GPSHDOP problem

So I had a bit of a scare today.  My hexa was set to loiter mode at about 10m altitude when all of a sudden it just took off like a bat out of hell, due North from its intended loiter position.  I was able to quickly regain control, but not before it had covered a good 15 to 20m.

Looking back at the log I noticed that the ground track showed a jump in the opposite direction from where it actually traveled.  This hinted at a possible error in GPS positioning.  I found the following jump in the GPSHDOP at that same moment:

Had the hexa been flying at a lower altitude it could have easily crashed into surrounding objects.  The questions are: 

-  Is it possible to limit this kind of reaction?

-  In the case of a large shift in dilution of precision, such as above, is it possible to limit the reaction of the vehicle?  Could APM fall back to some sort of dead reckoning temporarily?

Thanks for any coments

Tags: GPSHDOP, dilution, gps, loss, of, precision, signal

Views: 219

▶ Reply to This

Replies to This Discussion

Permalink Reply by Jake Stew on July 18, 2012 at 12:38pm

It would probably be a good idea to put in some error detection in the GPS interpretation code.  But AFAIK there's no dead reckoning capability in the APM, it is only an AHRS system.  Position is entirely taken from the gps.

Permalink Reply by Rigel on July 19, 2012 at 1:17am

Jake, would you know if the AHRS GPS gain could help in any way to smooth out such a response?  According to the ArduCopter wiki: "This controls how much to use the GPS to correct the attitude"  The possible values vary between 0 and 1 but there are no explanations as to what a change in the gain does exactly.

Permalink Reply by Jake Stew on July 19, 2012 at 2:10pm

This is a typo I think.  "Attitude" should be "altitude".  I think this is the ratio of barometer to GPS in determining the altitude.

The GPS doesn't provide a attitude, it can only provide heading (yaw), position (including altitude), and speed.

Somebody should fix this in the wiki.

RSS

Social Networking

Top Content 

1 APM Project vs DJI NAZA and WOOKONG

APM Project vs DJI NAZA and WOOKONG
2 ArduCopter-3.0 ready for wider use

ArduCopter-3.0 ready for wider use
3 Flying 3D Spline Curves between Waypoints with ArduCopter 3.0

Flying 3D Spline Curves between Waypoints with ArduCopter 3.0
4 APM Copter 2.9.1.b has been released

APM Copter 2.9.1.b has been released
5 APM 2.5 with NEO-6M ublox gps (not 3DR LEA-6)

APM 2.5 with NEO-6M ublox gps (not 3DR LEA-6)
6 10k autonomous flight - telemetry guided flight, and other APM tests!

10k autonomous flight - telemetry guided flight, and other APM tests!
7 MAAT final version is being tested

MAAT final version is being tested
8 Getting ready for Arducopter 3.0

Getting ready for Arducopter 3.0
9 Help Tuning Arduplane 2.73 With A Large Slow Airframe

Help Tuning Arduplane 2.73 With A Large Slow Airframe
10 SolarSight, The University of Michigan SolarDrones UAV

SolarSight, The University of Michigan SolarDrones UAV

Contests

Season Two of the Trust Time Trial (T3) Contest has now begun. The fourth round is an accuracy round for multicopters, which requires contestants to fly a cube. The deadline is April 14th.

A list of all T3 contests is here. 

Groups

Advertisement

© 2013   Created by Chris Anderson.   Powered by

Badges  |  Report an Issue  |  Terms of Service