4. DISCRETE CONTROLLER DESIGN
In controller design we try to meet some objective. Typical objectives include,
- positioning - for moving from position to position, where the setpoint is changed suddenly
- tracking - for following paths where setpoints are constantly changing
- disturbance resistant - unexpected variations can be compensated for
- multi-stage - for complex systems that need small errors
feed forward disturbance - can reduce effects of disturbances
feed forward command - to follow complex motions
cascade - a controller that examines intermediate steps of a process
typical constraints to be developed are,
- stability - does not diverge over time
- stability - sampling period is short enough (no-aliasing)
- realizable - does not refer to future values
