help with the electronics side of a DIY motoized timelapse dolly/slider

R

robicano22

New member
so a friend and i have been looking into building our own timelapse dolly. we figured we'd be able to build a track rather easily, we dont really have a plan yet tho. the tough part for us is the electronics side of things. we will be using a stepper motor in order to shoot starscapes so our foreground is sharp. the problem is we hardly know how to control one of these. once we have the motor what other parts will we need to control the motor? i dropped outta mechanical eng. after 3 semesters, so i have a bit of experience writing code, but still, i plan to find someone elses code online and use that. i actually have an arduino Uno from my eng. classes, so im hoping that will get us started? what other parts to we need? we'd like to be able to control how long the stepper holds at each stop (anywhere from half a second to 30 seconds) as well as properly synchronize the motors movements with the shutter release of the camera. so basically a synchronous intervalometer.

our budget isnt very high maybe 100 dollars on electronics? we will need a motor, arduino, servo?, lcd display, and battery.

anyone done their own coding/electronic work? any advice?

thanks,
aspiring cinematographer
 
It sounds like a pretty straight forward project. An Uno looks like it has what you need to do the job. The first thing to do is determine what type of motor/drive to use. You mentioned a stepper motor and you also mentioned servo. These are two different motor types that can achieve the same function.

Stepper Motor - A stepper motor uses inputs of STEP and DIRECTION. Each pulse of the STEP will advance the motor x degrees (depending on the number of steps the motor has). This is easy to control and has no feedback to the controller. The amount of movement would be very accurate. Since this is timelapse, motor noise and jitter of steps is not an issue. Stepper motor drivers are very common and relatively cheap. So the stepper motor is a good option.

Servo Motor - A servo motor uses a closed-loop feedback system. It will have a tachometer or other feedback that is sent to the motor controller to control movement. This is more complicated and expensive than the stepper. Not recomended.

RC Servo Motor - The motors used for remote control cars or airplanes. They have limited movement (90-180 degrees or multi-turn when modified). Not suitable for your application.

Another option is to use a plain DC motor without any control. Simply drive the motor for x seconds to move the dolly. It won't be 100% accurate, but it should be pretty darn good.

pololu.com has stepper motors, drivers, and controllers, including the arduino.
servocity.com has a lot of supplies you may need.
Both sites are helpful with support.
 
i just built a dolly like paul mentioned, plain dc motor, rc-car battery, and an intervall time switch (is this english???) - where you are able to adjust the time for how long the motor is running, and the time for how long the motor is not running, so you can get pretty nice timelapseshots... not most accurate, but works nice for me... if you want to go into hdr timelapse dolly movements - forget my solution and try to code anything like this: HDR 1st shot, 2nd shot, 3rd shot, dolly forward, hdr 1st shot, 2nd shot,.... and so on! taking long time exposures while moving the dolly, even if its just 2mm on your track will cause different angles of view and so your matched shots in hdr will look ugly as hell... :)
 
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