The UAV Devboard is back in stock at SparkFun, with a new design.The reason for the design change is that Analog Devices no longer makes the gyro that we were using on the previous board, so we have switched the design to the LISY300AL. Paul Bizard and I have thoroughly tested the new board on fixed-wing aircraft, the LISY300ALs work just great with DCM.We have modified all of our existing firmware to be able to run on either board, and will make sure that all future firmware will also work on either board. If you have written firmware for the UAV dev board, you will only have to make a few minor changes to run it on the new one. The two board designs are nearly identical. The only differences are:1. The new board uses LISY300AL gyros instead of the ADXRS401, and the 6g range instead of the 1.5g range for the accelerometers. This will allow you to provide aerobatic control without saturating the sensors.2. The gyros, the accelerometers, and the A/D reference voltage are all tied to the 3.3 volt regulated supply. This will totally eliminate drift of gyros and accelerometers due to supply voltage changes.Each firmware project now has both a "green" version for the previous board and a "red" version for the new board.
@William, do you think the LISY300 gyros would perform well enough to stabilize a helicopter or quadrotor? (Obviously I'd have to add magnetometer support back into the estimator algorithm).
@Hugo,
I am aware of the ADXRS610. I tried out the LISY300 instead because of the price. I had seen some good reports on it. I am hoping that SparkFun will pass along some of the savings, and lower the price of the board. At any rate, I have asked them to do that.
I did evaluate the LISY300 before deciding to use it. SparkFun made a prototype board for me to test before going into full production. I tested it and was very pleased with the results. The performance of my firmware in the new board is actually better than the previous board: I can rotate 4 times faster without saturating the gyros.
So, I am not sure why some folks have not seen the same good performance that I have seen. There could be any number of reasons, ranging from the algorithms that were used, to ESD problems, to noise pickup.
At the moment, I am waiting for the first board in the new production run. When I get it, I will test it thoroughly before releasing the new design.
I am not aware of any airframe that will pull 6gs, but so far I have limited experience with high performance planes. My plan is to use DCM as a copilot to work my way up to higher performance planes.
My logic in switching to the 6 g setting was simple: The performance of DCM was such that there was plenty of margin to raise the clipping limit. Also, I wanted to be consistent with raising the gyro saturation by a factor of 4. At the same speed, a turn that rotates 4 times faster also pulls 4 times the gs. So, I have a vision of some day meeting the "banked turn" challenge. My objective is to some day use DCM to stabilize a hot plane doing a continuous banked, level turn, pulling 6 gs all the while. So, I don't want to be limited by accelerometer clipping.
Basically, this new board should be able to keep up with whatever turning rates and accelerations that the hotest airframes today or in the future could ever throw at it.
All I can say is that the prototype board that I used to test the LISY300 performed flawlessly, even better than the previous board, because it can track 4 times the turning rate than the previous board.
I do not know if the good performance is because of the gyros, or because of the DCM algorithm. In either case, because the way that DCM algorithm performs drift compensation, it achieves "gyro lock", even if the gyro is drifting. DCM will work with just about any gyro.
As near as I can tell from my tests, the new board will perform even better than the previous one. The higher gyro range will allow you to perform tighter turns without gyro saturation.
I also discovered that there was a wide margin still available in the accelerometer, so I switched from 1.5 g to 6 g setting. The idea is that you can use the new board as a copilot while to do aggressive aerobatics, and can switch from manual mode to stabilized mode if you get in trouble.
Using the LISY300 allows me to run the gyros, accelerometers, and A/D analog reference all from the same 3.3 volt regulated supply. Since everything will be running "ratiometric", and since the 3.3 volt supply is fed from a 5 volt supply, there will be absolutely no contribution from supply voltage variation to accelerometer and gyro drift.
Also, Paul Bizard built his own board. He started with a 5 degree of freedom board with some other gyro, and added one LISY gyro. He had trouble with the other gyros, but the LISY performed just fine.
So, I fully expect the new board to perform better than the previous one.
Regarding price, I would expect the price will come down for the new board, but SparkFun has not told me yet what the price will be.
I do not know if it's my mistake (problem with my bad soldering pf the break out board to my PCB, or noisy power supply), but I have 5 out of 10 fail. There are 4 kinds of failure that I have :
- first functions perfectly, then fail
- first very noise then getting better
- first it has very large drift then stabilized
- not functioning at all
I also had not a very good experience with Melexis gyro. But I have a very consistent behavior from ADXRS and ID300 (although for the case of IDG300, it has different offset between each axis, but I only tried 2 of them)
I haven't tried them yet. I too am *very* interested in hearing more about the performance of the LISY300AL. @bcr, are you running an orientation estimator like William Premerlani's DCM estimator, or just looking at the outputs and "eye-balling" it. Have you comapred them to the IDG-300/500 or the ADXRSxxx?
p.s. William, the ADXRS610 should be an (almost) direct replacement for the ADXRS401. You can get them from Digikey for about US$34 each. Still 4 times more than the LISY though :-)
Also would be great if the other posters can explain the specific flaws in LISY300AL. Drift, other noise, non-linearity, offset, etc? I have 15 of these and have not seen any serious problems yet on the bench. I am using a custom breakout board w/ the two stage HW low pass filter from the pololu board (not present on the SF board).
Can you provide some background on the 6g accel change? I could see 1.5 or 2g clipping but are there airframes that will clip in 4g mode as well? I ask since I'm about to set this for my own HW (fixed on the layout). Thanks again.
Comments
I am aware of the ADXRS610. I tried out the LISY300 instead because of the price. I had seen some good reports on it. I am hoping that SparkFun will pass along some of the savings, and lower the price of the board. At any rate, I have asked them to do that.
I did evaluate the LISY300 before deciding to use it. SparkFun made a prototype board for me to test before going into full production. I tested it and was very pleased with the results. The performance of my firmware in the new board is actually better than the previous board: I can rotate 4 times faster without saturating the gyros.
So, I am not sure why some folks have not seen the same good performance that I have seen. There could be any number of reasons, ranging from the algorithms that were used, to ESD problems, to noise pickup.
At the moment, I am waiting for the first board in the new production run. When I get it, I will test it thoroughly before releasing the new design.
I am not aware of any airframe that will pull 6gs, but so far I have limited experience with high performance planes. My plan is to use DCM as a copilot to work my way up to higher performance planes.
My logic in switching to the 6 g setting was simple: The performance of DCM was such that there was plenty of margin to raise the clipping limit. Also, I wanted to be consistent with raising the gyro saturation by a factor of 4. At the same speed, a turn that rotates 4 times faster also pulls 4 times the gs. So, I have a vision of some day meeting the "banked turn" challenge. My objective is to some day use DCM to stabilize a hot plane doing a continuous banked, level turn, pulling 6 gs all the while. So, I don't want to be limited by accelerometer clipping.
Basically, this new board should be able to keep up with whatever turning rates and accelerations that the hotest airframes today or in the future could ever throw at it.
I do not know if the good performance is because of the gyros, or because of the DCM algorithm. In either case, because the way that DCM algorithm performs drift compensation, it achieves "gyro lock", even if the gyro is drifting. DCM will work with just about any gyro.
As near as I can tell from my tests, the new board will perform even better than the previous one. The higher gyro range will allow you to perform tighter turns without gyro saturation.
I also discovered that there was a wide margin still available in the accelerometer, so I switched from 1.5 g to 6 g setting. The idea is that you can use the new board as a copilot while to do aggressive aerobatics, and can switch from manual mode to stabilized mode if you get in trouble.
Using the LISY300 allows me to run the gyros, accelerometers, and A/D analog reference all from the same 3.3 volt regulated supply. Since everything will be running "ratiometric", and since the 3.3 volt supply is fed from a 5 volt supply, there will be absolutely no contribution from supply voltage variation to accelerometer and gyro drift.
Also, Paul Bizard built his own board. He started with a 5 degree of freedom board with some other gyro, and added one LISY gyro. He had trouble with the other gyros, but the LISY performed just fine.
So, I fully expect the new board to perform better than the previous one.
Regarding price, I would expect the price will come down for the new board, but SparkFun has not told me yet what the price will be.
Bill
I do not know if it's my mistake (problem with my bad soldering pf the break out board to my PCB, or noisy power supply), but I have 5 out of 10 fail. There are 4 kinds of failure that I have :
- first functions perfectly, then fail
- first very noise then getting better
- first it has very large drift then stabilized
- not functioning at all
I also had not a very good experience with Melexis gyro. But I have a very consistent behavior from ADXRS and ID300 (although for the case of IDG300, it has different offset between each axis, but I only tried 2 of them)
regards
-doni-
p.s. William, the ADXRS610 should be an (almost) direct replacement for the ADXRS401. You can get them from Digikey for about US$34 each. Still 4 times more than the LISY though :-)
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