Unknown constrained mechanisms operation based on dynamic hybrid compliance control

In order to operate unknown constrained mechanisms with assistive robot manipulators, a dynamic hybrid compliance control algorithm was proposed in the paper. The controller using the proposed algorithm was designed to estimate constrained frame, determine driving-axis and obtain control velocity. Firstly, the constrained frame was estimated online according to the previous motion direction, and a suitable direction was selected as driving-axis by selection matrix; then hybrid position/force control was adopted to decouple the driving-axis and non-driving-axis; finally, velocity control was used at the driving-axis and impedance control was used at the non-driving-axis. The proposed dynamic hybrid compliance control algorithm made manipulators find a suitable direction as the driving-axis to operate the constrained mechanisms. And the dynamic characteristics of operation were improved. The validity of the proposed method was verified by the experiments of autonomous door opening utilizing a 6-DoF manipulator.