Why do you need controls?
This may seem completely obvious since you are trying to build a self-driving car, but let's cover it quickly.
When you build a self-driving car, what are you trying to achieve? The ultimate goal is to get the vehicle to move from a start position to a destination by commanding actuators such as the steering, throttle, and brakes. Historically, the commands to these actuators have been provided by you, the human driver, via the steering wheel, and the throttle and brake pedals. Now you are trying to remove yourself as the thing responsible for primary driving tasks. So, what do you put in place of yourself? A controller!
What is a controller?
A controller is simply an algorithm that takes some type of error signal and transforms it into an actuation signal to achieve a desired setpoint for a given process. Let's define some of these terms as follows:
