Method and system for determination of at least one property of a manipulator

A system (1) for determining at least one compliance property associated with a selected axis of a manipulator (2), the system (1) comprising:

• a manipulator (2) with at least one axis comprising a joint and a linkage connected to said joint;
• at least one actuator configured to actuate the joint via a drive train by means of actuator torque;
• and
• a controller configured to control the manipulator (2), wherein the controller (19) comprises a control unit (20) and a computer readable storage unit (21) comprising instructions configured to:
• (a) make the control unit (20) clamp a movable part of the manipulator (2) to a point in space by controlling the manipulator (2) such that the manipulator (2) attains a clamped kinematic configuration;
• (b) select an identification joint set comprising at least one joint of the manipulator (2), wherein the at least one joint of the identification joint set is configured to control and monitor said selected axis whose associated at least one compliance property is to be determined;
• (c) select an excitation joint set comprising at least one joint of the manipulator (2) which for the clamped kinematic configuration of the manipulator (2) is configured to excite at least one link of the selected axis connected to the at least one joint of the identification joint set;
• (d) select a clamping configuration joint set of the manipulator (2), wherein the at least one joint of the clamping configuration joint set is not part of the identification joint set and the excitation joint set;
• (e) actuate said excitation joint set, such that said selected axis is excited while controlling the clamping configuration joint set such that the clamped kinematic configuration is maintained with the movable part of the manipulator at the point in space;
• (f) monitor one or more quantities related to joint torque and joint position obtained from actuator torque and actuator position for at least one joint in the identification joint set and/or in the excitation joint set;
• (g) determine the at least one compliance property of said selected axis based on the one or more quantities monitored;
• and
• (h) generate a compliance property signal indicating said at least one compliance property.

A computer program embodied in a non-transitory medium (21) readable by a control unit (19), wherein the computer program comprises instructions executable by the control unit (19) to cause the control unit (19) to perform a method for determining at least one compliance property associated with a selected axis of a manipulator (2), wherein said manipulator (2) is configured to be controlled by the controller (19), and comprises at least one axis comprising a joint and a linkage connected to said joint, wherein the joint is configured to be actuated via a drive train by torque from an actuator, the method comprising:

• (a) controlling the manipulator (2) to clamp a movable part of the manipulator to a point in space such that the manipulator (2) attains a clamped kinematic configuration;
• (b) selecting an identification joint set comprising at least one joint of the manipulator (2), wherein the at least one joint of the identification joint set is configured to control and monitor said selected axis whose associated at least one compliance property is to be determined;
• (c) selecting an excitation joint set comprising at least one joint of the manipulator (2) which for the clamped kinematic configuration of the manipulator (2) is configured to excite at least one link of the selected axis connected to the at least one joint of the identification joint set;
• (d) selecting a clamping configuration joint set of the manipulator (2), wherein the at least one joint of the clamping configuration joint set is not part of the identification joint set and the excitation joint set;
• (e) actuating said excitation joint set, such that said selected axis is excited while controlling the clamping configuration joint set such that the clamped kinematic configuration is maintained with the movable part of the manipulator at the point in space;
• (f) monitoring one or more quantities related to joint torque and joint position obtained from actuator torque and actuator position for at least one joint in the identification joint set and/or excitation joint set;
• and
• (g) determining the at least one compliance property of said selected axis based on the one or more quantities monitored.

A computer program product comprising computer instructions stored on a non-transitory computer-readable storage medium (21), wherein the instructions are executable by a computer to perform a method for determining at least one compliance property associated with a selected axis of a manipulator (2), wherein said manipulator (2) is configured to be controlled by the controller (19), and comprises at least one axis comprising a joint and a linkage connected to said joint, wherein the joint is configured to be actuated via a drive train by torque from an actuator, the method comprising:

• (a) controlling the manipulator (2) to clamp a movable part of the manipulator (2) to a point in space such that the manipulator (2) attains a clamped kinematic configuration;
• (b) selecting an identification joint set comprising at least one joint of the manipulator (2), wherein the at least one joint of the identification joint set is configured to control and monitor said selected axis whose associated at least one compliance property is to be determined;
• (c) selecting an excitation joint set comprising at least one joint of the manipulator (2) which for the clamped kinematic configuration of the manipulator (2) is configured to excite at least one link of the selected axis connected to the at least one joint of the identification joint set;
• (d) selecting a clamping configuration joint set of the manipulator (2), wherein the at least one joint of the clamping configuration joint set is not part of the identification joint set and the excitation joint set;
• (e) actuating said excitation joint set, such that said selected axis is excited while controlling the clamping configuration joint set such that the clamped kinematic configuration is maintained with the movable part of the manipulator at the point in space;
• (f) monitoring one or more quantities related to joint torque and joint position obtained from actuator torque and actuator position for at least one joint in the identification joint set and/or excitation joint set;
• and
• (g) determining the at least one compliance property of said selected axis based on the one or more quantities monitored.