AdvancedTopic 71 of 101Signals, Control & Comms
Adaptive control
Controller parameters adjust online.
In depth
Adaptive controllers adjust parameters online to cope with unknown or time-varying plants: MRAC (model reference), self-tuning regulators with recursive identification, gain scheduling. Need persistent excitation; stability proven via Lyapunov; risks from parameter drift and unmodelled dynamics.
Key points
- Parameter estimation (RLS)
- Certainty equivalence
- Dead zone and projection
ExampleAn adaptive controller compensates for payload changes on a robot arm.
What is Adaptive control?
Controller parameters adjust online.
Why is it important to understand adaptive control?
Adaptive control adjusts controller parameters online, so it copes with plants whose behaviour changes over time or with operating conditions.
What is an adaptive controller?
A controller whose parameters are estimated and updated while the system runs, using measured inputs and outputs.
What is the risk of adaptive control?
Parameter estimates can drift or be disturbed by noise, so stability and robustness must be guaranteed by design.
How is Adaptive control used in practice?
Typical applications include adjusting the gains of a controller as an aircraft changes speed and altitude, tuning an engine controller that changes with wear and maintaining performance in a process with unknown or slowly varying gain.
What should I learn before Adaptive control?
Study "Robust control" first (topic 70 of 101 in Signals, Control & Comms). It covers the groundwork this topic builds on.
What are the key points of Adaptive control?
Parameter estimation (RLS). Certainty equivalence. Dead zone and projection.
Can you give an example of Adaptive control?
An adaptive controller compensates for payload changes on a robot arm.
What comes after Adaptive control?
The next topic is "Feedforward and cascade control", which builds directly on this one.
How difficult is Adaptive control?
It is classed as Advanced in Signals, Control & Comms (topic 71 of 101). It is an advanced topic. It assumes you are comfortable with the intermediate topics in Signals, Control & Comms.