B. Hardware and Sofiware Partitioning and Tradeoffs
The analysis of the system functions and performance and the processor capabilities will permit the designer to partition the functions into modules. It has been proven that the modular design approach provides in general a high flexibility concerning analysis, design, construction, test, and debugging of the system.
The tradeoffs between hardware and software approaches to implement the different functions in a motion control system are done on the basis of performance-cost compromise. Most of the functions can be implemented by software or hardware. By software, processing time allowed to a given function will increase the sampling period resulting in performance decrease. By hardware, additional devices required by the functions will increase necessarily the system complexity and cost. Depending on the complexity of a specific function, the advantages of hardware approach versus software approach are not always evident. In general, hardware implementation is used to reduce the computing load of the CPU. In motion control, several time-consuming complex functions such as coordinates conversion (abc/dq conversion) or PWM modulation can be advantageously implemented using ASIC’s.