Replies to This Discussion

3D RoboticsPermalink Reply by Chris Anderson on September 16, 2011 at 10:34am

No, that just means that you haven't updated your Mission Planner recently. See this post.

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Permalink Reply by CyberCrash on September 16, 2011 at 11:00am

Thanks Chris.

 

Just installed MissionPlaner: 1.0.68

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Permalink Reply by Vincent Mees on September 16, 2011 at 12:24pm

Finally got the time and the weather to load up v42 and have to say its a big improvement!!

And I left everything default. Surpised be this because previous version Ialways had to twinker with stable P or D

Stable is stable like previous versions. Very good.

AH great at low and high alt.

Loiter seems great though needs some finetuning when there is some wind.

 

Tested RTL several times and the quad just comes back very easy. But altitude goes up and down. As AH pids are great, which should I change to adress the oscillating alt in RTL???

 

And the finally a mission. My first. Started of with 3 WP. WP 1 was just a waypoint, WP 2 loiter for 10 sec and WP 3 LAND. I took off switched to auto and of it went :-) What a great feeling.

But .... It seemed that the quad did everything I wanted but only at WP1??? So it went to WP1, stayed there for about 15sec and started to descend very slowly until it touched the ground.

 

I then reloaded the mission and tried again. But nogo. Samething and I had the impression that the quad was very unstable.

I'm doing something wrong??

 

What I also noticed on the planner is that the current altitude isen't correct. It also jumps up and down. I for example start at 0m and land after a flight with -8m?

 

A great leap forward.Thanks guys!!!!!!!! 

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Permalink Reply by u4eake on September 16, 2011 at 12:55pm

Vincent, the altitude displayed in the mission planner seems to be only the gps altitude.  GPS altitude is fairly unaccurate.  I also fly fpv with an OSD with gps altitude and often when I land, the gps altitude will display -5 to -15 values.  

It might be a good idea to replace gps alt with baro alt in the mission planner ?

 

Anyway, congrats on the mission !  Hope you find out why it stayed at wp1.

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Permalink Reply by Vincent Mees on September 16, 2011 at 1:20pm

Ok then, it would be nice if alt was more correct.

 

Here is the log of all the tests I did this evening;

Attachments:

• 2011-09-16 09-47 1.log, 3.2 MB
• 2011-09-16 09-47 1.kmz, 173 KB

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Permalink Reply by James Roney on September 16, 2011 at 10:51pm

What if they took sonar = ground 0, most sonars rated for 6M.  Use sonar to keep the the most acurate alt, 0 above ground when init.  At this point you could then perhaps have the baro calibrated because you know where ground 0 is, well which is 20cm off the ground because of min distance on sonar.  Then once in the air, use sonar for as long as possible before moving on to not just baro but gps too.  So you could perhaps use the average of the GPS and Baro to keep tabs on each other and everytime you get accurate alt data from the sonar (5secs solid data), use it to re-calibrate the baro and average out again with the GPS. Why does APM use the GPS alt, when we rely on the baro for general flight, doesnt make sense. 

I am sure one of you guys can articulate this better.

 

 

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DeveloperPermalink Reply by jasonshort on September 16, 2011 at 10:55pm

I wish the sonar were good enough to reset the Baro. I used to do that in fact, but many things can cause the Sonar to misread. This can lead to the copter rising indefinitely. Which it used to do. 

 

But I've found the Baro to be the most accurate sensor. Even better than the GPS. So adding in the GPS data would only worsen the reading.

 

The best way so far seems to be re-init the baro at arming. But I'm open to different idea. The best way is to clone the Git branch and try a few ideas out. Then share the results. 

Thanks!

Jason

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Permalink Reply by James Roney on September 16, 2011 at 11:20pm

Nice answer.

 

What about APM using GPS instead of baro data?

Regards,

Solo.

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Permalink Reply by Michael Pursifull on September 16, 2011 at 11:22pm

For what it is worth, my GPS altitude, even with a 9 satellites lock, varies by up to 16m while sitting still. 

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DeveloperPermalink Reply by jasonshort on September 16, 2011 at 11:23pm

I think that's more legacy. Doug was the one who got me converted to Baro only.

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Permalink Reply by James Roney on September 16, 2011 at 11:28pm

So APM Planner no longer using GPS data?

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DeveloperPermalink Reply by jasonshort on September 16, 2011 at 11:33pm

Sorry, I thought you meant Arduplane. I'm not sure what the planner is using. The Altitude is reported back via mavlink in Absolute (with GPS) and Local (baro offset from home). You'd have to ask Michael Oborne what he uses.

Jason

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