I don't care about start/stop details, as long as I can keep resetting it and repeating. What I need is a photograph successfully taken automatically (Arduino-controlled shutter, Canon CHDK fimware or modified shutter button) at an approximately exact horizontal position, while the camera is horizontally moving at an accurately measurable speed. The start/stop can be as messy or continuous; but ideally, I'd like something that fits on a desk, no more than for feet long. It also needs to be transportable to different sites, so I'll mount all of this on a portable platform.
Essentially, camera starts moving, accelerates, [BEGIN precision requirement] then takes a picture for 1/10th second [END precision requirement], then camera decelerates to a stop. I only need one picture, but when the shutter is open, the precision requierments apply.
Here are my preferred requirements:
(1) Must fit on a desk (ideally less than 1 meter long (1 to 3 feet long) maximum 4 feet long. Less than 1 feet deep).
(2) Speed control: 1mm per second increments, up to at approx ~300mm per second. (more is desirable -- but not needed now)
(3) Speed error: +/- 1mm per second error (@250mm per second)
(4) Positioning error: +/- 1 centimeter (Manual shutter timing fine-tuning should be manageable)
(5) Amount of time the precision is required: 1/10th second (macro mode)
(6) Moving mass required: Typical point-and-shoot camera (1/10sec allows use of lightweight camera w/manual exposure ability)
Acceptable precision degradations, if certain parameters are expensive/difficult to meet:
(2b) Speed control: 5mm per second increments (= 0.5mm per second difference during 1/10sec exposure)
(3b) Speed error: +/- 10mm per second (= 1mm error during 1/10sec exposure)
(4b) Positioning error: +/- 5 centimeter (I can do multiple attempts until subject matter is fully in the frame)
A conveyor belt? That could work, too. I'd put the camera on the conveyor surface, even duct tape it down, and press a button to start moving the belt (letting logic and triggers do the work for me).
I have a discarded inkjet printer too, just in case I use its ink cartridge platform as my camera platform. However, I'm open to ideas of easier-to-build solutions that fully meets my accuracy requirements, as my spare hobby build time is limited.
[P.S. If someone is willing to build this for me, there's some money in it for you, above and beyond parts cost. I will give you some publicity in my blog, if you open-source the build instructions.]