Run our first serious simulation

Let's place a Step block in the model, connect it to the Target Goto (whose corresponding From block is connected to the Target speed controller input), and set its Final value to 100 km/h.

Run the simulation and open the Scope block. The speed graph should be like this one:

Quite an overshoot! The vehicle speed reaches almost 150 km/h when the controller closes the throttle. This is due to a too high integral gain, K_i, forcing the vehicle to go a lot faster than intended. Who wants a ride?

Calibrate the PI controller

To calibrate the PI controller constants, K_p and K_i, we'll use this manual method of keeping K_i to zero and finding the K_p value to where the Throttle signal begins to oscillate.

Then we'll halve the found value and save it into K_p and tune K_i in order to reach the target speed with a minimum overshoot.

Calibrating K_p

Prepare the model by setting K_i to zero with this MATLAB command: Ki = 0.

We'll start with an insanely high proportional gain value,...