Control system for remote follow spot

Thread Starter

Georgeman

Joined Feb 13, 2020
6
Hi All,

I'm hoping someone out there can help me come up with a good way to create essentially a remote control for a moving head stage lighgt, to use it as a follow spot.

The lights have DMX control and have a channel for pan and a channel for tilt. At the moment i use desk sliders to manually control the position of the lights and it's a nightmare! What i would like to do is assign those two channels to some form of control interface. my initial thought was a joystick but even better would be something that pans and tilts in the same way as a normal follow spot does.

Once i have that it would be good to be able to customise the sensitivity of the pan and tilt sensors to be able to customise the range of movement of the light relative to the input from the operator!

So i guess this is partly a hardware and partly a software question! There are a couple of off the shelf solutions out there that go about it in different ways and they are all super expensive and require buying completely new light fittings as well as the controllers!
Any thoughts or suggestions would be really helpful!
 

Thread Starter

Georgeman

Joined Feb 13, 2020
6
So is that two potentiometers, one vertical and one horizontal? Would there be an easy way of adjusting the sensitivity through software? My thinking is venues of different sized might need faster or slower moving light movements depending on how far away the light is from the stage!

Is there an easy way to assign certain dmx channels to the potentiometers rather than sliders? On most lights the pan and tilt movements are assigned to different channels without any continuity throughout! it's really annoying
 

Thread Starter

Georgeman

Joined Feb 13, 2020
6
The sliders probably are potentiometers. If so, it sounds like a simple re-wire.

Can you explain?
I had been thinking of rewiring a dmx desk but the way a lot of moving heads work wouldn't really work for that. So a moving head is basically a light fitting that can pan and tilt, as well as having colour changing etc. The problem comes when you look at HOW they move. Most lights can pan through 540 degrees, but for use as a followspot you don't really want more than say 180 degree movement so using standard dmx sliders would result in lots of light movement for a small operator input.

The issue with channels is: i have two different brands of moving head light, on one brand the pan is channel 1 and tilt channel 2. The other brand the pan and tilt are ch6 and 7. So if i physically rewired ch1&2 to pan and tilt, on the second light it wouldn't work.

So my conclusion was i probably need a cpu to allow me to set the channels each time i move to a new light and configure custom functions such as colours etc... I have a very basic knowledge of circuit design, is this something i can muddle through with online help? or should i really be getting a pro to do it?
 

drc_567

Joined Dec 29, 2008
921
Some joysticks use the potentiometers as a variable current shunt. So connect appropriately, if that happens to be the case.... Think it was the Apple brand that was like this, when I took one apart.
 
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Alec_t

Joined Sep 17, 2013
11,746
The issue with channels is: i have two different brands of moving head light, on one brand the pan is channel 1 and tilt channel 2. The other brand the pan and tilt are ch6 and 7. So if i physically rewired ch1&2 to pan and tilt, on the second light it wouldn't work.
So my conclusion was i probably need a cpu to allow me to set the channels each time i move to a new light and configure custom functions such as colours etc...
In view of that channel non-standardisation I think your conclusion is correct. The CPU would enable mapping of the input values 0x00-0xFF to some smaller range for your required limited pan and tilt angles, and wouldn't necessitate controller console rewiring.
This might be a job for the ubiquitous Arduino, assuming it can handle the 250kb/S comms of the DMX protocol.
 
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condenser

Joined Nov 13, 2017
12
There are lighting control systems in the used market that would allow you to use a trackball and or a joystick. Those systems will also allow you to map the Dmx profile for each fixture.
One way to overcome the 540 degree movement issue would be to range lock the units in guestion.
With range lock you can limit the amount of pan and tilt available for each unit.
One control system that comes to mind is the old Martin Maxxyz. They can be had cheap if you look. Perhaps as low as 200.00 dollars. Go over to the old Martin Maxxyz user group on Facebook.
That group is modifying the consoles to use a windows based PC as a control mechanism. They replace the embedded system with a internal Windows PC.
If you do that you can then use some of the latest software from elation. It's now called obsidian. It also allows you to use Martin M-PC which is the same as the original software.
With the Maxxyz modified you will have at a minimum 4 DMX universes 2000 plus DMX addresses along with dual touch screens a trackball, joystick if you wish. There are also free offline visualizers to program your lighting without having it in front of you.
It sounds as if you are using an low end control unit now.
 

condenser

Joined Nov 13, 2017
12
Free or almost free software based systems, freestyler, Martin M-PC, Onyx there are more but all of them require an interface. Most will accept an enttec device to output DMX which can be had for about 50 dollars.

Grand Ma on PC is an industry standard and is free. It will not output anything until you attach their hardware node though. Those nodes can get pricey.

All of these will offer more control than it seems you now have.
 

RobNevada

Joined Jul 29, 2019
61
There are video tracking systems. I think that there was a board for about $40 on Ebay. These are used for video tracking and should have outputs for the pan and tilt. You would need a monitor to show where the target is and just put a box around the person and then the pan tilt would adjust automatically. A simple on off switch would allow control of the light. These tracking systems are very accurate and can track one person even if there are multiple people on stage. Another very high level tracking system is YOLO (you only look once) which can identify multiple targets in real time.
 

bassbindevil

Joined Jan 23, 2014
110
There must be PC software that would translate movements of a joystick or other game controller to DMX512 values. Old PCs and laptops and game controllers are basically free, so the only expense would be the DMX interface; under $15 US on eBay, or adapt an RS485 to USB interface: https://stevenbreuls.com/2013/05/diy-usb-dmx-dongle-interface-for-under-10/
And there's Linux, so maybe the PC could be replaced by a Raspberry Pi or other tiny computer: https://opensource.com/article/17/5/open-source-lighting
An Arduino-based thing might not cost much more, but would involve actual programming. Seeed offers a Grove DMX interface for $6.50 (which really just translates serial signals from your Arduino or whatever to RS485, using an SN75176 chip), and provides a DMX library for Arduino. http://wiki.seeedstudio.com/Grove-DMX512/ Then it's "just" a matter of figuring out the optimum way to translate joystick movements to the pan/tilt values. If you had a large joystick with no spring-return, and enough friction to stay put when let go, its movement could exactly mirror the spot movement. Or maybe you want a more normal spring-return-to-centre joystick, and the speed of movement is proportional to how far the joystick is deflected. Maybe the spot can only move at one speed; if so, might as well have a joystick with switches (think old-school video game/arcade controllers: Happ makes the real deal, for under $20). https://na.suzohapp.com/products/joysticks/
 
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