Electronic – Move servo relative to current position (analog)


I have 3 sensors that feed into a couple of comparators that determine whether to move the servo or not. I used to do the moving with a microcontroller but I need to free some pins badly so I'm trying to accomplish this without software.

The sensor circuit has two output pins that tell me whether to move clockwise or counter clockwise or stop. Take note that this is relative movement, so it doesn't know the current position of the servo. All it knows is whether it should move and in what direction, if further movement is not possible then it should just be ignored.

I thought I could accomplish this by using 555 timers, but I couldn't think of a solution! I reckon I could just use a stepper or an ordinary motor instead but they don't fit on the joint. Is there anyway to accomplish "relative" servo movement with just analog circuits (and without messing the innards of the servo)? Any suggestions?

Best Answer

I still would try to use a microcontroller, that's going to be the easiest solution. Do you plan to remove the sensor inputs and the servo output from the controller? That will give you 4 extra pins. Isn't there a device in the same microcontroller family with a few more pins?

Alternatively you could use a small separate microcontroller to handle the sensor data and servo. That will be more compact, cheaper and easier to control than solutions involving 555s and what mores.