# US 5,907,229 A · Method and device for calibration of movement axes of an industrial robot > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,907,229 A - Document ID: US5907229A - Status: Granted - Kind: A - Application number: 08/930,008 - Filed: 1997-09-29 - Granted: 1999-05-25 - Earliest claimed: 1995-03-30 - Assignees: Asea Brown Boveri AG - Inventors: John-Erik Snell - Web page: https://patentgrep.com/patent/US5907229A ## CPC - B25J 9/1692: {Calibration of manipulator} - G05B 2219/39025: Spheric tool interrupts transmitted calibration beam, in different configurations - 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 method for calibration of an industrial robot is provided. A calibration device comprising devices for emitting a calibration beam within the working range of the robot, and an interruption detector which detects an interruption in the calibration beam are arranged. During the calibration process, a calibration tool supported by the robot hand and comprising a sphere with a known radius is moved towards the calibration beam. When an interruption in the calibration beam is detected, the output signals from the position transducers of the robot axes are read and stored. This process is repeated a plurality of times with different configurations of the robot. Thereafter, the calibration parameters of the robot are calculated based on the kinematic equations of the robot, the read and stored position transducer signals, and the known radius. ## Claims ### Claim 1 A method for calibration of an industrial robot which has a plurality of movement axes (A1-A6) with a position transducer for each of said axes adapted to supply an output signal which defines the current position of the axis, a robot hand for supporting a tool, and a control system for controlling the position and orientation of the robot hand in accordance with a program, wherein a number of calibration parameters for the robot are determined by the following steps: a) providing the robot with a calibration tool, supported by the robot hand, comprising a sphere with a known radius (r), b) providing a member adapted to transmit a calibration beam within the working range of the robot, and a member connected to the control system which detects an interruption in the calibration beam, c) running the calibration tool towards the calibration beam, d) reading and storing the output signals from the position transducers of the robot when an interruption in the calibration beam is detected, e) repeating steps c) and d) a number of times at least equal to the number of calibration parameters plus two and with different configurations of the robot, f) calculating the calibration parameters based on: 1) the kinematic equations of the robot, 2) a model of the relationship between axial position and position transducer signal, 3) the read and stored position transducer signals, and 4) the known radius. ### Claim 2 (depends on 1) A method according to claim 1, wherein the calibration beam is arranged parallel to a plane (xY' xz, YZ) in the robot base coordinate system. ### Claim 3 A calibration device for determining calibration parameters for an industrial robot which includes a plurality of movement axes (A1-A6) with a position transducer for each of said axes adapted to supply an output signal which defines the current position of the axis, a robot hand for supporting a tool, and a control system for controlling the position and orientation of the robot hand in accordance with a program and adapted to receive the output signals of the position transducers the calibration device comprising: a calibration tool provided with a sphere having a known radius (r) and adapted to be supported by the robot hand, a member for transmitting a calibration beam within the working range of the robot, a member for detecting an interruption in the calibration beam for connection to the control system and for initiation of reading and storage of the output signals from the position transducers of the robot, and calculating means adapted to calculate a number of calibration parameters based on: 1) the kinematic equations of the robot, 2) a model of the relationship between axial position and position transducer signal, 3) the read and stored position transducer signals, and 4) the known radius. ### Claim 4 (depends on 3) A calibration device according to claim 3, wherein the calibration beam consists of a light beam.