Developer

MatrixNav revision 2 is released

Revision 2 of MatrixNav firmware has been flight tested and is now released. The documentation and operation stays the same as for the previous version. The link on the main page for the UAV DevBoard points to the new version. The documentation is available there, also.

The baud rate for the binary serial interface to the GPS has been raised in this version from 4,800 to 19,200. This eliminates a 12 second delay in the GPS information that was present in the previous version. As a result, performance in windy conditions has been improved.

If you are using the previous version of MatrixNav, replace it with this version. If you made any changes to the control gains in the file controlGains.h, be sure to either save your existing file, or record the values that you are using, and edit the controlGains.h file that is part of the new firmware.

The YAWKP and YAWKD gains in the new version have been lowered from the previous version by a fair amount, so that the turns are wider and smoother. In the previous version, a switch to RTL mode would result in your plane "turning on dime". In one of the comments below, Sid recommends lowering the gains. Just so there is no confusion, you should understand that they have been lowered.

Also, in the previous version of MatrixNav, YAWKP and YAWKD were postive. In this version they inadvertently wound up to be negative. So if your plane is already set up with the previous version, either make YAWKP and YAWKD positive, or toggle the position of switch SR1 on your board.

Bill Premerlani

Views: 161

Comment by sid on April 25, 2009 at 8:24am
Hi Bill,
I just flight tested the new revised code. It's great. It locks the airplane on RTL point. DCM rocks.
Regards
SID
Comment by OlivierD. on April 25, 2009 at 8:30am
Sid: Any videos of your flight?
Comment by sid on April 25, 2009 at 8:42am
@ OlivierD .. I could not take today's video but I have earlier one.. I mean with GPS delay .. You can download from below link.. I will make one dayafter tomorrow and post.. But I tell you DCM performs Awesome.
It simply locks on the RTL point.. You just need to lower gains by half (YAWKP AND YAWKD)

http://www.yousendit.com/download/dVlyeW42eFgzS3AzZUE9PQ

Developer Comment by William Premerlani on April 25, 2009 at 9:44am
Just to clarify the lowering of the YAWKP and YAWKD gains. The gains in the newly released code have been lowered with respect to the previous release, so you will probably want to try them just as they are before you try other values. When Sid used the previous release, the turning was rather aggressive, because the control gains were rather high. Basically, when Sid commanded RTL, his plane "turned on a dime". The values that I now use, YAWKP = 0.0625, and YAWKD = 0.25, produce firm, smooth control.

Also, you can change the sign of the feedback with either the signs of the gains, or with the servo reversing switches, SR1 and SR2, on the board. YAWKP and YAWKD must both be plus, or they both must be minus. It does not matter which, as long as they are the same. SR1 reverses feedback on the rudder, SR2 reverses feedback on the elevator.
Comment by MC on April 25, 2009 at 10:22am
Is there a version of the MatrixNav code to run on Ardunio Mega board and one of the 6DoF IMU board from Sparkfun?

Developer Comment by William Premerlani on April 25, 2009 at 10:36am
@MC,

No, right now MatrixNav runs only on the UAV DevBoard. If there are any volunteers who want to port it to either of the boards that you mentioned, I would be willing to give them a hand.

It is my understanding that Chris Anderson will develop an IMU shield for the ArduPilot. Jodi has contacted me, and the plan is for him to port DCM to the ArduPilot.
Comment by OlivierD. on April 25, 2009 at 4:23pm
@Sid:
Very cool video! Thanks for sharing! The turning was a bit violent when you engaged RTL but I imagine once you adjust the code properly, it must be nice and smooth. Good job Sid!
Good job William and Paul!
Comment by sid on April 25, 2009 at 8:23pm
@OlivierD Thank .. I will definately take a Video day after tom and upload it. Since I have to call my friend to take a Video (of course a Flyer otherwise you know what happens...you need a magnifine glass to look for the plane LOL:-)..After tuning the Gains it worked Awesome..very precise..
Comment by OlivierD. on April 26, 2009 at 11:40am
@Sid: looking forward to see the flight with the new settings. Good luck.
Comment by sid on April 26, 2009 at 7:10pm
@ OliverD ..Sure will post it tomorrow...

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