Constant Force Control and Trajectory Planning of Multi-Axis Polishing Machine Using Active Disturbance Rejection Control and B-Spline Curve Algorithm

The traditional force control strategy is on the basis of impedance control, which adjusts the position by adjusting the mechanical impedance between the end effector and the environment to achieve constant force control. In this paper, a new constant force control strategy based on B-spline curve and active disturbance rejection control (ADRC) is introduced, which is realized and verified in the polishing machine control system for polishing curved surfaces. First, the polishing machine is modeled as the impedance control object. Then, the B-spline curve is used to plan the trajectory of the polishing path, and the ADRC algorithm is calculated in each interpolation period to realize the constant force control. The advantage of this work is the use of B-spline curve algorithm to generate trajectory path, which only needs a few control points to realize motion control, and the use of auto-disturbance rejection differential tracker and disturbance estimation to control the real-time constant force. A simulation using MATLAB software and constant force experiment of polishing machine are performed to test the effectiveness of the proposed control strategy. The simulation and experimental results show that the proposed control strategy has better performance compared to traditional controller in terms of force consistency, trajectory accuracy, and polishing surface quality. The analysis shows that the proposed force-tracking control exhibits better performance, with trajectory errors at 0.634mm, overshoot of 4.16%, and a 98.40% reduction in roughness. Conversely, PID control, with a 96.25% roughness reduction, yields trajectory errors of 2.91mm and a 13% overshoot, proving less precise for high-precision tasks.