Can someone direct me to a discussion, or give me some information regarding good mag field range using the Ardupilot Mega 2.5+? I have read a lot on the forum telling individuals their values are too high, but what is normal? What is expected normal range between zero throttle to 100% throttle? I would assume the magnetic field will increase the higher the percent of throttle, correct?
I have been flying my copter since April with no problems, yet. I am new to this hobby and I have used the Loiter option once (no problems) and RTL (no problems). My concerns are reading all of the discussions regarding the mag field and compass settings. It seems there are a lot of possible solutions, but I am having difficulty determining my options. I'm nervous reading some of the crashes due to potential mag field and compass problems. Now I am afraid to test the Loiter, Alt Hold and RTL until I know what is a normal range.
Another mag field concern I have is using my GoPro with a brushless gimbal that runs on a standalone 2s .8mAh battery. The battery is approx. 7 inches away from the APM. The gimbal is close to 11 inches away (wires included). I read some posts that this can add to the mag field. I haven't noticed any problems during flight, but again I do not no the recommended range regarding the magnetic field.
Please correct me if I am wrong, but the magnetic field and compass calibration is critical to Loiter and Alt Hold compared to Stabilize, correct? It seems individuals who run into problems are in some mode other than stabilize.
I am replacing my current motors to larger, 2814 710kv motors with 11 x 5 Graupner props. Will I notice a difference in my mag field when reading my log? I know I can find out for my self once they are installed and tested, but if anyone has experience, I wouldn't mind a "heads up".
I would appreciate some assistance.
Thanks.
Dan
Replies
I've made a number of tutorial videos. You can see the full list here. but some of the more useful ones are:
Compass health check
The importance of the compass only became super critical with 3.0 because of the aggressive navigation controller and introduction of the inertial navigation....so 'yes', it's only really important for Loiter, RTL and AUTO. Stabilize always works fine.
I doubt if you'll notice a problem after changing the motors. The interference comes primarily from the power distribution board and wires. If you put your APM too close to those then you'll have a lot of interference and you'll see "toilet bowling" (circling around the target) or flying off in the wrong direction if the compass is really off (i.e. off by over 90 degrees).
Compass problems don't normally lead to crashes into the ground. Maybe crashes into a tree or neighbouring house as it goes in the wrong direction but not normally into the ground.
Re the DJI, yes, I'm sure the reason the gps is on a stick is not to help the GPS so much as to help the compass...although EMI from all the other devices people put on their copters can affect the GPS as well.
Good question,
I'm wondering on the same topic. I'm a noob and have been flying my hexa for about 2 weeks, loiter, RTL, missions, no problems that I can see. But I read about all these poor guys having their birds make an unexpected run for the horizon, or self-destructing into the ground, followed by mournful posts filled with gobbledygook from the logs.All blamed on Evil Compass.
What's up with that? While I'm on it, how do you get those pretty graphs? I can't get anything useful to display from my logs, because I'm an idiot. Does anyone have a simple log tutorial?