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This thread is privately moderated by mike_kelly, who may elect to delete unwanted replies.
Jun 09, 2015, 08:36 PM
Wisconsin
Thread OP
Mini-Review

Pixraptor a better Pixhawk?


I just reviewed the Pixhawk LITE a low cost small form factor Pixhawk clone offering from GoodLuckBuy. It seems like it will serve well as a replacement for APM.

But for my big multicopters I am more and more looking for reliability. I have learned a few things from my first builds and the top three are:
1. The quality control on the common parts we buy is poor.
2. You are going to crash and break things.
3. Because of #1 & 2 you better be able to fix your aircraft without tearing it down to bare bones because you will be doing it often.

If you don't want to be frustrated think reliability from the start of your build.



That is where the Pixraptor comes in for me. You might think why do we need another Pixhawk clone, especially one that is more expensive than other clones? Well this new Pixraptor is not your take-a-picture-and- copy-it-exactly type board. Somebody really took a look at what could be improved and tried to make a better product. I won't know if they met those lofty goals until the build is finished but the attempt was definitely made.



First thing I notice is the connectors all come out the sides. I like this. It is hard to make a build with clean wiring if all the connectors are pointing straight up. Next they used molex connectors instead of Df13. Some people hate DF13 connectors. The deal is the DF13 connectors require you to tilt the connect on edge and kind of rotate into the socket. If you don't do that installing and removing you risk tearing the connector off the board. The molex goes straight in and straight out, easy. The DF13 might actually be more secure I think but I do have a hard time getting them out. All the full size Pixhawk connections are there except the remote USB.




I got the ala carte version that only came with their combo buzzer/SW is well thought out. The unit is designed to foam tape down with the supplied round tape and allows you to push the button down without having to hold the switch in your other hand. In addition the LED is right there facing up.


On the output side we have the ubiquitous Dupont servo connectors conforming with the full sizePixhawk orientation.



The case comes apart with four screws and here is where the real differences start. One of the primary tasks in building a multirotor with a Pixhawk flight controller is to get your unwanted vibrations in check. The sensors need to know how the multirotor is moving in order to calculate how to power which motor and how much to correct the flight. But if the arms are shaking due to motor and prop vibration it confuses the sensors. So you can't have accurate control by the flight controller if the sensors are vibrating all over the place.

By now you may have read that there is a Pixhawk 2 flight controller in the new 3DR Solo multirotor. One of the features of this new version of the Pixhawk is that the sensors are suspended by a separate little board and a ribbon cable runs to connect its data lines to the main flight controller board. The cad drawing of it look like this:


Now the first thing I noticed when the top was off... wow this Pixraptor has the same design. The sensors are not on the main circuit board but suspended by GEL on a platform with a ribbon cable connecting to the main board. This took a lot of engineering to create rather than an exact copy of the original Pixhawk design. Unless it is a copy of Pixhawk 2?




The workmanship looks good and the unlike the Pixhawk LITE the labels appear to be right.

So I plugged it in and powered it up and got a nasty SOS alarm beeping and nothing else. I had not heard that before so I looked it up and it is because the micro sd card was not installed. So I pushed the card into it's slot and bingo the Pixraptor came to life.



Another nice change is that the LED's are in places you can actually see them on the ends of the case point out to the sides. The case tends to flare out the leds making them easier to read.

It connected first time to Mission Planner. Came with 3.2.1 installed. I calibrated the Accelerometer and the Compass without issue.

So I am encouraged. The designer has made and effort to make real improvements in the Pixhawk design. Nothing earth shattering but useful. The IMU suspension could really help get vibrations under control.

So I will have to see how it does in the air after the build is complete. But after the experience with the Pixhark LITE the Pixraptor was a breath of fresh air.
Last edited by mike_kelly; Dec 16, 2016 at 11:20 AM.
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Jun 09, 2015, 09:49 PM
Registered User
jjmelo's Avatar
Great review. Thanks. Saving for laterz
Latest blog entry: 3D Printing Services
Jun 10, 2015, 01:02 AM
Registered User
Mike, have you tried connecting dual GPS? My unit doesn't work when 2nd GPS is connected on serial 4/5. My other 2.4.6 pixhawk has no issues with this.
Jun 10, 2015, 06:05 AM
Registered User
Yana547's Avatar
Excellent review Mike, so I deleted pixhawk lite from my list. There will be pixraptor or pixhack (both have internal dampening) before Pixhawk2 available .

Now I'm curious how the vibration graph from the log look like , so far with fixhawk and AUAV- X2 I got between -8 to -10 using 2 layers of foam tape.
Jun 10, 2015, 07:21 AM
Wisconsin
Thread OP
Quote:
Originally Posted by zerstorer78
Mike, have you tried connecting dual GPS? My unit doesn't work when 2nd GPS is connected on serial 4/5. My other 2.4.6 pixhawk has no issues with this.
I'll check it.
Jun 10, 2015, 07:22 AM
Wisconsin
Thread OP
Quote:
Originally Posted by Yana547
Excellent review Mike, so I deleted pixhawk lite from my list. There will be pixraptor or pixhack (both have internal dampening) before Pixhawk2 available .

Now I'm curious how the vibration graph from the log look like , so far with fixhawk and AUAV- X2 I got between -8 to -10 using 2 layers of foam tape.
That is the key question, is the dampening effective?
Jun 10, 2015, 11:11 AM
Registered User
P.I.Engineer's Avatar
Thank you Mike, i've been looking at this board too.

If not too much trouble, could you take a size comparison picture to an apm or pixhawk or the pixhawk lite?

thanks
Jun 10, 2015, 12:21 PM
Wisconsin
Thread OP
Quote:
Originally Posted by P.I.Engineer
Thank you Mike, i've been looking at this board too.

If not too much trouble, could you take a size comparison picture to an apm or pixhawk or the pixhawk lite?

thanks
The Pixraptor and the Pixhawk are comparable size. You can see the Pixhawk vs the LITE on the lite blog entry for comparision.

Cheers

PS > the Pixraptor is thicker tho.
Last edited by mike_kelly; Jun 10, 2015 at 08:12 PM.
Jun 10, 2015, 12:22 PM
Wisconsin
Thread OP
Quote:
Originally Posted by zerstorer78
Mike, have you tried connecting dual GPS? My unit doesn't work when 2nd GPS is connected on serial 4/5. My other 2.4.6 pixhawk has no issues with this.
I pulled all the plugs from my Fixhawk, plugged into the Pixraptor and both GPS work correctly just as they did on the Fixhawk. So serial 4/5 works correctly for me.
Jun 10, 2015, 01:00 PM
Registered User
Hey Mike thnx for the review, so you got me interested in this board now, only wondering if its worth its price. have you had a chance to fly with it yet???
Jun 10, 2015, 01:15 PM
Wisconsin
Thread OP
Quote:
Originally Posted by LifeStyle
Hey Mike thnx for the review, so you got me interested in this board now, only wondering if its worth its price. have you had a chance to fly with it yet???
No unfortunately I have a backpacking trip I'm leaving on tomorrow
Jun 11, 2015, 07:56 AM
Registered User
Hello guys,

For those who did not see it yet, although in chinese there is an almost complete review about the Pixraptor here:
http://bbs.5imx.com/bbs/forum.php?mo...ad&tid=1065843

English translation:
https://translate.google.com/transla...843&edit-text=

BTW Mike, which GPS will you use ? I want to buy an M8N with a good antenna.

Something important to note is that although Molex sockets are on the Pixraptor back side we can also plug in the DF13 connectors (please correct me if I'm wrong), therefore all the Pixhawk accessories are compatible with the Pixraptor.

I'm still hesitating between the Pixraptor and the CUAV Pixhack which has a very nice and smaller aluminium case and dampened IMU as well. It is sold as a kit with dedicated accessories, it use another (better ?) type of sockets (Molex/JST GH 1.25mm)

Hope to read your flight review soon...
Jun 11, 2015, 08:32 AM
Wisconsin
Thread OP
Quote:
Originally Posted by patrick99
Hello guys,

For those who did not see it yet, although in chinese there is an almost complete review about the Pixraptor here:
http://bbs.5imx.com/bbs/forum.php?mo...ad&tid=1065843

English translation:
https://translate.google.com/transla...843&edit-text=

BTW Mike, which GPS will you use ? I want to buy an M8N with a good antenna.

Something important to note is that although Molex sockets are on the Pixraptor back side we can also plug in the DF13 connectors (please correct me if I'm wrong), therefore all the Pixhawk accessories are compatible with the Pixraptor.

I'm still hesitating between the Pixraptor and the CUAV Pixhack which has a very nice and smaller aluminium case and dampened IMU as well. It is sold as a kit with dedicated accessories, it use another (better ?) type of sockets (Molex/JST GH 1.25mm)

Hope to read your flight review soon...
I plan to use one M8N for greater satellite coverage and one Neo6 for better hdop. I think redundant GPS is a very important feature of Pixhawk.

The Pixhack is almost double the price is it not?
Jun 11, 2015, 09:18 AM
Registered User
Quote:
Originally Posted by mike_kelly
I plan to use one M8N for greater satellite coverage and one Neo6 for better hdop. I think redundant GPS is a very important feature of Pixhawk.

The Pixhack is almost double the price is it not?
Hello Mike,
Seems to be about $180 from different vendors for a complete set incl. shipping, not clear if it contains a 7M GPS or not, anyway still a fair price IMHO...

Cheers.
Jun 11, 2015, 12:05 PM
I'm New
unfaix's Avatar
Quote:
Originally Posted by mike_kelly
I pulled all the plugs from my Fixhawk, plugged into the Pixraptor and both GPS work correctly just as they did on the Fixhawk. So serial 4/5 works correctly for me.
Been out of the arducopter scene for awhile, what's the purpose of dual and tripple gps?

better accuracy?


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