Realtime wireless motor rotation using handheld encoder system.

theonlypsycho

Hello,
I'm new to the forum but have been using BS for a few years now. The title may have not made my project clear but this is it:

I need to build a handheld controller which is powered by battery and not connected to a computer, for the beginning the controller will have a knob to control a motor movement, the control will be 1-1, meaning that the amount a rotate the knob on the control the same amount will reflect on the motor, and it must be bi-directional, think of it as a knob that turns a wheel...but wireless. The precision of this system must be really high and realtime, the distance between the handheld controller and the motor controller will be max 10 meters so the fastest available link with the lowest power consumption can be used, which I presume is Wifi.

My main question is: which is the best solution for the knob part, a rotary encoder or is there something better?

Any help will be appreciated!

W9GFO

theonlypsycho wrote: »

Hello,
I'm new to the forum but have been using BS for a few years now. The title may have not made my project clear but this is it:

I need to build a handheld controller which is powered by battery and not connected to a computer, for the beginning the controller will have a knob to control a motor movement, the control will be 1-1, meaning that the amount a rotate the knob on the control the same amount will reflect on the motor, and it must be bi-directional, think of it as a knob that turns a wheel...but wireless. The precision of this system must be really high and realtime, the distance between the handheld controller and the motor controller will be max 10 meters so the fastest available link with the lowest power consumption can be used, which I presume is Wifi.

My main question is: which is the best solution for the knob part, a rotary encoder or is there something better?

Any help will be appreciated!

A potentiometer and a pair of XBees would work, if the knob does not need to turn continuously.

Describing the needed precision as "really high" is not helpful. Can you quantify what precision you need?

theonlypsycho

Hi, thanks for the reply, this system will control the focus of a videocamera lens, which means the movement will usually be really slow, and sometimes just a few degrees of the knob, thouse I believe it must be continuously rotating pot, since the one turn of the motor gear is not nearly enough to turn the focus ring all the way from min focus to infinity, of course if the ratio could be adjusted using another liner pot and not only by using a small gear on the motor that would be great. About the XBee, cause this won't be the only motor controlled and there may be other data received and sent will the XBee be fast enough? Also after searching a lil bit I'm in doubt if a servo will be the best motor or a stepper motor, the only limitation of the motor system is that it must not be bigger that 8-10 by 2-4cm, without including the motor controller which will the a separate box.

LoopyByteloose

If you want extreme accuracy at both ends, you should use a rotary encoder for your input and a stepper motor to drive the lens focus. I suspect the XBees are fast enough for you. And using a 10 turn poteniometer might be adequate instead of a rotary encode (this would make the input side an eaiser build).

Regarding speed, the eye doesn't see much faster than 1/30th of a second frame, so having a communications rate of the serial interface that is something like 19200 Baud is going to be able to respond faster than you can see or physically move.