Design and Control of Constant Force Control Components Based on Disturbance Conversion Compensation

Constant force control is significant for robot griding or polishing. Due to the influence of guide rail friction, the existing high precision force control employs air bearing and pneumatic control. Aiming at the problem that the precision of mechanical guideway force control system is affected by nonlinear friction, a design method is proposed that converts friction disturbance into elastic disturbance, which solves the problems of friction dead zone and static friction compensation. Specifically, the force control actuator is designed as a frame and working platform connected by a flexible hinge group. When the driving force is less than the friction force, the displacement is completely generated by the elastic deformation of the flexure hinge, eliminating the friction dead zone. The nonlinear friction disturbance is converted into the elastic deformation disturbance of the flexure hinge. Through the deformation amount and deformation rate of the flexure hinge, the elastic force and damping force are calculated for real-time compensation, which solves the problem of friction compensation. The experiment shows that the friction disturbance conversion design reduces the influence of friction, finally improves the force control accuracy to 0.08 N through measurement and compensation, which is 20~50 N times higher than the original, more than 10 times higher than the general air flotation accuracy, and maintains the advantages of fast response and low cost of the electronic control system.