Hi,
I am new to Servo and Robotics, with a beginner question:
I have a continuous rotation servo motor, and I’d like to have position encoding. What are cheapest options? Which encoders? Or maybe not to use servo motors at all?
way too wide open of a question. one of the first details is what sort of resolution are you looking for, and the second is if you are talking about simply incremental or absolute encoding. also when you say servo motor are you talking about an r/c servo that has been modified for continuous rotation or some purchased product (which would be most helpful for you to give detail about.)
ok so this is just a standard servo hacked for continuous rotation. cheap but not highly accessible for an encoder.
so some other ideas would depend on the mechanics of your wheels. I am guessing you are using the style of wheel that snaps directly to the servo output spline. would that be correct? if this is the case then possibly one of your best bets will be using alternating black and white pattern and a reflective sensor. this can be made in a graphics program like mspaint, printed on white paper, and glued or otherwise adhered to the wheels. you need to find a sensor and a place to mount it though… something like this could be adapted but you probably need to be able to adjust the LED current and a schmit-trigger input on the transistor output.
This page has some useful information and patterns you may be able to adapt to fit your wheels. They seem mostly to focus on photo-interrupter sensors rather than photo-reflective. The concepts are the same just the sensing technique is different.
On the Seattle Robotics Society workshop robot which uses two modified servos, they use a modified version of: nubotics.com/products/ww02/index.html
To do encoding.
Actually, I studied the links you kindly sent, and I have a problem in position encoding, which i explained how I’m going to solve it, here: washingtonhw.110mb.com/wheelproblem.html
and I made a new post here: lynxmotion.net/phpbb/viewtopic.php?t=4648
would you please continue to support there? I really need it !!! thank you )
Please don’t look at it as a very trivial deal, well this is only the beginning I am going to make a tutorial which ends with an Autopilot
So, helps and supports by giving ideas and so on are very helpful, to the link I gave above. The thing is that, the simple project explained there, is good to start to learn DSP filtering (Kalman) which is a solid basis for other good types of filtering. This ability is very helpful when you go designing an Autopilot.
