US 12,397,421 B2 · Contact force overshoot mitigation in pneumatic force control devices

Abstract

A force control device mitigates or eliminates impact force overshoot upon contact between a robotic tool and a workpiece. Contact is detected while operating the force control device in a position control mode, according to either of a steady state search method or a transient search method. The force applied to the workpiece upon contact is less than a predetermined setpoint force. Upon detecting contact, the force control device performs a bumpless transfer to a force control mode. In force control mode, the force control device ramps the contact force to the predetermined setpoint. The force ramp may be linear, or along a user-defined trajectory. The stiffness of the force control device is different in position and force control modes, controlled by backpressure in a pneumatic cylinder.

Claims33

Dependent claims

A method of controlling a robotic force control device comprising a robotic tool, comprising:

in a position control mode, positioning the robotic tool along a compliance stroke of the force control device, away from a mechanical stop in the force control device;
reducing a distance between the robotic tool and a workpiece;
detecting contact between the robotic tool and the workpiece;
performing a bumpless transfer from the position control mode to a force control mode in response to detecting contact between the robotic tool and the workpiece;
and
in the force control mode, increasing a force applied by the robotic tool to the workpiece to a force setpoint;
whereby the force applied by the robotic tool to the workpiece at contact is less than the force setpoint.

4 more elements

A force control device having compliance motion and configured to hold a robotic tool and apply the robotic tool against a workpiece with a desired force, wherein at least one of the robotic tool and the workpiece are configured to move so as to reduce a distance between the robotic tool and the workpiece, comprising:

a controller operative in a position control mode to position the robotic tool along a compliance stroke of the force control device, away from a mechanical stop in the force control device;
and
as the distance between the robotic tool and the workpiece is reduced, detect contact between the robotic tool and the workpiece;
the controller further operative in a force control mode to:
increase a force applied by the robotic tool to the workpiece to a force setpoint;
wherein the controller is configured to perform a bumpless transfer from the position control mode to the force control mode in response to detecting contact between the robotic tool and the workpiece;
and
whereby a force applied by the robotic tool to the workpiece at contact is less than the force setpoint.

5 more elements

Dependencies are inferred from the claim text.

Contact force overshoot mitigation in pneumatic force control devices

Life of this patent

Contact force overshoot mitigation in pneumatic force control devices

Life of this patent

Abstract

Claims33