A two-speed actuator for robotics with fast seamless gear shifting

摘要

In many applications, robots have to bear large loads while moving slowly and also have to move quickly through the air with almost no load. This leads to conflicting requirements for their actuators. Multiple gear ratios, like in a powertrain, address this issue by allowing an effective use of power over a wide range of output speed. However in robotics, as opposed to powertrains, the controlled load is not always inertial and acting as a low-pass filter; hence gear shifting is a more challenging issue in a robotics context. In this paper, it is proposed to address this problem using a dual-speed dual-motor architecture to maintain full control of the output during gear shifting. A dynamic model is developed and a controller using the redundancy of motors is proposed to enable fast seamless gear shifting even when interacting with unknown dynamic environments. Results are demonstrated with a proof-of-concept linear actuator.