Method of calibrating manipulator, control system and robot system

A control system for calibrating a manipulator of an industrial robot, the control system comprising at least one processor and at least one memory having at least one computer program stored thereon, the at least one computer program including a program code which, when executed by the at least one processor, causes the at least one processor to perform the steps of:

• receiving load data from a load sensor indicative of loads, the load sensor being positioned between a primary tool flange of a primary manipulator having one or more primary joints and a secondary tool flange of a secondary manipulator having one or more secondary joints, where the primary tool flange is rigidly connected to the secondary tool flange;
• controlling the primary manipulator to adopt at least one calibration state;
• for each calibration state, recording a primary joint position of at least one primary joint;
• calibrating the secondary manipulator based on the at least one recorded primary joint position;
• wherein the primary manipulator is controlled to adopt the at least one calibration state based on the load data and/or wherein the calibration of the secondary manipulator is additionally made based on the load data;
• and
• wherein the calibration of the secondary manipulator comprises:
• determining a primary tool center point, TCP, pose of the primary manipulator based on the at least one primary joint position, and based on the load data in case the calibration of the secondary manipulator is additionally made based on the load data, via forward kinematics for each calibration state;
• recording a secondary joint position of at least one secondary joint for each calibration state;
• calculating a calculated secondary joint position of at least one secondary joint based on the primary TCP pose, and based on the load data in case the calibration of the secondary manipulator is additionally made based on the load data via inverse kinematics for each calibration state;
• and
• calibrating the secondary manipulator based on the at least one recorded secondary joint position and the at least one calculated secondary joint position for each calibration state.

A robot system comprising:

• a primary manipulator,
• a secondary manipulator,
• a load sensor, and
• a control system including at least one processor and at least one memory having at least one computer program stored thereon, the at least one computer program including a program code which, when executed by the at least one processor, causes the at least one processor to perform the steps of:
• receiving load data from a load sensor indicative of loads, the load sensor being positioned between a primary tool flange of a primary manipulator having one or more primary joints and a secondary tool flange of a secondary manipulator having one or more secondar joints, where the primary tool flange is rigidly connected to the secondary tool flange;
• controlling the primary manipulator to adopt at least one calibration state;
• for each calibration state, recording a primary joint position of at least one primary joint;
• calibrating the secondary manipulator based on the at least one recorded primary joint position;
• wherein the primary manipulator is controlled to adopt the at least one calibration state based on the load data and/or wherein the calibration of the secondary manipulator is additionally made based on the load data;
• and
• wherein the calibration of the secondary manipulator comprises:
• determining a primary tool center point, TCP, pose of the primary manipulator based on the at least one primary joint position and based on the load data in case the calibration of the secondary manipulator is additionally made based on the load data, via forward kinematics for each calibration state;
• recording a secondary joint position of at least one secondary joint for each calibration state;
• calculating a calculated secondary joint position of at least one secondary joint based on the primary TCP pose, and based on the load data in case the calibration of the secondary manipulator is additionally made based on the load data, via inverse kinematics for each calibration state;
• and
• calibrating the secondary manipulator based on the at least one recorded secondary joint position and the at least one calculated secondary joint position for each calibration state.