Servos

Craig_Anto3 · Post by **Craig_Anto3** » Sun Aug 21, 2005 10:43 am

SCOTT!!!! your not dead!!!! how u been kind sir u gonna come to my AWS

EpicentrE · Post by **EpicentrE** » Sun Aug 21, 2005 12:19 pm

CRAIG!!! No I'm not! just been taking a bit of a break due to antweights consuming all my money

And yup, I should be able to come, I'll let you know nearer the time. Gonna be at RRC on the 10th though so I'll cya then

Still need an answer to my question btw

olivers · Post by **olivers** » Sun Aug 21, 2005 12:24 pm

By disconnecting the red wire you should be fine, it will stop the servo dead. If you disconnect the white signal wire the servo will move to it's default position (if it's not a modified servo).

EpicentrE · Post by **EpicentrE** » Sun Oct 30, 2005 6:45 pm

Just working on void for AWS18. the plan was to have a speed modded S136L running on 12v (3 lipos), to give me a really fast and powerful flip, unfortuntly it seems that the board does not respond fast enough when the servo is speed modified, as it constantly jitters and swings back and forth. For AWS18 I'm just gonna use it with normal gearing, still on 12v, for a slow but powerful flip, but I was wondering, is there any way around this problem, to make the servo controller respond quicker, so it can be fast and accurate? Or are there any commercially available controllers that I could use instead, that would take feedback from a pot, to work just like a normal servo board? Or is it simply not possible to have something respond quickly enough.

Thanks in advance

Simon Windisch · Post by **Simon Windisch** » Sun Oct 30, 2005 6:57 pm

The Solarbotics secret motor driver may be what you need http://www.solarbotics.com/products/ind ... earch_id=8

I have one of these that I couldn't get to work for me, if you'd like to have a go.

Simon

EpicentrE · Post by **EpicentrE** » Sat Nov 12, 2005 7:00 pm

Either I'm missing something Simon, or you misunderstood

I need a controller that will work exactly the same as a standard servo controller (i.e, take input from a PWM signal from an RX and also the position of the potentiometer, and output to the motor) The trouble is the s136L board, while taking 12v quite happily, does not respond quick enough to the changes on the potentiometer, so by the time the controller has realised that the servo arm is where you want it to be, the actual arm has already swung past that point, so the board pulls it back, overshoots the position it's meant to be in again, and just repeats this adinfinitum, meaning the servo output just constantly swings back and forward. So I either need a controller which does respond quick enough, and also can take feedback from the potentiometer, or failing that, if anyone can suggest a way (electrically or mechanically) I could stop this problem happening, I'd be most grateful.

I did try sanding away some of the material on the peice that connects the servo output to the potentiometer, my thinking being that the arm could overswing slightly without moving the pot, so the arm would stop, it didn't work very well at all however. The system would only really work if the output gear was pulling the potentiometer around, instead of pushing it, and it released it once you told it to stop, but again, I can't think of any way of doing that. Damnit

peterwaller · Post by **peterwaller** » Sat Nov 12, 2005 7:15 pm

The problem is that the servo system is set up for the speed of the motor running at 6 volts. At 12 volts you are probably doubling the speed and therefore the system overshoots. It may be possible to alter the damping by changing a resistor value but you would need to get the data sheet for the servo IC.

EpicentrE · Post by **EpicentrE** » Sat Nov 12, 2005 7:52 pm

I think I may have come up with a system using microswitches and diodes to limit the movement so that there is no way the arm can swing past the end point on either end. I need some diodes however, and not being an electrical bloke I have no idea what type I need, They'll need to take 12v and probably no more than an amp. If I can get the system to work I'll post details of it so others can use it in the future.

paul · Post by **paul** » Sun Nov 13, 2005 8:11 am

i know this may sound preaty simple but, just have a metal bar or similar to stop it going past that point, and have it connected to the servo itself so the servo doesnt wiggle free due to the bar.

just a thought, it may not work,
paul

Post by **BeligerAnt** » Sun Nov 13, 2005 8:24 pm

Scott, microswitches and diodes should work, and if you've worked out the required logic correctly, you're most of the way there!

Any standard switching diode will withstand 12V (in the reverse direction), something like a 1N4001 should be fine for your needs. Also they only cost a few pence each.