can u help me design this circuit?

I would like to get help on a situation of mine.
I want to design a circuit to measure the speed in rpm of a shaft and then in accordance to the measured value of the speed I would have to operate 3 motors.There is one more constrain to this,the 3 motors will have to be operated in the both directions(forward and backward) in accordance to the speed detected.
Please help me.

I am working on similar project.
More details are appreciated I think you can make one.
I have done after Running motors in both direction, Just need more details on Running 3 motors based on rpm of first motor.
REgards

Either use a microcontroller to measure the speed of the first motor then switch the other motors or if you want to use discrete components use a frequency to voltage converter and some comparators/logic to do the rest.

Does it have a inbuilt hall sensors or any kind of motion sensing?? If not then rpm need to check with the tachometer.
Need to know what kind of outputs are available for you from motors.
Kindly post your motor details. Preferably part number.

yuh can use the counter in any mcu for detecting the rpm and then use the pwm of the same for controlling the speed of the motor. (you may need an mcu having both counter and pwm like at mega 168)