A kinematic CAD tool for the design and control of a robot manipulator

The correct relationship between two connective joint coordinates of a robot manipulator is defined by four link parameters; one being the joint variable and the other three the geometric values. The basis for all open-loop manipulator control is the relationship between the Cartesian coordinates of the end-effector and the joint coordinates; therefore, the fidelity of the Cartesian position and orientation of the end-effector to the real world depend on the accuracy of the four link parameters of each joint. In this paper, a linear analytic error model describes the six possible Cartesian errors and the four independent kinematic errors from which the Cartesian error envelopes due to any combination of four kinds of kinematic errors can be uniquely determined. From a design standpoint, this error model can be used as a guide to minimize the open-loop kinematic errors of the robot manipulator. Finally, a new calibration technique based on this model has also been developed that can be used to correct the kinematic errors of the robot manipulator.