Due to the poor GPS performance of the Iris and issues on some of them where the GPS presses down on the Pixhawk causing a wide array of other issues, i just ordered a mast kit for the Ublox GPS.
It will take custom cuts int the top cover so it will have a slot for removal but I'll figure it out when I get all the parts.
My GPS has been sent back for replacement and I have asked 3DR not to remove the protective cover from the new GPS. If they don't follow those instructions I won't be able to use the mast kit.
Anyone else tried this?
Mark Prince
Replies
Looks good so far! How is the engagement on the mast when moving the mast into the upright position? Does it snap or pop into place?
Yes it snaps into place. By my estimates the slot I cut will not intervene with the thread bulkheads of the original GPS mount. It will however come pretty close to the thread bulkhead for the cover screws.
I first considered folding the mast forward but then the GPS hangs out with no support when folded down. With the planned method the GPS housing will rest on the motor arm not causing any stress on the plastic mast when transporting.
I'll also have to make an adjustment to the compass parameters since the compass will be rotated 90 degrees relative to the stock installation.
Yes, I will have a hole in my cover but it's bound to help the GPS performance which has been randomly poor while also solving the space issue between the Pixhawk and the GPS.
Definitely let us know what change in HDOP you observe as a result of the mod!
I've made the cut in the cover and this is what it looks like with the bare mast. The GPS is supposed to be delivered today or tomorrow. Once I get everything permanently mounted and wired up i'll post a pic with the cover and without.
Success! I have a functioning mast on my Iris.
I got hdop of less than 1.5 sitting in the driveway. First flight went good but the jury is still out until I get 7 to 10 flights on it.
My first test was tonight(hover only) and it was the first time I have ever maintained <2.0 hdop when the Iris was off the ground. As low as 1.35.(log file is attached.)
See below for a couple of pics with the mast upright and folded down.
75.BIN
Since installing the mast on the Iris I have had 25 completely trouble free flights. Many of them autonomous missions. Every single flight maintained DOP values of less than 2. Sometimes values as low as 1.2.
No compass issues either. IT now flies the way I would have expected it to out of the box over 100 flights ago. The Ublox module pressing down on the Pixhawk causes MANY random problems.
Even though 3DR has yet to provide advice for a fix after several queries I can say that support otherwise has been excellent. They have a replaced a motor and a GPS free of charge and without question as well as the longer motor bolts. All other purchases I have made have been delivered and handled in an expedient and professional manner.
mp
After installing the mast it was totally different. I always get HDOP less than 2 and sometimes as low as 1.2.
pic is attached.
Did you recalibrate everything after putting the GPS module up on the mast? Getting the mast today. After the last firmware, I was suddenly unable to take off in my garden. DOP about 2.7.
Looking forward to trying out the mast solution of yours.
Oystein
Right now my concept is to mount the mast base on the top board in front of the Pixhawk.
The Ublox mast kit allows the mast to be folded down for transportation and convenience.
I plan to cut a slot the width of the mast in the cover from where the mast protrudes through the cover all the way to the front edge of the cover. This would allow the mast to be folded down towards the front allowing the cover to be easily removed.
Thats the plan anyway. Once I get all the pieces delivered and laid out with a couple of creative Budweiser tall boys I might think of something else:)
mp
they normally just send out the GPS retail kit for GPS replacements which has the GPS in the 3DR case..at least mine arrived that way. I also ordered a mast but since I have been experimenting with Pregnant IRIS for increased battery space I have now boosted the top cover up 10mm also. I would love to find or make an STL file for a Vacumn form mold so that I could alter it to provide for covering in the expanded body cases..
hzl
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