Behavior:PID Control

PID Control
Type	Behavior (Algorithm)
Requires Capabilities	Any sensing capability that provides error measurement
Enables Activities	Activity:Line Following (smooth), precise position control, speed control
Difficulty	Intermediate
Status	Stub - Algorithm not yet implemented

PID Control is a behavior (algorithm) that uses proportional, integral, and derivative terms to minimize error in control systems.

Overview

This is a stub page. This behavior is not yet implemented in any BRS robot. This page exists to:

• Document the algorithmic concept
• Invite community members to implement it
• Provide a starting point for algorithm design

Required Capabilities

This behavior requires:

• Capability:Line Sensing
• Capability:Optical Odometry

Enables Activities

Implementing this behavior enables:

• Activity:Line Following

Algorithm Outline

PID control is a feedback loop that continuously calculates an error value and applies a correction:

• **P (Proportional)**: Correction proportional to current error
• **I (Integral)**: Correction based on accumulated past errors
• **D (Derivative)**: Correction based on rate of error change

The output is: output = Kp × error + Ki × ∫error·dt + Kd × d(error)/dt

Pseudocode

# PID Controller
error = setpoint - measured_value
integral = integral + error * dt
derivative = (error - previous_error) / dt

output = Kp * error + Ki * integral + Kd * derivative

previous_error = error
apply_output(output)

Implementation Challenges

• **Tuning**: Finding optimal Kp, Ki, Kd values requires experimentation
• **Integral windup**: Integral term can accumulate excessively
• **Derivative noise**: Derivative is sensitive to sensor noise
• **Sampling rate**: PID requires consistent timing for accurate integral/derivative

Contributing

Want to implement this behavior? Here's how:

1. Study the algorithm outline above
2. Implement in your language of choice (MicroPython, C++, Arduino)
3. Test on a robot with the required capabilities
4. Create an Implementation page (e.g., YourRobot:PID Control Implementation)
5. Update this page with algorithm refinements
6. Share working code on GitHub

See Also

• Behaviors - All behaviors
• Capabilities - Hardware required
• Activities - What this enables
• Robotics Ontology - How behaviors fit into BRS knowledge structure