Matrix Nav experience.

Hi All,I'm doing my walk around testing, I thought I might list the sequence/experiences that I had. I have MatrixNav (Red, 1.7) loaded but referred to the Aileron assist document as it describes the initial set up and where the servos plug in a little better. My LED on the EM406 glows a very faint red while powered up, I would like to know if others have observed this, it still seems to operate correctly.Firstly, I set up my 3 position flap switch (JR 2720 radio) as follows:Position 'Norm': Flaps at 25% downPosition 'Mid': Flap at 10% upPosition "Land': Flap at 100% upThe trims on my transmitter are digital and therefore awkward to move full left or right, the flap switch works a treat.If you power up in an electrically noisy environment i.e. next to my PC then the green LED will come on and after a few seconds the servos will go crazy. The green LED reflects a TX signal (valid or otherwise).If you power on in a quiet environment, then green LED stays off and the servos don't move. Switching on the TX results in the green LED coming on and the servos responding correctly.The red should flash for about a second and then go off. On GPS lock the aileron servo will move back and forth seven times and then it seems set. This takes around 30s if the GPS has been off for awhile. If the GPS does not have a lock (i.e. you are indoors), the mode switch is ineffective.In a 'normal' mode the green LED is on and the red off, in assist mode the green is on and the red is on, in RTL mode the red flashes and theWhat I did find that I cannot explain, the switches do not change the direction of the servos! I tried moving the switches while powered up and after resetting the board but the directions didn't change. I haven't tried changing the gains to a negative value.Once, after switching off the transmitter and switching it on again, the board would not return from RTL mode! I had to reset the board to get it working again, I haven't been able to duplicate that and so I have put it down to something that I did.Manual stick movements will still move the servos even in RTL mode. I am not sure if this is correct?The RTL is fairly untested as I didn't walk that far and every step I took resulted in some servo jitter. I think it was behaving correctly but I will try later at the field where there is more space.I hope the above is useful to the first timers.Cheers,

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Replies

  • Bill,
    I just read Greg's latest post. Is it true that you need to rebuild or make the project every time you make changes to waypoints (or the options.h file)?
    Thanks-----
  • T3
    Belli,

    One more thing...the instructions for operation and setup for MatrixNav and AileronAssist are nearly identical, so I am puzzled as to why you prefer the AileronAssist instructions. Then I went back to look at the UAV DevBoard home page, and realized that I was not consistent about the use of the terms "documentation" and "instructions". When I first started out, I prepared some lengthy, detailed, documents that detailed the inner workings of the firmware. Later on, I streamlined things.

    So, I think you might have a link to one of the older MatrixNav "documents" rather than "operating instructions". Anyway, in case you somehow missed it, I think you should take a look at the latest version of the operating instructions for MatrixNav.

    Best regards,
    Bill
  • T3
    Belli,

    Thank you very much for sharing your observations. I have operated my own boards so many times, I take some of the things you report for granted. Everything you report is normal, with the exception of the problem you report with the switches on the board, which I hope is just a misunderstanding.

    My firmware places the GPS in binary mode. That has the side effect of turning off the LED on the GPS. Nothing can be done about that, its just how the EM406 operates.

    Regarding the polarity of servo responses....the switches on your transmitter will control the polarity of the response of the servos to your transmitter. The switches on the board will control the polarity of the response of the servos to feedback signals generated in the board. So, for example, switch SR2 should control the direction of the response of the elevator to pitch, when in RTL or stabilized mode. If it does not, then perhaps the switch has an open solder connection.

    One way to test the switches is by running the self-test firmware, in one position, the gyro signal is fed to the corresponding channel, in the other, its the accelerometer for that channel. If you have steady hands, you could also test the switches with a meter.

    If any of the switches are not working, you could contact SparkFun and ask for an exchange. I highly recommend setting the polarity of the responses with the switches, not with changing the signs of the gains, unless you can be very careful and patient. Within the software, I have packaged up the signs that go together, so that when you flip a switch, you might be changing the sign of several gains at once. If the gains in a given group do not all have the same sign, then you could run into a situation where some of the feedback terms could be fighting each other.

    Regarding your board getting stuck once in RTL mode, that could happen if your battery was low on your receiver. One other pilot reported this symptom to me, and then later discovered he had a bad Rx battery. The firmware does a health check on the pulses coming in. As the battery on the receiver gets low, the pulses become erratic, and the board goes into RTL mode to bring your plane back to you before the battery dies. I have logged over 50 flights, and have spent many days doing walk-around testing, I have not seen my boards ever getting stuck in RTL mode. The logic is rather simple on this. The firmware monitors channel 4 PWM input for valid pulses coming from the Rx. A valid pulse is any pulse with a pulse width between 1 and 2 milliseconds, plus or minus a margin for error. If there are 50 valid pulses in 2 seconds ( 25 Hz), the firmware declares a healthy radio, and honors the PWM inputs. Otherwise, it ignores all PWM inputs, and goes into RTL mode.

    The manual stick movements will contribute to the response of the servos in RTL mode. It goes all the way back to when I first started testing some of my ideas, I wanted to be able to continually adjust the trims if I wanted to during RTL. Then I realized that it would be a good feature to leave it that way. The idea is that you have the option of working with RTL, or leaving it alone. RTL is intended to help you get your plane back if it gets too far away. You can sit back and watch it return on its own, or you can help, if you want. For example, if your plane is heading back in a strong wind, you can adjust the trim accordingly to pick up some speed.

    If you want to get a better idea of whether or not RTL is working right, you can turn off the damping terms while you are doing a walk around. These are the parameters PITCHKD and YAWKD in the file controlGains.h. You could temporarily set them to zero during your walk arounds, this will give you a better idea if everything is working the way that you want. Then you can turn them back on later. They improve the stability, but they tend to generate "noise" during a walk around unless you can hold the plane very steady. That is the point...when the plane is flying, PITCHKD and YAWKD will counteract any twitches the plane makes.

    In many respects, the philosophy of RTL in my firmware is similar to the idea of the stabilized mode....the electronics and you are working together to make your flying experience fun, safe, and secure.

    Best regards,
    Bill
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