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I am trying to make one H bridge for four identical motors. I do not want to make more than one H bridge by any means. I got a way to do that but I need your recommendation. I am going to make all the motors in parallel to each other so that the current, that comes from one branch in the H bridge, splits apart to all the four motors.

Specifications:

Each one of those four motors has the following features:

"Voltage:DC 6V
Current:120MA
Reduction rate:48:1
RPM (With tire):240

Motor Weight (g):50
Motor Size:70mm*22mm*18mm"

Purpose of use: Building a small robot that moves with 4 wheels.
Each wheel is with one motor.
Sounds a good idea? Tell me.

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  • \$\begingroup\$ The slightest imbalance in the motors' characteristics will make things... interesting. \$\endgroup\$
    – Ignacio Vazquez-Abrams
    Commented Jun 14, 2015 at 1:40
  • \$\begingroup\$ More information will get more useful answers. What power, what voltages, what application, why 4 motors, how crucial is motor response matching?, ...? | Series resistor per motro will help balance them - OK for small motors. \$\endgroup\$
    – Russell McMahon ♦
    Commented Jun 14, 2015 at 1:43
  • \$\begingroup\$ @Russell McMahon Even without the H bridge, we will get response matching issues and we are gonna fix that. Add to that the H bridge's matching issues ones as well. So, we really need to minimize that for quality purposes. \$\endgroup\$
    – Gold_Sky
    Commented Jun 14, 2015 at 1:54
  • \$\begingroup\$ Imbalance is liable to always exist. The motors MAY track each other on a smooth flat surface but any unevenness in loading will imbalance the distance travelled by each motor. \$\endgroup\$
    – Russell McMahon ♦
    Commented Jun 14, 2015 at 2:26
  • \$\begingroup\$ How do propose to steer your robot? \$\endgroup\$
    – WhatRoughBeast
    Commented Jun 14, 2015 at 2:56

1 Answer 1

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As a general concept I don't see any problems, as long as you don't expect the robot to move in a perfectly straight line. It may well be pretty good, but you seem to be aware of the problem of motor/wheel matching.

And I presume you are aware that the motors on the left side must be wired the reverse of the motors on the right.

When you graduate to differential steering, you will need 2 bridges. Get used to it. Actually, since you are talking about 4 motors I assume you have a 4-wheel vehicle with a motor on each wheel. Be aware that differential steering works very poorly on 4-wheel vehicles.

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  • \$\begingroup\$ I would say as long as you don't expect the robot to move in anything reproducible, and certainly not in a straight line. \$\endgroup\$
    – Wouter van Ooijen
    Commented Jun 14, 2015 at 9:01

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