Dynamic modeling and control of high-precision piezoelectric-driven slit based on Hammerstein model under strong...

The four-blade slit is an important part in the neutron beamlines, which can help to regulate the flow of neutron beams through the slit. The current phase II of the China Spallation Neutron Source has higher requirements for the precision of neutron beamline control. Piezoelectric platform facilitates precise control of slit position and can be used in environments with strong magnetic fields. In order to improve the tracking accuracy of the piezoelectric platform, a Hammerstein model composed of improved P-I model and ARX model was established to characterize the hysteresis of the piezoelectric actuator. The third-order transfer function obtained from the identification of the electromechanical coupling model of the system characterized the dynamic characteristics of the system. Then, a dynamic model of piezoelectric positioning platform with hysteretic nonlinear input is obtained. At the same time, the Hammerstein inverse model is established to design the feedforward controller and feedforward PID compound controller. The experimental results show that, under feedforward PID compound control, the root mean square error of the tracking signal displacement is lower than that under feedforward control, and the tracking precision is better. This study provides a dynamic control model and theoretical support for the design of piezoelectric-driven neutron slits, which can be extended to other applications of high-precision control under strong magnetic fields.