I'm trying to further tune my bird, and in doing so I'm trying to make sure I understand the data in my GPX files. FYI, I'm flying at 13.9 pounds with dual 8000mA 4S LiPo bats on a stock Quadrocopter-supplied Cinestar 8 with 2-Axis Radian-stabilized gimbal (powered separately) at around sea level. Here is a file from an uneventful 8 minute or so flight at my local park. I am curious about a number of things. the log indicates "Motor Run, Fly, Vario trim up, Vario trim down" when flying normally. What is the "vario" thing, and is it normal? my current max's out at 88A and almost 1300W...is that acceptable? based upon the 'C' rating of my batteries (and the fact that I'm running 2 in parallel), it seems as though I am at around 50% of capacity, but maybe my calculations are wildly inaccurate (that is not unexpected). it seems i'm hovering at 65 amps or so (in PH/AH). again, is this kosher? Looking at the MotorCurrent field, I see cases where one or more of the motors is at almost 2X the current draw of others. Is that an indication of a balance problem? Thanks so much for taking a peek! Steve
Steve 1. The Vario trim is a good question. Maybe Andy can tell us from the programing what the source is for that log item. 2. Your current sounds normal for the load you are carrying. 3. 65 amps sounds normal again for the load 4. May be a balance issue. If you have the wireless connection for the copter using the 'XBee' or equivalent you can run MKTool and look at the balance screen. It will quickly tell you what is going on, real time. You can also check balance by hanging the copter from a string similar to the setup suggested for the 3 axis. Looking at the file, while you are right about the spread, that is at the low end. Looking the averages the difference between high/low is only 2.9 amps. That looks normal. Other factors would be the amount of wind you are flying in, flight maneuvers, etc. And man you were really moving at the 370 point! 33 km/h
1. I'll agree with Gary in that the Vario flags indicate you are in vario altitude hold mode. Vario trim up is when your stick is positioned above the hover point and thus climbing... 4. It could also indicated you were yawing the copter at that point in time on the log. Every other motor would indicate drawing more power to torque the copter. It could also be a balance problem or misaligned booms.. Loose props.. I'm sure the list goes on..
The vario thing is weird. When I turn on my copter and the mx20 with my earphones on, Ms Graupner says "Altitude On" even though it's not. But when I look at the flags in SmartOSD and KopterTool, the switch for AH on/off is working. And the copter is flying normally. And when I *do* turn on AH, it does work. I wonder if this is a confusion in the GPXtool? Like maybe it's reading a flag incorrectly? I'd like to know...
At the college I work at we have an industrial design department and I talked about balancing the copter and how some try to balance the copter with 4 fixed points like in the video you posted above. They agreed with me that unless the 4 points were exactly off center the same "EXACT" distance on the battery plate, and the straps were folded over exactly in half there could be inaccuracies to that procedure. What I am in the process of doing is mounting a plate directly above the battery. I've purchased M3 stand off's from MSC direct to extend the new plate higher than the battery and then I've cut an aluminum plate that will have a dead center spot with a hook on it so I can tie a fishing line to it. I have 75 pound fishing line. When I have it finished I will post.
Steve: In the GPX file, the Vario value is calculated like this: CurrentVariometer = (PreviousVariometer + (2 * (CurrentAltitude – Previous Altitude)) / 2 Line 613 spi_slave.c (NC board) So it's a moving average of the altimeter setting (which is based on the air pressure sensor). The Vario flags seem to be used when the FC board is controlling the throttle for AH. I've not looked at that code for a couple of weeks, so I'm not 100% sure, but it's as though the MK lads use "Vario" into separate contexts: 1. Variometer: measures rate of ascent/descent with respect to time. 2. Variable : As in Vario Altitude Hold where the setpoint is variable using the throttle stick in AH. These are two distinct and different meanings. Hmmm. Well, I guess you could kinda see how they might possibly linked conceptually, if you use the Variometer reading to determine whether or not you're on hover. Andy.
Also remember the logging is at a one second sample, that means you're missing a lot of data -- it means you can only faithfully capture anything changing at 2 Hertz or slower! So all hell could be breaking loose in real time -- hence the XBee realtime monitoring on the scope and exporting the values would be a far better method of seeing what is going on -- even then I'm not sure what the default sample rate of the scope is off-hand. Andy.
Just a friendly suggestion for monitoring real time in MKTools. Get a screen capture piece of software, Andy you can suggest what you use, and record the flight in MKTools. The only thing I have ever checked real time was the balance. Couple of quick glances at it to see where I might be off balance. Other than that fly the aircraft FIRST. Landscape littered with real airplanes where the crew got distracted. Remember the guys a year ago that go so engrossed in their laptops they passed over the landing city and were at the east coast before discovering the error?
There's a $37 program called FRAPS out there (surprise! It's at fraps.com). That typically records videogames at high frame rates so is also ideal for capturing MK Tool output. If you want to edit the video after you've captured it, Camtasia's pretty good but more costly. http://www.techsmith.com/camtasia.html There are, of course, several others. Yeah, that flight crew that got distracted worried me.....I kept wondering whether they were using Microsoft Flight Simulator to get the hang of the landing part.... Andy.
Yeah. "Hours of boredom punctuated by moments of panic" I seem to recall. Pretty much the same for PAX too. Andy.