Author Topic: Beta-DMX Servo Controller Project (See first post for specs and features)  (Read 37536 times)

Offline shaunkad

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Re: Lynx DMX Servo Controller Project ???
« Reply #15 on: March 14, 2011, »
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Me too. should it do steepers as well?

Steppers are quite a different animal compared to servos. Full rotational movement with indexed positioning. Although they don't typically provide postion feedback. In what kind of scenario would you use this? If you're considering continuous rotation with speed control, a servo can do that with a minor modification. This is common with small robotics to use servos as wheel drive motors. With this mod done, the PWM sent to the servo will control rotation direction and speed. It requires nothing different in the PWM transmission. Check out this page for more info: You are not allowed to view links. Register or Login
I have no current use for this at the moment. I was asking just to ask. I had seen some questions about them in a couple of other threads and  had not on this one.
« Last Edit: March 14, 2011, by shaunkad »

Offline mnarel

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Re: Lynx DMX Servo Controller Project ???
« Reply #16 on: March 14, 2011, »
count me interested as well.   Been looking for a way to add servo animated skulls and creatures to my Halloween display.   ON the Christmas side, think of singing choirs, flying Santa sleighs, galoping reindeer, ringing bells..... It's a Small World DLA styel!!!  Bring it.

Offline packetbob

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Re: Lynx DMX Servo Controller Project ???
« Reply #17 on: March 14, 2011, »

Hi dlhoppe,
While ideally you'd setup the linkage to make full use of the servos range (therefore never having to worry about limits or accidently stressing out a poorly designed linkage) in reality this is not always practical..
I have several 3 axis servo driven skulls and often you only need a short range of the servos travel and there is no cost effective way to avoid it (not to mention the tiny amount of space you have to work in)...

Since in my case, the projects are for fun, I end up using whatever servos and linkage I can make up out of what I have in n the junk box...

While you can setup limits in the DMX control software, this still leaves room for user error or misconfiguration...

Having the limit set feature on the servo controller itself would be a great feature that would ensure you couldn't distroy your project by pushing a servo too far.....


Bob
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Bob, 

Endpoint adjustments can (and should be) done via mechanical linkage using the servo horns. That's why the horns have multiple holes on each arm and most servos come with an assortment of different sized horns. Computerized end-point control is certainly more convenient, but  people mistakenly rely too much on the computer settings and don't think about the mechanical ratios required to get maximum performance from a servo. Remember, the more you limit travel using mechanical linkages, the more torque you get and the less stress is placed on the servo. Not to mention lower power consumption. It's clearly better for the servo. Set your "gear ratio" so that full travel (min to max) does not exceed the range of the driven item. With DMX, you can then use min and max dimmer values to limit futher. All that assumes that you've chosen the correct servo for the job in the first place.



Mike,
That would be great if you could help out. Let's see what the admins and RJ think of this idea and then we'll go from there in terms of design criteria and features. I would prefer to keep things simple and deliver it in a timely fashion. Although I'd be happy to see someone else step up and build something more elaborate and robust if that's the direction this needs to go.




Dave



Offline n1ist

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Re: Lynx DMX Servo Controller Project ???
« Reply #18 on: March 14, 2011, »
It shouldn't be too hard to add limits to the firmware.  I guess you could use a separate configuration mode that would interpret DMX values as limits and save them away. 

I better stop now before this turns into too much of a design session on the boards here...
/mike

Offline rayster

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Re: Lynx DMX Servo Controller Project ???
« Reply #19 on: March 14, 2011, »
I am in also, could use for both Halloween and Xmas.

Ray

Offline dlhoppe

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Re: Lynx DMX Servo Controller Project ???
« Reply #20 on: March 14, 2011, »
Bob,

I understand what you're saying. I've given your request a little more thought. If this project gets off the ground, I have an idea for implementing programmable endpoints using a really simple method. I have a number of other features in mind as well. Things like servo reversing, fail-safe positioning, DMX signal loss indication, etc.  

The main thing I'm concerned about with such a project is the cost-benefit of any given feature. If it's overly complex to implement a given feature for what I think might be little gain (benefit to the general DLA user group), I'll probably not go there.

We'll see where this all goes once the DLA leadership chimes in.



Dave

Offline dlhoppe

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Re: Lynx DMX Servo Controller Project ???
« Reply #21 on: March 14, 2011, »
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It shouldn't be too hard to add limits to the firmware.  I guess you could use a separate configuration mode that would interpret DMX values as limits and save them away. 

I better stop now before this turns into too much of a design session on the boards here...
/mike



Great minds.... ;D

Offline FireMedic4Christ

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Re: Lynx DMX Servo Controller Project ???
« Reply #22 on: March 14, 2011, »
Count me interested too!

Offline dlhoppe

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Re: Lynx DMX Servo Controller Project ???
« Reply #23 on: March 14, 2011, »
Ok,  Mike and I are going take a crack at this.


Here are some features I'm thinking of for starters:

Servo Reversing
End Point Adjustment
Programmable DMX Address (either starting address or per servo)
Programmable Fail Safe Position (for loss of DMX signal)


We'll post our progress as well as any additional features in this thread.

As to technical design and solutioning, we need to follow the rules and keep that out of the forums here. The admins have been lenient with me in the past, but I need to tow the line in that regard going forward. The one thing I will tell you is it will be a PIC based solution with ICSP for simple firmware loading. This will keep it consistent with other DLA equipment.


Cheers,
Dave

Offline jess_her

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Re: Lynx DMX Servo Controller Project
« Reply #24 on: March 15, 2011, »
Dave mike
Can another more technical thread start here in the forum, I really like to follow this maybe help.
Jess
Only limitations in life is your imagination

Offline dlhoppe

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Re: Lynx DMX Servo Controller Project
« Reply #25 on: March 15, 2011, »
Sorry Jess. We can't discuss the technical design here. If you want to discuss features, that's fine. We just can't get into how to implement them. 

Feel free to use PMs if you want.


Dave

Offline jess_her

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Re: Lynx DMX Servo Controller Project
« Reply #26 on: March 15, 2011, »
Dave ok   I'll PM or Email  what ever work the best with you guys
Please let me know

Jess
Only limitations in life is your imagination

Offline shaunkad

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Re: Lynx DMX Servo Controller Project
« Reply #27 on: March 16, 2011, »
How many servos would it control? Three would be good then you would have XYZ coverd.

Offline maffeirw

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Re: Lynx DMX Servo Controller Project
« Reply #28 on: March 16, 2011, »
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How many servos would it control? Three would be good then you would have XYZ coverd.

For skulls you would need another for the jaw movement, two more if you want 2-axis eye movement,  ;) two more for eye brow movement that makes eight. Times that for a quartet.  32 channels sounds about right to me. ;D 

And I'm only half kidding
PS - I guess I can use an RGB controller to light the eyes so we won't count those 12 channels.
Luceat lux vestra

Offline ILOVETOTRYDIY

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Re: Lynx DMX Servo Controller Project
« Reply #29 on: March 16, 2011, »
It would be nice if you could incorporate an audio driver some how like this:

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It could greatly reduce programming time.
When you're curious, you find lots of interesting things to do.  Walter Elias Disney