Servos
Moderators: BeligerAnt, petec, administrator
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
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
Scott Fyfe-Jamieson, Captain of Epic Robotics. Champion of AWS38/41/42.
http://www.epicrobotics.co.uk
http://www.epicrobotics.co.uk
- peterwaller
- Posts: 3213
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- Location: Aylesbury Bucks
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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.
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.
Scott Fyfe-Jamieson, Captain of Epic Robotics. Champion of AWS38/41/42.
http://www.epicrobotics.co.uk
http://www.epicrobotics.co.uk
- BeligerAnt
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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.
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.
Gary, Team BeligerAnt
For aws17 Buddy got some new servos, Waypoint - 150 (Now called Bluebird BMS380), which I haden't heard of before. These were a bit tricky to hack to 360 rotation, as one of the gears only had half of it gears. After a bit frustration I came up with some drilling and make my own gearbox out of aluminum.
I advice you to not buy this servo. But I also have a question: Does all these Bluebird servos have the same type of gear, like the one with only half gears?
I advice you to not buy this servo. But I also have a question: Does all these Bluebird servos have the same type of gear, like the one with only half gears?
-
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http://www.jrpropo.co.jp/robot/servo.html
Top servo, it's in Japanese but in English:
DSR8801
size: 32.7?21?40.5mm -
torque: 28.5kg * cm -
speed: 0.14s/60? -
weight: 66g -
largest operational angle: 180 MARU -
Operating voltage: 4v - 9v (7.4v measurement) -
Thats 34Kg/cm at 9V, new pants for me mum.
Top servo, it's in Japanese but in English:
DSR8801
size: 32.7?21?40.5mm -
torque: 28.5kg * cm -
speed: 0.14s/60? -
weight: 66g -
largest operational angle: 180 MARU -
Operating voltage: 4v - 9v (7.4v measurement) -
Thats 34Kg/cm at 9V, new pants for me mum.