Controlling rate of climb and decent in stabalise and auto

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Controlling rate of climb and decent in stabalise and auto

Postby spinner » Thu Aug 08, 2013 1:28 pm

Hi,

I've got a test setup where I have one standby circle setup at 100m height with 100m radius. I've then with the same center got a decent circle setup at 60m height and 80m radius. When going from the standby to the circle the fuselage on my sky walker broke as the rate of decent was so big. I'd done smaller tests before of like 20m and I thought I'd changed the configuration in "Advanced" - "Control" - "Pitch between" and I changed to -20 -> +20. Maybe even this was too high but is this the correct place to change it and what is the relationship between this and the stabalise mode rate of climb and decent which both seem to be much smaller and actually a bit too small and so I'd like to increase the rate in stabalise mode but decrease it in autopilot.

Thanks,
Tim.
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Re: Controlling rate of climb and decent in stabalise and au

Postby Tom » Thu Aug 08, 2013 2:41 pm

Hi Tim,

This value configures the maximum and minimum pitch angle. This means when having to climb a lot, the pitch angle will never exceed 20 degrees. When having the descent a lot, the pitch angle will never be less than -20 degrees. (personally i set it a bit lower for descent because I mainly descent by cutting throttle in auto throttle mode).

It seems very unlikely that your plane would brake by descending at 20° for only 40 meters. Did you see it happen? I think the plane should be strong enough do go even straight down.

For the moment this minimum and maximum pitch angle is the same for both stabilized and autopilot mode.
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Re: Controlling rate of climb and decent in stabalise and au

Postby spinner » Thu Aug 08, 2013 5:39 pm

Hi Tom,

Saw it and heard it :) it was when it was leveling out I think.

In all of this I am still controlling the throttle, how do you control the throttle dynamically to lose height as I'd like to do the same for climb however in the auto throttle settings I'm just finding on the "Basic Configuration" a check box to turn them on or off and set a cruise throttle percentage and then again on "Advanced Configuration" in "Control" I'm seeing a Min / Cruise / Max and a "Throttle P-gain".

Could you explain the "Throttle P-gain" from what I've read I'm guessing it's the amount to increase the throttle per m/sec of ground speed that's lost if heading into wind, is the base reference value for speed the "Default Speed" ?

Thanks,
Tim.
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Re: Controlling rate of climb and decent in stabalise and au

Postby Tom » Thu Aug 08, 2013 6:45 pm

Indeed,

Cruise throttle is when the altitude is good.
Otherwise the throttle percentage is changed according to the P-value (0.9 means 0.9% per meter wrong altitude)

And normally you should:
Enable auto-throtlle
Configure cruise, min and max throttle
Configure minimum and cruise speed

This is all that is needed in v0.10

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Re: Controlling rate of climb and decent in stabalise and au

Postby spinner » Thu Aug 08, 2013 8:22 pm

I'm still on version 0.9 but aim to upgrade once I've got learnt more.

So as a worked example for take off when I've put in a "CLIMB" command. I'm at 0m height for launch and I've put in to climb to 50m. If I enable auto throttle and I set something like Min ( 0 ) / Cruise ( 45 ) / Max ( 80 ). I'm not sure what the default speed would be but I guess this would be normal cruising speed. So would the throttle then be set to

( 45 ) + ( 50 * 0.9 ) = 90

This is more than the max so does it get cut down to 80 ?

And then say in the case of my decent issue the height difference is 100m - 60m so 40m

( 45 ) - ( 40 * 0.9 ) = 9

This maybe the issue with the decent as in I was losing a lot of height and at same time keeping at 45 on the throttle.

Thanks,
Tim.
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Re: Controlling rate of climb and decent in stabalise and au

Postby Tom » Thu Aug 08, 2013 9:34 pm

Yes your calculations are correct. Only the CLIMB command gives max_throttle until the target altitude is reached.

The config really depends on your plane. I tend to use light motor, so auto-throttle is never really a problem. If you have a very strong big motor, you may need to handle it a bit more carefully.

In version 0.10 you can configure minimum speed as well. auto-throttle will give more throttle when you reach the minimum speed. When flying in heavy winds (upwind), you need more throttle to keep advancing. So you will see a lot more variation the throttle in v0.10
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Re: Controlling rate of climb and decent in stabalise and au

Postby spinner » Thu Aug 08, 2013 10:55 pm

Can I confirm one question on CLIMB, at the moment in my START block I have CLIMB to 30m as the last statement in the block. At the moment I do not have autopilot on for launch I just stand there and throw it with around 80% throttle and press up in manual. My STANDBY block is normally running when I flick into Autopilot on my transmitter as in it has already reached 100m with me controlling it normally in Stabalise so it has already passed the CLIMB block.

As a test then could I change CLIMB to 60m do a manual take off, get upto 40m and then enter autopilot and in theory it should still be at the CLIMB statement and start to climb in the take off direction upto the required 60m ?
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Re: Controlling rate of climb and decent in stabalise and au

Postby Tom » Fri Aug 09, 2013 6:25 am

Yes that is correct. The plane will continue at max throttle and max pitch angle until it reaches 60 meter.
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Re: Controlling rate of climb and decent in stabalise and au

Postby kuchnaii » Mon Mar 02, 2015 7:26 am

If I enable auto throttle and I set something like Min ( 0 ) / Cruise ( 45 ) / Max ( 80 ). I'm not sure what the default speed would be but I guess this would be normal cruising speed. So would the throttle then be set to
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