Replies to This Discussion

Permalink Reply by Dr Mike Black on November 4, 2009 at 4:50pm

Hi, Saiful,

OK i have no pics at this time, but will take some tomorrow, but essentially all i did was turn my hotglue gun to the high setting, wait for it to get mostly hot, not smoking, then run glue all ovet the sensor boards, making sure that all components are covered,

UPDATE on v2.4: I WAS USING 2.3.1....lol...dont get them confused..

Airspeed sensor refuses to calibrate on v2.4.....i get -276....so after ferriting about in the software i found where calibration is done and made the correction so that it adds 276 to the number it reads and then i get 0, tested the throttle setpoint on GS all works as it should now...

Weird thing is on 2.3.1 it calibrates fine....also tried this on both boards now (I have a couple of Ardus) the old one i thought might be gettign tired, but the new one deos the same..... so Jordi...the code is very different for the calibration, maybe an explanation as to the difference? I cant be alone in this?!?!?! (and im no programmer..lol)

However the work around is easy, if anyone wants me to post it..

I just find it odd that both my boards do the same thing, and no im not using the same preasure sensor!!...lol

DeveloperPermalink Reply by jasonshort on November 5, 2009 at 12:30am

I had a question about the throttle code. The PI loop outputs a percent for throttle, but the throttle_max values used to constrain is a PWM value of 1800. Is this a mistake?

throttle_output = constrain(throttle_output, 0, throttle_max);
throttle_output = constrain(throttle_output, 0, 1800);

throttle_output is sent directly to pulse_servo_0 and limited to 100;

void pulse_servo_0(long porcent)//Will convert the angle to the equivalent servo position...
{
porcent=constrain(porcent,0,100);
...
}

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Permalink Reply by Dr Mike Black on November 6, 2009 at 3:57am

Jason,

I suspect that 1800 is just a figure, as most Esc`s auto configure as to thier travel, also if you want to you can put 1000,2000 millis which most servos travel, then calibrate the esc to travel this...

Not sure about teh deadband bit, cant see where its used....

however if you have 600 travel (1200-1800) then teh esc would not normally go to close, but also not full throttle either, just 60% of its travel will effect throttle position. So you would end up with (at full throttle) 100% of 60% (80% Throttle) and at 0% throttle you would have 0% which is in reality 20% throttle..
this bit of code to me anyway is very ambigious, adn have struggled to work out why my aircraft tried very hard not to do as i told it...

If i have understood teh code properly...

I find it hard to believe that we/I am the only poeple having this problem, unless of course i have done somthing horribly wrong or everyone is flying Easystars.......(fairly unlikely)

I have also found a strange anomally as you posted in another thread about the serial...this must have an effect, especially on tracking....

Thoughts?

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DeveloperPermalink Reply by jasonshort on November 6, 2009 at 9:30am

I am 99% sure the 1800 number is a leftover from when the code dealt with pwm ranges instead of percentages. It should be 80. The servo function which pulses out the throttle, may have expected pwm sized value at one point in the past, but now expects 0-100.
I just rewrote my code which is similar and I'll fly it this weekend and let you know. I was also having lots of trouble with the gps code from ardupilot I would get 1 of 5 gps outputs to pass the checksum. I rewrote the parser and am having better luck, but i'm not exactly sure why.
My shield issue turned out that the serial mux requires the remove before fly pin in place to talk to the FTDI cable. I don't use the pin so I have to set the outputs on pin7 correctly to switch the mux.

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DeveloperPermalink Reply by jasonshort on November 6, 2009 at 11:33am

Mike did you ever solve your throttle issue? Could you run this code and let me know what value your airspeed sensor outputs? Blow on the tube and check that value. Then, reverse the tube on your sensor note the value.

Attachments:

• sensortest.zip, 2 KB

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Permalink Reply by Dr Mike Black on November 7, 2009 at 12:54am

Hi Jason,
Yeah you must pull the pin before any data appears, i think the main reason for this is that, if you flood the telem link on power up with serial, it can corrupt your xbees, had it happen once on my xtends.

yes throttle sorted, i will post the code change for you latter when i go into the workshops,

Happilly test your code then ans report back..

Big desaster yesterdat, we lost U2, went off on a sight seeing tour and went in,,we havnt found it yet.....

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Permalink Reply by Toby Stein on November 11, 2009 at 2:27am

Hi all,
Newbie here. (crash course in more ways than one :)

I flight tested an easystar with ArduPilot Ublox 5 for GPS and Xbee 900's and ArduStation for telemetry

Telemetry was coming through fine but my airspeed said 216. Dunno if this could have something to do with it. Struck me as kind of odd considering the plane was not moving.

Shouldn't ArduStation read 0 ASP while plane is stationary?

Having not tested the throttle, anxious to fly I Uploaded my waypoints and off to the air field. I luanched her, got up to about 100 feet or so (was not watching ArduStation.. duh.) and flicked it in to WP mode. The plane went into a beautifully flat holding pattern above my head. I've read they tend to drift a little before heading to the waypoint. So I let her go for a bit, but she seemed to just be thermaling higher not really going towards the waypoint. So I took control. I did not know if the plane would go to it's waypoints, or just thermal out of range..

I noticed during ground testing, the rudder and elevator react properly when I do the hand test.

How do I ground test the throttle?

I'm thinking, once a waypoint is uploaded GPS is locked, it should start throttling when switched WP mode. Not the case.

Thanks in advance
Toby

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3D RoboticsPermalink Reply by Chris Anderson on November 11, 2009 at 8:22am

You ground test the throttle with the "test throttle" (9-6) option in the config file.

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Permalink Reply by Toby Stein on November 13, 2009 at 12:38am

I upgraded to brushless motor and esc today..powered her up gps locked and the motor went gradually to full throttle. whoo hoo!

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Permalink Reply by Dr Mike Black on November 13, 2009 at 12:54pm

Toby ,

Which version of the files are you using?as there is a known fault with 2.4, with 2.43 on its been sorted...if you get stuck i can post the somewhat crude workaround, but you must have 0 or near to 0 on startup calibration.....

Also something i noticed,,,is that if teh aircraft si pointing into wind when you calibrate (remove the flight plug) it can have a spazzy calibration, all i do is put my finger lightly over the pitot to stop that happening. when that is sorted, you can look at the cruising speed..(dont know what airframe you are flying)

when you get there come back, if alls not right.

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