Robot Machining Method Bases on Dynamic System and Compliant Control This paper proposes a force control strategy based on velocity modulation and impedance control algorithm to address unstable contact problem between the tool and workpiece in machining. In many application scenarios of industrial robots, contact force is required to some extent. Therefore, a force control component guarantees that robot can maintain stable contact force with the predetermined trajectory and react in the rapidly changing environment. The position controller is used to adjust the movement of the robot. During movement, position controller combined with speedbased impedance control can compensate for the uncertainty of controller and robot Meanwhile, the velocity of the robot is controlled in the velocity modulation subspace to reduce the vibration force in contact, thus the contact overshoot decreases and the machining accuracy of the workpiece is improved. Evaluations through noncontact to contact transition experiment indicates that low contact vibration and reliable positionforce control can be achieved by this proposed controller.

Sensorless Hybrid NormalForce Controller With Surface Prediction In this paper, an improved sensorless hybrid controller for constant force control along normal direction is proposed for applications including polishing, milling and deburring. No additional sensors are involved. External joint torques of all joints can be calculated from their electric current, dynamic model and friction model. With the help of dynamically consistent generalized inverse matrix, they can be converted to external forcetorque at the endeffector. The underlying force control strategy is the integration of impedance control model and explicit force control. The novel improvement is the realtime prediction algorithm of surfacexe2x80x99s shape profile and normal direction without any prior knowledge. So, this force controller has great adaptiveness to arbitrary unknown surfaces. Experiments were performed on a 7 degreesoffreedom (DOFs) robot to test the controllerxe2x80x99s capability and utility on an inclined plane and curved surface. Results prove the credibility of external force estimation. The normal force tracking accuracy is adequate for targeted applications. Realtime prediction is functional as the robot adjusts its orientation accordingly.