Just give the stock roomba motors 12v , give your h bridge a 12v supply in and pwm panel let's you control speed.

The stock motors are to small for the robot I am making because I am using a tristar wheel system. I want the Roomba to control the 12v power car door motors so it can go back to the charger. I like the way the Roomba when it approches the charger it slows way down so not to crash into the docking station. This tells me that.it.may already have a PWM setup. Thanks for the help this has been a great learning experience for me, just when I think I'm close to understanding things I find another road block.

So I can help better can you explain the.robot. Drawings? What size and weight? The stock roomba motors are said to handle 60 pounds of weight. Are you trying to change the drive.system?

can easy run them at 12 volts,voltage they use is 15 volts yes as i said too they will handle 60 lbs may be more ,because of the gear box on the omnibot 2000 if using in a different robot design the torque will be diiferent

brush motors on the roomba are much more rated torque also on the roomba drive motors if using the complete wheel system is does have encoder i repair and redesign roomba's ,plus repair NEAT XV-11 vacuum cleaners too and have a lot of parts for both i sell on EBAY i made a upgrade for the drive motors to give double the torque

What's this upgrade you made to drive motors for more torque. Do they have stronger motors than the roomba a you sent me?

no.they are not drive motors i sent you,drive motors has less torque and smaller design is using the motors i sent you ,plus changes to the H-BRIDGE

Thanks for.the intel on the motors.