Having some problems getting my quad (GAUI 330x) to fly autonomously using APM1 (including GPS and Xbee modules from the diydrones store). Flew it under RC control and it was great. Got it out in the field and, using the mission planner(1.1.56), told it to take off to 2m, loiter for 30s, and then land. Instead it shot up to 30m, reached 13m/s, and in (about) 10s came crashing down to earth. Luckly most of the damage was to the fame and the electronics, appear, to have escaped.
My question is how do I keep from crashing again?
To be more specific: could the crash have been caused by my lack of magnetometer, something wrong with my loiter command or land command, or is it something else?
Also, does anyone have an example of the commands needed for a basic auto flight (including takeoff and landing) I can look at?
I am now planning on getting the quad to autonomously takeoff to 2m and then I'll switch it back to stabilize mode and land it manually. For landing I'm going to manually hover it to 2m then switch it to Auto mode and have it programmed to land as the first command.
Will this work? And will it work if I don't have a magnetometer?
If you want to fly autonomously, then you must have a magnetometer. Otherwise, the APM has no absolute bearing reference for turning. A GPS only gives the direction in which the quad is already travelling.
As for the hover/loiter problem, what version APM firmware are you running? v2.5 had an issue with Throttle Hold. I understand that's fixed in v2.5.3. You do need to fly and hover for a few minutes for the Throttle Hold value to calibrate, then land and Disarm for it to be saved.
Finally got a magnetometer! I now have a magnetometer and a GPS hooked up to the APM1.
So, any thoughts about the safest way to check the autonomous functionality of the APM1 with the most current Mission Planner software?
For example, is it better to test takeoff and landing first (tell the quad to take off to 2m and then land) or should I manually get the quad off the ground first and test loiter with a zero radius (I think this will make it alt hold)?
Also, to tweak the autonomous functions do you change PID settings?
You can do a takeoff to 2m and land, I have done it a bunch BUT always keep your finger on mode switch - sometimes wind can bring it in at an angle instead of straight down, so be alert.
Sometimes the safest way is to start a hover, then hit auto mode and the mission will start, then hit stable mode when it gets to about a foot hi.
HOWEVER- so far I have had poor luck incorporating loiter in a mission. Although it will loiter within a few meters, in a mission it seems to keep resetting and never terminates loiter (I had 10 in time and it went several minutes). A mission made up of takeoff-waypoints-land works remarkably well now.Make sure MP has the right home and altitude.
Another good test is fly a flight and trigger ch7 to save waypoints. land, start a hover, and hit auto and it will repeat the mission. This is easier than planning one because you are in the real space and know what it should do.
HOWEVER, make sure the correct home point and only the home point is in MP, or ch7 just adds waypoints to an exixting mission.
Loiter is still an issue in terms of accuracy and definitely how it acts in a mission. I can't wait for next version!
Thanks for the advice John!
I'm a little confused when you say ch7 will save waypoint. Did you program ch7 on your radio using MP to save waypoints? do you trigger it before you fly the waypoints or after? and do you have to 'un-trigger' it when you land?
In MP under 'OLD Arducopter Config' they have the channel 7 options, I think 'Save Waypoint' is the default. I have the switch off when I takeoff, and when I hit a waypoint I want to save just flick it on for a second and then off. After you have recorded a few you can repeat the mission as many times as you want - just takeoff in stable mode and flip to 'auto' and it will repeat it. If you go back to stable then 'auto' again it will restart the mission. Another setting to look at here in 'NAV WP' is 'm/s' - this is the speed it goes between wp. I have slowed mine down to 2 m/s and it makes me much less nervous.
I Always set my mode switch to stable when down, auto when up as a panic switch - I then decide in my head what will be an abort (1 meter from tree, etc) and just hit the switch should bad things happen. This is so stable it is very easy to just drop it and land.
When you reconnect MP there will be the mission in 'Flight Planner' and under 'terminal' you can dump the log of it to google earth. I am having good luck repeating multiple waypoints (no loiter)
Anyway, fear not - this is really fun and you have a good chance of success. If you have any results let us know!
2m seems way too low to me unless you have sonar for altitude control.
basically i wouldnt go any lower than 10m in auto, and even at this altitude if something goes wrong you still only have a fraction of a second to regain manual control.
John and James,
Thanks for the info. I'm going to try an Auto flight this week. I'll let you know.
Auto Flight Update:
Tried the Alt Hold mode and the Pos Hold mode.
Alt Hold works like a charm. I was able to get an awesome hover and it was a lot easier to fly than stabilize mode; although there were times when the quad would hit the ground. Is this because I set the Alt Hold at to low an altitude?
Pos Hold doesn't work at all. Every time I went into that mode the quad would drift in the same direction (even against the wind) and begin to lose altitude. Any ideas about how to fix this?