Sensor for Stepper Motor

Using Arduino Project Guidance
1

Hi folks..

I'm planning on controlling 4 bipolar stepper motor using RAMPS 1.4. But I will not be making a printer.. I'll be doing different thing(something like position control).. With regards to sensor for stepper motor what can i use best to detect the position of the stepper motor(feedback)..

Thanks,
endl3ss

2

The beauty of stepper motors is that each electrical step moves the rotor the same amount, so you can just count the number of steps sent to the motor.

Many / most CNC machines have limit switches which alert the controller that the carriage is near the end of travel so if it looses track of the position or number of steps it won't try to drive through the stop and damage anything. These can also be used at 'reference' points to reset the position.

If all else fails, use an encoder.

Steve

3

sdturner:
The beauty of stepper motors is that each electrical step moves the rotor the same amount, so you can just count the number of steps sent to the motor.

Many / most CNC machines have limit switches which alert the controller that the carriage is near the end of travel so if it looses track of the position or number of steps it won't try to drive through the stop and damage anything. These can also be used at 'reference' points to reset the position.

If all else fails, use an encoder.

Steve

Okay thanks.. I also plan on using a home sensor.. which is better?.. an encoder or a home sensor?..
When the system starts it turns the motor until it finds the home position.. then i can use this reference point to get repeatable positioning.. So what do you think is better to use?

4

Better depends on the application. An encoder gives immediate feedback if the motor ever slips, but is more expensive and requires more processing and possibly more pins. A simple limit switch is very easy to implement and only needs one pin.

5

A simple limit switch is very easy to implement and only needs one pin.

It has the disadvantage, though, of not providing any feedback along the way that the stepper HAS stepped to the correct position. Depending on how accurate you need to be, position-wise, and how over-engineered your stepper motors and support structure are (i.e. how overpowered your steppers are with respect to the amount of power needed to move the structure), you may NEED encoders to assure that you have indeed stepped the n steps needed to get to position x.