[Lyapunov Analysis](https://kaikwan.notion.site/Lyapunov-Analysis-6eaf32b27d1744fa8f7f369ca59fab36) (TODO)
[Trajectory Optimization](https://kaikwan.notion.site/Trajectory-Optimization-417e509dcf254519aa33730ae02bab5e)
Open-loop control system - no feedback
Closed-loop control system - with feedback and gain
An Introduction to Types of Closed-loop Motor Control - Technical Articles
RL is just control but ML
Double integrator - classic ode example
$\ddot{q} = u, \quad |u| \le 1$
some notation - u is effort/force, x is full state
To drive the double integrator to the origin, we can have the following objective
quadratic cost: exponential approach to the goal
minimum-time: arrive at the goal in finite time
Say we decide a point to apply the brakes to arrive at the origin