A universal digital motion controller design for servo positioning mechanisms in industrial manufacturing

Abstract

• A universal digital motion controller design with theoretical analysis is presented. • The controller uses a synergy of linear and nonlinear control with disturbance rejection, and achieves desirable performance. • The controller is fully parameterized, with the advantage of fast implementation and convenience of on‐line tuning. • The controller has the potential of integration with an identification algorithm to form a self‐tuning motion control system. • The design was verified on a DSP-controlled testbed, and demonstrated a competitive performance against the popular ADRC. A parameterized design of universal motion controller is proposed in discrete-time domain using composite nonlinear control approach for high-performance servo mechanisms in industrial automation. First, the model of servo mechanisms is converted into discrete-time state-space form, and a linear control law is designed, consisting of state feedback, reference feed-forward and disturbance compensation. Next, a nonlinear control law is constructed to smoothly modulate the closed-loop damping as the system output approaches the reference. To estimate the unmeasurable velocity and disturbance, a reduced-order extended-state observer is adopted. The final controller is a combination of the above three parts and is fully parameterized in some fundamental tuning parameters. The controller was applied to a permanent magnet synchronous motor (PMSM) drive, which usually serves as the actuator for high-performance motion control systems. After MATLAB simulation, experimental test using a digital signal processing board was conducted, to verify the effectiveness of the proposed design.