Replies to This Discussion

Permalink Reply by John C. on April 21, 2010 at 3:45pm

I'm going to add a +1 to this. Same servo setup for me with a normal -1.

I've had 2 flights with 2.6 now.

First flight: Fairly good stabilization and navigation out of the box with -1. Nudging in AUTO mode was REVERSED.

Second flight: Switched to 1 on REVERSE_PITCH/ROLL. Plane flies inverted.

I finally sat down and bench tested this a bit more, and -1 is still the right setting for me but here are the issues.

1) in AUTO mode nudging is reversed in its control input
2) in FBW_B stabilization works well, but I have ZERO control input

Manual mode works just fine. Let me know if there are any permutations that would help.

Thanks!

John C.

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DeveloperPermalink Reply by Doug Weibel on April 21, 2010 at 8:45pm

Hey Tom and John,

I have never tested the stick mixing, and now that I think of it I may never have tested FBW-B either, so it is quite possible that there is a bug there. I will check it out as soon as time permits.

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Permalink Reply by John C. on April 21, 2010 at 9:29pm

Thanks for the reply Doug.

I was going to monkey around a bit with it as well. Seems like this would be a likely place to look in the attitude routine.

// Mix in stick inputs in STABILIZE mode or if AP_STICK_MIXING = 1
// ---------------------------------
servo_roll += (1.0f - ch1_inf) * (ch1_in - ch1_trim) * 45.0f / 400;
servo_pitch += (1.0f - ch2_inf) * (ch2_in - ch2_trim) * 45.0f / 400;


Any other tips on where else to look? In looking back at 2.5, you obviously handle attitude in a completely different way.

Thanks!

JC

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Permalink Reply by John C. on April 21, 2010 at 9:50pm

Seems like this may be a suspect section in the main routine on the FBW_B issue.

if (control_mode == FLY_BY_WIRE_A || control_mode == FLY_BY_WIRE_B) {
// fake Navigation output using sticks
nav_roll = ((ch1_in - ch1_trim) * (long)HEAD_MAX * REVERSE_ROLL) / (ch1_max - ch1_trim);
nav_roll = constrain(nav_roll, -HEAD_MAX, HEAD_MAX);

// nav_pitch is the amount to adjust pitch due to altitude
nav_pitch = ((ch2_in - ch2_trim) * -1 * (long)PITCH_MIN * REVERSE_PITCH) / (ch2_max - ch2_trim); // We use PITCH_MIN because its magnitude is normally greater than PITCH_MAX
nav_pitch = constrain(nav_pitch, PITCH_MIN, PITCH_MAX);
}

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DeveloperPermalink Reply by Doug Weibel on April 22, 2010 at 6:38am

JC - looks like we just need REVERSE_ROLL and REVERSE_PITCH in the nudging calculation.

However I'm not seeing a problem with FBW_B right off. Can you please look at the code revision you are using and see if in the main file you see the line:
boolean takeoffComplete = 0; // Flag for using take-off controls

If so please change the 0 to 1 and retest.

Regards,
Doug

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Permalink Reply by Tom Hastie on April 22, 2010 at 6:45am

Hey Doug,

I don't think the problem exists in FBW_A or FBW_B. These are the two that work great for me with REVERSE_ROLL/PITCH set to -1

The problem exists for sure in STABILIZE mode for me, and I think also in AUTO modes. I haven't flown any AUTO modes yet, so I can't say for sure.

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Permalink Reply by John C. on April 22, 2010 at 7:29am

Nice work Doug. Changing the takeoffComplete variable to 1 gave me FBW control.

The control in FBW works accurately.

AUTO nudging is still reversed. I agree that the nudge calc is just missing the reverse vars.

Thanks! Looks like I should be able to get her back in the air today if the weather keeps cooperating.

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Permalink Reply by John C. on April 22, 2010 at 9:01am

I'm not much of a programmer, so I'm not sure if this is the right way to do it or not, but this is a fix that works for me.

In the attitude routine, change this:

// Mix in stick inputs in STABILIZE mode or if AP_STICK_MIXING = 1
// ---------------------------------
servo_roll += (1.0f - ch1_inf) * (ch1_in - ch1_trim) * 45.0f / 400;
servo_pitch += (1.0f - ch2_inf) * (ch2_in - ch2_trim) * 45.0f / 400;


To this:

// Mix in stick inputs in STABILIZE mode or if AP_STICK_MIXING = 1
// ---------------------------------
if (REVERSE_ROLL == 1) {
servo_roll += (1.0f - ch1_inf) * (ch1_in - ch1_trim) * 45.0f / 400;
} else {
servo_roll -= (1.0f - ch1_inf) * (ch1_in - ch1_trim) * 45.0f / 400;
}
if (REVERSE_PITCH == 1) {
servo_pitch += (1.0f - ch2_inf) * (ch2_in - ch2_trim) * 45.0f / 400;
} else {
servo_pitch -= (1.0f - ch2_inf) * (ch2_in - ch2_trim) * 45.0f / 400;
}

Let me know if it's a reasonable solution...thanks!

JC

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DeveloperPermalink Reply by Doug Weibel on April 22, 2010 at 10:38am

Yeah JC that is fine. You can do it a bit cleaner by just multiplying in the reverse parameters. I will get it added on the next revision.

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Permalink Reply by cholo on April 27, 2010 at 2:48pm

hi
is it normal I've got no manual control over throttle while in stabilize mode (throttle is fixed at about 20%) ?

regards

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