Level 5 — Control Systems
Feedback, stability, and precise motion
Control systems define how a robot behaves in time. Mechanics decide what is possible, sensors describe what is happening, and control systems determine how the robot reacts.
This level focuses on deterministic control methods used in classical robotics — systems that are stable, predictable, and explainable.
Open-loop vs closed-loop control
Open-loop control sends commands without checking results. Closed-loop control uses feedback to correct errors.
- Open-loop — simple, inaccurate, sensitive to disturbances
- Closed-loop — accurate, stable, responsive
- Feedback is the defining feature of robotics
Control objectives
A control system is designed to achieve a specific objective:
- Position control — reach and hold a target position
- Speed control — maintain constant velocity
- Force or torque control — apply controlled force
PID control
PID controllers are the backbone of classical robotics. They correct errors based on proportional, integral, and derivative terms.
- Proportional — reacts to current error
- Integral — eliminates steady-state error
- Derivative — predicts future error
Proper tuning is critical. Poor tuning leads to oscillation, sluggish response, or instability.
Stability and response
A stable system converges to its target without diverging or oscillating uncontrollably.
- Fast response increases stress and noise sensitivity
- Slow response improves stability but reduces performance
- Control is always a trade-off
Discrete-time control
Digital controllers operate in discrete time steps. Sampling rate directly affects control quality.
- Low sampling rate causes delay and instability
- High sampling rate increases noise sensitivity
- Controller timing must be consistent
Common control problems
- oscillation and overshoot
- slow convergence
- integral windup
- noise amplification
What you should know after Level 5
- why feedback is essential
- how PID control works conceptually
- how stability affects robot behavior
- why control tuning matters more than code complexity
Next: Level 6 — Embedded Logic