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, Ki, forcing the vehicle to go a lot faster than intended. Who wants a ride?
To calibrate the PI controller constants, Kp and Ki, we'll use this manual method of keeping Ki to zero and finding the Kp value to where the Throttle signal begins to oscillate.
Then we'll halve the found value and save it into Kp and tune Ki in order to reach the target speed with a minimum overshoot.