Motor control

From CandyFabWiki

(A broad topic indeed.) There are three main types of motors applicable to cnc:

• Steppers
• Servos
• Dc Motors

All three have different control schemes, as detailed below.

[edit] Steppers

Stepper motors have two or more coils, and the most common types are unipolar and bipolar. They require a special stepper controller board, such as one of those offered by www.hobbycnc.com. Another common solution is to construct a controller with two h-bridges. Steppers are the most commonly used motors for cnc applications, therefore options to control them are quite common.

[edit] Servos

Servo motors are perhaps the easiest type to control, as most of the circuitry is built into the motor. They have three pins, V+, Gnd, and control. V+ and Gnd are connected to a 4.5-6.0 volt power supply, and control is connected to a pwm port of a micro controller. They are easily controlled with the servo libraries available with the arduino. Servos are not a common option for CNC, as their motion is extremely accurate, although their accuracy makes them desirable for some aspects.

[edit] DC Motors

DC Motors are controlled with an H-Bridge, a series of four transistors which allow the voltage to either of the pins to be reversed. They are generally inaccurate, and need some sort of feedback to be useful. They are very dificult to get accurate enough for delicate cnc due to their high inertia and low precision. (This article is a stub. Please help us to improve it.)