Get Using A Fixed-point Digital Signal Processor As A Pid Controller. 2359

Manual PID tuning is done by setting the reset time to its maximum value and the rate to zero and increasing the gain until the loop oscillates at a constant amplitude. (When the response to an error correction occurs quickly a larger gain can be used. If response is slow a relatively small gain is desirable).

To implement the PID controller in the software the continuous Laplace domain equation must be transformed into the difference equation. Once transformed into a difference equation, this equation can be implemented to develop a digital PID controller to control any closed-loop system.

General Tips for Designing a PID Controller Obtain an open-loop response and determine what needs to be improved. Add a proportional control to improve the rise time. Add a derivative control to reduce the overshoot. Add an integral control to reduce the steady-state error. Adjust each of the gains , , and.

Analog PID is limited in complexity. Digital PID can implement more advanced control algorithms. Analog PID controllers are generally cheaper for simple control tasks. Digital PID provides flexibility and precision for complex systems.

These designations refer to the format used to store and manipulate numeric representations of data. Fixed-point DSPs are designed to represent and manipulate integers – positive and negative whole numbers – via a minimum of 16 bits, yielding up to 65,536 possible bit patterns (216).

Analog PID is limited in complexity. Digital PID can implement more advanced control algorithms. Analog PID controllers are generally cheaper for simple control tasks. Digital PID provides flexibility and precision for complex systems.

A PID controller calculates the control signal based on three control terms: proportional, integral, and derivative. To compute the output, the algorithm simply multiplies each of them by a gain and sums these three addends. If a gain is set to zero, the whole term becomes zero.

To implement the PID controller in the software the continuous Laplace domain equation must be transformed into the difference equation. Once transformed into a difference equation, this equation can be implemented to develop a digital PID controller to control any closed-loop system.