Class Meeting 03: Sensory-Motor Control
Today's Class Meeting
- Recapping Lab A's exercises: spinning in circles and stopping in front of a wall
- Learning about sensory-motor control and PID control - here's a link to today's slides
What You'll Need for Today's Class
- Your Ubuntu 20.04 programming environment
Sensory-Motor Control and PID Control
The content in this section summarizes the main points covered in today's lecture.
One foundational concept in robotics is sensory-motor loops and control. The robot's sensor readings inform how it moves in its environment, which will then influence the next sensor readings from the robot, and the loop goes on. One of the most well known sensory-motor control methods is PID (Proportional Integral Derivative) control, which is depicted in the block diagram below:
The PID control function can be represented as follows:
Where Kp, Ki, and Kd, are the constant coefficients for the proportional, integral, and derivative terms; e(t) represents the difference between the goal (setpoint) and the sensor measurement (process variable). The three following graphs display how a system responds to a step change in the setpoint to each component of the PID controller separately and all the components combined at different values of Kp, Ki, and Kd.
Response of the process variable to a step change of the setpoint for different values of Kp. Source: Wikipedia.
Response of the process variable to a step change of the setpoint for different values of Ki. Source: Wikipedia.
Response of the process variable to a step change of the setpoint for different values of Kd. Source: Wikipedia.
This YouTube video by Brian Douglas is a great resource providing a clear explanation of the PID controller.
Looking Ahead
In tomorrow's Lab B, you'll have the opportunity to implement proportional control on the turtlebots by programming them to follow a line on the floor.