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.

Abstract: Pressure disturbances in a pneumatic robotic force control device—including force overshoot upon initial contact between a robotic tool and a workpiece—are mitigated by increasing the mass air flow in or out of a pneumatic chamber via one or more force overshoot mitigation air passages formed in the robotic force control device. The force overshoot mitigation air passages may connect the two chambers in air flow relationship, or may allow air flow from a chamber to the exterior. The force overshoot mitigation air passages may have a static or variable effective area. The optimal area may be calculated based on measured flow rates and pressures during typical use cases.

Abstract: Force and torque measurements from a robotic F/T sensor are compensated for the effects of gravity, and optionally additionally for the effects of robot motion. The weight of an attached tool Wtool, and a vector {right arrow over (r)}CG from the F/T sensor body CF origin to a center of gravity of the tool are obtained, such as from user input or by parameter identification. During a robotic operation, a rotation matrix RInternational CFBody CF from the F/T sensor body CF to an inertial reference frame is obtained, such as from an internal inertial measurement unit (IMU), or from forward kinematics data from the robot. The force and torque measurements resolved by the F/T sensor from transducer outputs are compensated for gravity based on the Wtool and {right arrow over (r)}CG, and the instantaneous value of RInternational CFBody CF.