Cross-Coordinated Control: An Experimentally Verified Technique for the Hybrid Twist and Wrench Control of a Voltage-Controlled Industrial Robot

摘要

Applications for modern industrial robots have generally been limited to low-precision, non-contact tasks, because in practice, it is generally not possible to adequately engineer even a manufacturing environment to a sufficiently high degree of precision such that position control, alone, is adequate. Cross-coordinated control serves to extend that range by providing a practical, experimentally verified solution to the problem of simultaneously controlling both the motion of and the constraint forces acting upon a robot end-effector, which is in contact with a rigid environment. This work provides a semi-empirical method for the hybrid control of a voltage-controlled industrial robot, such that the geometric constraints are explicitly accounted for. The kinestatic analysis was based on a model of the environment using Ball's reciprocal screws to characterize the nature of the constraints. The resulting theoretical development, combined with a laboratory implementation which employed an instrumented, anisotropic, mechanically complaint wrench sensor, resulted in a system that is kinematically, dynamically and kinestatically stable. Consequently, this approach constitutes a general solution to the problem of performing the commonly encountered industrial tasks which, if automated, would require contact between the robot's end-effector and a rigid environment. This method is well suited for implementation as an augmentation, thus permitting the continued use of most existing motion control hardware and software. (jhd)