im working on my first robot project and i need to choose a motor fit for its purpose.
I basically going to rebuild my old mechanical vending machine to take electronical payment.
For this i need a motor witch can turn the the plate with dropout holes for the goods to come out.
This pate have a hole circle on three holes with a 120 degree spacing.
Therefore i need a motor witch can do a exactly 120 degree revolution every time it gets a signal from my visa card device
So my question is: If i choose a stepper witch turn 1.8 degree for every pulse it will take 67 steps to reach a 120.6 degree revolution.
So i would have to make a step back(1.8 degree) for every third operation (3x120.6) to even out the “overstep”
If not my vending machine will eventually not give out goods when its supose too.
As i understand, even if i control with microstepping it will give me overstep.
You could certainly take a backward step, but what I would do is just step 67, 66, 67 for 120.6, 239.4, 360 degrees
I wouldn’t try microstepping The motor isn’t “stable” if power is removed at an in between position.
Depending on the motor and the required torque, you may need to gear down the stepper motor anyway, in which case the problem may go away.
You could also use a gear motor with switches that indicate when it is in the proper position and can cut power (or brake)
Yes. But if power is removed you need some way of knowing where the motor is in its sequence. That is true no matter what step sequence (or motor type for that matter) you use. The normal way is some type of “limit switch”.
