Motor control system

{
  "publication_number": "US10365083B2",
  "country": "US",
  "kind": "B2",
  "title": "Motor control system",
  "abstract": "A motor control system includes a motor, a rotational angle sensor that detects a rotational angle of a motor shaft of the motor, a torque sensor that detects shaft torsion torque between the motor shaft, and an output shaft fixed to a load member driven by the motor, and a motor controller that controls the motor. The motor controller estimates a rotational angle of the output shaft, based on the rotational angle of the motor shaft, the shaft torsion torque, and torsional rigidity obtained in advance with respect to a region between the motor shaft and the output shaft, and controls the motor, using the estimated rotational angle of the output shaft.",
  "claims": [
    "1. A motor control system comprising: a motor; a rotational angle sensor that is configured to detects a rotational angle of a motor shaft of the motor; a torque sensor that is configured to detects a shaft torsion torque between the motor shaft, and an output shaft fixed to a load member driven by the motor; and a motor controller that is configured to controls the motor, wherein the motor controller is configured to estimates a rotational angle of the output shaft, based on the rotational angle of the motor shaft detected by the rotational angle sensor, the shaft torsion torque detected by the torque sensor, and a torsional rigidity obtained in advance with respect to a region between the motor shaft and the output shaft, and the motor controller is configured to controls the motor, using the rotational angle of the output shaft.",
    "2. The motor control system according to claim 1, wherein a value of the torsional rigidity is changed, according to the shaft torsion torque detected by the torque sensor.",
    "3. The motor control system according to claim 1, wherein at least one of a rotational angular velocity and a rotational angular acceleration of the output shaft is estimated, based on the rotational angle of the motor shaft detected by the rotational angle sensor, the shaft torsion torque detected by the torque sensor, and the torsion rigidity obtained in advance with respect to the region between the motor shaft and the output shaft, and the rotational angle of the output shaft is estimated, based on at least one of the rotational angular velocity and the rotational angular acceleration of the output shaft.",
    "4. The motor control system according to claim 2, wherein values of the shaft torsion torque are divided into two or more sections, and the torsional rigidity in each section is set to a constant value."
  ],
  "description_excerpt": "The disclosure relates to a motor control system.\n\nIn recent years, a servomotor is employed in a joint of a robot arm, for example, for driving a link that constitutes the robot arm with high accuracy. In Japanese Patent Application Publication No. 2004-80973 (JP 2004-80973 A), a motor control system using a full closed control method is disclosed which performs velocity control based on a velocity signal of a motor, and performs position control based on a position signal of a load member driven by the motor.\n\nThe inventor and others found the following problems concerning the motor control system. The motor control system of the full closed control type as disclosed in JP 2004-80973 A generally includes an output shaft rotational angle sensor that detects the rotational angle θ L of an output shaft fixed to the load member driven by the motor, in addition to a motor shaft rotational angle sensor that detects the rotational angle θ M of a motor shaft of the motor. Therefore, the position control can be performed with high accuracy. However, the configuration of the motor control system may lead to increase of the size of the system, and increase of the manufacturing cost.\n\nOn the other hand, in the case where the output shaft rotational angle sensor is not provided, it is considered to perform control simply using θ M /r obtained by dividing the rotational angle θ M of the motor shaft by the reduction ratio r, as the rotational angle θ L of the output shaft.",
  "cpc": [
    "G01B 7/30",
    "B25J 9/1633",
    "B60G 17/019",
    "B62D 5/0463",
    "G01L 25/003",
    "G01L 3/109",
    "G01L 5/0042",
    "G05B 2219/39188",
    "H02P 23/14"
  ],
  "ipc": [
    "B25J 9/16",
    "B60G 17/019",
    "B62D 5/04",
    "G01B 7/30",
    "G01L 25/00",
    "G01L 3/00",
    "G01L 3/10",
    "G01L 5/00"
  ],
  "assignees": [
    "Toyota Motor Corp"
  ],
  "inventors": [
    "Taro Takahashi"
  ],
  "filing_date": "2017-12-12",
  "publication_date": "2019-07-30",
  "grant_date": "2019-07-30",
  "priority_date": "2016-12-26",
  "application_number": "US-201715839136-A",
  "family_id": "60629520",
  "cited_by_count": 2,
  "citations": [
    "US4989161A",
    "US5932980A",
    "US6371218B1",
    "JP2004080973A",
    "US20040113579A1",
    "US9043119B2",
    "US9126378B2",
    "US20120103643A1",
    "US20130090761A1",
    "JP2013257857A",
    "US8975854B1",
    "EP3032735A1"
  ]
}