Version 1.0, August 31, 2001, Copyright, Hugh Jack 1993-2001

4. DISCRETE CONTROLLER DESIGN

 

· In controller design we try to meet some objective. Typical objectives include,

  1. - positioning - for moving from position to position, where the setpoint is changed suddenly
    1. deadbeat control
    2. first order
  2. - tracking - for following paths where setpoints are constantly changing
    1. first order
  3. - disturbance resistant - unexpected variations can be compensated for
    1. step response
  4. - multi-stage - for complex systems that need small errors
    1. feed forward disturbance - can reduce effects of disturbances
    2. feed forward command - to follow complex motions
    3. cascade - a controller that examines intermediate steps of a process

 

· typical constraints to be developed are,

  1. - stability - does not diverge over time
  2. - stability - sampling period is short enough (no-aliasing)
  3. - realizable - does not refer to future values

 

 

4.1 POSITIONING CONTROLLERS

4.2 TRACKING

4.3 DISTURBANCE RESISTANT

4.4 MULTI-CONTROLLER SYSTEMS

4.5 SAMPLE TIME

4.6 SUMMARY

4.7 PRACTICE PROBLEMS