Hello Jianghui Xu,
my name is Christoph and I have been in the team that has developed this course. Great to hear that it is helpful to you.
To answer your questions:
We have on purpose given certain inputs to the car, such as a speed reference, gear shift and brake actions, in order to show how it behaves. If you want to assign your own 'driving commands' to the car, please edit the following block (see also figures attached):
- Step function block "Speed reference"
- Signal builder block " GearShift"
- Step function blocks "Front/Rear Brake Force"
Does that help you?