Validate Gain-Scheduled Control Systems
Tuned gain schedules require careful validation. The tuning process guarantees suitable
performance only near each design point. In addition, the tuning ignores dynamic
couplings between the plant state variables and the scheduling variables (see Section 4.3,
“Hidden Coupling”, in [1]). Best practices for validation include:- Examine tuned gain surfaces to make sure that they are smooth and well-behaved.
- Visualize tuning goals against system responses at all design points.
- Check linear performance of the tuned control system between design points.
- Validate gain schedules in simulation of the full nonlinear system.
Check linear performance on a denser grid of σ values than you used for design. If
adequate linear performance is not maintained between design points, you can add more
design points and retune.Perform nonlinear simulations that drive the closed-loop system through its entire
operating range. Pay special attention to maneuvers that cause rapid variations of the
scheduling variables.Examine Tuned Gain Surfaces
After tuning, examine the tuned gains as a function of the scheduling variables to make
sure that they are smooth and well-behaved over the operating range. Visualize tuned
gain surfaces using the viewSurf command.Visualize Tuning Goals
Use tuning-goal plots to visualize your design requirements against the linear response of
the tuned control system. Tuning-goal plots show graphically where and by how much
tuning goals are satisfied or violated. This visualization lets you examine how close your
control system is to ideal performance. It can also help you identify problems with tuning
and provide clues on how to improve your design.For general information about using tuning-goal plots, see “Visualize Tuning Goals” on
page 10-187. For gain-scheduled control systems, the tuning-goal plots you generate with
viewGoal provide additional information that helps you evaluate how each tuning goal
contributes to the result.11 Gain-Scheduled Controllers