# US 2008/0188985 A1 · Robot control unit for stopping a movement of a robot according to a force detection value detected by a force sensor > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2008/0188985 A1 - Document ID: US20080188985A1 - Status: Published application - Kind: A1 - Application number: 12/010,957 - Filed: 2008-01-31 - Published: 2008-08-07 - Earliest claimed: 2007-02-06 - Assignees: Fanuc Corporation - Inventors: Tetsuro Sakano - Web page: https://patentgrep.com/patent/US20080188985A1 ## CPC - B25J 9/1648: {non-linear control combined or not with linear control} - G05B 2219/39082: Collision, real time collision avoidance - G05B 2219/39325: External force control, additional loop comparing forces corrects position - G05B 2219/39529: Force, torque sensor in wrist, end effector - G05B 2219/49141: Detect near collision and slow, stop, inhibit movement tool - B25J: MANIPULATORS; CHAMBERS PROVIDED WITH MANIPULATION DEVICES ({manipulators specially adapted for use in surgery A61B34/70; manipulators used in cleaning hollow articles B08B9/04}; manipulators associated with rolling mills B21B39/20; manipulators associated with forging machines B21J13/10; {manipulators associated with picking-up and placing mechanisms B23P19/007}; means for holding wheels or parts thereof B60B30/00; {vehicles with ground-engaging propulsion means, e.g. walking members B62D57/02, B62D57/032; devices for picking-up and depositing articles or materials between conveyors B65G47/90, B65G47/91; manipulators with gripping or holding means for transferring packages B65H67/065}; cranes B66C; {manipulators used in the protection or supervision of pipe-line installations F17D5/00; walking equipment adapted for nuclear steam-generators F22B37/006}; manipulators specially adapted for, or associated with, nuclear reactors G21C; {apparatus used for handling wafers during manufacture or treatment of semiconductor H10P72/50}) - G05B: CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS (systems for controlling or regulating non-electric variables G05D; systems for regulating electric or magnetic variables G05F; control devices or systems insofar as characterised by mechanical features only G05G) ## Abstract A robot control unit (10) having a designated speed adjusting means for adjusting a designated speed, which is contained in a robot command program, to a value not more than the designated speed, comprises: a decoding means (38) for decoding a movement stopping command of stopping a movement of the robot (1) according to a force detection value detected by a force sensor (2) attached to a wrist of the robot (1); a movement command means (36) for generating a movement command of moving the robot by the designated speed in the designated direction contained in the program without activating the designated speed adjusting means; a force calculation means (31) for calculating a change in a force detection value from a reference value as a present force value; and a comparison means (32) for comparing a present force value, which is repeatedly calculated at a predetermined period by the force calculation means, with a predetermined force designated value while the robot is moving. When the present force value is not less than the designated force value, the movement command means stops the robot. Due to the foregoing, a force applied from the outside to the robot can be highly sensitively detected and the robot can be highly accurately stopped. ## Claims ### Claim 1 A robot control unit having a designated speed adjusting arrangement for adjusting a designated speed, which is contained in a robot command program, to a value not more than the designated speed, comprising: a decoding arrangement for decoding a movement stopping command of stopping a movement of the robot according to a force detection value detected by a force sensor attached to a wrist of the robot; a movement command arrangement for generating a command of moving the robot by the designated speed contained in the program in the designated direction contained in the program without activating the designated speed adjusting arrangement in the case where the movement stopping command is decoded by the decoding arrangement; a force calculation arrangement for calculating a change in a force detection value from a reference value as a present force value when a force detection value of the force sensor at the time of starting a movement of the robot is used as the reference value; and a comparison arrangement for comparing the present force value, which is repeatedly calculated at a predetermined period by the force calculation arrangement, with a predetermined designated force value while the robot is moving, wherein when the comparison arrangement judges that the present force value is not less than the designated force value, the movement command arrangement stops the robot, and the robot control unit further comprising a stopping position reading arrangement for reading a stopping position of the robot. ### Claim 2 (depends on 1) A robot control unit according to claim 1, further comprising a changeover arrangement for changing over whether the latest force detection value of the force sensor at the time of starting of a movement of the robot is employed as the reference value or the reference value, which was set before, is continuously used without being changed. ### Claim 3 (depends on 1) A robot control unit according to claim 1, wherein when an amount of movement of the robot reaches an amount of the predetermined limitation of movement without an increase in the present force value to a value not less than the designated force value, the robot is stopped and a predetermined processing with respect to the amount of movement of the robot is carried out. ### Claim 4 A robot control unit having a designated speed adjusting arrangement for adjusting a designated speed, which is contained in a robot command program, to a value not more than the designated speed, comprising: a decoding arrangement for decoding a movement command having a force limitation of stopping a movement of the robot according to a force detection value detected by a force sensor attached to a wrist of the robot; a movement command arrangement for generating a command of moving the robot by the designated speed contained in the program to a designated position contained in the program in the case of decoding the movement command having the force limitation by the decoding arrangement without activating the designated speed adjusting arrangement; a force calculation arrangement for calculating a change in a force detection value from a reference value as a present force value when a force detection value of the force sensor at the time of starting a movement of the robot is used as the reference value; and a comparison arrangement for comparing the present force value, which is repeatedly calculated at a predetermined period by the force calculation arrangement, with a predetermined designated force value while the robot is moving, wherein when the comparison arrangement judges that the present force value is not less than the designated force value, the movement command arrangement stops the robot and a predetermined processing is executed for the robot, and when the robot reaches the designated position while the present force value is being maintained at a value not more than the designated force value, the movement command arrangement stops the robot and the original processing of the robot in the program is continued. ### Claim 5 (depends on 4) A robot control unit according to claim 4, wherein when the robot is stopped as a result of the judgment by the comparison arrangement that the present force value is not less than the designated force value, the robot stopping position is compared with a predetermined allowable range and when the robot stopping position is out of the predetermined allowable range, a predetermined processing with respect to the allowable range is executed. ### Claim 6 (depends on 2) A robot control unit according to claim 2, wherein when an amount of movement of the robot reaches an amount of the predetermined limitation of movement without an increase in the present force value to a value not less than the designated force value, the robot is stopped and a predetermined processing with respect to the amount of movement of the robot is carried out. ### Claim 7 (depends on 1) A robot control unit according to claim 1, wherein when the robot is stopped as a result of the judgment by the comparison arrangement that the present force value is not less than the designated force value, the robot stopping position is compared with a predetermined allowable range and when the robot stopping position is out of the predetermined allowable range, a predetermined processing with respect to the allowable range is executed.