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November 20, 2006
News - According to Pete: August… |
about 8 months ago
I’ll also add that GPS is velocity should also be logged. You can get the 3D velocity vector out of that chip in either ECEF or NED. GPS velocity should go into your filter also. It would be foolish not to use sensor fusion in this situation. Also those helicals are kind of meh in terms of performance. You will do better with a patch in this instance, but for what you are using GPS for, I might take that back, you should be OK either way. GPS velocity is generally more accurate than position because of the way it is measured. Vertical velocity suffers from the same constellation geometry issues that vertical position does, but it is not as noisy because of the different measurement process.
You can pretty easily write a complimentary filter that will pit the strengths and weaknesses of the baro and the GPS against one another. The GPS can be considered drift free over a very long time scale and noisy in the short term. The baro has qualities complimentary to that. You would take the time rate change of this filtered, or combined, altitude as the source for your vario. Here’s a a pro tip: get this thing in the air as soon as you can logging real, raw data. Then, back in the comfort of your shop, which looks eerily like mine, you post process that raw data and come up with all you “magic numbers” for the filter. The gains, the high/low pass time constants, etc.
News - July Caption Contest |
about 8 months ago
Once the iron reaches 600 degrees F, one can melt anything. In this example, we will reflow a giant aluminum energy drink can with a mythical man-beast.
News - NeverNude Prototype |
You are extremely funny. And so is AD. And, by all means, Go Gators, jorts and all.
Product SEN-11486 |
about a year ago
Man, is the mag junk though compared to the Honeywell units. I had to reconfigure my filter from some of the earlier breadboard mechanizations. I have flown a ton of competing MEMs sensors on my breadbord over the last few years. The 9150 is the one that made it to PCB however.
I love the chip though I have not tried Sparkfun’s breakout board. I have it as a part of a autopilot that I have developed. The DMP stuff was also interesting to me, and I joined the developers site and so forth, but found it easier to write my own sensor fusion stuff. I would love to pit my own 7 state Kalman against the MPU algorithms on my shaker table, however.
Product PRT-11231 |
about a year ago
OK, duh I got it, the safety circuit is preventing me from seeing any voltage. Presumably trickle charging will bring the cell back into a ‘safe area’, beyond some gate, and then I will see it on the JST again. Just not use to Lipos with this type of circuit. Thanks.
I cut into the kapton to get some measurements. Using a Fluke 179:
The taps going to the JST pigtail = 0.001 V
The larger pads which presumably go directly to the cell = 2.972 V
So not sure what is going on with the little embedded safety circuit.
All this being said, I bet the thing is going to work. I just need to learn some more about it, and bring the EN line into the project while it is still in the bread board stage.
I will occasionally bring back Lipo’s with a non-zero voltage by constant current charging them at some low value. Since these have been depleted to zero, and the batteries were less than $10 per, I don’t feel it is worth my time or the risk.
I used mine stock, as they came, without the LVDO jumper. I plugged in 2 brand new batteries I bought at the same time. Charged them up. Let them sit for a couple of weeks. Now the batteries are pulled down to zero, nothing, nada. I’m not overjoyed at the moment.
No public wish lists :(