A symmetry-oriented stick–slip piezoelectric actuator with reduced parasitic displacement and improved bidirectional consistency

Abstract This study addresses the persistent problems of forward–reverse asymmetry, large parasitic displacement, and unstable stepping in conventional stick–slip piezoelectric actuators, which constrain dynamic stability in high-performance motion systems. A symmetry-oriented stick–slip piezoelectric actuator is proposed to reduce parasitic displacement and improve bidirectional consistency. The flexure-based amplification mechanism is modeled and optimized using the pseudo-rigid-body method, the elastic beam model, and finite-element analysis, and a prototype is fabricated for experimental validation. Under driving voltages of 90, 120, and 150 V, the actuator maintains highly consistent forward and reverse stepping. In the 2–20 Hz range, the bidirectional deviation ratio remains below 5%, with a minimum of about 2.0%, and stable stepping is preserved up to 100 Hz; the single-step resolution reaches 319 nm. Driving-foot measurements confirm reduced parasitic displacement and lower cross-axis coupling compared with conventional stick–slip designs. Furthermore, a cooperative driving strategy increases step size without enlarging the structure or degrading stability, and a fractional-order PID–based closed loop achieves accurate trajectory tracking with a steady–state error of 1.868 µ m.