🚀 go-pugleaf

This is a question for stepper motor gurus out there. We recently bought a few
stepper motors with gearboxes from a surplus parts store for a project. We've
been trying to drive the motors and have run into a problem. I've described it
below :

The motor looks like this (from one side)

---------------------------
|         |           |   |
| ||||    | ||||      |   |==== shaft is about ----> axis.
| ||||    | ||||      |   |
--||||------||||-----------
  ||||      ||||
  BWRY      BWRY

The motor has got two connectors on it with 4 wires each, labelled (B)lue,
(W)hite, (R)ed and (Y)ellow. The B and W wires are shorted on each connector.
What we did was to ground the BW wire and pulse the R and Y in sequence. We
found out that the connector on the right drove the shaft forward, while that
on the left drove the shaft backward. We also discovered that the motor would
not run if any combination of the right and left connectors was pulsed. In
other words, we needed to energize the right connector's wires to move forward
and the left connector's wires to go back.

Our problem is that when we apply a torque on the motor shaft, the motor
sometimes starts rotating in the opposite direction!! The torque is pretty high.

Does anyone have any ideas on a better way to drive the motor (I mean
connections, pulse sequence, etc) so that we can develop more torque and
prevent this problem of direction reversal?

Please reply by email to charath@cs.tamu.edu

Thanks

- Charath Ram
  Robotics Lab, Texas A&M University