| Linear ultrasonic motor(LUSM)plays an increasingly significant role in microminiaturing precision driving system for their attractive advantages,and becomes a powerful supplement of traditional electromagnetic motor.According to the working mechanism of ultrasonic motor,a high voltage sinusoidal driving signal with ultrasonic frequency is required.Meanwhile,the ultrasonic motor is a capacitive load of the driver,and a matching circuit must be used to ensure that the motor operates efficiently.Compared with the travelling wave rotary ultrasonic motor,the standing wave type LUSM has more serious nonlinear and internal variable coupling,therefore,a high control performance is hard to obtain.To improve the speed characteristics and position resolution of LUSM,and realize a highprecision motion control,the driving circuit and control strategy of LUSM is necessary to be explored in depth.This paper takes a butterfly-shaped LUSM as the research object,and the drive and control technology of LUSM are studied.To conclude,the main contents and contributions are as follows.1.A characteristic testing system of LUSM was constructed.The transient and mechanical characteristics of a butterfly-shaped LUSM were tested and analyzed.A driving controller based on dual PWM was designed,and the matching circuit was studied by the equivalent circuit model of the motor.2.Based on the precision motion stage system driven by the butter-fly shaped LUSM,the microstep characteristics of LUSM,the speed control model of the system,and a model parameter identification method were thoroughly studied.By analyzing the transient response of LUSM,a driving signal turn off method of the driving controller was studied.The influence of driving signal cycle number,driving voltage amplitude and driving signal time interval on the micro-step of the LUSM were studied by experiments.The speed control model of LUSM was established by using the step response method,and an improved PSO-GA hybrid parameter identification algorithm was proposed to solve the parameter identification problem.3.A fractional order PID controller was proposed to achieve the speed control of LUSM.In terms of ITAE criterion and fuzzy control method,the fractional-order PID controller based on ITAE parameter setting criterion and the fractional-order PID controller based on fuzzy adaptive control were carried out successively.The experimental results show that the fractional order PID controller has a better dynamic performance,anti-jamming capability,and tracking performance.4.Based on the fuzzy PID control and micro-step characteristics of LUSM,a low speed control method was studied.The experimental results show that the motor has a good speed stability even at 10μm/s.The dead-zone compensation of LUSM was studied,and the speed tracking performance of the motor was improved greatly.5.Aiming at the requirements of the precision motion system,a series of positioning control technologies of LUSM were studied.Firstly,the effects of switch control,improved switch control,PID positioning control,micro-step positioning control and continuous PID+ micro-step positioning control method on positioning accuracy and positioning time were deeply analyzed and studied.Secondly,based on different characteristic curves,the acceleration or deceleration positioning control of LUSM were discussed.Then,the dual-loop control,compound control and model-free adaptive control methods were proposed to realize the trajectory tracking control of LUSM.Finally,the contour tracking control of the two-dimensional precision motion stage was studied experimentally.6.The error compensation technology of the precision motion stage and the evaluation method of the position accuracy were studied.Firstly,through the analysis of the error sources of the stage,the static error compensation methods were studied experimentally.The relevant standards and characteristics of position accuracy evaluation were introduced in detail.And the position accuracy of the precision motion stage were measured. |
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