Thanks in advance for Help, I need opinions Please
For use with a 450 Helicopter is it worth the expense to upgrade to a Pixhawk PX4 2.4.8 from a APM 2.6 with Ver 3.2.1 firmware. Is the larger faster processing power and the use of the newer firmware versions Ver 3.4.6 a noticeable difference in the flight performance of the 450 Helicopter, is it worth the expense?
Trying to decide and help is appreciated?
No, it is not. Two days ago I set up a brand new Trex 500 Dominator with a APM2.8 with internal compass, no GPS or external compass on it, no MavLink radio. Disabled the DCM in it. Disabled the Acro Trainer thing, disabled the Acro Expo. Turned off all rate PID’s and only using Rate Feedforward for direct stick to swash. Only two flight modes - Stabilize and Acro. Set up Normal Mode and Idle1 and Idle2 in the radio with different rates, expo and throttle/pitch curves for each Idleup. It flies every bit as good as a Pixhawk with no EKF problems. Could put GPS on it if we want, but the heli is going to be used for fun flying, pylon racing, and sport aerobatics and 3D. So no need for GPS. Did five minutes of hard 3D with it yesterday afternoon to test the tuning and you’d never know it only has a 8-bit ATMega2560 in it. After that flight brought it in and switched to Normal Mode in Stabilize and it hovers tame as a kitten. The fellow I set it up for left with it totally happy that he didn’t spend $150 on a MicroBeast.
The Pixhawk can’t do any of that with the newer firmware because the EKF leaves town and loses its attitude solution. The old APM doesn’t depend on it. It’s pretty much the cheapest $30 FBL there is.
If you’re setting up a UAV heli the Pixhawk has some advantages because it has more features and can do more advanced stuff. But flight quality is not one of 'em.
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Chris, what do you mean by disable DCM in AC3.2? If you do that, you have NO attitude estimator at all, and no flight modes will work at all.
William, there are massive differences between the newer firmware and hardwares. I could only see the case for using it ONLY as a FBL system. But even then, why not just use a cheap knock-off FBL controller?
Set it to zero. It disables the check so it doesn’t waste cpu cycles worrying about constant DCM Bad Heading errors. The cheap FBL units like a Tarot ZYX is just that - cheap. They don’t work all that well. The APM has optional GPS. The cheap FBL units don’t, and at $30 it’s pretty hard to beat for a cheap FBL unit that actually has decent quality hardware and firmware in it. It beats the Pixahawk for robust if you want to toss the heli around. People got 'em laying around, why not use 'em? They might not be the slick ticket for quads anymore. But if you got a scale heli, or just one for fun flying - throw it in there. It “just works” without any of the EKF or setup hassles.
I robbed the Pixhawk out of my Trex 500 this afternoon because it’s going in my Synergy E5S/626. Took me all of 15-20 minutes to tune it up with a APM2.8 in it. Then after you get it tuned, turn everything off in it you don’t need including the logging, and just go out and fly it and have fun.
What parameter are you setting to zero to disable DCM?
DCM_CHECK_THRESH , 0
Have to have more words in the post to make it accept it. Hope this line does it.