Force sensor correcting method

{
  "publication_number": "US9563601B2",
  "country": "US",
  "kind": "B2",
  "title": "Force sensor correcting method",
  "abstract": "The present invention provides a force sensor correcting method which is simple and capable of performing correction, with the force sensor remaining mounted at the end of an arm without an exchange of an end effector. In the present invention, a force sensor 1 of one robot 101 has already been corrected, and a force sensor 2 of the other robot 102 is an object to be corrected. First, hands 3 a, 3 b of a pair of robots 101, 102 are made to abut on each other (abutting step). A detected signal of the corrected force sensor 1 of the one robot 101, generated by execution of the abutting step, is converted into a measured value indicating a force or a moment (measurement step). Based on the measured value obtained in the measurement step, a value indicating a force or a moment acting on the hand 3 b of the other robot 102 due to a reaction generated by the abutting step is obtained (calculation step). The conversion data is updated such that a detected signal, outputted by the force sensor 2 as the object to be corrected of the other robot 102 in the abutting step, is converted into an identical value to the value indicating the force or the moment obtained in the calculation step (correction step).",
  "claims": [
    "1. A force sensor correcting method in a robot system which includes a pair of robots each having an arm and an end effector provided at the end of the arm via a force sensor for sensing a force and a moment, the method comprising: a first abutting step of making the force sensor of the pair of robots abut on each other by activating the pair of robots such that the respective robots have plane-symmetrical postures with respect to a virtual plane; a first measurement step of obtaining a first value indicating a force of the force sensor of one robot and a second value indicating a force of the force sensor of the other robot, generated by execution of the first abutting step; a first correction step of updating a first conversion data of the force sensor of the other robot, which converts the second value into the first value; a second abutting step of making ends of the end effectors of the pair of robots abut on each other and making the force sensors of the pair of robots be spaced away from each other by activating the pair of robots such that the respective robots have plane-symmetrical postures with respect to the virtual plane; a second measurement step of obtaining a third value indicating a moment of the force sensor of one robot and a fourth value indicating a moment of the force sensor of the other robot, generated by execution of the second abutting step; and a second correction step of updating a second conversion data of the force sensor of the other robot, which converts the fourth value into the third value.",
    "2. The force sensor correcting method according to claim 1, wherein concavo-convex units that can be fitted into each other are formed in the respective end effectors, and in the first abutting step, positioning is performed with the concavo-convex units of the respective end effectors being fitted into each other.",
    "3. The force sensor correcting method according to claim 1, wherein in the first and second abutting steps, the pair of robots is imaged, to perform position correction of the pair of robots, and the end effectors of the pair of robots are made to abut on each other.",
    "4. The force sensor correcting method according to claim 1, wherein the force sensor of the one robot is already corrected before performing the force sensor correcting method."
  ],
  "description_excerpt": "The present invention relates to a correcting method for a force sensor mounted in a robot in a robot system.\n\nThere is known an industrial robot system which includes a robot provided with an end effector such as a hand at the end of an arm via a force sensor. In this kind of robot system, in the case of the robot performing assembly of parts, a force or a moment component generated at a wrist portion at the time of an assembly operation is detected by the force sensor, to control a posture of the robot including the hand.\n\nAt the manufacturing stage of a force sensor, variations in output with respect to an external force occur, and hence the output needs to be corrected. Therefore, when the sensor is a six-axis force sensor, respective axes, such as forces Fx, Fy, Fz and moments Mx, My, Mz, are provided with a force by means of weights or the like, to perform correction based on the outputs. This corrected force sensor is mounted on the arm and used.\n\nMeanwhile, when the robot mounted with the force sensor is in use, an excessive load may be erroneously applied, to cause occurrence of plastic deformation or the like, thereby leading to lower measurement accuracy. In that case, what has been done is to temporarily remove the force sensor from the arm and perform a re-correction operation, which requires time and trouble. As opposed to this, there has been proposed one that corrects a force sensor in a mounted state. For example, in Japanese Patent Application Laid-Open No. H11-237296, In PTL 1, first, reference data is previously acquired when the force sensor is normally functioning.",
  "cpc": [
    "B25J 9/1682",
    "B25J 13/085",
    "B25J 9/1692",
    "B25J 9/1694",
    "G05B 2219/39051",
    "G05B 2219/39058",
    "G05B 2219/40586",
    "G06F 17/00"
  ],
  "ipc": [
    "B25J 13/08",
    "B25J 9/00",
    "B25J 9/16",
    "G01L 25/00",
    "G06F 17/00"
  ],
  "assignees": [
    "Canon Inc"
  ],
  "inventors": [
    "Shuuichi Sato"
  ],
  "filing_date": "2011-06-07",
  "publication_date": "2017-02-07",
  "grant_date": "2017-02-07",
  "priority_date": "2010-06-30",
  "application_number": "US-201113704958-A",
  "family_id": "44629212",
  "cited_by_count": 4,
  "citations": [
    "US4620436A",
    "US4699414A",
    "US5021728A",
    "US5162721A",
    "US5693871A",
    "JPH11237296A",
    "US6382012B2",
    "US6711469B2",
    "DE19960482A1",
    "US20050273198A1",
    "US20090105880A1",
    "US8365615B2",
    "US20110084932A1"
  ]
}