As a follow up to an indoor test we did a about a month ago (blog post here), Assistant Professor Nagatani-san of Tohoku University, Izu-san of EnRoute (a primarily Japan based RC company) and I tested dropping a 2.5kg rover from a 4kg Hexacopter outfitted with an APM2.5 running ArduCopter 2.9.1. The test was done on the side of a semi-active volcano, Shinmoe which is in Kyushu, Japan.
The flight was all in Loiter mode with the release of the Rover via a servo controlled by the Camera Shutter function attached to channel 7 on the transmitter. The pilot (me) was positioned right near where the video was shot from.
Basically it worked but there we hit a number of issues:
AC 2.9.1's Loiter has a 5m radius deadband meaning it moves back to it's original target unless you move more than 5m away (from the target). This meant that repositioning the copter precisely was quite difficult.
As it was shot on the side of a Volcano at >1100m elevation, the wind was relatively strong and pushed the copter around at times.
the release mechanism for the rover was slightly damaged in transport meaning it took multiple attempts to get it to release.
Next time we will try to do it fully autonomously.
We also took the opportunity to fly a separate large Quad outfitted with a 10000mAh battery up for a view of the crater. The flight took about 12min but it could have flown at least another 5min. Problems we hit included:
Like the large rover-carrying-hexa this quad had very large propellers which could be caught by the wind at times meaning the controller had a lot of work to do to keep it upright at times.
Arducopter 2.9.1 has a bug in that it proceeds to the next waypoint once it's reached the target lat/lon. This is fine for mostly horizontal flights but it's serious trouble for a flight like this in which the vertical component takes longer than the horizontal. The solution was to set the target take-off altitude to 150m and reduce the WP_SPEED to 2m. We ended up overdoing it so we flew the mission higher and more slowly than necessary.