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I need help

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Puzzled

New Member
I am looking for a servo motor controller that has programmable memory. What I need this board to do is this.
Using a simple on/off switch
Example:
Switch is turned to "on"
first servo motor turns continuous for a pre-programmed distance
then stops.
The second motor once the first has stopped starts and turns a specific distance then stops.

When the switch is turned to "off"
The motors reverse there respected courses
(2nd motor starts moves back to start point then stops)
(1st motor then starts, moves back to it's original position, then stops)

The board must remember these motions everytime it is switched on and off. Also I must have speed control. I will be using typical r/c motors.
If anybody can tell me what I need it would be appreciated

Thank you :?
 

crust

Member
If you are using regular RC servos, this is very easily done in a simple PIC or AVR that has eeprom (unless you wont be changing the settings once the part is programmed). The RC moves to a position proportional to the pulse width that it receives from the controller. So when the switch is in position 1, you send out a pulse of t1 width. In position 2, you send out a pulse with t2 width. You can then just store the position in the internall eeprom for later retrieval.
 

Puzzled

New Member
Anybody know where I can purchase what I need?
What I am trying to do is similar to a cnc machine.
(2) axis moves
Thanks again
 

Nigel Goodwin

Super Moderator
Most Helpful Member
Puzzled said:
Anybody know where I can purchase what I need?
What I am trying to do is similar to a cnc machine.
(2) axis moves
Thanks again
An R/C servo only moves a limited number of degrees, presumably for this you will need many revolutions of the motor. Usually you would use stepper motors, or motors with some kind of feedback from the mechanics - counting pulses from an optical or hall effect sensor.

If you do a google search you can find loads of web sites dealing with this subject, one example is at http://www.luberth.com/cstep/.
 

crust

Member
I concur with Nigel, that you cant use RC servos to move a stage on a CNC machine. The easiest way is to use stepper motors to drive linear ball screws (or cheaper threaded rods). Alternatively, you can use regular motor and a distinct encoder (optical, hall-effect, etc) on each shaft in a closed loop system. You would probably need encoders to feedback to your control system anyway. If you use threaded rods, be certain that you get the type with lots of threads/inch as that will give you the best precision. However, they have very high friction since they are not really designed for continuous motion.
 
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