Control apparatus of vibration-type actuator

Abstract

Information regarding a rotational speed is detected by utilizing a variation in the amplitude at a frequency corresponding to the number of a plurality of protrusions of a vibrating member generated in an S-phase signal detected from a vibration detection electrode of a vibration-type actuator.

1 . A control apparatus of a vibration-type actuator that rotates, relative to a vibrating member, a moving member that is in contact with a plurality of protrusions of the vibrating member by applying an alternating voltage to an electromechanical energy conversion element of the vibrating member including the electromechanical energy conversion element and by generating elliptic motions in the plurality of protrusions of the vibrating member,
 wherein information regarding a rotational speed of the moving member is obtained using information regarding a frequency corresponding to the number of the plurality of protrusions, the information regarding the frequency being included in a detection signal from the electromechanical energy conversion element for detecting vibration provided in the vibrating member.   
     
     
         2 . The control apparatus of the vibration-type actuator according to  claim 1 , further comprising:
 a repetitive controller that performs repetition control on the detection signal in order to detect the information regarding the frequency corresponding to the number of the plurality of protrusions,   wherein a repetition period of the repetitive controller is set to a reciprocal of a frequency represented by a product of the number of the plurality of protrusions and a target velocity or to half the reciprocal.   
     
     
         3 . The control apparatus of the vibration-type actuator according to  claim 1 , further comprising:
 a band-pass filter that detects the information regarding the frequency corresponding to the number of the plurality of protrusions and that limits a bandwidth of the detection signal; and   an adjuster that changes a frequency passband of the band-pass filter in accordance with a frequency of the alternating voltage.   
     
     
         4 . The control apparatus of the vibration-type actuator according to  claim 3 , further comprising:
 a memory that stores a relational expression or a table representing a relationship between the frequency of the alternating voltage and the rotational speed of the moving member,   wherein a center frequency of the frequency passband of the band-pass filter is set to a value calculated using the information regarding the rotational speed obtained from the relational expression or the table and the information regarding the frequency corresponding to the number of the plurality of protrusions.   
     
     
         5 . The control apparatus of the vibration-type actuator according to  claim 1 , further comprising:
 a band-pass filter that detects the information regarding the frequency corresponding to the number of the plurality of protrusions and that limits a bandwidth of the detection signal; and   an adjuster that changes a frequency passband of the band-pass filter in accordance with the detection signal.   
     
     
         6 . The control apparatus of the vibration-type actuator according to  claim 5 , further comprising:
 a Fourier transformer that performs a frequency analysis on the detection signal,   wherein a center frequency of the frequency passband of the band-pass filter is set to a frequency at which an amplitude detected by the frequency analysis is largest.   
     
     
         7 . The control apparatus of the vibration-type actuator according to  claim 1 , further comprising:
 a repetitive controller that detects the information regarding the frequency corresponding to the number of the plurality of protrusions and that performs repetition control on the detection signal; and   a Fourier transformer that performs a frequency analysis on the detection signal,   wherein a repetition period of the repetitive controller is set to a reciprocal of a frequency at which an amplitude detected by the frequency analysis is largest or to half the reciprocal.   
     
     
         8 . The control apparatus of the vibration-type actuator according to  claim 1 , further comprising:
 a phase difference detector that detects a phase difference between the alternating voltage and the detection signal,   wherein the information regarding the rotational speed of the moving member is obtained by detecting the information regarding the frequency corresponding to the number of the plurality of protrusions using the phase difference.   
     
     
         9 . The control apparatus of the vibration-type actuator according to  claim 2 ,
 wherein the repetition period of the repetitive controller is set to the reciprocal of the frequency represented by the product of the number of the plurality of protrusions and the target velocity or to half the reciprocal,   the control apparatus of the vibration-type actuator further comprising:   an amplitude detector that detects an amplitude of an output signal of the repetitive controller when the frequency of the alternating voltage is swept; and   a pulse generator that sets a frequency at which the amplitude is largest as a frequency of the alternating voltage.   
     
     
         10 . A control apparatus of a vibration-type actuator that rotates, relative to a plurality of vibrating members, a moving member that is in contact with a plurality of protrusions of the plurality of vibrating members by applying an alternating voltage to an electromechanical energy conversion element of each of the plurality of vibrating members having different numbers of protrusions and by generating elliptic motions in the plurality of protrusions of the plurality of vibrating members,
 wherein information regarding an absolute position of the moving member is obtained by detecting a phase difference between signals having frequency components corresponding to the numbers of the plurality of protrusions of the plurality of vibrating members using information regarding frequencies corresponding to the numbers of the plurality of protrusions of the plurality of vibrating members, the information regarding the frequencies being included in detection signals from the electromechanical energy conversion elements for detecting vibration provided in the plurality of vibrating members.   
     
     
         11 . A control apparatus of a vibration-type actuator that rotates, relative to a vibrating member, a moving member that is in contact with a plurality of protrusions of the vibrating member by applying an alternating voltage to an electromechanical energy conversion element of the vibrating member having a region in which the plurality of protrusions that are provided periodically do not exist and by generating elliptic motions in the plurality of protrusions,
 wherein information regarding an absolute position of the moving member is obtained using information regarding a frequency corresponding to the number of the plurality of protrusions, the information regarding the frequency being included in a detection signal from the electromechanical energy conversion element for detecting vibration provided in the vibrating member.