Hi Steve,
I agree with Russel that a micro would do exactly what you want. I would use the LMD18200 H-bridge with 3A max current. Voltage control using PWM so you can vary the speed of the motor. I could make you a functional 'controller' (PCB design, micro codes, etc) but I'm half way across the world from you :-(
BTW, how fast you want this?
Can you get someone to assemble the board and program a PIC microcontroller?
Regards,
Basir
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