APM1 > APM2?


To avoid confusion, I ought to preface this post by mentioning that I began tests quite some time ago with the APM2 purple board. Since then I've gotten my hands on it's older brother the APM1 (hey, they're cheap now and then!). I have the APM2 in my heli now, so I decided to throw the APM1 on my quad in place of the APM2 to see how things compare...

So that might be a bit of an excessive title, but if I didn't know the differences between the two boards, I would claim that the APM1 is superior to the APM2!

A lofty claim, you might suppose, but let me explain why.

Firstly, the yaw issue I had with my APM2 is completely gone after installing the APM1. I'm using the same quad frame I had my APM2 on. Perhaps shuffling the ESC's around a bit helped. I moved them a bit farther away from the center and they now reside near the motors themselves. I've heard that to be a good thing, and I've heard it to be a negative thing having long + and - wires, so who knows.

The most surprising observation I made was with regard to loiter. This is the first time I've gotten anything to loiter. I can't claim to have even once gotten my APM2 to loiter, but right off the bat with default parameters, the APM1 on my quad loitered amazingly well (both using 2.5.5). Why? I have no idea. I didn't run a long test, but take a look at the results in the picture. The longest distance traveled was about 7 meters. There was a slight breeze. I suppose this warrants some careful comparisons of mounting, wiring, etc. for me in the future.

Anyway, that was my surprise for the day. I know the APM2 board is quite an improvement upon its predecessor, and I'm really not claiming otherwise. I suppose all I'm doing is pointing out the causes for my sudden onset of confusion and hope. Either way I'm happy. I have an APM1 in my plane, APM1 on my quad, and APM2 on my heli. No complaints here (except crashing the plane repeatedly, but that's another story...)


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  • Is it possible for the mission planner to identify APM1 vs APM2 and install different default parameters for each?  If not, then could the docs can be modified to highlight the issue?

  • Chris, I can't wait to try the new code! I only modified the stab and rate terms as I expected I'd have to for this frame, nothing too unusual there. Both boards fly fine and do what they ought to in that respect. The big differences have been with yaw and loiter issues. I've done my best to eradicate the yaw issue with APM2, and get it to loiter, each with minimal success - default parameters or not. When 2.6 arrives I'll give it a try on both boards and see how things go.

  • 3D Robotics

    Eric, if you're using the default gain settings, this is probably more about the settings than the boards. Through 2.5.5, we've been releasing code optimized for the APM 1, since that's what most people have. Starting with 2.6 (which should be out today or tomorrow), the code will be optimized for APM 2, since there are now so many out there. It should still fly fine with APM 1, but you should see the APM 2 improvements more clearly. 

  • I think so, APM1 better than APM2, I have both

  • Thank you that help alot.

  • The log is automatically accompanied by a KMZ file which opens in Google Earth (or maps, if you want). When you download a flight log from the APM, the log and KMZ are placed in the "logs" folder in your APM Planner directory. 

    Looking at logged values such as sonar is a different story. I do not believe there is a way to view that in Google, but you can graph it in Mission Planner. To do so, after you have downloaded the log go to the Terminal tab, and click "Log Browse." Then select the desired log and click on one of the "CTUN" boxes in the first column (play around with the other ones too, there's lots of good data logged!). You'll see the third column header labeled "Sonar Alt." Click on the cell which corresponds to the Sonar Alt column and CTUN row and click the "Graph this data" button. You can graph several other parameters on the same graph to compare different things. I hope that helps.

  • Hello, how did you get that leveling into google maps. I have searched this site on a how to to see the sonar reading but have failed in this,

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