A 7 DOF Wearable Robotic Arm Using Pneumatic Actuators

Abstract

As human-friendly robot techniques improve, the concept of the wearability of robotic arms becomes important. A master arm that detects human arm motion and provides virtual forces to the operator is an embodied concept of a wearable robotic arm. The medical orthosis used in the medical rehabilitation can also be included in the category of a wearable robotic arm. For the application areas such as human-power amplification or virtual reality experience, a kind of wearable robotic arm is also needed. In this study, we design a 7 DOF wearable robotic arm with high joint torques. An operator wearing this robotic arm can move around freely because this robotic arm was designed to have its fixed point at the shoulder part of the operator. The proposed robotic arm uses parallel mechanis ms at the shoulder part and the wrist part on the model of the human muscular structure of an upper limb. To reduce the computational load in solving the forward kinematics and to prevent singularity motions of the parallel mechanism, yawing motion of the parallel mechanisms was separated using a slip ling mechanism. A small-size pneumatic proportional control valve was also developed to improve the response characteristics of pneumatic actuators and to reduce the total weight of the robotic arm. The total weight of the proposed robotic arm is about 4 kgf. Some motion and force tracking experiments were performed to evaluate the capability of pneumatic control system of the proposed robotic arm. Some application examples using robotic arm such as teleoperation and VR experience are also described to show its validity.