Trajectory tracking control strategy for biaxial systems based on disturbance rejection and axis-coupled interpolation command modifier

This paper proposes a new control strategy for biaxial systems. It improves the trajectory tracking capabilities of biaxial system by enhancing the tracking performance of feed axes, disturbance rejection capabilities of feed axes, and consistency of dynamics between axes. First, the axis position controller is designed, it uses the feedforward controller and the state feedback controller to realize the active control of the low-order resonant modes of the mechanical system. In addition, a reduced-order extended state observer is designed to estimate the unknown state variables and disturbances in real time. The estimated disturbances will be compensated to the control loop to enhance the disturbance rejection capability of the axis. Second, the interpolation command modifier is designed. It is axis-coupled, which can not only compensate for the error caused by the axes themselves, but also compensate for the error caused by the coupling dynamics between axes. Finally, the effectiveness of the proposed integrated control strategy is experimentally verified. The experimental results show that the trajectory tracking accuracy of the biaxial systems and its robustness to load variations are both improved by using the proposed control strategy.