Wednesday, August 19, 2009

Auto Car 05 - Output DC Motor

This is going to be a short post because it is a simple actuator. A Direct Current Motor (DC Motor). DC motor is a transducer to transfer from electrical energy to kinetic energy.

DC Motor consists of 2 pin. If you put one pin with + voltage and another with 0 voltage, it will turn one side and if you reverse the poles, it will turn the other side. Simple.

Another concept of DC Motor is the speed. If you want the speed to be faster, just put in more voltage. Ideally you can put as much voltage to a DC Motor to produce very high speed.

If you put the voltage to a certain voltage (we put it as D volts), it will produce S radian per seconds (rad/s is a unit for angular speed). If we put D volts but there is a load, it will produce a speed less than S rad/s, the motor will keep on drawing more and more current until it reach S rad/s.

Therefore, if the load is significantly large, if you still put D voltage, the motor still won't move but it will keep on drawing current. If the voltage is increased, until a threshold, the current will be very large and the motor will burn.

The nature of a DC motor to reach the required speed according to the voltage given by drawing more current is considered an Integrator.

In the auto car, we will control the direction and speed. Direction can be controlled by a motor driver and speed will be controlled by PWM.

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