Control apparatus of vibration-type actuator and control method of vibration-type actuator

The control method for a vibration-type actuator, wherein

• the vibration-type actuator includes a plurality of vibrators each having a contact portion contacting an object to be driven, such that, responsive to a common alternating current signal to the plurality of vibrators, the plurality of vibrators move, through the contact portions, the object relative to the vibrators, to generate an elliptical motion of the object, wherein
• the control method comprises a frequency determining step for setting a frequency of the alternating current signal, and,
• in the frequency determining step, the frequency of the alternating current signal is set for changing an ellipticity of the elliptical motion, within an overlapping frequency range in which frequency ranges of ellipticity changing each set for each of the plurality of vibrators are overlapped, and
• the frequency ranges of changing the ellipticity are set for the vibrators as a frequency range between an upper limit and a lower limit, such that the lower limit is a maximum resonant frequency in all case of changing the ellipticity, and the upper limit is larger than the lower limit and is a maximum frequency for the relative movement of the object.