FORC · Lecture 11

Reinforcement learning for feedback control

Simeon Nedelchev

Full notes, practice, and references

Markov decision process

State, action, transition, reward, termination.

J(π)=Eπ∑kγkrkJ(\pi)=\mathbb E_\pi\sum_k\gamma^kr_k

The task definition determines what the policy learns.

Q-learning

Q←Q+α(r+γmax⁡a′Q(s′,a′)−Q)Q\leftarrow Q+\alpha(r+\gamma\max_{a'}Q(s',a')-Q)

True terminal states omit the bootstrap term.

Numerical update

Q=2Q=2, r=−1r=-1, γ=0.9\gamma=0.9, max⁡Q′=3\max Q'=3, α=0.2\alpha=0.2

New value: 1.94

With terminal transition: 1.4

Training and evaluation

Training explores.

Evaluation freezes the policy and uses independent episodes.

Reward design

High return can coexist with unwanted behavior.

Report task success and violations alongside return.

Scope of the practice

A tabular regulation task makes the learning loop inspectable.

Continuous robot policies are the extension.

Reading

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