A novel multi-fingered exoskeleton haptic device using passive force feedback has been proposed by the authors. The haptic device solves the conventional problems of previously developed master-slave systems with force feedback, such as oscillations, complex structures and complicated control algorithm. However, some problems still remain in the conventional passive elements. In the present paper, an ultrasonic clutch for multi-fingered exoskeleton haptic device with passive force feedback function is developed. The ultrasonic clutch can solve problems of conventional passive elements, such as time delay, instability, and large size, by using unique characteristics of ultrasonic motor, as fast response, silent motion, and non-magnetic feature. It can also be designed to be smaller than conventional elements due to its simple structure. The clutch locks or releases the rotor by use of ultrasonic levitation phenomenon. First, we have designed the structure of the ultrasonic clutch using an equation of ultrasonic levitation phenomenon, results from structural analysis and finite element (FE) analysis of piezoelectric material of the vibrator. Then we have manufactured the ultrasonic clutch and have conducted a driving experiment. Finally, we have demonstrated that the maximum levitation force is around 20 N and the static friction torque of the ultrasonic clutch is up to 0.14 Nm.

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This paper introduces a novel type of actuator for force-reflection to haptic master interfaces. The actuator is based on a DC motor that is relocated from the mechanism joint by means of bowden cable transmissions. After an introduction and formulation of the project goals, the paper highlights some important bowden cable transmission characteristics that influence the design of the necessary hardware. Next, a hardware prototype is presented that has been built to analyze the transmis-sion characteristics of the bowden cable transmissions between actuator and robotic joint. The prototype was used next to investigate achievable actuator performance in force-feedback control with a slave. Results are presented, which show good performance and contact stability in a 4 channel control scheme. The actuator has low movement resistance in free motion and can reflect high torques during hard contact situations with a slave.

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An important goal in rehabilitation engineering is to develop technology that allows individuals with severe motor impairment to practice arm movement without continuous supervision from a rehabilitation therapist. This paper describes the development of such a system, called Therapy WREX or («T-WREX»). The system consists of an orthosis that assists in arm movement across a large workspace, a grip sensor that detects hand grip pressure, and software that simulates functional activities. The arm orthosis is an instrumented, adult-sized version of the Wilmington Robotic Exoskeleton (WREX), which is a five degrees-of-freedom mechanism that passively counterbalances the weight of the arm using elastic bands. After providing a detailed design description of T-WREX, this paper describes two pilot studies of the system’s capabilities. The first study demonstrated that individuals with chronic stroke whose arm function is compromised in a normal gravity environment can perform reaching and drawing movements while using T-WREX. The second study demonstrated that exercising the affected arm of five people with chronic stroke with T-WREX over an eight week period improved unassisted movement ability (mean change in Fugl-Meyer score was 5 points plusmn2 SD; mean change in range of motion of reaching was 10%, p<0.001). These results demonstrate the feasibility of automating upper-extremity rehabilitation therapy for people with severe stroke using passive gravity assistance, a grip sensor, and simple virtual reality software.

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This research aims to develop a portable haptic master hand with 20 degrees of freedom (DOF). Master hands are used as haptic interfaces in master-slave systems. A master-slave system consists of a haptic interface that communicates with a virtual world or an end-effector for tele-operation, such as a robot hand. The thumb and fingers are usually modeled as a serial linkage mecha-nism with 4 DOF. So far, no 20 DOF master hands have been developed that can exert perpendicular forces on the finger phalanges during the complete flexion and extension motion. In this paper, the design and development of two concepts of a portable 4 DOF haptic interface for the index finger is presented. Concept A is a statically balanced haptic interface with a rolling-link mechanism (RLM) and an integrated constant torque spring per DOF for perpendicular and active force feedback. Concept B utilizes a mechanical tape brake at the RLM for passive force feedback. The systematic Pahl and Beitz design approach is used as an iterative design method.

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An important goal in rehabilitation engineering is to develop technology that allows individuals with severe motor impairment to practice arm movement without conti-nuous supervision from a rehabilitation therapist. This paper describes the development of such a system, called Therapy WREX or (“T-WREX”). The system consists of an orthosis that assists in arm movement across a large workspace, a grip sensor that detects hand grip pressure, and software that simulates functional activities. The arm orthosis is an instrumented, adult-sized version of the Wilmington Robotic Exoskeleton (WREX), which is a five degrees-of-freedom mechanism that passively counterbalances the weight of the arm using elastic bands. After providing a detailed design description of T-WREX, this paper describes two pilot studies of the system’s capabilities. The first study demonstrated that individuals with chronic stroke whose arm function is compromised in a normal gravity environment can perform reaching and drawing movements while using T-WREX. The second study demonstrated that exercising the affected arm of five people with chronic stroke with T-WREX over an eight week period improved unassisted movement ability (mean change in Fugl-Meyer score was 5 points 2 SD; mean change in range of motion of reaching was 10%, 0 001). These results demonstrate the feasibility of automating upper-extremity rehabilitation therapy for people with severe stroke using passive gravity assistance, a grip sensor, and simple virtual reality software.

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