Development of variable control mechanism to amplify operating range of end-effector of wearable haptic device (Proposal and evaluation of force feedback system in wide operating range)

Abstract

The objective of this study is to develop the wearable haptic device having widely operating range and highly efficient dynamic characteristics of the end-effector located on the tip of the haptic device. The conventional haptic device displays pseudo translational force to the operator's hand. However, there is a problem that the dynamic characteristics of the end-effector of these devices are restricted to the response of motion of the actuator. To improve the dynamic characteristics of the end-effector, the variable structure control which is able to choose either connection or disconnection between the actuator and the end-effector is developed. The proposed system controls (opens or closes) the hinge mechanism, so that the actuator and the end-effector can be connected or disconnected depending on the opened or closed status of the hinge mechanism. Accordingly, we develop the control system including the coordinate transformation of the displaying force using the angle sensor by taking into account large range of motion in the end-effector. To confirm the effectiveness of the proposed control method, experiments of force display for human operators were carried out. The experimental results show that the proposed system is able to improve the dynamic characteristics of the end-effector and to amplify the operating range of the hand motion in the force non-displayed condition.

Keywords

• haptic device
• parallel mechanism
• human interface
• virtual reality
• robot
• myoelectric signals