cruise control for atv

I have a quad bike that I  use for watering our garden. I find it quite tiring to keep the speed of the quadbike constant. At times i find that some parts of the garden have more water sprayed on than others. I was advised to buy a cruise control unit to keep the speed of my quadbike constant but I find these units too expensive. Luckily I have a little experience in microprocessors and electronics so I thought of building a cruise control unit myself. If their's anyone that did this before and could give me advice on building my own unit it would be very much appreciated.

Thank you.

C 

It shouldn't be too hard to do with a uC.

Set up an external interupt and connect it to the vehicle speed sensor.  If you don't have a sensor you can add a magnetic switch to the driveshaft (has to be the output shaft otherwise it won't work).  For low speed applications it may require two magnets 180 degrees from each other.

Every time the switch pulses record the frequency - this is the speed you need to meet.

Use a PID loop with the VSS frequency set as the control input.

Then you'll need some sort of linear actuator that will be driven by the control output of the PID loop.  The linear actuator will connect to the throttle.

Not a bad project to keep you busy for an evening.