2. The numerical range should be determined according to specific requirements. Generally, the proportional link will be larger, which can be compared with two digits and three digits or across orders of magnitude. Moreover, the adjustment of the proportion link is generally carried out in the first step, before integration and differentiation; The integration link is mainly to eliminate the steady-state error. Generally, choose the speed regulation of teaching institutions within 10, and practice in other cases. Differential is mainly used to control overshoot, and its value range is similar to that of integral link. Generally, assume kp first, then keep kp unchanged, and then adjust ki and kd in combination to eliminate steady-state error and reduce overshoot, which can be determined according to your motor power.

3. As a sensor, photoelectric encoder provides feedback signal, so it can be used.

4. I have only done fuzzy control to get the lookup table according to the control rules, and I have not done PID, so there is no way.