Usual, we just enter the voltage and DC current source to the DC motor, Makes motor can be rotated. If will modify or regulate the speed in rotation of the motor. Wewill need to enter the voltage look into pulses or periodically. Which will makes the average voltage at output is different. By the pulse voltage is high frequency will has the average voltage than the low frequency pulse. The same with the pulse has over duty cycle value, it will has the average pressure much than low duty cycle value.