Development of joint module with integrated torque sensor featuring two-stage characteristics

Abstract

For humans and robots to coexist and cooperate, robots need to be inexpensive to lower the hurdle for introduction, and they need to make gentle contact with humans, objects, and the environment, so force control is a key technology. Torque sensor feedback is used to achieve contact, but the mounted torque sensor must be able to detect both small forces to realize skillful work while contacting an object and large forces such as collision. In this research, we focus on a method of using thrust displacement in the worm reduction mechanism when load torque is applied to the worm gear for sensing, and develop a low-cost, space-saving, and lightweight joint module in which the torque sensing function and drive unit are integrated without the need for additional sensor devices. Furthermore, two types of elastic support structures are used to provide two-stage characteristics to achieve fine to wide range torque sensing.