Some successful flying

This weekend we got some encouraging flight results with the hexacopter.  After making some modifications to the camera mount and spending some time building confidence with the flight simulator, we were hoping to get some usable photos and maybe even work up the courage to try a flight with the autopilot in control.

Site:  Carstairs farm
Conditions:  Sunny, light breeze from the west.
Camera:  Canon Powershot A2300, shutter speed set to 1/2000, ISO 100
GPS:  uBlox LEA-6H

The first flight went well, with the exception of the landing, which was done with only five propellers.  Surprisingly, there was little damage to the copter (one arm needed to be replaced, no props broke).

The photos are not terribly interesting, unless you like looking at targets on the lawn.  Here is a close up of the resolution target from an altitude of roughly 15m.:

On the second flight we tried the autopilot, with a modest program of four waypoints.  The results were not that good, likely because I entered a radius of 2m for each waypoint which is too tight for the system to lock on to.

The photos have some more interesting subjects, but we had to curtail the flight since the autopilot was not cooperating.  Looking at the flight logs, it's clear that the problem is that the waypoint radius is too small.

The third flight didn't really have any goals, other than to do some more flying.  I suppose if we had been more ambitious we could have reprogrammed the waypoints and tried the auto mode again.   But instead we just let the autopilot fly in loiter mode, into the trees.

oops

The photos are more of the same.

Some concluding thoughts:

• I think the camera mount is providing reasonable results given the quality of the camera.  It would be nice to improve the CHDK script so that the shutter speed selection would be handled automatically
• The next flight with the autopilot needs to have a better program, we need to spend some time understanding the options and their impact on the system, specifically the waypoint radius and delay values.
• The flight simulator is a great tool for improving pilot confidence, but more practice is definitely required, particularly for landings.

Canon Camera Shutter Release Cable

Using a Canon handheld camera with the APM 2.5 looks to be an easy low cost method of collecting some aerial imagery.  We have a couple of suitable cameras to try out:

Canon Powershot A2300:  16MP, $100 at Walmart

Canon Powershot SD800IS:  7.1MB, $25 off Craigslist

Both cameras are supported by the Canon Hack Development Kit (CHDK) which adds two valuable features to these low cost devices:  scripting and a remote shutter release via the USB port.

The remote shutter release simply monitors the presence of a voltage on the USB power pin.  Following the instructions here, I made up a test cable using a battery and a momentary contact switch.  Testing with various voltages, it seems to need at least 4.1V to reliably trigger the shutter.

CHDK Remote Cable Test Rig W/4.8V Battery

To connect to the APM, we'll need to use one of the digital I/O pins (3.3V) as a trigger, with voltage supplied by the 5V supply pin.  Testing with the battery indicates that the current drain is negligible, so here is the circuit we came up with, based on a 4049 hex inverting buffer:

CHDK Camera Circuit

Here's the completed circuit, needs some strain reliefs, heatshrink, 

A small ceramic capacitor is bridged across 5V-GND as a buffer.  On initial testing, it works!  Next steps are to test with the APM and fine tune the scripting on the camera and autopilot.

Many thanks to my friend paulb for the expert advice, parts, soldering, and correction of errors.  I did, however, supply the beer.

Here is a discussion and some code for scripting the camera.