Robotic system for moving a payload with minimal payload sway and increased positioning accuracy

A method for controlling a robotic system for use with a payload, comprising:

• connecting a compliance mechanism in series with a robot;
• connecting the payload to the compliance mechanism, wherein the compliance mechanism has unactuated joints collectively providing the robotic system with multiple unactuated degrees of freedom (DOF), and wherein the robot includes actuated joints collectively providing the robotic system with multiple actuated DOF;
• measuring corresponding joint positions of the actuated joints and the unactuated joints via a set of position sensors;
• and
• via an electronic control unit (ECU) in communication with the robot and the set of position sensors:
• generating a payload trajectory signal in response to at least one dynamic control input using a trajectory generator block of the ECU;
• applying predetermined damping and stiffness parameters to the payload trajectory signal via an impedance control unit (ICU) of the ECU to generate an initial velocity control signal;
• generating a velocity offset using a stiction compensation block of the ECU;
• applying the velocity offset to the initial velocity control signal to produce a final velocity control signal;
• and
• transmitting the final velocity control signal to the robot to thereby cause the robot to move the payload.

A computer-readable storage medium on which is recorded instructions executable by a processor of an electronic control system of a robotic system, the robotic system having a compliance mechanism connected to a robot and to a payload, wherein execution of the instructions causes the processor to:

• receive corresponding joint positions of actuated joints and unactuated joints of the robotic system from a set of position sensors of the robotic system;
• generate a payload trajectory signal in response to at least one dynamic control input using a trajectory generator block of an electronic control unit (ECU), the at least one dynamic control input including maximum velocities and maximum accelerations of the payload and the robot;
• apply damping and stiffness parameters to the payload trajectory signal via an impedance control unit (ICU) of the ECU to generate an initial velocity control signal;
• generate, using a stiction compensation block of the ECU, a velocity offset as a function of a maximum displacement of the compliance mechanism;
• apply the velocity offset to the initial velocity control signal to produce a final velocity control signal;
• and
• transmit the final velocity control signal to the robot to thereby cause the robot to move the payload.