Control device, mechanical system, and time synchronization method

{
  "publication_number": "US11378936B2",
  "country": "US",
  "kind": "B2",
  "title": "Control device, mechanical system, and time synchronization method",
  "abstract": "A control device controls a mechanical device having a movable member driven by a motor. The control device includes a radio signal exchange unit that receives a sensor signal indicating a position, a velocity or an acceleration of a tip part of the movable member, a data acquisition unit that acquires first time-series data of acceleration based on the received sensor signal, a data calculation unit that calculates second time-series data of acceleration at the tip part based on a drive command to the motor, a delay time calculation unit that calculates, when the mechanical device performs a predetermined basic operation, a delay time of the first time-series data to the second time-series data, based on a degree of correlation between the first and second time-series data, and a time synchronization unit that synchronizes time of the sensor part and control device based on the delay time.",
  "claims": [
    "1. A system comprising: a mechanical device having a plurality of motors and a movable member with a tip part; and a control device configured to control the mechanical device, the control device comprising a processor configured to: receive a sensor signal indicating a position, a velocity or an acceleration of the tip part of the movable member of the mechanical device periodically detected by a sensor part arranged to the tip part; acquire first time-series data of acceleration at the tip part of the movable member, on the basis of the position, the velocity or the acceleration in the received sensor signal; calculate second time-series data of acceleration at the tip part of the movable member corresponding to the first time-series data, on the basis of a drive command to one of the plurality of motors; calculate, when one motor, which is arranged closest to the tip part of the movable member to which the sensor part is arranged, of the plurality of motors of the mechanical device is driven to rotate the tip part of the movable member, a delay time of the acquired first time-series data with respect to the calculated second time-series data, on the basis of a degree of correlation between the first time-series data and the second time-series data; and synchronize time of the sensor part and time of the control device, on the basis of the calculated delay time.",
    "2. A control device configured to control a mechanical device having a movable member to be driven by a motor, the control device comprising: a radio signal exchange unit configured to receive a sensor signal indicating a position, a velocity or an acceleration of a tip part of the movable member of the mechanical device periodically detected by a sensor part arranged to the tip part; a data acquisition unit configured to acquire first time-series data of acceleration at the tip part of the movable member, on the basis of the position, the velocity or the acceleration in the received sensor signal; a data calculation unit configured to calculate second time-series data of acceleration at the tip part of the movable member corresponding to the first time-series data, on the basis of a drive command to the motor; a delay time calculation unit configured to calculate, when the mechanical device is made to perform an operation indicated in a program to be executed by the control device at a velocity equal to or less than a predetermined value instead of a velocity indicated in the program, a delay time of the first time-series data acquired by the data acquisition unit with respect to the second time-series data calculated by the data calculation unit, on the basis of a degree of correlation between the first time-series data and the second time-series data; and a time synchronization unit configured to synchronize time of the sensor part and time of the control device, on the basis of the delay time calculated by the delay time calculation unit.",
    "3. The system according to claim 1, wherein the mechanical device is a robot, and the control device is a robot control device.",
    "4. The control device according to claim 2, wherein the mechanical device is a robot, and the control device is a robot control device.",
    "5. A control system comprising: a mechanical device having a movable member to be driven by a motor; and the control device according to claim 2.",
    "6. A time synchronization method for performing, in a mechanical system including a mechanical device having a movable member to be driven by a motor and a control device for controlling the mechanical device, time synchronization between a sensor part arranged to a tip part of the movable member of the mechanical device and the control device, the time synchronization method comprising: a radio signal exchanging step of receiving a sensor signal indicating a position, a velocity or an acceleration of the tip part periodically detected by the sensor part; a data acquiring step of acquiring first time-series data of acceleration at the tip part of the movable member, on the basis of the position, the velocity or the acceleration in the received sensor signal; a data calculating step of calculating second time-series data of acceleration at the tip part of the movable member corresponding to the first time-series data, on the basis of a drive command to the motor; a delay time calculating step of calculating, when one motor, which is arranged closest to the tip part of the movable member to which the sensor part is arranged, of a plurality of motors including the motor of the mechanical device is driven to rotate the tip part of the movable member, a delay time of the first time-series data acquired in the data acquiring step with respect to the second time-series data calculated in the data calculating step, on the basis of a degree of correlation between the first time-series data and the second time-series data; and a time synchronizing step of synchronizing time of the sensor part and time of the control device, on the basis of the delay time calculated in the delay time calculating step.",
    "7. A time synchronization method for performing, in a mechanical system including a mechanical device having a movable member to be driven by a motor and a control device for controlling the mechanical device, time synchronization between a sensor part arranged to a tip part of the movable member of the mechanical device and the control device, the time synchronization method comprising: a radio signal exchanging step of receiving a sensor signal indicating a position, a velocity or an acceleration of the tip part periodically detected by the sensor part; a data acquiring step of acquiring first time-series data of acceleration at the tip part of the movable member, on the basis of the position, the velocity or the acceleration in the received sensor signal; a data calculating step of calculating second time-series data of acceleration at the tip part of the movable member corresponding to the first time-series data, on the basis of a drive command to the motor; a delay time calculating step of calculating, when the mechanical device is made to perform an operation indicated in a program to be executed by the control device at a velocity equal to or less than a predetermined value instead of a velocity indicated in the program, a delay time of the first time-series data acquired in the data acquiring step with respect to the second time-series data calculated in the data calculating step, on the basis of a degree of correlation between the first time-series data and the second time-series data; and a time synchronizing step of synchronizing time of the sensor part and time of the control device, on the basis of the delay time calculated in the delay time calculating step."
  ],
  "description_excerpt": "This application is based on and claims the benefit of priority from Japanese Patent Application No. 2019-098455, filed on 27 May 2019, the content of which is incorporated herein by reference.\n\nThe present invention relates to a control device, a mechanical system, and a time synchronization method.\n\nHigh speed operation of a robot enables to shorten the cycle time thereof, resulting in leading to efficient production. However, as the velocity of the operation of the robot is increased, the tip part of the robot vibrates due to some factors such as insufficient rigidity of a reducer or a robot arm.\n\nThe technique to cope with such a problem has been proposed, in which the acceleration sensor attached to the tip part of the robot detects the vibration during when the robot operates, and learning control is performed so as to reduce the vibration. For example, Patent Document 1 shall be referred to.\n\nIn some cases, an acceleration sensor (hereinafter, also referred to as a wireless sensor) configured to wirelessly transmit a measured acceleration to a control device is used because of the complexity of wiring of the cable connecting the acceleration sensor and the control device for controlling the robot. It is noted that the vibration of the robot is calculated on the basis of the comparison between the command acceleration output by the control device and the acceleration detected by the wireless sensor. This requires that the time of the control device and the time of the wireless sensor are synchronized with each other.",
  "cpc": [
    "G05B 19/4155",
    "B25J 13/006",
    "B25J 13/088",
    "B25J 9/161",
    "B25J 9/1612",
    "B25J 9/1651",
    "B25J 9/1661",
    "B25J 9/1689",
    "B25J 9/1694",
    "G05B 19/414",
    "G05B 2219/34406",
    "G05B 2219/37532",
    "G05B 2219/41298",
    "H04B 7/2678"
  ],
  "ipc": [
    "G05B 19/4155",
    "H04B 7/26"
  ],
  "assignees": [
    "Fanuc Corp"
  ],
  "inventors": [
    "Satoshi Inagaki",
    "Hajime Suzuki"
  ],
  "filing_date": "2020-04-15",
  "publication_date": "2022-07-05",
  "grant_date": "2022-07-05",
  "priority_date": "2019-05-27",
  "application_number": "US-202016849168-A",
  "family_id": "73265046",
  "cited_by_count": 0,
  "citations": [
    "JP2015163416A",
    "US9321178B2",
    "JP2018130800A",
    "US20190383701A1"
  ]
}