most existing haptic gloves require lots of external auxiliary equipment. Because of this, the motion of the user is restricted by the length of the electric wires or pneumatic tubes attached to this equipment. A compact actuation system, including related equipment, is thus indispensable for a wearable haptic glove to be truly effective. To resolve the problem of hampered motion and reach, a micro hydraulic actuating system was developed in this research. It was composed of a slim, flexible artificial muscle, a compact hydraulic module for actuating the muscle, and a micro pressure sensor for measuring without flux loss. The characteristics of the muscle were investigated for their control capacity. The step and sinusoidal responses were analyzed to evaluate the performance of the micro hydraulic system. Once these analyses were completed, a lightweight and compact actuation system was built incorporating a wearable haptic glove. By virtue of the developed micro hydraulic system, the wearable haptic glove was able to operate independently of any external equipment, and movement was completely free of any restrictions from wires or tubes.

In this paper, multi-fingered tactile display modules are proposed. Each tactile display module is comprised of a 4 times 4 piezoelectric ultrasonic actuator array with a spatial resolution of 1.5 mm and a temporal resolution of 20 Hz. The objective of this research is to build a small and lightweight tactile display system so that the system including the display modules and complete controller parts is wearable by a user. It was found that various types of texture information can be generated using a static indentation or through the vibration of each pin. Three tactile display modules were utilized for interaction with a 3D virtual environment. As the developed tactile display modules consume less power and are connected wirelessly to a host PC, the system is applicable to various types of texture representation systems.

Stable haptic interaction has been studied extensively by an energy-based approach. However, the energy in the haptic system is not directly measurable, but estimated from some measured quantities such as force and velocity; therefore, the estimated energy is occasionally inaccurate. To resolve this problem, a new observer, working in the frequency domain, is proposed in this research. The observer quantifies the degree of instability of a haptic system, and a proposed controller generates variable damping in proportion to this quantitative instability. Especially, for a double layered virtual wall, the proposed methods were much faster in detecting haptic instability than other schemes, and successfully reduced unstable behavior.

In this paper, a compact tactile display which consists of multiple vibrotactile actuators with 4-different vibrotactile unbalanced masses and a Peltier thermoelectric module is proposed. By stimulating 2 different sensory channels including mechanoreceptors and thermoreceptor simultaneously, surface texture and material composition can be displayed using the implemented device. 3 experiments were conducted for the performance evaluation of the proposed device through discriminating various patterned textures. Experimental results show that the developed device can be used to display surface texture and temperature together and suggest the possibility of implementing a small-sized, multi-fingered tactile display device.

Surface roughness is one of the most intractable physical properties and its sensing heavily depends on the application and the capability of the sensor. In this paper, a pen-type sensor is proposed for sensing surface roughness. The sensor with a rigid contact probe is able to measure 3D contact forces and the dynamic contact responses along the axial direction of the probe, which facilitate the roughness representation using parameters of roughness profile rather than complex, high level interpretation methods. Strain gauges and a force sensor are used for measuring contact forces and a PVDF sensor is used for the dynamic sensing. The sensor is a self-contained one, and it can transmit sensed data via Bluetooth to the host computer. As preliminary tests, experiments are performed on the measurement of the coefficient of friction and the response to dynamic stimuli of different surface patterns.

In this paper, a sound synthetic technique (SST) based on sinusoidal frequency modulations with irregular primitive function algorithms for tactile perception is suggested. Investigations of the benefits of real-time SST for haptic interaction were referenced. Performance was evaluated in two ways; 1) a unimodal analysis of synthesized sounds in terms of whether they can induce tactile perception, and 2) multimodal analysis of the relationship between tactile perception and the generated sound. The unimodal analysis of sound suggested that meaningful spectrum contents can be generated using the proposed SST. The result of the multimodal analysis showed that auditory-haptic multimodal perception increases human sensitivity of texture perception.

In this paper a hand-held sensor for surface texture perception is presented. The sensor with a metal contact probe is able to measure the roughness and frictional property of a surface, which are among the most important parameters for contact texture perception. Two strain gauges and a force sensor are employed to measure 3D-contact forces at the tip of the contact probe. The friction coefficient can be calculated by using the normal force and tangential one. A PVDF film is used for the dynamic sensing of contact stress in the axial direction of the contact probe. Measurement results are transmitted to a host computer via Bluetooth wireless communication link for further data processing. Design issues are discussed in details, and the preliminary experimental evaluations are performed.

In this paper, an anthropomorphic robot hand called SKKU Hand II is presented, which has a miniaturized fingertip tactile sensor. The thumb is designed as one part of the palm and provides the mobility of the palm. The fingertip tactile sensor, based on polyvinylidene fluoride (PVDF) and pressure variable resistor ink, is physically flexible enough to be deformed into any three-dimensional geometry. In order to detect incipient slip, a PVDF strip is arranged along the direction normal to the surface of the finger of the robot hand. Also, a thin flexible sensor to sense the static force as well as the contact location is fabricated into an arrayed type using pressure variable resistor ink. The driving circuits for the SKKU Hand II are embedded in the hand, and each driving circuit communicates with others using CAN protocol. In addition, a tactile sensing system is developed with miniaturized electronic hardwares such as charge amplifier, signal processing unit etc., and it is integrated into the robot hand. The SKKU Hand II is manufactured and feasibility of the hand and the fingertip tactile sensor is validated through preliminary experiments

This paper presents a flying display system using an autonomous blimp (small indoor airship) with a visual tracking system and an image projection system. The real-time visual tracking system tracks the blimp while it flies along a given spatial path to follow a wall. The image projection system projects still images or a video stream, whose rectangular shape is pre-compensated to look natural and flat using an image warping algorithm, on the surface of the blimp. The blimp is designed to have holonomic dynamics and it can maintain a stable pose and position in the presence of bounded air flow disturbances during the wall following motion. The real-time visual tracking system tracks the blimp and calculates its position in three dimensional space. Finally, we verify the capability of the autonomous blimp, the real-time visual tracking and the image projection system by experiments in the public exhibition environment. We also verify that the system is useful for transferring information and advertising in a crowded public area such as an exhibition hall or a department store

This paper presents a wearable haptic system to interact with virtual environment. The proposed haptic system makes a user interact intuitively with virtual environment, while the user moves freely around the environment. To make wearable system, the light-weight and compactness are emphasized during the design process. MR(magneto-rheological) brakes are adopted as actuators for the device, because a brake (passive actuator) has much larger value of a relative torque/weight ratio than a motor (active actuator). As a result a new wearable haptic system, which is folded to compact size and has large workspace, is developed. To evaluate the proposed system, tangible studio is implemented to experience a virtual heritage alive

Tangible interface is a newly defined concept, which provides effective and seamless interaction between a human as a subjective existence and a cyberspace as an objective existence. As one of the tangible interface, tactile interface is essential for many exploration and manipulation tasks in the tangible space. In this paper, we suggest a design of an integrated tactile sensor-display system that enables both of tactile sensing and display with kinesthetic force, pressure distribution, and vibration. A human-like tactile sensing system with PVDF strips and a display system with bimorph actuators have been developed and integrated in the tangible space. In the demonstration scenario of haptic navigation in the tangible space, the developed tactile sensing to display system is successfully experimented.

This paper presents design and integration of the ROBHAZ-DT3, which is a newly developed mobile robot system with chained double-track mechanisms. A passive adaptation mechanism equipped between the front and rear body enables the ROBHAZ-DT3 to have good adaptability to uneven terrains including stairs. The passive adaptation mechanism reduces energy consumption when moving on uneven terrain as well as its simplicity in design and remote control, since no actuator is necessary for adaptation. Starting from this novel design, dynamic analysis and simulation were conducted to verify the mobility of the double-track mechanism and to obtain significant design parameters such as a suitable track size and an allowable attack angle. Based on this novel mobile platform, a rescue version of the ROBHAZ-DT3 with appropriate sensors and a semi-autonomous mapping and localization algorithm is developed to participate in the RoboCup2004 US-Open: Urban Search and Rescue Competition. From the various experiments in the realistic rescue arena, we can verify that the ROBHAZ-DT3 is reliable in travelling rugged terrain and the proposed mapping and localization algorithm are effective in the unstructured environment with uneven ground.

In this paper, a fingertip tactile sensor is presented which can detect contact normal force as well as incipient slip. The sensor, based on polyvinylidene fluoride (PVDF), and pressure variable resistor ink, is physically flexible enough to be deformed into any three-dimensional geometry. In order to detect incipient slip, a PVDF strip is arranged along the direction normal to the surface of the finger of the robot hand. Also, a thin flexible sensor to sense the static force as well as the contact location, is fabricated into an arrayed type using pressure variable resistor ink. In addition, a tactile sensing system is developed with miniaturized electronic hardware such as charge amplifier, signal processing unit etc., and it feasibility is validated experimentally.

In this paper, design and control of a safe arm with passive compliant joints (PCJ) are presented. A new manipulator with passive compliance property has been developed at KIST. Strategy for the joint control method is implemented. Because the PCJ is a flexible joint, unwanted vibration is occurred during the joint motion. To reduce this vibration, we use the input-preshaping method which is motivated by the input shaping technique (IST) based on impulse response. The control method for a time-varying system like the safe arm is described in detail. The result of simulations and experiments proves that a fast motion of the safe arm without residual vibration can be achieved.

In this paper, design and integration of the ROBHAZ-DT3 are introduced which is a newly developed mobile robot system with double tracks. It is designed to curry out military and civilian missions in various hazardous environments. The rotational passive adaptation mechanism equipped between the front and rear body enables the ROBHAZ-DT3 to have good adaptability to uneven terrain including stairways. The passive adaptation mechanism reduces energy consumption in moving on uneven terrain as well as it offers simplicity in design and teleoperation. Based on this new design concept, dynamic simulation was conducted to determine the significant parameters such as optimal track size and allowable attack angle. Also dynamic effects in vehicle turning are investigated to assess proper load torque. The ROBHAZ-DT3 system developed was successfully experimented in stair climbing case.

This paper describes a multi-modal interface design and its implementation to a teleoperated field robot system. The ROBHAZ-DT2 is developed as a teleoperated mobile manipulator for hazard environment applications (e.g. rescue, explosive ordnance disposal, security). To complete these missions in outdoor environment, the robot system must have appropriate functions, accuracy and reliability. However, the more functions it has, the more difficulties for the operator to control the functions. To cope up with this problem, an effective user interface should be developed. The main challenge of this research is to make a simple and intuitive user interface and teleoperate the slave robot easily. This paper provides multi-modalities such as visual, auditory and haptic sense. It enables an operator to control every functions of a field robot, ROBHAZ-DT2 more easily. In this paper, an EOD (explosive ordinance disposal) demonstration is conducted to verify the validity of the proposed multimodal interface.

When we use a tactile sensor, sensing mechanism and restoration of texture from electric sensing signals are important issues. The objectives of this research are to design a new texture sensing system and to develop a new signal processing algorithm which can restore various texture. The new texture sensing system is designed to get texture with high resolution and wide velocity range, which uses a PVDF sensor and has fixing components for several types of objects in precise condition. Next, a new signal processing algorithm is developed to restore texture. In the previous researches, forward model is needed and then it is inverted by using some regularized inversion formula in frequency domain, where there exist problems such as amplification of noise due to ill-posedness, modeling uncertainty due to orientation and position of PVDF films and silicon rubber, and difficulty to add nonlinear terms into model in frequency domain. While, in this paper, we model directly the relation containing transient-state from measured signals to texture by using model structure of multi-input multi-output nonlinear autoregressive moving average and a time domain least squares estimation. The direct modeling can be done by the use of F/T sensor which is not used in the previous researches. Finally the several texture is experimentally reconstructed from sensing signals using the developed signal processing algorithm.

The design and integration of ROBHAZ-DT2 is presented which is a newly developed mobile manipulator system. It is designed to carry out military and civilian missions in various hazardous environments. In developing the integrated ROBHAZ-DT2 system, we have focused on two issues: 1) novel mechanism design for mobility and manipulation and 2) intuitive user interface for teleoperation. In mechanism design, a double tracks connected by a passive joint has been designed to achieve high speed and rugged mobility on uneven terrain. In addition, a six-dof foldable manipulator suitable for the mobile manipulation has been designed. Secondly, a new compact 6-dof haptic device has been developed for teleoperation of the ROBHAZ-DT2. This haptic device is specially designed for simultaneous control both of the mobile base and the manipulator of ROBHAZ-DT2. As a result of integration of ROBHAZ-DT2 and the user interface unit including the haptic device, we could successfully demonstrate a typical EOD task requiring abilities of mobility and manipulation in outdoor environment.

This paper presents a novel design of indoor airship having a passive wheeled mechanism and its stationary position control. This wheeled blimp can work both on the ground using wheeled vehicle part and in the air using the floating capability of the blimp part. The wheeled blimp stands on the floor keeping its balance using a caster-like passive wheel mechanism. In tele-guidance application, stationary position control is required to make the wheeled blimp naturally communicate with people in standing phase since the stationary blimp system responds sensitively to air flow even in indoor environments. To control the desired stationary position, a computed torque control method is adopted. By performing a controller design through dynamic analysis, the control characteristics of the wheeled blimp system have been found and finally the stable control system has been successfully developed. The effectiveness of the controller is verified by experiment for the real wheeled blimp system.

In this paper a safe arm with passive compliant joints and visco-elastic covering for human-friendly service robots is presented. The passive compliant joint (PCJ) is composed of a magneto-rheological (MR) damper and a rotary spring. The rotary spring gives the arm compliant property, but also it might be a source of vibration. Therefore the damper is introduced for damping effect and works as a rotary viscous damper by controlling the electric current according to the angular velocity of spring displacement. In an unexpected collision, the joints and cover passively operate and attenuate the applied collision force. The force attenuation property is being verified through collision experiments showing that the proposed passive arm overcomes limitations of an active compliant control approach.

Presents the utilization of inertial effect in damping-based posture control of a mobile manipulator. As a measure for redundancy resolution of a mobile manipulator, an effective inertia at the end effector in the operational space is proposed and investigated. By changing the effective inertia property via null-motion, we can get the reduced inertial property of the mobile manipulator. The reduced effective inertia has a significant effect on reducing the impulse force in collision with the environment. To find a posture satisfying both the reduced inertia and joint limit constraints, we propose a combined potential function method which can deal with multiple constraints. The proposed reduced inertia property algorithm is integrated into a damping controller to reduce the impulse force at collision and to regulate the contact force in mobile manipulation.

A new wheel assembly automation system is proposed which assembles a wheel into a hub on a car body on a moving hanger in the car manufacturing line. A vision system is used to track the position of the hub on the moving hanger A macro-micro structure is applied to increase a system bandwidth and accuracy to meet an insertion tolerance. The redundancy problem is solved without complicated calculations by assigning different functions that the macro manipulator tracks a velocity error and the micro regulates the position error. Experimental results show that the proposed system can be applied to the wheel assembly task on a moving hanger in the car manufacturing line.

Deals with the reduced inertial effect in damping-based posture control of a mobile manipulator. As a measure for redundancy resolution of a mobile manipulator, an effective inertia at the end effector in the operational space is proposed and investigated. The reduced effective inertia has a significant effect on reducing the impulse force in collision with environment. To find a posture satisfying both the reduced inertia and joint limit constraints, we propose a combined potential function method that can deal with multiple constraints. The proposed reduced inertia property algorithm is integrated into a damping controller to reduce the impulse force at collision and to regulate the contact force in mobile manipulation. The experimental results show that the reduced inertial effect of the mobile manipulator alleviates the impact force at collision.

A two-arm cooperative assembly (or insertion) algorithm is proposed. As a force-guided control method for the cooperative assembly, the adaptive accommodation controller is adopted since it does not need any complicated contact state analysis nor depends on the geometrical complexity of the assembly parts. Also, the RMRC (resolved motion rate control) method using a relative Jacobian is used to solve inverse kinematics for two manipulators. By using the relative Jacobian, the two cooperative redundant manipulators can be structured as a new single redundant manipulator. The two arms can perform a variety of insertion task by a relative motion between their end effectors. A force/torque sensing model, using an approximated penetration depth calculation algorithm is developed and used to compute a contact force/torque in the graphic assembly simulation. By using the adaptive accommodation controller and the force/torque sensing model, a spatial cooperative assembly tasks have been successfully executed in the graphic simulation. Finally, through a cooperative assembly task experiment using a humanoid robot, CENTAUR, which inserts a spatially bent pin into a hole, its feasibility and applicability are verified.

This paper presents a motion planner for robots in a game situation, in which the agents involved have conflicting goals. More specifically, a human-computer boxing game system is developed in a graphical environment. One boxer is controlled by a human through a motion tracking system, while the other is controlled by a motion planning algorithm. The planner has a defensive and an offensive strategies. The defensive strategy tries to move one of the forearms between the opponent's fist and its body, while the offensive strategy locates an exposed part of the opponent's body and throws a punch at it. To achieve an interactive operation, the motion planner considers only kinematic and geometric constraints during the search. This project is also aimed at integrating a planner with all actual robot, and investigating associated technological bottlenecks.