双模态超声波电机抗慢速爬行驱动模式研究

Study on anti-slow crawling actuation mode of bimodal ultrasonic motor

针对双模态超声波电机(bimodal ultrasonic motor,BUSM)存在的慢速爬行问题,提出了一种基于小波驱动与预紧角控制相结合的BUSM驱动模式,从BUSM驱动机理的研究上解决BUSM慢速爬行问题。理论分析和实验结果表明,小波驱动的引导波能够促使工作台静动摩擦系数的转换,并使工作台获得初始冲量,小波驱动的工作波所产生的压电驱动力与初始冲量力同向控制时,工作台可以获得较为平滑的驱动,避免了慢速爬行现象;预紧角控制能够减小BUSM的驱动角,提高增摩区间的驱动力,减弱超声振动减摩效应。此外,通过预紧角控制可以将BUSM大行程范围内的正反驱动特性之间的误差减小到5%以内。

Considering the slow crawling problem of bimodal ultrasonic motor（BUSM）, a novel actuation mode of BUSM combined with wavelet drive and pretension angle control through the further study of BUSM drive mechanism was presented, which demonstrated its advantages in solving the slow crawling problem. The theory analysis and test results showed that the guide wave in wavelet drive benefited the conversion from static friction coefficient to dynamic friction coefficient of stage and made the stage acquired initial momentum, when the piezoelectric force of BUSM produced by working wave in wavelet drive was controlled in phase with the force of initial momentum, the better smoothing drive of stage was obtained and the slow crawling phenomenon was avoided. Pretension angle control could decrease the driving angle of BUSM on stage, by which the driving force of friction enhanced area was increased and the friction reduction effect caused by ultrasonic vibration was weakened. Besides, through the pretension angle control, the error between positive and negative actuation characteristic of BUSM in large travel range could be decreased less than 5%.