Striving to be the person my dog thinks I am.

While the task of creating a suitable platform for aerial survey may seem like a daunting one, breaking the project into stages and getting each part to function properly before moving on to the next is perhaps the best way to tackle this.  To have a useful platform to create a series of images over a specified area, there are certain points that I envision being required to get the data as accurately and as fast as possible.  These are as follows:

1. The camera mount - In order to capture accurate images of terrain below that can later be montaged onto a platform such as Google Earth (GE),  it is required that the lens of the camera be pointing directly downwards at the moment the picture is taken.   This will be the topic of this post, so I will come back to this later.
2. Constant altitude - To create a seamless montage of photographs, the aircraft will have to be kept at a constant and known altitude.  To accomplish this, a commercial altitude-hold unit would be required, and they are available at a reasonable cost, depending on the unit one selects.
3. Guidance - To capture images of the area of interest, it is required that the aircraft be guided to the exact point where it needs to take the photograph.  The only way I can see this being done with any reliability, is with a commercial waypoint navigation system.  A pre-determined route can be set that the plane will follow so that at specified intervals, a photograph will be taken.  While commercial units have the ability to follow a specified course, I have yet to comprehend how the shutter can be triggered at a pre-determined point in the flight, and this will be the challenge.  If one does not require automated take-off and landing capabilities, commercial waypoint navigation systems are relatively inexpensive to acquire.

Following these steps, a capable UAV can be created, with the task of image processing to follow.  This process will be a whole new topic that can be addressed at a later stage in the project, but with accurately geo-coded images, should be possible.

A good place to start will be creating the camera mount.  This can be fitted to any standard radio controlled aircraft to test,  and images can be analyzed to determine their quality and accuracy before proceeding.  To stabilize the camera, I propose using the FMA Copilot infrared stability system.  While this product is commonly used for levelling a model aircraft in pitch and roll, it should also work for levelling a camera on a gimballed mount.  With the camera mounted pointing downwards on a plate, the copilot can be fastened to the underside of the plate and connected to servos to control the attitude of the camera mount.  This will keep the lens of the camera perpendicular to the surface of the earth.  I have done some preliminary drafting work on such a mount, so rather than try to explain it, you can perhaps get a better idea of what I am planning by looking at the attached pictures.

The first picture shows the main structure of the mount, with three carbon fibre plates and a number of aluminium blocks for pivots.  The second image shows the camera, servos, copilot, and control rods in place.  Overall height of the mount is roughly 3.5″, so mounted to the bottom of an aircraft will not cause significant ground clearance problems.

Camera Mount - image one

Camera Mount - image two

This drawing is still in its early stages, so I will post new screenshots as I make progress on the design and construction.