Comment by u4eake on August 3, 2012 at 5:27pm

Allright, I found why th mission planner ain't updating heading with ardurover if the gps doesn't have a fix.

JLN put the code to calc compass heading inside the update_gps function and inside a if (g_gps->new_data && g_gps->fix) statement.  So if the gps has no fix or no new data, then no compass heading is calculated either.

I have removed the compass heading calc out of the if statement, so that it gets executed with every update_gps call and now my gps is responding crisp in mission planner, wether the gps had fix or not.  The heading in mission planner is also MUCH more stable and precise, just like it is in arducopter.

Unfortunately it's 2.25 AM here now so I can't test on the car.  I should go to sleep :)

Comment by KM6VV on August 3, 2012 at 5:46pm

See anything to extrapolate the position if GPS fix is lost (dead reckoning from inertial and/or odometry ?)

what file are you in?

Alan

Comment by u4eake on August 3, 2012 at 5:51pm

Alan, no there's no dead reckoning or inertial navigation.  But the mediatek does lag behind about 1.2 sec, so it will happily keep sending data if fix is momentarily lost.

Also, for arducopter, Jason had made a lead filter, which counters the 1.2 sec lag from the gps by calculating real position, based on speed an direction.  So it estimates where the copter will be, 1.2 sec after the reported gps position. I would like to try and get that into ardurover as well.

I'm in the ardurover.pde file, almost at the bottom in the update_gps() function.

Comment by KM6VV on August 3, 2012 at 11:36pm

Hi eake?

Well that sounds close.  I'm looking for something to "fill in the gaps" when the GPS update is not available, like when the 'bot goes under a tree or too close to tall buildings.

Alan

Comment by Biz18434 on August 5, 2012 at 4:06am

Hello eake,
You said "I have removed the compass heading calc out of the if statement, so that it gets executed with every update_gps call and now my gps is responding crisp in mission planner, wether the gps had fix or not. The heading in mission planner is also MUCH more stable and precise, just like it is in arducopter." Can you please provide for information on how you did this?
Thank You,
Biz

Comment by u4eake on August 5, 2012 at 8:08am

It should be 'the compass is responding crisp in mission planner".  

Comment by u4eake on August 6, 2012 at 4:14am

Finally success !  Today during luchbreak I had my first successfull mission with ardurover :-)  It works very nicely !

After previous post I still had compass troubles.  It just kept pointing in wrong directions.  Yesterday it finally struck me : I had a magnet on my camera to hold the wide angle lens and this was about 10cm (4inch) away from the compass.  Ofcourse it was always pointing in the wrong direction.

Comment by u4eake on August 8, 2012 at 1:15am

Here's a video of a pretty successfull run.  Stil trying to figure out why it sometimes makes a 270° turn around a waypoint instead of a 90° turn the other way.

Comment by Biz18434 on August 9, 2012 at 10:06pm

Hello,
I have a Traxxas Slash 4X4 with an ArduPilot Mega 2.0 and a Sharp IR distance sensor for obstacle avoidance. I have no issues running my rover from my RC controler but when I switch to Auto my rover takes off at full speed. After watching U4eake's video (Congratulations for your successfull run) I noticed at time;
0:34 Speed can be set and throttle limited for safety.
0:39 Throttle limited to 15%
Can someone please tell me what parameter was adjusted to set speed and to limit the throttle.
Thank You,
Biz

Comment by u4eake on August 10, 2012 at 3:57am

There are 2 parameters that influence this, cause I found that the rover doesn't really obey the set speedlimit.

But it obeys Throlle_slew_limit (I use =2) which limits how fast your throttle changes, so it takes of gently instead of immediately full throttle and Throttle_max ( I use 65, which equals 15% cause 50% is no throttle and below 50% is braking/reverse)

You can change them with mission planner (parameter list)

Let me know how it goes !!

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