Better late than never

In a vain attempt to keep up with the modern world and ways of presenting my work I've started up this rather late blog for my interest in Timelapse motion control photography.

My current hardware project - UM12, is about 75% the way towards completion.

The requirements of the this unit is for timelapse using a DSLR camera with realtime movement for preview purpose. Not to rely on mains power or a laptop computer due to remote locations that it's likely to find itself in.

What I'll put up here is all my problems and solutions to both hardware and software.

But first I'll list off the basics of the hardware in the current version I'm working on as of this moment.

The system has Track, Pan, Tilt, Focus and Zoom which are all controllable. Added to this is also the ability to animate (control) Interval and Exposure.

The hardware itself is based around a Servo City 785 Pan and Tilt system attached to a custom made dolly running on a simple pair of 25mm aluminium tracks mounted to a ladder.

Closeup of current controller on Dolly which contains the ChipKit Max32 processor and 5 Easydrivers

All the motors are stepper. All motors are controlled by EasyDrivers v4.1 except the Track which is controlled by a Leadshine M542 which gives higher microstep abilities. This said I'm in the process of purchasing replacement controllers for all the steppers except the Track. The reason is I've recently realised that the EasyDrivers 1/8 step mode (1600 steps/rotation) is way too large for my system. I will replace all these with Leadshine "DM422 Anti-Resonance Stepper Motor Drivers" which has a higher stepper rate up to 51000 per rotation, although I plan to use about 12,000 steps/rotation.

There are two computer controllers in the UM12. One is mounted on the dolly and this is centred around a ChipKit  Max32 board. I call this the Main Controller. The other processor is an Arduino Mega2560 which is contained in the Hand Controller. The two units talk to each other via Zbee wireless. The reason for using a ChipKit Max32 over an Arduino board is that it runs several times faster which is necessary for realtime movement, and has much more SRAM for storage. It also runs Arduino code making for easy programming.

The older version of the Hand Controller - the new version has 7 Keyframe buttons and extra Command buttons. Note that I also removed the Data Entry wheel at the top left.

The reason for splitting the processors like this was to avoid having too many cables dragged by the dolly when moving along the track. At the moment the only cable that does hang from the dolly is the power line which is both 12 and 24 vdc coming from a battery pack.

As mentioned, one of the main requirements for this system is that it doesn't rely on an external computer like a laptop or need a mains power supply. Many of the places I travel to for timelapse doesn't have mains power. Of course charging the batteries is still an issue but I do have plans for a solar panel to deal with this. Another related problem is I still need something to download my gigabytes of photos to ?

The dolly mounted on it's new track system for the first time

As you can see from the above picture the dolly is moved along with the help of a cam belt. The motor for the dolly is mounted underneath the dolly. Three metal bearings on each side of the dolly run on the tracks.

The Pan and Tilt axes have a 203 tooth gear meshed to a 20 tooth gear mounted on the stepper motor to allow for finer movements but currently this is insufficent until the stepper controllers are replaced.

The dolly's processor or Main Controller also contains the shutter controller and power regulator to supply power to the camera. I currently plan to run 2 different cameras on this dolly, a Canon 450D and 5Dmk2. The 5D is primarily used for night time star work and the 450D will be used for most other work.

The current, portable power supply is two 12v sealed lead acid battery rated at 18 amps which are wired in parallel to give the 24vdc. This can be seen in the above photo sitting against the window. It's all mounted inside a plastic toolbox which also contains another project I built for use with my telescope.

The Hand Controller can have 7 keyframes which represents a position per axis which includes Interval and Exposure. The movement types are currently linear or a simple ease in / ease out movement with various weighings. I plan to also look into bezier type movements once the system is up and running. Added to this, each keyframe per axes can have a pre and post hold frame value. I can vary the number of total frames, sub start and end frame position, save shots and load saved shots back in. Since the types of moves are more complicated than a simple dolly move I have a real time preview ability as to show what the shot will look like.

So that's the basics. There are several issues at the moment. As mentioned above the replacement of the stepper controllers is needed and I am having issues with wobble due to the bulk of the unit which I'm looking to reduce.