I'd do it with just an arduino/stepper driver or shield/ir receiver/few resistors
read the IR codes and drive a stepper or other suitable motor.

 

Back to linear code strip. Seems like plenty of room for a nice wide code strip, 6 bits for coarse location, repeating patern of 4 bits for vernior control of 2 in segments. Coarse stops motor, fine, burps motor, say 250 ms on 250 off untill final position is reached, maybe 2 to 3 sec.
How far does curtain move after moter shutdown, guessing less than 2 in ??
Could use DIP SW's to prigram stops, then remote only needs to address the registrars.

 

No need to divide up the code, if motor overruns address, comparator sais go back; with just a few jiggles,& motor will be going slower at each giggle, it will be on the mark. If tolarance is loosend to 3/8 in or 1 cm, then only 8 bit 's of comparator & 8 bit DIP's will be needed.

 

bertz, I want to thank you for giving me a nice option to look at here for the pick and place machine I want to build. That motor is awesome to say the least! Sorry I know this post was not related to the question, I just had to comment.

 

It seems to me that the solution to your problem is pretty straightforward and there is no need to re-invent the wheel.

Step 1. Convert your electro-mechanical system to a DC servo motor with a rotary encoder. What does this accomplish? First it has gobs of torque; second, the encoder allows the system to "memorize" the locations where you want the mask to stop. If it overshoots, it will correct itself. If someone tries to move it, it will resist. DC servo motors can be a little pricey compared to AC gearmotors or (UGH) stepper motors, but you don't need to take out a second mortgage. Also, some good can be had on e-bay. As I said, there is no need to re-invent the wheel here. DC servo motors have been the basis for machine tool motion control for a long time.

http://www.teknic.com/products/clea...=27793230486&gclid=COzU647zzLwCFSzNOgodvS8A_A

Step 2. How to control this sucker. The motor is supplied with a control package which includes a thing we refer to as a "drive". Now most of the drives I have come across have either a 0-5 or 0-10 VDC control input for speed and a feedback loop using the encoder for position control. Typically we used to control these bad boys with a PLC, but we have used a windows based PC with a special "servo" card for control.

http://www.automationtechnologiesin...axis-cnc-usb-card-mach3-200khz-breakout-board

There is no reason why a PIC based microprocessor could not be interfaced with the USB servo card. Hardware and software could easily be incorporated to include an IR decoder based on the Sony SIRC protocol. Thus you could use any after market remote to control your system. Then all you have to do is program in your stops, and after a little trial and error your good to go.

Good luck

Al

P.S. I don't do this anymore, I'm happily retired and more interested in catching fish and flying model helicopters.

Done a little looking into this as it seems like a good idea. I haven't researched hard but I have a couple of questions.

1) Seems most of these are not up to the torque specs I require, min of 70 inch pounds. I did find a couple.

2) The ones I find that meet my torque say rated at say 970 rpms. Well the max I want is around 20 rpms, so will it make that torque at such a slow speed

3) when you say it will resist movement I assume that it is using some amount of power at all times to resist. This will be on 24/7 but I don't want it costing me money to leave on all the time. What I have now only uses power when it is activated.

 

The set up you show, shows a timing belt coupling, it would easy at this stage to include some gearing by pulley ratio, even 2:1 reduction increases your torque X2.
The rpm demands of your app is minimal.
One of the main reasons for reduction, is to economize on motor and drive costs.
Max.

 

Done a little looking into this as it seems like a good idea. I haven't researched hard but I have a couple of questions.

1) Seems most of these are not up to the torque specs I require, min of 70 inch pounds. I did find a couple.

2) The ones I find that meet my torque say rated at say 970 rpms. Well the max I want is around 20 rpms, so will it make that torque at such a slow speed

3) when you say it will resist movement I assume that it is using some amount of power at all times to resist. This will be on 24/7 but I don't want it costing me money to leave on all the time. What I have now only uses power when it is activated.

As maxheadroom says, speed is not a critical requirement here, so you can gear down to whatever speed you require. However as you gear down, you multiply the torque. So let's say you put a 40:1 reducer on that 70 in-lb @ 970 rpm servo motor. The output shaft of the reducer is now around 24 rpm but the torque is now a whopping 2800 in-lbs! So you can see it isn't going to take much of a servo motor for the application you are looking at. By the way, you don't have to get all of the speed reduction through a gear motor or pulley system. You can set the motor speed by controlling the input voltage to the driver. Be careful with servo motors, you have to look at the data sheets and in particular the rpm vs torque curves in order to insure that the motor meets your specific application requirements. There is NOT a 1:1 relationship between speed and output torque with these motors.

Yes, the drives will be powered up 24/7, but they wont be drawing any more current than a night light unless they are moving the curtains or resisting someone trying to move the curtain manually. Its only when they are doing work that they draw significant amounts of current.

 

2) The ones I find that meet my torque say rated at say 970 rpms. Well the max I want is around 20 rpms, so will it make that torque at such a slow speed

The average manufacturers continuous torque curve for most quality servo motors starts at maximum at zero rpm and usually tapers down slightly up to the rated max rpm.
The important thing to look out for is that the motor does not transition into the Peak torque zone or area for any length of time as this is where motor burn out is experienced.
Normally seen at accel/decel times, but may not apply that much in this application.
Max.

 

One added benefit of speed reduction is that you can have increased resolution provided there is minimal 'slop" in the mechanism. Timing belts are good for this too.

 

Mopar Mudder, if you are satisfied with present operation, why not just control present motor? Assuming that we have a 6 ft 8 track binary coded strip with 8 photoreflective sensors riding along, we could add some IC's to make a motion control system. I drew up an abreviated outline of a proposed system.
Each of the 7 addresses would have a 8 position DIP SW to program a position in binary from 0 to 192- - 3/8 in steps. The remote would need to transmit a binary word to Control, decoded to 1 of 10 to enable one of the 7 addresses. The selected address would be directed to the comparator inputs via the 8 ea 8 input OR gates. U 15 controls all LSB, least sig. bits, & U 22, all MSB's'
When comparator coded strip inputs match programed inputs , the power relay is opened as is either left, L, or right, R, relay. If inputs are unequal, motor will run in direction to bring equality & stop.
It's a thought at least

 

Mopar Mudder, if you are satisfied with present operation, why not just control present motor? Assuming that we have a 6 ft 8 track binary coded strip with 8 photoreflective sensors riding along, we could add some IC's to make a motion control system. I drew up an abreviated outline of a proposed system.
Each of the 7 addresses would have a 8 position DIP SW to program a position in binary from 0 to 192- - 3/8 in steps. The remote would need to transmit a binary word to Control, decoded to 1 of 10 to enable one of the 7 addresses. The selected address would be directed to the comparator inputs via the 8 ea 8 input OR gates. U 15 controls all LSB, least sig. bits, & U 22, all MSB's'
When comparator coded strip inputs match programed inputs , the power relay is opened as is either left, L, or right, R, relay. If inputs are unequal, motor will run in direction to bring equality & stop.
It's a thought at least

I am happy with the current operation of what I have. What you propose seems like it would be the most economical way to do it. Adding the code strip to the track should be no problem, and adding sensors to the trolley would not be an issue. I am afraid it may just be a little over my head trying to program it am make it all work. I have no problems building circuit boards and such as long as I have some kind of plan and component list to go off from.

To do the servo motor deal it seems I need the following.

1) motor
2) gear reduction, needs to be silent
3) Motor control of some sort
4) Power supply (does the control include a power supply)
5) I way to control it with IR remote

Seems it could get spendy putting all the pieces together, but probably the best in terms of control and abilities

I do have a timing belt on their now yes, it is a 1:1 ratio. I hate to up the motor speed too much because it can create to much noise and vibration. In my previous version of this I ran an AC motor at full rpm and did all the gear reduction with the timing belt. It was very loud and distracting, the way I have it right now it is dead quiet. Actually the loudest part for some reason is the magnet spinning around on the back of the motor for the Hal pick up.

 

Sorry for re-post.
I had given up on finding one.

It took a while to find , but some of the earlier positioners used pot feedback.

http://www.ebay.com/itm/Drake-ESR-2...US_Satellite_TV_Receivers&hash=item1c3c9f73c0


That and a dc gear motor with dynamic braking may help overcome some of your issues.

The Drake ESR-2400 and 2024 could use pot type.
As would some Channel Master and prosat.

Here is a Drake model with manual and remote.
Antique but very accurate positioning.

Shown is the 10T pot and worm which will read about 300 turns motion.

 

No gearbox needed - use timing belt & pulleys for torque multiplier (if needed).

You need to add a DC power supply.

Control can be manual or microprocessor.

Cheap? No! Affordable? Yes!

http://www.teknic.com/products/clea...=27793236126&gclid=CLbrs-vZ07wCFURnOgodQR0AUw

 

I am going to dig in deeper here and really start looking at this harder. Everyone has given me some great ideas.

Using a sat rotor system is good idea, and cheap. I wonder though if it will be any more accurate then what I am using now with it a regular antenna rotor system, I would imagine so as the sat is more picky about its positioning.

Again I would rather do a gear reduction then timing belt as it is quieter and smoother.

Some have asked about how many revolutions are made. I need to make 8 revolutions after final gearing.

 

The satellite actuator will stop within 1 count if the motor does.

If there is a way to at least double the output speed of the gearbox and put the magnet wheel there, it will help the accuracy. I was expecting a lot more turns. Sometimes the gear box will have access to a higher speed shaft.

I deleted the other post because I was starting to think that is what you had tried.

Actually you could try one with what you have now and switch to dc motor and higher count rate as needed.

http://www.ebay.com/itm/Nextwave-Sa...US_Satellite_TV_Receivers&hash=item3f1231f89f

The advantage of the IR remote input is hard to overlook.

 

Here is a typical count wheel for use with reed switch or hall effect.

I often made my own from cutting slots in the outer edge of a plastic disk and using a slotted optic sensor.

Inputs are ttl levels mostly.

 

Is their a good way to test a Hall Effect to see if it is picking up all of the magnetic triggers. I wonder if part of the problem with what I have is the Hall Effect not counting all the triggers.

I am guessing it would take some special equipment that I don't have.

 

No gearbox needed - use timing belt & pulleys for torque multiplier (if needed).

You need to add a DC power supply.

Control can be manual or microprocessor.

Cheap? No! Affordable? Yes!

http://www.teknic.com/products/clea...=27793236126&gclid=CLbrs-vZ07wCFURnOgodQR0AUw

Looking at these motors it looks like the built in controls only allow for 4 positions? I will need more then that.

 

Is their a good way to test a Hall Effect to see if it is picking up all of the magnetic triggers. I wonder if part of the problem with what I have is the Hall Effect not counting all the triggers.

I am guessing it would take some special equipment that I don't have.

I don't know what kind of sensors you have but many are open collector output, if so it could be as simple as placing a LED in series with the collector load resistor for a in-situ permanent indicator.
Max.

 

Is their a good way to test a Hall Effect to see if it is picking up all of the magnetic triggers. I wonder if part of the problem with what I have is the Hall Effect not counting all the triggers.

I am guessing it would take some special equipment that I don't have.

You should be able to cycle several times to see if it gets out of step.

The old satellite actuators display the count.

The hall effect sensors were very sensitive to adjustment.

Also, I don't know if you are running at the same speed as original counter.
If it's like the sat. actuators there will be a narrow window of pulses per minute that it will respond to.

They ignore others as noise.