DC Motor Controller Problem

I am trying to meke a Robot which can make a 360 rotation with 4 motors. I am trying to make backward motors and forward motors act
simultaneously . But when I do that then battery gets short circuit and creates spark. Can anyone suggest circuit for this or any other solution ???
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Are you using windshield wiper motors or some other type of automotive motor? Is your chassis metal(conductive to electricity)? These types of motors and others are grounded to the body of the motor. So, when you run two of the motors at different directions you will have a short across the body of your robot.
If this is the case you will have to find a way to electrically insulate the motors from the chassis.
I built a sumo robot a few years ago that used windshield wiper motors for the drive and had this problem. I ended up mounting the motors with nylon screws and rubber washers.
Joe Mckibben
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