| High intensity focused ultrasound (HIFU) is one of the prospective new technologies for tumor treatment. Ultrasound transimission property summons the choice of multi postures and large enough workspace for practical HIFU treatment. For this purpose, this paper puts forward a serial-parallel mechanism, and applies it in the studied HIFU prototype machine. The dynamics transmission system and servo system of series-parallel HIFU treatment machine have been setup. The reason for the choice of the key hardware and related application details have been given. What's more, forward and backward kinematics of the parallel part have been studied with respect to the overall serial-parallel HIFU treatment machine structure and dynamic transmission mechanism. Motion control algorithm has been setup on the theoratical basis of above results. Hardware configuration is introduced according to related important I-variables and ACC8S interface connections. Motion control algorithm is implemented on a 2-grade interpolation scheme, where the upper grade PC does the rough interpolation work and the lower grade, PMAC, does the fine one. Pre-Acceleration method is employed and the choice of interpolation time constant has been given in addition to the detail interpolation algorithm. Fine interpolation utilizes the linear movement mode offered by PMAC hardware and post-acceleration method is implemented automatically by PMAC configuration. The software control flowchart has been generalized. The software moduls design and implementation have been introduced from the viewpoint of mult-tasks realtime management. Details have been given for PMAC communication, interrupts implementation under Windows environment, and multi-thread programming under VC environment. In the end, this paper generalizes the overall work and the summary has been given. Existing problems have been analyized and future work has been directed.
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