Introduction to PID control (Kevin Lynch)

For more information, see nu32.org. This video is a supplement to the book "Embedded Computing and Mechatronics with the PIC32 Microcontroller," Lynch, Marchuk, and Elwin. It is part of Northwestern University's ME 333 Introduction to Mechatronics.
L-comp: Explain why the action of the proportional term in the PID control law is similar to a spring.