Lateral controller is not cascaded P-P, but PD controller

[fabianlischka]

In the solution, in the function lateral_position_control in controller.py, the target velocity_cmd is computed and limited, but then ignored, and a bog standard PD controller applied to acceleration (without velocity limit).

I think this

acceleration_cmd = acceleration_ff + \
                            self.Kp_pos*(local_position_cmd-local_position) +\
                            self.Kp_vel*(local_velocity_cmd-local_velocity)

should be replaced by

acceleration_cmd = acceleration_ff + \
                            self.Kp_vel*(velocity_cmd-local_velocity)

[fabianlischka]

Though, then the commanded velocity local_velocity_cmd is entirely ignored.

I think the lesson/instructions should be adapted a bit here -
if I interpret this correctly, a cascaded P-P controller is suitable when you want to control a position given a commanded acceleration with limits on the velocity, but a PD controller is suitable when you want to control a position given a commanded acceleration and a commanded velocity. How limits on acceleration/velocity interact with this could be elucidated a bit more (windup?).