Research On Force And Displacement Self-sensing In Piezoelectric Gearshift

As the main actuator in automatic gearbox,multiple solenoid valves jointly control the Gearshift.With the development of piezoelectric valve technology,piezo valves have become an ideal substitute for solenoid valves.Compared with traditional solenoid valves,piezo valves have advantages of high precision,fast response,lower power,continuous displacement control and compact structure.In addition,the piezo valve can also work as a displacement sensor to provide feedback for control.This paper proposes a piezoelectric valve that self-sense displacement and driving force at the same time,which can realize the displacement control and real-time monitoring of driving force.In this paper,the relationship between valve displacement,driving force,piezoelectric charge and driving voltage is established to decouple the sensing signal from the control signal.The displacement and driving force of the piezoelectric valve are estimated by electric charge and driving voltage.The piezo valve is composed of a piezoelectric stack as a driving element,a disc spring for providing pretension force,and a regular octagonal spacer for avoiding shear and torsion.The control system is composed of a NI acquisition card and LabVIEW program,which is used for voltage and charge data acquisition,displacement setting and control.The charge is obtained by software integration of the piezoelectric current sampled by a precision resistor,which has the advantage of compensating leakage current by pre-estimating the leakage resistance.For displacement control of valve,a PID controller with feed-forward is used.This part includes an analytical form inverse model of the Prandtl–Ishlinskii model to compensate the piezoelectric hysteresis.The results of displacement control experiment show that the controller can track target displacement within 2.03% of error,track force within 1.80% of error,and the hysteresis of actuator is reduced from 37% to 3.75%.The displacement and driving force of the piezoelectric valve can be estimated at the same time.And only simple calibration is required before engineering application,rather than complex system parameter identification.