I have two ArduCopters... One with the 850kv motors, 10x45 props and a MB1260 XL-MaxSonar-EZL0 sonar. The second one is a 880kv motors, 12x45 props and LV-MaxSonar-EZ4 sonar. Both on the latest firmware compiled in arduino-0022, 2.0.35 and uploaded to both from arduino-0022.
Something changed in 2.0.35 which causes the motors to gun instead of slowly ramp up to adjust altitude while in alt-hold/loiter. This of course happens on both of my quads.
The larger quad (880kv ez4 sonar) seems to alt-hold and loiter OK but there is an issue with altitude considering the engine gunning.
The 850 kv quad with the ezl0 sonar has worse problems. Alt hold may hold (considering the engine gunning) for a few moments but eventually rises and does not stop or it descends to the ground. Sometimes it will descend to the ground and then fly back up either to a random height OR it will just keep climbing until i recover manually.
The one issue is a code issue, the gunning, this was something chris had done to test some sensors and was going to move the alt-hold code back to where it belonged, this has not happened yet.
So my question is.. Is the ezl0 sensor different in some way that may be causing this behavior? (climbing and not stopping, i was having random problems with this one before).
Im going to disable sonar and give it another go. Attached is the log from the flight with all the alt-hold issues.
Well assuming that the units in the graph for the barometer are in CM then i would say it is accurate. The sonar never registers more then 500cm while the altitude varied from near ground level to about 15-20 meters high.
Perhaps its this particular sonar, i will know in a few days once the 1200 arrives.
I believe both my ELZ0 and EZ4 are junk or something is wrong with them. I was having difficultly with both so loaded up the ranger test code to run on both of them. The ez4 will not read anything but 20cm, the elz0 will only start-up showing a range SOME of the time... if its showing a range it seems to be accurate but seems to have allot of noise OR it ramps up to 700 (when the quad is sitting flat and level)(this is cli only test on usb and battery power, same results each time).
I was thinking maybe my IMU was bad (it wouldn't surprise me, i messed up two of them already).
Today i got a mb1200 EZ0 sonar in the mail and that sonar seems to work fine. I hardly had any testing time because of a bad windy storm in the area but i manage to hover a few minutes in alt-hold which seemed to function properly (even in the wind).
please keep us posted on your findings.
I flew a total of about 30-40 minutes today and allot of it in alt-hold and loiter and must say that alt-hold is pretty solid now.
The new position/mounting suggestion for the sonar in the wiki is probably the best position for it but i did not have anything handy to mount the sonar out away from the ESC. Instead it is mounted directly under one of the front arms on two of the longer plastic standoff's included with the kit (as pictured below).
I tested it also with one long and one half standoff included with the kit but i got noise on the sonar.
In another thread it is also suggested to use a shielded cable (which will be my next mod). Eventually i will get the sonar mounted on an arm but for now this works very well for me and is noise free. I just do not like how low it is to the ground.