Control method for piezoelectric drive device, piezoelectric drive device, and robot

{
  "publication_number": "US11515812B2",
  "country": "US",
  "kind": "B2",
  "title": "Control method for piezoelectric drive device, piezoelectric drive device, and robot",
  "abstract": "A control method for a piezoelectric drive device includes a first step of executing first control to decrease a frequency of a drive voltage applied to a piezoelectric vibrator from a predetermined first frequency while acquiring a pickup voltage representing vibration amplitude of the piezoelectric vibrator, and a second step of executing second control to increase the frequency of the drive voltage applied to the piezoelectric vibrator to a second frequency as a frequency of the drive voltage applied before a second time when the pickup voltage is higher from a first time to the second time and the pickup voltage is lower from the second time to a third time.",
  "claims": [
    "1. A control method for a piezoelectric drive device including a piezoelectric vibrator, comprising: a first step of executing first control to decrease a frequency of a drive voltage applied to the piezoelectric vibrator from a predetermined first frequency while acquiring a pickup voltage representing vibration amplitude of the piezoelectric vibrator; and a second step of executing second control to increase the frequency of the drive voltage applied to the piezoelectric vibrator to a second frequency as a frequency of the drive voltage applied before a second time when, in the first control, the pickup voltage is higher from a first time to the second time and the pickup voltage is lower from the second time to a third time.",
    "2. The control method for the piezoelectric drive device according to claim 1, wherein the second frequency is a frequency of the drive voltage applied to the piezoelectric vibrator before the first time.",
    "3. The control method for the piezoelectric drive device according to claim 1, wherein the second frequency is lower than the first frequency.",
    "4. The control method for the piezoelectric drive device according to claim 1, further comprising a third step of executing third control to adjust the second frequency to fix the pickup voltage after the second step, wherein the first step is executed again when an amount of change of the second frequency is equal to or larger than a predetermined value at the third step.",
    "5. The control method for the piezoelectric drive device according to claim 1, wherein the second control is executed at the second step when the pickup voltage is larger from the first time to the second time and an amount of change of the pickup voltage from the second time to the third time is equal to or larger than a predetermined value in the first control.",
    "6. A piezoelectric drive device that drives a driven member, comprising: a piezoelectric vibrator that drives the driven member; and a control unit, wherein the control unit executes first control to decrease a frequency of a drive voltage applied to the piezoelectric vibrator from a predetermined first frequency while acquiring a pickup voltage representing vibration amplitude of the piezoelectric vibrator from the piezoelectric vibrator, and second control to increase the frequency of the drive voltage applied to the piezoelectric vibrator to a second frequency as a frequency of the drive voltage applied before a second time when, in the first control, the pickup voltage is higher from a first time to the second time and the pickup voltage is lower from the second time to a third time.",
    "7. A robot comprising the piezoelectric drive device according to claim 6."
  ],
  "description_excerpt": "The present application is based on, and claims priority from JP Application Serial Number 2019-230203, filed Dec. 20, 2019, the disclosure of which is hereby incorporated by reference herein in its entirety.\n\nThe present disclosure relates to a control method for a piezoelectric drive device, a piezoelectric drive device, and a robot.\n\nRegarding a control method for a piezoelectric drive device, for example, JP-A-6-269179 discloses a control method for an ultrasonic motor including a vibrator having an elastic body and a piezoelectric element, and a rotor in pressure contact with the vibrator. JP-A-6-269179 discloses a technique, in control to increase vibration amplitude to target amplitude by reducing a drive frequency from a high-frequency side, of reducing the target amplitude to the maximum value of the vibration amplitude when it is anticipated that the vibration amplitude does not reach the predetermined target amplitude.\n\nHowever, the relationship between the maximum value of the vibration amplitude as the target amplitude and the drive frequency of the vibrator may vary due to temperature changes of the vibrator or the like. Accordingly, when the vibrator is controlled based on the target amplitude, appropriate setting of the drive frequency may be difficult.\n\nAccording to a first aspect of the present disclosure, a control method for a piezoelectric drive device is provided.",
  "cpc": [
    "H02N 2/145",
    "B25J 9/12",
    "H02N 2/0025",
    "H02N 2/02",
    "H02N 2/04",
    "H02N 2/062",
    "H02N 2/103",
    "H02N 2/142"
  ],
  "ipc": [
    "B25J 9/12",
    "H02N 2/10",
    "H02N 2/14"
  ],
  "assignees": [
    "Seiko Epson Corp"
  ],
  "inventors": [
    "Kiichi Kajino"
  ],
  "filing_date": "2020-12-18",
  "publication_date": "2022-11-29",
  "grant_date": "2022-11-29",
  "priority_date": "2019-12-20",
  "application_number": "US-202017126047-A",
  "family_id": "76383509",
  "cited_by_count": 0,
  "citations": [
    "JPH06269179A",
    "US9318980B2",
    "US11203040B2"
  ]
}