Development of a Walking Support Robot with Velocity and Torque-based Mechanical Safety Devices

Safety is one of the most important issues in walking support robots. We have proposed a walking support robot equipped with velocity-based mechanical safety devices. The safety device is attached to each drive-shaft of the robot. If the safety device detects an unexpected high angular velocity of the drive-shaft, the safety device stops the robot. In this paper, we propose a walking support robot equipped with not only the velocity-based mechanical safety devices but also torque-based mechanical safety devices, in order to further improve human safety. A torque limiter and a switch are used in the torque-based safety device. The torque-based safety device is also attached to each drive-shaft of the robot. If the torque-based safety device detects an unexpected high torque of the drive-shaft, the torque-based safety device switches off all motors of the robot. The velocity-based safety devices and the torque-based safety devices can work even if the robot's controller does not work, because these safety devices consist of only passive mechanical components without actuators, controllers, or batteries. Firstly, we describe the characteristics of the velocity-based safety device and the torque-based safety device. Secondly, we explain the walking support robot equipped with the velocity-based safety devices and the torque-based safety devices. Thirdly, we show the walking support robot which we developed. Finally, we verify the effectiveness of the velocity-based safety device and the torque-based safety device by experiments.