Comment by Cronselaar on April 15, 2010 at 7:18am

This is exactly what we've been needing for a while now. Combined with Events it's a real treat. Waypoint reached- Quickly cut throttle 5seconds, snap a photo and go to next waypoint.

Well done! If only i knew how to implement it...

Developer Comment by jasonshort on April 15, 2010 at 7:27pm

Just read the code and it looks great. Next question is how shall we use the capability? What are your thoughts?

Comment by Tom Hastie on April 15, 2010 at 7:39pm

Thanks Jason... good to know I'm on the right track.

Well first, my plan is to tune the aileron elevator gains to get fly by wire mode working well on this aircraft. My rudder channel is currently a pure pass through in fly by wire mode.

Once that's done, my first thought is to write a rudder control loop to zero the lateral (wingtip to wingtip) acceleration of the aircraft. Basically use the rudder to co-ordinate each turn (Ardu-"step on the ball"?). On this particular airframe the adverse yaw isn't too bad (nearly non existent), but this is the most basic use for rudder in most aircraft.

In the long run if I can teach this thing to do aerobatics, the rudder rules will depend on the particular maneuver:
In rolls, rudder and elevator must be used together to maintain the resultant of lateral and vertical acceleration at 1G.
In looping maneuvers, the rudder needs to be used to zero out yaw rate.

In preparation for this, I've already added Yaw/Pitch/Roll Rate and Normal/Vertical/Lateral Acceleration to the binary data coming out of the ArduIMU.

Tom

Comment by Ony Arifianto on April 26, 2010 at 3:04am

Nice work Tom, do you add some jumper wires to the ArduPilot board?

Developer Comment by Mark Colwell on April 26, 2010 at 4:47am

Tom great work,
I was able to get ch-4 running in the same fashion with normal mode back in ArduPilot v 2.2, but I used slightly different value for:

ISR(TIMER2_COMPB_vect ) //Interrupt of timer 2 compare B, ch4
{
PORTB &= 0xF7; //Putting the pin D11 (PB3) low. 0xF7 is the NOT of 0x08
}

you are using 0x77 .... what value works better??

and I combined these two into a single line...

void init_PWM( )
{
...
TIMSK2 = _BV(OCIE2A); // Timer/Counter2 Compare Match A
TIMSK2 |= _BV(OCIE2B); // Timer/Counter2 Compare Match B Interrupt set active.
...
}

my single line...
...
TIMSK2 = (1OCIE2A) | (1OCIE2B); //interrupt masks for Timer2 counter A and B
...
These two are line are equal, I think

I am using Ch-4 for flaps on my Ventus 2hx powered glider

Ch-4 is reliable, but a little course, but great for flaps.

I will inject your newer version Ch-4 into v2.6 and see how it works...

Comment by Tom Hastie on April 26, 2010 at 6:26am

Hey Mark..

I think your F7 value is more correct than my 77 value. &= 0x77 will toggle boththe 4th and the 8th Bit of the PORT B register. When I formed that hex value on my , I obviously missed the hightest bit. I think my code has been toggling that 8th bit this whole time. (Seems to work but might have some unintended consequences). I think I'll switch to F7 like you.

Developer Comment by Mark Colwell on April 26, 2010 at 10:49am

Finished update of AP 2.6 with ch-4 mods, after several attempts got it to compile fine, now to test in ArduPilot! I still need to add jumper from Pin 12 to Rudder servo in signal.
I changed code so rudder/yaw behaves like Aileron / Elevator, channels 1 & 2
added trim function. Added some defines to header AP_2_6.h and some inits to main AP_2_6 also.

Comment by Geert Folkertsma on June 2, 2010 at 1:00am

Hello Mark,
I'm doing a project where I'm also going to need an extra channel. I've got a couple of questions:
- Is the code above (in the linked files) your latest version?
- Why did you change the ch3_in code? (radio.pde, line 39)
- You use PB4 to capture the rudder channel - normally it is used for the GPS lock led. Did you just get rid of that?

Comment by Geert Folkertsma on June 2, 2010 at 1:01am

My bad, of course the files above are not yours.. should have asked Tom. Anyway, same questions hold ;-)

Developer Comment by jasonshort on August 3, 2010 at 6:52pm

Tom,
I have a new version of 2.7 to upload soon that has double the CH3 and CH4 resolution - 4µs steps. You should be able to try it by tomorrow if testing goes well.

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