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.