US 2022/0088804 A1Published application

Method for determining a weight and a center of gravity of a robot manipulator load

AssigneeFranka Emika GmbH

InventorsAndreas Spenninger, Fangyi Streitel

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Abstract

A method of determining a weight and a center of gravity of a load for a robot manipulator, the method including: gripping the load using an end effector; moving the load into a number n of distinct static poses; determining an external wrench wrench Fext for each of the n static poses; determining, in a base coordinate system, at least components of each external wrench Fext that indicate the external forces; determining a particular estimation of the weight of the load from a particular component pointing in a direction of a gravity vector from among the components of each external wrench Fext that indicate the external forces in the base coordinate system, and from a magnitude of the gravity vector; determining the weight of the load by averaging respective estimations of the weight of the load; 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 or the particular estimation of the weight of the load determined for a particular static pose and based on the components of the external wrench Fext that indicate externally acting torques; and determining the center of gravity of the load by averaging respective estimations of coordinates of the center of gravity.

Claims18

Dependent claims

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 has a plurality of links, and the links are connected to one another by joints and movable or rotatable relative to one another by actuators on the joints, and wherein the robot manipulator has an end effector for gripping the load, the method comprising the steps of:

gripping the load by the end effector;
moving the load into a number n of distinct static poses;
determining an external wrench Fext for each of the n static poses, wherein a respective external wrench Fext 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 imagined to be 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;
determining the weight of the load by averaging the respective estimations of the weight of the load;
determining estimations of coordinates of the center of gravity of the load for each of the n static poses based on the basis of the weight of the load or the particular estimation of the weight of the load determined for a particular static pose and based on the basis of the components of the external wrench Fext that indicate the externally acting torques;
and determining the center of gravity of the load by averaging the respective estimations of coordinates of the center of gravity.

5 more elements

A system to determine a weight and a center of gravity of a load for a robot manipulator, wherein the robot manipulator is arranged on a base and has a plurality of links, and the links are connected to one another by joints and rotatable relative to one another by actuators arranged on the joints, and wherein the robot manipulator comprises:

an end effector designed to grip the load;
a control unit designed to control the actuators arranged on the joints for moving the load into a number n of distinct static poses;
an estimation unit designed to determine an external wrench Fext for each of the n static poses, wherein the respective external wrench Fext indicates external forces and torques acting on the robot manipulator;
and
a processing unit designed to:
indicate at least components of each external wrench Fext that indicate the forces to be indicated in a base coordinate system, 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;
determine 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 in the base coordinate system that indicate the external forces of each external wrench Fext, and from the magnitude of the gravity vector;
determine a weight of the load by averaging respective estimations of the weight of the load;
determine 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 or the particular estimation of the weight of the load determined for a particular static pose and based on the components of the external wrench Fext that indicate the externally acting torques;
and
determine the center of gravity of the load by averaging respective estimations for coordinates of the center of gravity.

8 more elements

Dependencies are inferred from the claim text.

Facts

Application: 17/420,017Filed 22 Jan 2020
Priority: DE 10 2019 101 595.223 Jan 2019
Published: 24 Mar 2022
Term ends: Not estimatedThe source records don’t support an estimate.

Classification9 codes

B25J 19/02
Accessories fitted to manipulators, e.g. for monitoring, for viewing; Safety devices combined with or specially adapted for use in connection…
B25J 9/1638
Characterised by the control loop: compensation for arm bending/inertia, pay load weight/inertia
G01G 19/52
Weighing apparatus or methods adapted for special purposes not provided for in the preceding groups: weighing apparatus combined with other…
G01M 1/122
Static balancing; Determining position of centre of gravity: determining position of centre of gravity