I’ve been playing around with dropping a 5" miniquad running arducopter from a larger heavy lift quadrotor using THROW mode (set to drop), and have had lots of success doing so from a ~10m tethered servo drop mechanism.
I have another servo drop mechanism that attaches to the landing gear of the larger quad that I’d like to use, however I’m noticing that while the small quad recovers extremely reliably, it appears to recover “too quickly” and makes me nervous to drop it closer to the larger (and much more expensive) heavy lift quad. I’d love to let it fall 10-20m before it triggers a recovery.
Is there a way I can set up the miniquad to trigger the drop recovery at a lower altitude? I wasn’t sure if THROW_ALT_MIN and THROW_ALT_MAX would work, as by the time it hits this altitude window, it will already have been falling for tens of meters and I wasn’t sure if the mini quad would still detect this as a drop even if it has the prerequisite velocity.
Any insight is super appreciated, and thanks in advance! Also, I can’t believe how well the mini quad flies on Arducopter, it’ll effortlessly do 55-60mph missions with lots more in the tank!
I think if THROW_ALT_MAX is set to a non-zero value (either positive or negative) it will not detect the throw until it has fallen below this altitude-above-home (code is here in case that is of interest).
I think you can leave the THROW_ALT_MIN set to 0 so that it is ignored.
Just be careful to confirm what the little copter thinks it’s altitude above home is…
Due to the little copter resetting home altitude upon arming (which is default behavior as far as I know), I’m thinking this Altitude range will need to be negative because we currently arm just before drop. I’d love to arm on the ground but I’m thinking that because the larger quadrotor is exceeding the “triggering” velocities during travel to the drop location, the little copter would sense a throw while still connected to the drop mechanism, at least with the default coded values.
We’re hoping to get out this afternoon and do some testing. Thank you for the link to the code as well! I’m thinking this might eventually need to be custom firmware to have this work as well as possible, so it’s great to see what it looks like now.
By default home is automatically set when the vehicle is armed but this won’t happen if the home position has already been set manually. This can be done in a few ways:
The user can set home using Mission Planner (and perhaps other GCSs) by right-mouse-button-clicking on the map and selecting “Set Home Here” >> “Set Home Here”. This is similar to how the EKF origin is set which is shown on this wiki page.