TLA: Motion Test Video

This video shows a test of the truck and pan motions moving my K10D and Sigma 17-70. In this video, both are running at their maximum speeds (approximately 3.7 in/min for truck and 1 deg/sec for pan) and the video is running at twice normal speed.

There are still some problems to be worked out, especially with the cart and the software (it’s amazing the sorts of bugs that pop up only after motors have been attached!) – but I’m pleased with the progress thus far. However, I am a little concerned about the rough nature of the pan movement. Only being able to move 1 degree as a minimum movement will probably result in rough movements in the video. If it becomes problematic, I’ll have to replace the servo with a stepper motor. And, you know how these things go – if I have to use a stepper motor, I’ll likely have to add another arduino for motor control, or a break0out controller for the stepper, as I have no pins free on the arduino.

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~ by c.a. church on July 21, 2008.

2 Responses to “TLA: Motion Test Video”

  1. Looking groovy!

    Hi C.A.

    I was very happy to come across your time lapse motion control project using Arduino because I’m currently working on a VIDEO motion control rig with Arduino!

    The only big difference I can see between our two projects is speed… I need to move much faster than you!

    I too am using an LCD, but with just a 3 button interface at the moment (up. down and menu). Are you using the 4bit LCD library which would get your pin count down to 6?

    I’ve setup a blog to document my progress but haven’t had time to document anything yet(!), but I have uploaded a few vids to youTube… http://www.youtube.com/view_play_list?p=B318CCD79FAC40CB

    You mention possibly using steppers… may I recommend to you Brian Schmalz’ “EasyDriver” board? It takes two Arduino pins – step and direction. Very simple, very controllable. You send it a pulse and it steps – more exactly it microsteps. It does 8x microstepping so the resolution is incredible.
    See… http://greta.dhs.org/EasyDriver/

    Right now I’ve got to find time to work on it. Life is busy. That’s frustrating because I want to start using it and making money out of it.

    At the moment I’m only driving the dolly… pan and tilt, are next… followed by zoom and focus!!

    All the best.

    Marcel

  2. Hey Marcel – thanks for stopping by! Your project looks great – I like the twin video =)

    I’m definitely using the 4-bit LCD interface, and have considered switching to Peter Fleury’s LCD interface to avoid the delays introduced by LCD4bit. But, at this point it’s largely moot as I’m moving all motor control to a second MCU. This will let me expand to a larger number of axis of control (4-5) and allow me to create a more rich instruction environment. After the first version is complete, I plan to start on a motion control system using n-d space in processing. Where you visualize the movements over time for each axis.

    Speed is definitely a different beast, however, with it introduces another issue – the size of a step. In a time-lapse video, the steps have to be extremely small to avoid a ‘jerky feeling’ — in a 24fps ‘live’ video, that 1-second move of .3 degrees gets spread nicely over all 24 frames, but the same 24fps video shot 1 frame/sec, just sees huge jumps. In fact, I’ve had to abandon servos for pan + tilt as even though (reference the post following this one) I was able to get them to a higher resolution of less than .3 degrees/movement, those changes still happened too fast. Rather than do serious re-gearing to compensate for the inability to operate the servo at a speed low enough to be smooth, I re-built the entire pan assembly using a DC gear motor (spec’d at 3 RPM, geared 5:1, making it a max speed of < 1 RPM). I’ll be posting in the next couple of days the new design.

    I like that you’re working on focus – as I intend to control that as well. How do you intend to do so? Are you going to control it directly (via software) on your video camera, or are you going to manually control focus via a motor? In my situation, a software control in-camera is not possible, so I intend to use a small motor that will be adjusted via a spring for tension against the focus wheel of my lenses – adjustable for length of lens and width, of course.

    I feel you on the finding time to work on it issue – it seems like I’ve been working on it so long, that I’m going crazy. I just want to get to a point where its ready to be taken out into the field and used! Looks like there’s still a month to go before I’m ready for that though. =(

    !c

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