Position/force decoupled bilateral communication without force controller in slave side by using multirate control

Abstract

Bilateral communication is remote control and composed of position/force tracking between a master (local) robot and a slave (remote) robot. Therefore, conventionally, hydraulic actuators, which have low force control performance, are not good candidates for bilateral communication. However, we found that the lack of force control of the hydraulic actuators can be compensated by helps of electric actuators. If multirate controllers are implemented in bilateral communication; sampling periods of electric actuators are shorter than those of the hydraulic actuators, position and force controllers of bilateral controllers are decoupled without force control of hydraulic actuators. Here, the master robot is driven by an electric actuator and the slave robot is driven by a hydraulic actuator. The proposed method is given by a couple of two sampling points. In the first sampling point, the master and slave robots cooperate to establish position tracking. The force task is given by a mean master's output of the first and second sampling points. Therefore, the sampling period of the slave robot is twice longer than that of the master robot. The effectiveness of the proposed method is verified by simulations, and is experimentally shown by using hydraulic actuators with a proportional fluid valve.