Cambot part 3

Continued from; Cambot pt2 (BRAIN storming)

I’ve been thinking a lot and working on my Cambot. I try to keep the end goal in sight as I am teaching myself just enough to make this work. In the end I’m hoping to be able to set it up for both live action and StopMo, on a stage and out on location. So it needs to be somewhat modular and self-contained in the end, so not (solely)controlled by a computer.

I’m not much of an engineer, more of a hardware-hacker and I’m basically teaching myself this as I go along, which is partly why I’m working it out in parts. I’ve also not got access to a proper machine shop, so I’ll either be at the mercy of my friends, looking into buying a mini mill, or attempting it with hand tools.

But first some inspiration from Vimeo user Displacment1, who has some really amazingDragon Stop-mo MoCo rigs;

I’m really liking these designs, modular and adjustable. As much as I like the simplicity of my Geared tripod head I think I’m going forward with this sort of a nodal pan/tilt head design.

Mohan has made some really slick 15mm-based pan/tilt/slide rigs. He appears to be using carbon fiber 15mm rail rigs, so it’s both light-weight and strong! which he has custom built using stepper motors and custom gearing;
Another similar 15mm pan/tilt head was found on the dynamic perception’s forum here. He says he was able to assemble the whole thing for $450, which seems low to me, especially after seeing other offerings.

The miniengine seems to be a really cool way to run time lapse, or shoot-move-shoot based moco. It seems to be well-supported and designed, and actively developed. The next version seems even better, definitely something to keep an eye on…

BFG motion control seems like a great system. They provide a hardware encoding box and GUI interface for designing complex shots. However their price of $1000, which is reasonable for something of this kind, is outside my budget for this project. I’m really hoping to put the whole thing together for 1k, and there is a lot of hardware to put together…

Cambot Plan

I’m getting close, my research and brainstorming seem to have brought me to a clear path. Well I say one path, but its more like a three phase plan.

-Realtime mode

-Playback mode

-Program mode

Realtime mode – Hardware rig

The first step is assembling the rig, the real hardware of it. That will show me the physical limitations of the rig; size, weight, as well as the number and positions of axis.

This is where I am now, essentially a manual stopmotion rig;

cambot’s geared pan/tilt head

Bogen geared pan/tilt head, mounted to Jib(rigged to raise and lower with an automotive jack), on machinist’s rotary table and linear slide. Current arrangement is set up for manual moments. Turning the wheels incrementally of the geared head and cross slide allow for an animate-able camera.

cambot’s cross slide x/y axis

Pros/Cons; It works… mostly. It is limited to either stop motion animation for camera moves, which takes a lot of patience and focus for long, smooth camera moves. To move increments as well as animating the puppet or prop actually in the scene, or for an actor I can release the jack and move the jib smoothly, for hand-operated movements but its a bit wobbly, and requires an operator.

On to the next phase!

Playback/Live mode

The next phase involves motorizing it all. I’ve got the motions plotted out, but it needs to drive itself, So I’m beginning to add gears and motors now. The goal is to rig it so that it can be remotely operated. (with speed controllers). I’m looking into offset gear motors, DC motors, and gearboxes. I’m planning to work out/test 2 axis at a time in realtime, and possibly set it to record/playback once that is working.

I’m starting off by setting up my hardware to run off an Dynamic Perceptions AT-2 controller, starting with ez-swap dc motor or a a gear motor like these or a DC motor like these.Which will get me the chance to set up all the mechanical parts of the rig properly.

This real-time controlled live action remote rig gives me the ability to control and test two axis of DC motors.
Here is my rig as it currently stands, 2 geared axis hooked up to a joystick

From here, an idea for self-contained playback in the mean time, this servo recorder, seems like it could record up to 3min of motion for 4-axes, and with speed controllers it could control DC motors, then play back recorded motions.

This really seems like a good place to get, since it seems like I’d be able to control pan/tilt/focus and movement, either; slide/track/jib/rotate, however it’ll be $3-400, for it and I’m still not 100% sure it’ll work reliably/repeatably… DC motors aren’t really known for their detail in movements, and while my gearing may help I just don’t know, really people tend to use other types of motor for this sort of design, i.e. steppers or servos.

Program mode MoCoBus Rig; stepper motors, nanoMoCo, upgrade device…

Once the mechanical parts are working for live playback, I’ll be looking into swapping the DC motors for steppers driven by a computer, or potentially some portable brain. Ideally I’d have a magic box which allowed me to move the rig however I wanted, then have it repeat the move and export a 3d camera move which could be imported into effects software.

This post from Dynamic Perceptions got me very excited. There are plans to take the AT2 and use it to communicate with record-able repeatable systems. Naturally it wouldn’t work with DC motors.

If I rig my mover with stepper motors, like these Phidgets or NEMA-17,
or  another stepper, I’d expect I need some sort of driver card for each them. I’d need something like the easydriver. I don’t really know a lot about steppers, yet. But I’ll learn.

NEMA-17 stepper

Currently I’ve got my sights set on Dynamic Perception’s MoCoBus, driving the stepper motors via their nanoMoCo cards. The whole system chain (MoCoBus) will feed into a computer, (potentially a netbook) for movement recording/edit/playback, StopMo, etc. (Software Workflow)The upgrade device will also allow me to drive the steppers and record the AT2 joystick’s movements into the MoCoBus chain.

Then when the upgrade becomes available I can upgrade my whole system to use MoCoBus. Then I would need to swap the DC or gear motors out for steppers to use the nanomoco on,

Itd be great if I could rig all my motors with nanomocos as drivers, control 2-axes of them analog for now. Once its all working smoothly, I’d plan to delve into chaining all the axes via mocobus and get more complicated multi axis moves through Graffik on the computer. And hopefully by that point I’d have access to the adapter and this updated workflow.

Continued here;  Cambot pt4