US 8,601,897 B2Granted

Force limiting device and method

AssigneesGM Global Technology Operations LLC, Universite Laval

InventorsNicolas Lauzier, Clement Gosselin, Dalong Gao, Martin Grenier, Robin Stevenson

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Abstract

The present invention relates to a method and apparatus for limiting the contact force between a moving device and another object, using a parallel mechanism and torque limiters where the threshold force to activate the force limiting mechanism is not related to the configuration of the moving device or the location of the contact force relative to the activation point of the force limiting mechanism, and where the mechanism may be configured for one, two or three degrees of freedom. A counterbalance mechanism is also provided to counteract gravity load when the force limiting mechanism is configured for three degrees of freedom and responsive to contact forces including a vertical element. In particular, the invention relates to a method and apparatus for limiting the contact force between a moving robotic device and a contactable object.

Claims14

Dependent claims

A force limiting device attachable to a moving object and configured to limit a contact force of the moving object with a contacted object, the device comprising:

a first attachable portion defining a first end of the force limiting device and including an interface configured to fixedly attach the first attachable portion to the moving object;
a second attachable portion defining a second end of the force limiting device and including an interface connectable to a suspended portion;
a parallelogram linkage including two legs;
wherein each leg is rotatably connected to the first attachable portion and to the second attachable portion;
and
a torque limiter including an input shaft in communication with the parallelogram linkage;
wherein the torque limiter has an activation torque and is configured to be activated from a non-activated state to an activated state when an input torque transmitted through the parallelogram linkage to the input shaft exceeds the activation torque;
wherein the torque limiter in the non-activated state restrains rotation of the legs relative to the first attachable portion and the second attachable portion to define a fixed orientation between the first attachable portion, the second attachable portion and the legs;
wherein the torque limiter in the non-activated state prevents movement of the second attachable portion relative to the first attachable portion when the input torque transmitted to the input shaft is less than the activation torque;
and
wherein the torque limiter in the activated state releases the legs to passively rotate relative to the first and second attachable portions to decrease the contact force between the moving object and the contacted object in response to the input torque defined by the contact force transmitted through the force limiting device.

8 more elements

A robot system configured to be movably attached to an overhead suspension, the robot system comprising:

a robot configured to be movable relative to the overhead suspension;
a suspended portion movable by the robot toward an object;
a force limiting device fixedly attached at a first end to the robot and at a second end to the suspended portion;
the force limiting device activatable at an activation level;
wherein:
the force limiting device includes a parallelogram linkage rotatably attached to the first end and the second end of the force limiting device;
the parallelogram linkage is activatable from a non-compliant state to a compliant state by activation of the force limiting device;
the parallelogram linkage in the non-compliant state is fixed in a first position relative to the robot and the suspended portion to rigidly attach the robot to the suspended portion;
the parallelogram linkage in the compliant state is passively moveable from the first position to a second position such that in the second position the suspended portion is compliantly attached to the robot by the force limiting device;
wherein the suspended portion is configured to exert a contact force against the object when the suspended portion is moved into contact with the object
and upon contact immediately transmit an activation force opposing the contact force to the force limiting device;
wherein the force limiting device is configured to prevent movement of the parallelogram linkage from the first position when the activation force is less than the activation level;
wherein the force limiting device is activated when the activation force transmitted to the force limiting device exceeds the activation level;
and
wherein the force limiting device when activated activates the parallelogram linkage from the non-compliant state to the compliant state to decrease the contact force exerted against the object by the suspended portion.

12 more elements

Dependencies are inferred from the claim text.