US 12,311,538 B2
Method for determining a weight and a center of gravity of a robot manipulator load
Andreas Spenninger, Karlsfeld (DE); and Fangyi Streitel, Munich (DE)
Assigned to Franka Emika GmbH, Munich (DE)
Appl. No. 17/420,017
Filed by FRANKA EMIKA GMBH, Munich (DE)
PCT Filed Jan. 22, 2020, PCT No. PCT/EP2020/051453
§ 371(c)(1), (2) Date Jun. 30, 2021,
PCT Pub. No. WO2020/152191, PCT Pub. Date Jul. 30, 2020.
Claims priority of application No. 10 2019 101 595.2 (DE), filed on Jan. 23, 2019.
Prior Publication US 2022/0088804 A1, Mar. 24, 2022
Int. Cl. B25J 9/16 (2006.01); B25J 19/02 (2006.01); G01G 19/52 (2006.01); G01M 1/12 (2006.01)
CPC B25J 19/02 (2013.01) [B25J 9/1638 (2013.01); G01G 19/52 (2013.01); G01M 1/122 (2013.01)] 20 Claims
OG exemplary drawing
 
1. A method of determining a weight and a center of gravity of a load for a robot manipulator, wherein the robot manipulator is arranged on a base and comprises a plurality of links, the links connected to one another by joints and movable or rotatable relative to one another by actuators on the joints, wherein the robot manipulator further comprises an end effector to grip the load, the method comprising:
gripping the load by the end effector,
moving the load into a number n of distinct static poses, wherein the load is moved into the number n of distinct static poses only by controlling a number k of actuators, with k≤n, wherein the number k is a predefined quantity and the k actuators are arranged on or assigned to k joints that are closest to the end effector;
determining an external wrench Fext for each of the n static poses, wherein a respective external wrench Fest indicates external forces and torques acting on the robot manipulator;
determining, in a base coordinate system, at least components of each external wrench Fext that indicate the external forces, wherein the base coordinate system is a Cartesian coordinate system and arranged in a body-fixed manner on the base of the robot manipulator, and an axis of the base coordinate system is parallel to a gravity vector;
determining a particular estimation of the weight of the load from a particular component pointing in a direction of the gravity vector from among the components of each external wrench Fext that indicate the external forces in the base coordinate system, and from the magnitude of the gravity vector;
determining the weight of the load by averaging respective estimations of the weight of the load for the n static poses;
determining estimations of coordinates of the center of gravity of the load for each of the n static poses based on the weight of the load as averaged and based on the components of the external wrench Fext that indicate the externally acting torques; and
determining coordinates of the center of gravity of the load by averaging respective estimations of coordinates of the center of gravity.