Real-time control of CMU direct-drive arm II using customized inverse dynamics

Real-time control of fast manipulators requires efficient control algorithms to achieve high sampling rates. Practical implementation of the inverse dynamics to achieve high sampling rates demands an efficient algorithm which utilizes the capabilities of modern digital hardware. To reduce the computational requirements of the Newton. Euler (N-E) algorithm for real-time applications, we propose the concept of customizing the algorithm for specific manipulator designs. We analyze the computational requirements of the algorithm for designs incorporating kinematic and dynamic parameter simplifications. We illustrate our approach by customizing the NE algorithm for the CMU DD Arm II (the second version of the CMU direct drive arm). The customized algorithm reduces the computational requirements of the general-purpose algorithm by 56 percent. We also describe the hardware system for real-time control of the CMU DD Arm II and the implementation of our customized algorithm on a Marinco processor and highlight its impact on Manipulator control.