Servo for translating movement?

Hey everyone,

I’m trying to use a pretty standard hobby servo to drive a linear translating stage for my optical bench

(Z-Translation stage with fine-adjustment screw) … a12f9fdb5#

it doesn’t have to be overly accurate. I’ve tried doing this by removing the internal pot from my servo and replacing it with a linear slide pot of the same resistance. This works fine for positioning but for some reason, as the slide approaches the specified loacation it slows down massively.

Is there a way to stop this slowing of the servo?

or are there any other suggestions on how i can use a servo or other to control this slide? thanks everyone :slight_smile:

Very neat idea!

I ran into the same problem using servos to drive a small robot arm with rotary and linear potentiometers moved out to the arm. The problem seems to be with the servo’s internal control loop. It’s expecting the potentiometer to be moving pretty darn fast, so as it approaches the commanded position it slows way down so as not to overshoot. Since I can’t play with the internal parameters, nor could I make a slight change to the internal gear ratio of the servo, I decided to abandon the motor and gear-train of the servo all together and use its control board to drive a slightly faster, similar torque gearmotor, the Solarbotics GM7 (same specs as the gm6).

I’m about 90% sure this will work from my alligator-clip and holding things together test, and I lathed the final output splines from my servos down to press-fit onto the motors, and I designed new motor mounts, and I went to go cut them out…and the campus shop with a laser-cutter was closed until after 6 that day, and work got busy, and the semester started, and I haven’t done anything about it in four months!

Anyway, if the slow final positioning bothers you, this could speed things up for less $$ than getting a real configurable control system.