Set Line Tracking Speed and PID
Function:

Description: Set line tracking speed and PID
Parameter:
- speed: line tracking speed. data type: float; range: 0~30 cm/s
- Kp: value of p (proportional). data type: float; recommended value: 0.5
- Ki: value of i (integral). data type: float; recommended value: 0
- Kd: value of d (differential). data type: float; recommended value: 0.5
- Return: null