Force regulation and contact transition control

In this article, a new sensor-referenced control method using positive acceleration feedback together with a switching control strategy is developed for robot impact control and force regulation. The robot dynamic model is feedback-linearized and decoupled for the free-motion mode, the phase-transition mode, and the constrained-motion mode. Considering the detection of the impact as an event, the event-driven switching control strategy is used to deal with the inadvertent loss of contact of the robotic manipulator. Bouncing can be eliminated after finite switches. A stable transition can be achieved with a nonzero impact velocity; large impact forces can be avoided and the output force can be regulated after contact is established. Stability analysis based on the Lyapunov-like method is given for the proposed system. The scheme was implemented and tested on a 6 DOF PUMA 560 robot arm