# Continous Servo and Action

Newbie here - I have a Parallax continuous servo connected to a Mini 12. My ignorance is due not finding any REAL introductory documentation on the duration/speed/acceleration/delay of servos. My center position of the servo is 1500 with a MIN of 500 and max of 2500. In my mind, if you go ccw XX settings, to back to the starting position, I should just enter the same settings in the cw direction? Right? WRONG.

In Maestro Center I do…

(speed and accelerations are all the same, “0”)
Frame 1 - 1500, delay 500 (center position)
Frame 2 - 1000, delay 500
Frame 3 - 2000, delay 500
Frame 4, 1500, delay 500 (stops rotation)

I’m basically trying to move from CENTER and return. thanks in advance for your help.

Hello,

Are you trying to get a continuous rotation servo to return exactly to its starting position? Continuous rotation servos do not have any feedback, so the best you could hope for is to adjust your frame times to get it to end up approximately where you want. It might also help if you stop the servo in between forward and backward motions so that the situation is more symmetric.

By the way, you described in detail what you tried, but you did not say what happened (except that it was “WRONG”), so it is hard to give you any more specific advice.

-Paul

Paul, thanks for the info. Sorry about the WRONG. Didn’t mean to scream at you - just wanted to be clear.

It makes sense and now that you say it, I recall you answering a similar question. What it did was - my first action took it from 0 to 90 degrees, the reverse action would take it from 90 to 30 degrees (apprx.).

I can accept your answer that the servo gives no feedback, but can you explain why in one direction it gives 90 degrees, but the reverse would only give 60? Same duration/speed/acceleration.

thanks,

Hello,

It is the same duration and acceleration, but the forward motion starts from a stopped position and the reverse motion starts from full-speed forward motion. So it has to spend time to slow down and reverse direction, which could easily take 100 or 200 ms.

That is why I said you could add another 1500 frame: to stop the servo and make the situation more symmetric.

-Paul