> -----Original Message----- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] On > Behalf Of Nicol Carstens > Sent: Friday, March 23, 2007 5:51 AM > To: flightgear-devel@lists.sourceforge.net; [EMAIL PROTECTED]; > [EMAIL PROTECTED] > Subject: [Flightgear-devel] Phidot not zero.. And bank angle > constant... > > > Hi guys. > > First of all (before I start "complaining") let me start off > by saying: > thanks for sharing your work publicly! MUCH appreciated. If > you don't mind, and have some time to spare me, I need to ask > a question... > > About myself and my project: I am qualified as an electronic > engineer (did a masters in control of a model RC helicopter), > and have about 6 years simulation experience in the Aerospace > industry. I am trying to use FlightGear for autopilot/AHRS > development work... I am looking at the data as received from > the Native-FDM UDP packet (at 20-40Hz). Maybe I am missing > something (not at all impossible)... but I think something > might be wrong... > I am using FlightGear Version 0.9.10. > > My question: > If I put the aircraft (Cub or 172) into a constant bank and > pitch angle turn ("trimmed"), I expect phidot and thetadot to > be near zero, and psidot non-zero... Yet, I see thetadot near > zero, and phidot and psidot non-zero (as a matter of fact: > phidot is almost as "large" as psidot). Surely this can't be > right? According to the FlightGear (and MathsWorks / Matlab) > documentation, this is not p,q,r but Euler/Gimbal angular > rates in rads/sec... not body rates... > > I know that the pitch and roll angles are constant because I > can see it visually in the sim, and confirmed looking at the > UDP data (roll, pitch, yaw)... > > My goal: I want to derive p,q,r (simulate rate gyroscope > sensors) and calculate the horizon... Building an AHRS. But > if I use the current data, the angles are drifting even > faster than using the real hardware!! > > Am I missing something, or is there a bug?? > > Kind Regards, > Nicol.
Sorry, but I don't have ANY time to respond to this, but keep in mind that you are looking at BODY-AXIS rates and accelerations. If you are in a turn, the pitch and roll are going to show values. Bill ------------------------------------------------------------------------- Take Surveys. Earn Cash. Influence the Future of IT Join SourceForge.net's Techsay panel and you'll get the chance to share your opinions on IT & business topics through brief surveys-and earn cash http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV _______________________________________________ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
