As a follow-up to the rover drops #1 and #2 I spent a day with Assistant Professor Nagatani-san of Tohoku university in Japan (and his students) and Izu-san of EnRoute (a company that specialises in Industrial use multicopters and hobby use RC vehicles here in Japan and China) at Karuizawa's Mt Asama attempting to autonomously drop a 2.5kg rover from a large (4kg+) EnRoute "ZionPro" hexacopter.
The flight was completely autonomous including activating the servo release which held the rover to the hexacopter (we used the camera shutter release). After being released the rover was "lowered" on a 30m wire wound around a brushless motor which was meant to slow it's descent (with mixed results). If you've never heard of this mechanism before, it seems if you connect the bullet connectors of a brushless motor together it resists being turned. If you attach a resistor between the bullet connectors it will resist less strongly. In this way we could somewhat adjust the speed at which the rover descended at.
A couple of things that we learned from this test in case you try something similar:
- the altitude reported by a Ublox GPS (i.e. APM/PX4) vs a hand held GPS can vary by 10m.
- the altitude reported in google maps (and thus the mission planner) can vary by 20m from reality because they only provide the average altitude for the area. I'm not sure how big that area is but we found that google maps altitudes could be high or low from reality depending upon where you were on the slope.
- trying to drop from a wire is tough! we need a more reliable system for the next test. Maybe use a range finder to get the copter closer to the surface without hitting it or perhaps measure the motor output to determine when the dangling rover has reached the ground.
- the hexacopter and battery were more than sufficient to carry the rover the 600m covered in this test. At least twice that distance would have been possible.
- AC3.0.1 is very capable of the accuracy required for this mission. It was a thing of beauty.
There will be one more attempt within the next 2 months which should be pretty much the same except the distance will be further and the dropping mechanism will be improved!
Thanks and all comments, input welcome!
Comments
Yup, really cool project. And a it was very neat to see the copter flying autonomously through the mist. I can just imagine a system like this being used... say a volcano is erupting, and scientists would like to deposit a seismometer, or get a camera view of the caldera, but poisonous gasses make it impossible for a man to do it.
I think it makes more sense to have the winch system on the rover, so that it after deployment, the weight of the winch isn't on the copter. And the copter also would have the cable release at it's end. This would allow it to free itself if anything goes wrong. Especially important when the copter is more valuable than the payload.
What a fascinating field test! While probably not as accurate for positioning the rover to collect data in a specific zone, I wonder if it could be dropped with a parachute, with the parachute automatically jettisoned upon impact. Maybe you've already tried that approach.
The sonar module will give more accurate readings when nearing ground level.
really great! your work is awesome!
I am interested in the ways a quadcopter reacts if it loose significant wheight.
my congratulations!
Very cool, the KMAX has a beacon system for the drop point maybe you could do something like that.
Fantastic! You've really got those copters dialed in beautifully. The scene (6:00) where it goes into the cloud and then the view switches to the drop zone with the crew waiting for a flying robot to emerge from the mist had me on the edge of my seat!
-
1
-
2
-
3
of 3 Next