Experimental Simulation of Manipulator Base Compliance

Many future applications of robotic systems will require manipulators to operate from moving vehicles. Such vehicles will be compliant in comparison to the rigid bases on which most manipulators are mounted today. Base compliance can seriously degrade system performance. Statically base compliance may lead to error in the position of the end effector, and dynamically base compliance may interact with the motion of the manipulator and impair the stability of the system. The accuracy of the manipulator may be improved by modelling the base compliance and compensating for its deflection. Further improvement in accuracy may be achieved by endpoint feedback control of the position of the end effector relative to the task frame. A Vehicle Emulator System (VES) has been developed for experimental investigation of the static and dynamic behavior of manipulators mounted on compliant bases. The VES operates under admittance control and can experimentally simulate a wide variety of linear and non-linear sixdegree-of-freedom compliances. A series of experiments are described that use modelling of the base compliance and end point control to achieve precise positioning of the end effector of a manipulator manipulator mounted on a compliant base.