If you don't need to move a precise number of millimeters between frames, a simple DC motor will be much more simple to control. This can be done with a single chip (a CMOS hex inverter) making several pulses in series, plus output drivers for the motor and camera. An alternative circuit might be based on a digital counter, depending on what the timing parameters are.
No microprocessor, no programming, one knob for the motor run time. A solid DC voltage regulator for the motor should assure constant running speed as the battery discharges.
Run the motor for a time. (turn on/wait/turn off)
Wait. (let vibrations die down)
Trigger the camera.
Wait.
Run the motor ...
How fast is the camera moving, or what is the approx time between frames?
How long is the track?
Is running a wire to the camera to trigger it acceptable, or would the wire get tangled up in things surrounding the track?
Where are you located?
ak