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Selecting Gearing for Your Motion Control Rig


After you've selected the motor type appropriate for your project, it's time to move to the next stage of building your first motion control rig: gear selection.  Unless you've bought a motor with an attached gearbox (and even if you have, in some cases), it's time to figure out exactly how you intend transfer power from the motor into your final motion.  Just like the process of selecting a motor, you'll need to first examine your requirements, and how they might change over time.  In this article, we'll walk through the basic process of selecting the proper gear train, and the different factors that should affect your decision.


 


The basic factors to consider are: building vs. buying, complexity, gear ratio, precision, and braking requirements.


 

Choosing a Motor Type for Your Motion Control Rig

One of the more daunting tasks for your first motion control project is to decide on which kind of motor you need.  The right choice in motor can save you money and effort in the long run, not to mention increase your chances of getting the shots you're looking for.  Before selecting your motor, you need to first examine what your requirements are, and how they might change over time.  In this article we'll walk you through the process of selecting a motor for a motion control rig and the different factors that should play into the decision.

 

 

The basic principles you'll need to consider in motor selection, outside of cost, are: timeframe (how long your shoots will run for), power requirements, and repeatability.

 

An OpenMoco Hardware Prototype

We're making progress with hardware kits that will soon (maybe early Q2 2010?) be available for purchase. The idea is to use laser-cut acrylic panels and mostly off-the-shelf hardware (there will only be a couple of custom circuit boards, and one gear has to be custom-bored) to provide simple kits for the DIY motion control enthusiast to build their own systems without heavy investment in tooling and without having to focus on all of the fundamentals. In such a world, you could create new software, or just get out and shoot without first buying expensive CNC machines, or have to figure out yet one more way to come up with that right gear ratio.

The idea is that these kits would trade a little sweat equity from the end-user for cost, providing a system capable of just about anything you can imagine at a fraction of some of the pre-built systems' cost.

Motion Techniques and Terminology

When building a motion control rig for timelapse, gigapano, or other photographic motion control, it is important to first establish which type of motion technique will be appropriate for your project. You must know which technique(s) you wish to employ before beginning motor selection and overall system design.

While some of the techniques described here will be well-known and agreed upon by the time-lapse community and others, some are purely hypothetical and crafted to encourage experimentation and thought on the subject.  Please feel free to add any additional techniques, or discussion as a comment to this article.

OpenMoco TimeLapse Engine 0.81 Released

Version 0.81 of the OpenMoco Timelapse Engine is now available for download.

Changes in this release:

The OpenMoco Reference Design

Here on the OpenMoco.org website, you'll find a number of open-source, free, and user-contributed software and hardware designs.  The core focus of the OpenMoco system is the Official OpenMoco Reference Design.  This design includes the system architecture, the system software components, and the system hardware components.

 

OpenMoco Architecture High-Level View

 

What is Moco?

The term 'Moco' is short for 'Motion Control' (wikipedia).  In general motion control is precise mechanical movement of objects, in our case the object is a camera.  The basics of photographic or cinematic motion control are to achieve predictable accurate camera movement and thus smooth changes in point of view.  Moves can be made up of a pans (horizontal turn), tilts (vertical turn), dollys (linear travel), rolls (circular camera movement), booms (long arm cantilevers) or any combination of these movements.  Photographic and cinegraphic moco can also include control of lens functions such as zoom and aperture.  The apparatus that makes all these automated movements and adjustments possible is typically called the 'rig' (which can also refer to non automated or hand driven camera apparatus).

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