# US 2019/0168389 A1 · Robot apparatus, control method for controlling the same, non-transitory computer-readable recording medium, manufacturing system, and method for manufacturing an article > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2019/0168389 A1 - Document ID: US20190168389A1 - Status: Published application - Kind: A1 - Application number: 16/181,823 - Filed: 2018-11-06 - Published: 2019-06-06 - Earliest claimed: 2017-12-01 - Assignees: Canon Kabushiki Kaisha - Applicants: Canon Kabushiki Kaisha - Inventors: Kenji Shino - Web page: https://patentgrep.com/patent/US20190168389A1 ## CPC - B25J 9/1694: {characterised by use of sensors other than normal servo-feedback from position, speed or acceleration sensors, perception control, multi-sensor controlled systems, sensor fusion} - B25J 9/0009: {Constructional details, e.g. manipulator supports, bases} - B25J 9/1674: {characterised by safety, monitoring, diagnostic} - B25J 13/088: {with position, velocity or acceleration sensors} - B25J 17/02: Wrist joints - B25J 18/00: Arms - 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}) ## Abstract A robot arm includes a joint and links connected via the joint, a first encoder configured to detect information related to a position of the joint, a second encoder configured to detect information related to the position of the joint independently from the first encoder, and a controller configured to control an operation of the joint. The second encoder includes a scale in which a pattern is formed and a detector configured to detect position information of the joint by reading the pattern of the scale. The controller is configured to, in a case where a reading error occurs in the detector of the second encoder, execute encoder redetection processing of driving the joint of the robot arm on a basis of the detection result of the first encoder and redetecting the position information by the second encoder. ## Claims ### Claim 1 A robot apparatus comprising: a robot arm comprising a joint and links connected via the joint; a first encoder configured to detect information related to a position of the joint; and a second encoder configured to detect information related to the position of the joint independently from the first encoder, the second encoder comprising: a scale in which a pattern is formed; and a detector configured to relatively move with respect to the scale in a case where the joint operates, the detector being configured to detect position information of the joint by reading the pattern of the scale; and a controller configured to control an operation of the joint of the robot arm on a basis of detection results of the first encoder and the second encoder, the controller being configured to, in a case where a reading error occurs in the detector of the second encoder, execute encoder redetection processing of driving the joint of the robot arm on a basis of the detection result of the first encoder and redetecting the position information by the second encoder. ### Claim 2 (depends on 1) The robot apparatus according to claim 1, wherein, in the encoder redetection processing, the controller drives the joint of the robot arm on the basis of the detection result of the first encoder and performs reading of the position information by the second encoder until the detector of the second encoder reads the pattern from the scale without the reading error. ### Claim 3 (depends on 1) The robot apparatus according to claim 1, wherein the second encoder has a function of an absolute encoder, and wherein a driving amount in a case of driving the joint of the robot arm on the basis of the detection result of the first encoder in the encoder redetection processing is set to an amount equal to or larger than a resolution of the absolute encoder. ### Claim 4 (depends on 1) The robot apparatus according to claim 1, further comprising a transmission configured to transmit a driving force from a drive source to the joint, wherein the first encoder is an input shaft encoder configured to detect rotation of an input shaft of the transmission, and the second encoder is an output shaft encoder configured to detect rotation of an output shaft of the transmission. ### Claim 5 (depends on 1) The robot apparatus according to claim 1, wherein at least one of the first encoder and the second encoder has a function of an absolute encoder and a function of an incremental encoder. ### Claim 6 (depends on 1) The robot apparatus according to claim 1, wherein the second encoder has a function of an absolute encoder and a function of an incremental encoder, and wherein, in a case where a detection result of the absolute encoder of the second encoder includes a reading error, the controller drives the joint by using the detection result of the first encoder and a detection result of the incremental encoder of the second encoder and redetects the position information by the second encoder, in the encoder redetection processing. ### Claim 7 (depends on 6) The robot apparatus according to claim 6, wherein, in a case of obtaining the position information after finishing the encoder redetection processing, the controller obtains a value by adding or subtracting an output value, which is detected after the encoder redetection processing has finished, of the incremental encoder of the second encoder to or from the position information detected by the absolute encoder of the second encoder in the encoder redetection processing, and sets the value as position information of the absolute encoder of the second encoder. ### Claim 8 (depends on 7) The robot apparatus according to claim 7, wherein the controller sets the position information detected by the absolute encoder of the second encoder in the encoder redetection processing as an initial value of position information detected by the second encoder after the encoder redetection processing. ### Claim 9 (depends on 1) The robot apparatus according to claim 1, wherein the scale comprises a first track in which pattern elements in which information for specifying an absolute position of the joint is embedded are periodically arranged, and a second track in which pattern elements are arranged in a shorter period than in the first track, and wherein a plurality of the pattern elements of the second track are comprised in a reading range that the detector can read at once. ### Claim 10 (depends on 9) The robot apparatus according to claim 9, wherein, in the encoder redetection processing, the controller repeats an operation of driving the joint by a predetermined amount on the basis of the detection result of the first encoder and reading the position information by the second encoder unless the detector reads the pattern from the scale, and finishes the encoder redetection processing in a case where the detector reads the pattern from the scale without a reading error, and wherein the predetermined amount is equal to or larger than a driving amount corresponding to one period of the first track. ### Claim 11 (depends on 1) The robot apparatus according to claim 1, wherein, in the encoder redetection processing, the controller drives the joint, by using the detection result of the first encoder and teaching point information for controlling a position of the robot arm, aiming for a position of the joint corresponding to a specific teaching point comprised in the teaching point information, and then redetects the position information by the second encoder. ### Claim 12 (depends on 1) The robot apparatus according to claim 1, wherein, in the encoder redetection processing, the controller drives the joint, by using the detection result of the first encoder and teaching point information for controlling a position of the robot arm, stops driving of the joint in a state where the robot arm is on a robot trajectory connecting teaching points comprised in the teaching point information, and redetects the position information by the second encoder. ### Claim 13 (depends on 1) The robot apparatus according to claim 1, wherein, in the encoder redetection processing, the controller drives the joint, by using the detection result of the first encoder and teaching point information for controlling a position of the robot arm, and redetects the position information while the robot arm is moving along a robot trajectory connecting teaching points comprised in the teaching point information. ### Claim 14 A control method for controlling a robot apparatus with a joint connecting links of a robot arm and first and second encoders each configured to detect position information of the joint, the control method comprising: error determination processing of determining whether a reading error has occurred in the second encoder; and encoder redetection processing of, in a case where it has been determined that the reading error has occurred in the error determination processing, driving the joint of the robot arm on a basis of a detection result of the first encoder, and redetecting the position information by the second encoder. ### Claim 15 (depends on 14) A non-transitory computer-readable recording medium storing a program for executing the control method according to claim 14. ### Claim 16 (depends on 1) A manufacturing system comprising: a plurality of manufacturing machines comprising the robot apparatus according to claim 1; and a control system configured to cause the plurality of manufacturing machines to cooperate to manufacture an article. ### Claim 17 (depends on 1) A method for manufacturing an article, the method comprising: a step of preparing a manufacturing system comprising the robot apparatus according to claim 1; and a step of manufacturing the article by the manufacturing system.