Given the popularity of the 230/250 quads at the moment (blackout etc), I thought - wouldn't it be cool to have a rig that can do the ground skimming proximity stuff, but also with the normal "mod cons" of the APM?
Traditionally though, an APM would never fit. Until HK released the mini...so I built one.
I started with the Haldey-Bocks 230 frame, in Carbon Fibre. This was a mistake. I should have gone for the 250, because the fitting of the ESC's was a bitch of a job, especially with the thick 3DR power module hanging off it. And naturally, I forgot to solder in the XT for the video feed, so had to start again...
Anyway, this is the bare airframe:
So onto the fun part...
First, I fitted the camera, so I could make sure the clearances were good. I mounted it directly to the front CF plate to make sure I had as much room as possible behind it.
Second, I mounted the GPS antenna pole. This required a lot of trial and error, but eventually I found a position which worked.
Third, I fitted the APM mini in front of the post, and behind the camera. There is *just* enough room to do this. It is currently mounted with double 3M pads - I will review vibe damping after the first flight. Supposedly the blue balls do the "clean/dirty" thing, but is it enough to keep the APM within Z axis tolerances? Time will tell. These rcx are not the smoothest I have to say, and a propless spin up was really vibey.
I wired in the GPS, and the radio.
Then I mounted the 3DR telemetry radio to the roof. It is likely I will replace this with a minimOSD, and run a really simple OSD - volts, ground speed and home distance.
I then cable-tied the xt60 back on on itself on the PM - it was interfering with the props.
CoG is spot on, even though I thought it would be rearward.
Weight with tx will be 505 grams as you see it here. I have a wiring exercise to do (shorten and tidy), and to enclose the APM with some foam (for the Baro), and I hope that brings it down below the target 500 grams.
And that's it! It all fits together nicely. All the normal calibrations done - just compassmot to do (want to wait until I've got the camera and tx wired in first). Going for a really small 200mW 32ch 5.8. Will fit perfectly.
I didn't have time to get the thing in the air, but should able to get it in the air at the weekend. Can't wait to use DRIFT on this...:-)
Comments
Wow that sounds great. I love my apms. Can't wait to use it for mini racing.
Goodluck leonard.
Hi all,
I thought you would be interested to know that I am working with Josh Welsh to get our ACRO up to speed. I think we are pretty close with the latest release. I am currently adding an expo function to the ACRO roll and pitch input based on Josh's feedback.
I have built a QAV250 that I will be using to make sure our filtering is appropriate for these smaller quads. I also hope to get Autotune working reliably on the more agile copters (small or high powered copters). The other area I am considering is making more use of our internal throttle curve.
This has been a long road for me as ACRO is the whole reason I got involved in the dev team. It has taken almost 2 years to get the code to a point where I can start implementing the ideas I had for ACRO. Now we are working through the process of tuning the code and making sure we have all the premium features to make the most fussy FPV pilot happy.
The other point I would like to emphasize. The FPV pilot is the most fussy pilot we have to work with because they see every wobble and reaction to disturbances. If we can get this right I think all the other modes will benefit significantly.
Thanks everybody for your ideas and feedback!!
Now I'm stalking Shay's youtube – but I notice he has oscillations with his mini like mine does on heavy throttle. @Euan, have you eliminated? Is your acro on par with CC3D?
https://www.youtube.com/watch?v=-79MrxgR9Ro
@Shay would also like to see your settings. Trying your filter param and still noticing oscillations on heavy throttle. Might increase.
I've gone back to front and believe my PIDs are very strong. Measured IMU and it's within limits.
Starting to think that you might have one of the first APM minis that actually flies.
@Shay, your flight video looks no horrible shake and good. How is your PID and filter setting?
On the opposite, these small frames are very rugged and with small props there are no vibrations.
Most Arducopter buils are around much bigger and more vibrating frames, thats why the default LPF is 20hz, my guess is that it doesn't fit a mini, I decoupled the roll and pitch, and i'm almost there on the PIDs, still a bit shaky on the fast forwards :)
https://www.youtube.com/watch?v=7vGS0P1bVSI
Euan, Can you tell me what your settings are at now? I may use them as a starting point on my current 200 size build.
I replaced my hobbywing ESC's with some afro's from Hobbyking, and it flies totally fine now. I didn't autotune - I did it the old fashioned way.
So what the hell is wrong with Autotune? Why can't it work on this size frame? I thought the vibrations were too high. It seems like nobody can seem to get the apm to work on a 200-250 size frame...
An old post, but I just built a Mini based on Mini APM, Kim250pro frame sunnysky 2300kv and 6" props.
It was very stable on high PID but oscillated on throttle and wobbly on low PIDs but ok on throttle.
What really really helped is: I raised the LPF (low pass filter of the MPU6050) from the default 20hz to 98hz!! I was really amazed that it wasn't going crazy and more amazed and how much better it works, these small frames with small props don't have so much vibrations that why the LPF can be raised.
Not completely good on the PIDs but almost there,
What really annoys me is that Autotune can't complete on this build and I don't know why.
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