Lil Wayne (4 axis Robot)

Lil Wayne
Pan, Tilt, Slide, Focus
4 Axis control with two Auxiliary ports.
Chronos Micro timelapse rail
eMotimo TB3
Dragonframe control

Lil Wayne. I like this robot. The eMotimo TB3 took some pretty heavy modifications to get everything to finally play nice.  I like the TB3. The hardware is excellent! Well built, and capable of some very fine movements, but the factory firmware and the inability to control more than 3 motors was a bit of a problem.

The standard “out of the box” configuration of the eMotimo creates an extremely user friendly and versatile system, and while it does support Dragonframe integration, it was a bit lacking for my needs.

First, looking at the stock firmware of the eMotimo, you just cant get more user friendly than it is. It works like a dream!  You have the ability to set either 2 or 3 keyframe movements by positioning the camera in the starting point, then a mid point (for 3 keyframe setup) and then the final point. The Pan and Tilt can both do 3 keyframes, but the AUX motor only does 2 for some reason.

WTF is a Keyframe? There are probably a lot of definitions that would be more appropriate than my own, but Ill describe it in the function in which I use it. A Keyframe is a logged set of information about the position of the camera. Another way to describe it would be a position target. Keyframe 1 is the beginning position, Keyframe 2 would be the final position of the camera. With a 3 keyframe setup there would be an intermediate position between the beginning and end that you can lock down. The eMotimo then does all the mathematics needed to make a nice graceful move between those keyframes. You can have it do hard moves with constant speed which gives a very mechanical look, or you can have it gracefully feather the speeds in and out making nice swooping arcing motions.  I also use keyframes in Dragonframe, but on a much more complex scale.

While the eMotimo makes keyframing so simple your dont even know you are doing it, when dealing with focus you generally need quite a bit more keyframes than 2 or 3. Normally I will use 8-10.  I first setup the path of the camera with keyframes, then I will move along that path making small adjustments to just the focus, and locking in additional Keyframes to keep it in focus. If I tried to use just 3, I would end up with a clip that starts in focus, drifts out, then back in, then back out, and ends in focus. Hardly the way I want it to look. And also I have had some issues in the past triggering the eMotimo from an external source. I am not sure if Brian’s wiring is wrong, or if I have things backwards with the ChronoControllers, but it was always sort of bitch to get them to work together.

With the ability to drive 3 motors, you have Pan, Tilt, and a spare driver that can be used to control a focus motor, or maybe a linear rail, a cart, or whatever you want. However I wanted 4 axis control.

All of this can be resolved by using the eMotimo Dragonframe integration mode.

This also allowed me to get Pan/Tilt/Slide/Focus even though the eMotimo only had 3 motor drivers, as Otto has 2 spares. So the eMotimo controlled the Pan, Tilt, and Linear Slide, while a spare channel on Otto handled the Focus control. I ran into some annoyance with the Dragonframe integration however as it kept dropping connection. It would run for about a day, sometimes two, then Dragonframe would show an error that it lost connection to the eMotimo and I would have to go through the process to set it back up.

The worst part is once I had it reconnected, Dragonframe would assume the eMotimo had moved back to its zero position. This is a problem because when the BCM (Biolapse Control Module) would try to trigger Dragonframe it would freeze everything and put a note stating the motors had to be moved to the current shooting position. If I clicked YES while the eMotimo had a live 12v power source, it would start moving the Pan/Tilt/Slide and completely jack up the routine it had been capturing. I would have to remember to unplug the power from the eMotimo (the logic side of the emotimo is still powered off the USB connection) then let it think it had moved the motors, and then plug the power back in.

To cause even more problems, if the eMotimo connection was set to “Connection Required for Shooting”, and the connection to eMotimo was dropped, an error would pop up on Dragonframe and Otto would quit shooting as well.  Unfortunately quite a bit of very excellent footage was ruined because of this.  I had tried everything I could think of. Replaced the USB cable, adjusted the USB power settings on the computer, dug through the USB logs looking for any errors, and replaced it again with an active extender. It still would continue to drop.

Luckily I am not the only one who dealt with those drops, and the answer came in the form of some software for the eMotimo that basically bypassed all the eMotimo firmware and created direct access to the Dragonframe portion. This resolved the dropping issue, and now that connection is rock solid.

Even though that fixed the issue, I still wanted to make the most of the system so I designed a circuit board that would house 6 stepper drivers. I removed the Wii Remote bluetooth module, the screen, and the stock circuit board with my own design. Now it allows for control of up to 6 motors instead of 3. I could have gone with 8, but felt 6 was pretty substantial, and it was much easier to fit it inside the eMotimo.  To power the system I picked up a 12v 10 amp AC-DC power supply.  Now I plug the eMotimo directly into the wall and it has all the power it needs to run the additional motors.

Just a disclaimer, my uses of equipment are extremely demanding, not only on the hardware but also the software. I need precision control with extremely high mechanical resolution. The eMotimo TB3 is an excellent piece of hardware and the software on it is top notch. It just works so well. Even though I just spend the last several pages going over the problems I had, I have very particular needs, and for an overwhelming majority of users the TB3 is up to the task of most people, and I would wholeheartedly recommend it to anybody who is not doing 2-3 week long macro timelapses of plants.

For the Linear Slide motion I just wired in my Chronos Lite Micro rail. It is perfect for this sort of work as a 3 foot or 6 foot slider is just way too big. About 16 inches of linear motion is about perfect for this type of work.

We used to use 20tpi lead-screws, (this is the screw that runs down the inside of the track and connects to the carriage. As the screw is turned the carriage will move towards or away depending on the direction you turn the motor), but on this one I have a 4 TPI screw which causes it to lose some holding strength at the sacrifice of speed. It went from super strong, and super slow, to Strong and Sorta slow.

The focus is controlled by one of our old Lens Apparatus systems. Like Otto this is directly mounted to the lens via a customer 3d printed bracket(The orange part). Unfortunately this bracket ONLY fits the Nikon 60mm f/2.8 macro lens. I do have a new Universal Lens Mounted Focus Puller that I am testing which works very well and may replace the lens apparatus.  I steer clear of anything mounted to the 15mm rod systems as it causes lens tug when shifting directions on the focus due to inherent slop in the lens mount. I dont know the quality on Cine lenses and professional video cameras, but even on pro grade DSLR’s there is always some tiny rotational slop on the lens mount.  By mounting direct to the lens you can eliminate any lens tug.  It may seem like a minor issue, but once you see it in a timelapse it is obvious as hell that it is there.

I have yet to truly run Lil Wayne through the paces. So far it has performed flawlessly, and it is going to be an integral part of my arsenal for the foreseeable future.

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