resulting in a smoothed phase coherent drive signal that is then down loaded to the dsp 39 s feed forward storage table as the waveform phase generator advances it indexes into the feed forward table as well a similar linear interpolation procedure is used to calculate the intermediate feed forward values which are added to the drive signal in the output stage of the dsp 39 s calculations over time this corrective signal reduces the error to nearly negligible levels without significant operator intervention in certain embodiments the control system of the present invention can be comprised of several subsystems as illustrated schematically in fig4 software running on a pc provides the user interface and manages the databases for the calibration information the waveform ensemble the control loop tuning information and the soft tissue model it also provides the adaptive control algorithm iterative learning control data and control communications between the digital signal processor dsp and pc are carried out over an ethernet physical layer via tcp ip the dsp sub system handles all the real time control and data acquisition tasks a flexible modular arrangement of calculation and control blocks makes it possible to allocate dsp resources to optimally configure the system for different tasks and different simulator hardware scenarios the system is designed to interface with single and multi station simulator machines supporting up to twelve stations of control and data acquisition a multi processor architecture can be used to implement the virtual soft tissue control system to provide real time reliability and future extensibility an ad2181 dsp digital signal processor from analog devices inc can provide the core functionality for the real time control and data acquisition system for coding efficiency a symmetrical implementation of four channels of control can be implemented where each channel provides a.