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you'll need to know how many degrees per step the motor is capable of
and you'll need to know the ratio of the worm gear
for the software i mite have some stuff i wrote a long time ago that will do what you want it to I'll have to check
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Hi there, I figured I would post this over on this forum because the people here actually work with this kind of stuff(although probably more machine related).
What I am trying to do is make an elevation control for a ham radio antenna system. The antennas need to be able to rotate at least 90deg, and the rotation speed of the boom should be about 1rpm (or, more specifically, 90deg in 15 seconds). I cant have it set up to where I push a button to rotate the antennas and it spins around 3 times
Can you guys give me some insight as to controlling a stepper motor for this application? I Want to have at least 1 worm gear drive in the system so the antennas stay put where they are moved. 2 worm gears would probably be the best option.
I would like the display to show degrees of elevation rather than decimal numbers and have "limit switches" set for 0deg and 90deg so I cant over rotate the array. I am guessing that the control parameters would all be set up with a computer program, right? So I would just have to have a way of reading the steps and then have a formula to convert the step count to degrees. That seems simple enough. Is there a way to figure out the calculation and then build a control box for the steppper motor that doesnt need a computer?
The array is not going to be very big, and it will be ballanced so it wont take a whole lot of force to move. Gearing it down to 1rpm will give me more than enough torq I would say. What kind of stepper motors should I look at? I saw the ones on the hobby cnc site that were 200oz or so of torq. With this geared down to a 1rpm final drive that would probably do the trick.
Steve
you'll need to know how many degrees per step the motor is capable of
and you'll need to know the ratio of the worm gear
for the software i mite have some stuff i wrote a long time ago that will do what you want it to I'll have to check
DC motor hooked up to the worm with a potentiometer sensing angle.
Use the same type of potentiometer as the control.
Subtract the two wiper voltages for an error signal, amplify, integrate and sum for a PI loop. Use a BJt push-pull pair to drive the motor from the summing amp.
Take the wiper voltage from the antenna pot and scale/offset to 0-900mV in order to use a cheap panel meter for display.
Aaron
Aaron, thanks for the tip on the pots. I have heard of that done before, but I figured it would be more difficult to set that up for computer control.
Are there any good single stepper motor control boards that would fit this application? And can I store a program withen those boards, or do they strictly take the input from a computer and transfer that into the code that controls the motor?
holbieone, what kind of program(s)? Would it be a simple matter of entering in a formula for converting steps to degrees and giving it an upper and lower limit? Or is there anything more involved in it?
Steve
you can use a basic stamp to control the board
I haven't played with these - yet.
http://www.phidgets.com/index.php
But seems like it could almost be plug and play. 'Spose you want the readout (they have LED modules too) to get good azimuth/elevation? de KF4JQB - let me know your solution when you get it sorted - pm or via winlink...
Jim
Experience is the BEST Teacher. Is that why it usually arrives in a shower of sparks, flash of light, loud bang, a cloud of smoke, AND -- a BILL to pay? You usually get it -- just after you need it.
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