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Controlling the gripping force on objects has been a challenging task for industrial grippers. Its realization often requires an electric gripper with embedded force sensors and control feedback. This approach is costly and introduces extra complexity for grippers. To avoid damage while handling fragile objects, this paper presents a novel force regulation mechanism (FRM) to be installed on grippers...
A wearable robot is constantly in contact with its user. To properly and safely perform tasks together with the wearer, such as walking and load carrying, it is important that the robot is able to control its joint torques. To enhance the performance of torque/force controllers, feedforward controllers such as velocity and friction compensation are commonly used. Although such controllers are able...
A real snake has simple figure like a string, and has highly adaptability corresponding to the environments/tasks. A snake-like robot mimics such highly adaptability of the real snake, is expected as an adaptable robot corresponding to the environments/tasks. Many literatures have reported with respect to locomotion controls of the snake-like robot, but haven't reported studies for applications. However,...
Control of complex dynamical systems such as electrohydraulic systems is challenging. This paper presents force control of an electrohydraulic actuator using the super-twisting algorithm (STA). The STA is one of the most promising highorder sliding-mode control algorithms. It guarantees robustness with respect to modeling errors, uncertainties and external disturbances while reducing the chattering...
Hemiplegia is the lingering effect after a stroke and causes varying impairments. The ability to generate and modulate force is frequently impaired. This study focuses on a rehabilitation technique that encourages force generation in an arbitrary direction. The authors introduced a physiotherapy technique into a rehabilitation robot. Force visualization was provided as a feedback strategy to facilitate...
This paper discusses the calibration of two-axis force sensors which were embedded into the fingertip of a three-fingered robot hand. In a previous work, a functioning prototype of the three-fingered robot hand has been successfully developed. However, the performance of the robot hand for grasping was insufficient. Therefore, the improved design fingertip was developed to enhance the existing design...
An approximate system model for force tracking has been formulated here for a low-cost electrohydraulic system with a moderate-friction single-rod cylinder and a large-deadband proportional valve. A controller based on first-order sliding mode along with adaptation of controller parameters through Lyapunov functions has been developed to tackle the severe nonlinearities of the system. The system model...
It has become a trend that ankle rehabilitation robots replace traditional therapist in rehabilitation field. Many ankle rehabilitation robots have been proposed for rehabilitation training by researchers. However, most of current researches are only focusing on providing the passive training. They not only ignore the active force training for patient, but also neglect the relationship between passive...
This paper reports relations between force control performance and output direction at an end-effector of a limb when a human apply force to a rigid object. A highly backdrivable rehabilitation supporting system is used to provide an evaluation program. It is also used for repetitive force sensing. Measurement on twelve seated subjects can quantify force control accuracy when the subjects try to output...
The basic structure and null space analysis of 5 DoF implant assist robot for position and angle adjustment is conducted in this paper. The problem of position control using the inverse matrix is the singular postures that make the system unstable. In this paper, the modulated potential field is also extended to 5 DoF robot manipulator for both position adjustment and angle adjustment. It is proposed...
In the painting process of automotive manufacturing, the buffing process for the repair polishing is done manually by a worker with a sufficient skilled technique. However, the number of a skilled worker is decreasing with the aging of the skilled worker. In addition, the polishing time and the surface quality after the repair polishing are dependent on the proficiency level of the worker. Thus, skill-independent...
This paper proposes a design method of command compensator with transition of state for command shaping. In the future, a robot is required to be introduced in human society. In this case, force control of high performance is important element of a robot control system. Moreover, it is important that a robot automatically changes a command in accordance with circumstances and a control specification...
This paper focuses on storage and reproduction systems for environmental haptic sensations. A large force vibration is caused by the differential of viscosity momentum in the reproduction system based on force control. To solve this problem, the reproduction system based on momentum control has been proposed in previous our research. The improved reproduction system has a configuration that the momentum...
In this paper, a bilateral control method of master slave robot system is conducted. The authors propose a bilateral control method by fusing for force control system and position control system. The master slave robot system is that angle of master robot arm as position information by operator send to slave robot system as control command and then a load received from slave robot arm send to master...
Exoskeleton robots are developed for human rehabilitation and power augmentation. Human and robot interaction is an important issue involved with these robots. In this paper, the interaction force reduction is considered leading to the transparency of a lower limb exoskeleton during swing phase of walking. Achieving this goal, a robust Lyapunov based motion control method has been developed. The desired...
In this paper, the problem of controlling multiple different tasks in various points on the robot body is considered. The proposed approach guarantees the execution of multiple various tasks (force, position and orientation control) in the presence of intentional or accidental interaction with robot body. The control law distinguish between desired and accidental external forces. Magnitude and/or...
This paper proposes a new controller for the robot which realizes motor system rehabilitation task. The proposed controller simultaneously realizes rehabilitation motion tracking and force generation that were predefined through a musculoskeletal model based optimization process. We introduce control parameters of weighted control action priorities for the motion tracking task and force generation...
Robotic telesurgery application could greatly benefit from force control, providing safe and stable application even under time delays and other disturbing conditions. This paper describes a soft tissue model which can be integrated into the control loop of a teleoperational master -- slave robot. Three alternations of the Wiechert model have been implemented and matched against experimental data...
This paper proposes a new robust position control method for a novel series elastic actuator (SEA). It is a wellknown fact that SEAs provide many benefits in force control, e.g., lower reflected inertia and impedance, greater shock tolerance, safety, and so on. However, current SEA designs have a common performance limitation due to the compromise on the selection of spring stiffness. The performance...
The design of a stable and robust force controller is one of the most important and difficult tasks in rehabilitation robotics. In previous works, the Universal Haptic Pantograph (UHP) was presented as an alternative to conventional arm rehabilitation after a stroke. This robot is composed by a Series Elastic Actuator (SEA) and a Pantograph. In this work an enhanced force control for the UHP is presented...
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