Motor control device, robot hand, robot, and motor control method

{
  "publication_number": "US9461569B2",
  "country": "US",
  "kind": "B2",
  "title": "Motor control device, robot hand, robot, and motor control method",
  "abstract": "A motor control device controls a motor using an angle data signal and a rotational speed signal output from a rotation detector detecting a rotation state of a rotating shaft of the motor. The motor control device includes a speed control unit that outputs a torque instruction signal corresponding to a difference between the rotational speed of the rotating shaft and a speed instruction using the speed instruction of the rotating shaft and the rotational speed signal, a limit value setting unit that sets a torque limit value indicating the maximum value of the torque applied to the rotating shaft, and a torque limit control unit that limits the torque of the rotating shaft driven by the torque instruction signal to the torque limit value or less.",
  "claims": [
    "1. A motor control method of controlling the rotation of a rotating shaft of a motor, comprising: setting a target rotational speed which is a target value of a rotational speed at which the rotating shaft rotates and a torque limit value which indicates the maximum value of a torque to be applied to the rotating shaft; detecting the rotational speed to output a torque instruction signal corresponding to a difference between the rotational speed and the target rotational speed; subtracting an excess torque signal, which is a signal indicating a magnitude by which the torque applied to the rotating shaft by the torque instruction signal is larger than the torque limit value, from the torque instruction signal; changing the torque limit value when the rotational speed of the rotating shaft is lower than a speed determination value; and driving the motor with a torque of the torque instruction signal.",
    "2. A motor control device that controls a motor using a rotation detection signal of a rotating shaft of the motor output from a rotation detector detecting a rotation state of the rotating shaft of the motor, the motor control device comprising: a power transistor that drives the motor; a speed controller configured to output a torque instruction signal corresponding to a difference between a rotational speed of the rotating shaft and a target rotational speed of the rotating shaft using the target rotational speed of the rotating shaft and the rotation detection signal; and a torque limit control unit configured to limit the torque of the rotating shaft driven by the torque instruction signal to a torque limit value or less, wherein: the torque limit value is changed when the rotational speed of the rotating shaft is lower than a speed determination value that is used to determine whether to change the torque limit value.",
    "3. The motor control device according to claim 2, wherein the torque limit control unit subtracts an excess torque signal, which is a signal indicating a magnitude by which the torque applied to the rotating shaft by the torque instruction signal is larger than the torque limit value, from the torque instruction signal.",
    "4. The motor control device according to claim 2 further comprising: a limit value setting unit configured to set the torque limit value indicating the maximum value of a torque to be applied to the rotating shaft, wherein: the limit value setting unit sets the speed determination value, the limit value setting unit detects the rotational speed of the rotating shaft using the rotation detection signal, and the limit value setting unit changes the torque limit value when the rotational speed of the rotating shaft is lower than the speed determination value.",
    "5. The motor control device according to claim 2 further comprising: a limit value setting unit configured to set the torque limit value indicating the maximum value of a torque to be applied to the rotating shaft, wherein: the limit value setting unit sets the speed determination value, the limit value setting unit receives the torque instruction signal, and the limit value setting unit changes the torque limit value when the target rotational speed is smaller than the speed determination value and the torque instruction signal is larger than a torque determination value.",
    "6. The motor control device according to claim 2 further comprising: a limit value setting unit configured to set the torque limit value indicating the maximum value of a torque to be applied to the rotating shaft, wherein the limit value setting unit lowers the torque limit value after the rotational speed of the rotating shaft reaches the target rotational speed.",
    "7. The motor control device according to claim 2, wherein the speed controller includes: a speed-proportional control unit configured to output a first torque instruction signal proportional to the rotational speed; a speed-integral control unit configured to output a second torque instruction signal proportional to an integrated value of the rotational speed; and an adder adding the value of the first torque instruction signal and the value of the second torque instruction signal to output the torque instruction signal, and wherein the torque limit control unit causes the speed-integral control unit to stop an integrating operation and to maintain the value of the second torque instruction signal after the value of the torque instruction signal reaches the torque limit value.",
    "8. The motor control device according to claim 2, wherein the rotation state of the rotating shaft detected by the rotation detector is a rotational speed.",
    "9. A robot comprising: a robot hand that includes a moveable part and a motor that drives the moveable part; and a control unit that includes a motor control device that controls the motor using a rotation detection signal of a rotating shaft of the motor output from a rotation detector detecting a rotation state of the rotating shaft of the motor, the motor control device comprising: a power transistor that drives the motor; a speed controller configured to output a torque instruction signal corresponding to a difference between a rotational speed of the rotating shaft and a target rotational speed of the rotating shaft using the target rotational speed of the rotating shaft and the rotation detection signal; and a torque limit control unit configured to limit the torque of the rotating shaft driven by the torque instruction signal to a torque limit value or less, wherein: the torque limit value is changed when the rotational speed of the rotating shaft is lower than a speed determination value that is used to determine whether to change the torque limit value."
  ],
  "description_excerpt": "1. Technical Field\n\nThe present invention relates to a motor control device, a robot hand, a robot, and a motor control method.\n\n2. Related Art\n\nA method of controlling a stop position of a movable part using a servomotor in a robot or a machine tool has been widely used. When a robot hand grasps a grasped object or inserts a member into a hole, the movable part may not move before the movable part reaches a prearranged position. At this time, a system for setting a torque limit in a motor and controlling a movable part is disclosed in JP-A-5-6210. According to this technique, the control system includes a storage unit storing plural torque limit values and switches the torque limit values for every work detail carried out by a motor or a movable part to be driven.\n\nA method of improving the controllability of a rotational speed without rapidly changing a torque during the rotational driving of a motor is disclosed in JP-A-2011-147268. According to this technique, in a speed control of the motor, a deviation between an instructed speed value and a detected speed value is amplified by the use of a speed regulator including a proportion-integration adjuster to calculate an instructed torque value. A method of controlling the current of the motor so as to match the actual torque with the instructed torque value is employed. Here, the optimal adjustment of the speed regulator is performed on the basis of the value of the moment of inertia. A torque feed-forward compensator calculates a torque feed-forward compensator using the value of the moment of inertia and the instructed speed value.",
  "cpc": [
    "H02P 6/16",
    "B25J 13/00",
    "B25J 13/085",
    "B25J 13/088",
    "B25J 9/1612",
    "H02P 21/13",
    "H02P 21/14",
    "H02P 23/0004",
    "H02P 23/0027",
    "H02P 23/0036",
    "H02P 27/06",
    "H02P 27/08",
    "H02P 7/18"
  ],
  "ipc": [
    "B25J 13/00",
    "B25J 13/08",
    "B25J 9/16",
    "G05B 19/18",
    "H02P 21/13",
    "H02P 21/14",
    "H02P 23/00",
    "H02P 27/06",
    "H02P 27/08",
    "H02P 29/00",
    "H02P 6/16",
    "H02P 7/18"
  ],
  "assignees": [
    "Seiko Epson Corp"
  ],
  "inventors": [
    "Isamu Sejimo",
    "Daisuke Sato"
  ],
  "filing_date": "2012-10-10",
  "publication_date": "2016-10-04",
  "grant_date": "2016-10-04",
  "priority_date": "2011-10-11",
  "application_number": "US-201213648435-A",
  "family_id": "48042584",
  "cited_by_count": 1,
  "citations": [
    "JPH056210A",
    "JPH10138997A",
    "US6356807B1",
    "US20040135533A1",
    "JP2003284399A",
    "US20070252839A1",
    "JP2008199760A",
    "US20100222970A1",
    "JP2010005732A",
    "JP2010063306A",
    "US20110309781A1",
    "US8515579B2",
    "JP2011147268A"
  ]
}