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Vehicles - Fixed Wing / Re: AutoCruise Mode for a FixedWing
« Last post by TheOtherCliff on July 13, 2019, 11:14:13 pm »
For those that might not know, roll/pitch/yaw PIDs on a fixed wing are tuned for one specific airspeed but you don't fly at one specific airspeed.  If a Revo class FC has an airspeed sensor enabled (even the GPS based one) it uses measured airspeed to change the PIDs to fit the airspeed and you always have the correct PIDs.

With thrust control coded like is being discussed here (e.g. when pitching up, throttle output is automatically increased by a user configurable number and simple trig to maintain the same airspeed without actually measuring the airspeed ... within known limits), airspeed more reasonably corresponds to throttle input (stick) position (airspeed doesn't change when you pitch up/down) and the code could modify the roll/pitch/yaw PIDs during flight with this airspeed cousin in the same way we already modify the PIDs using the real airspeed sensor (including the GPS based airspeed sensor).

The throttle to speed curve is not linear (can't be used as an airspeed approximation, even with simple scaling).  When flying straight and level, 100% throttle is generally not exactly 2 times as fast as 50% throttle.  Probably the most useful way to handle this is to convert the throttle stick position into an actual approximate airspeed using a non-linear function.  Thus, any code that wants the airspeed can use this approximation of airspeed.

Here is the kicker.  Once this is set up (tuned) by the user, it gives you this airspeed approximation, even when you are not using this new thrust mode, so your PIDs are always correct and you always have an airspeed approximation available for other uses (e.g. telemetry).  No airspeed sensor required.  No GPS required.
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General Discussion / Re: two servos gimbal problem
« Last post by TheOtherCliff on July 13, 2019, 07:45:50 pm »
It's possible that only the 1 or 2 servo/PWM outputs where the servos were connected are damaged.

You might try powering the CC3D with 5V and configuring the CC3D to use a different servo/PWM output to see if the CC3D is usable that way.  :)

It's also possible that all servo/PWM outputs are damaged.  :(
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General Discussion / Re: two servos gimbal problem
« Last post by TheOtherCliff on July 12, 2019, 09:26:39 pm »
For years I used a 5V BEC to power four 9 gram servos through a CC3D board.  There was even some servo oscillation while I tuned the PID.  Nothing ever went bad, but I never used 8.4V input power voltage, always about 5.2V.

It sounds like you think you have one good CC3D left.  I would measure good CC3D resistance (lowest ohms scale with all CC3D cables disconnected) from PWM ground pins to power input ground pins, and again from PWM V+ pins to power input V+ pins.  Both measurements should show a direct wire connection (about 0 ohms).  That is a good reading.  It will show you what a good board measures.  Now measure a "broken" CC3D the same way.  Did both boards measure 0 ohms?  If so, then the traces on the bad board are OK and NOT the problem.

Important:
Another thing to know is that the CC3D PWM signal pins need a 3.3V signal but are "5V tolerant".  If you have 8.4V power connected to CC3D and you plug in a servo, then if (50%-50% chance) the signal pin (outer pin on servo connector) and V+ pin (center pin on servo connector) make contact before the ground pin (the other outer pin on the servo connector), then you have effectively connected 8.4V directly to the 3.3V (5v tolerant) PWM signal pin (through the servo which is acting like a resistor at this point).

You can see that the other chance (also 50%-50%) is that the V+ and ground connect first so it is not like just connecting signal to V+ through a resistor (the servo).

If the CC3D is actually broken, but the V+ traces are OK from power input to servo connector and the ground traces are OK from power input to servo connector, then this is what may have damaged the PWM signal output.  :(
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General Discussion / Re: two servos gimbal problem
« Last post by facenorbert on July 12, 2019, 06:43:46 pm »
2S Lipo is too much voltage for some kinds of servos.  You should use a voltage regulator like BEC or ESC/BEC to reduce voltage to 5V.

Using USB 5V power works well, but does not have much current, but your small servos do not need much.  It is possible that your servos are burned out.  :(

Whatever voltage you put in the CC3D is exactly what you get out to power the servos.  It is a direct wire connection.


It was working fine with this setup until I put weight on it [action camera] then start playing up.
It had happened two times on atom and standard cc3d board
So in the end I have lost two boards now


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