A walking support robot with velocity, torque, and contact force-based mechanical safety devices

Abstract

Safety is one of the most important issues in walking support robots. We have proposed a walking support robot equipped with velocity and torque-based mechanical safety devices. The velocity-based safety device and the torque-based safety device are attached to each drive-shaft of the robot. If the velocity-based safety device detects an unexpected high angular velocity of the drive-shaft, it stops the robot. If the torque-based safety device detects an unexpected high torque of the drive-shaft, it cuts off the torque transmission and switches off all of the robot's motors. This paper proposes a new walking support robot equipped with not only the velocity-based and torque-based safety devices but also contact force-based safety devices. The contact force-based safety device stops the robot if it detects an unexpected large contact force between the robot and the environment (e.g. humans). These safety devices will work even when the computer breaks down, because they consist of only passive mechanical components without actuators, controllers, or batteries. Firstly, we describe the walking support robot with the safety devices. Secondly, we show the prototype walking support robot which we developed. Finally, we verify the effectiveness of the safety devices by experiments.