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[PART, 1.0.2] Anatid Robotics / MuMech - MechJeb - Autopilot - Historical thread

r4m0n

By r4m0n
in KSP1 Mod Releases

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futrtrubl

futrtrubl

Posted
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I noticed two things: first the terminal velocity indicator is completely off and second the atmospheric drag indicator shows drag even when I'm well above the atmosphere (even if only picometer/second)

this was right after liftoff and the terminal velocity is ridiculously high to be so low in the atmosphere.

http://i.imgur.com/xNTlCyp.png?1

and this is the atmospheric drag indicator

http://i.imgur.com/FPElqd9.png?1

That terminal velocity looks about right to me. You are going about mach 1 so your drag coefficient is at it's maximum and you are only getting about 1/5g (2.2m/s2) drag. Your craft is pointy so your drag coef will drop significantly after transonic so your terminal velocity (where drag =1g) should be at least 2.2x your current speed and very likely more than 5x your current speed, so >700m/s for sure and probably more than 1500m/s.

Do not base your assumptions on pre-1.0 ksp.

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RyanK

RyanK

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Yesterday I dropped the latest version of MechJeb into the Gamedata folder (ver. 1.0.2) and I've lost the some functionality. When automatically executing a node MechJeb will control the ship but it won't activate the throttle. I can make it work with manual throttle control. It all worked fine with the previous version of MechJeb. I checked all the settings but I haven't found anything obvious. Any ideas?

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futrtrubl

futrtrubl

Posted
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Yesterday I dropped the latest version of MechJeb into the Gamedata folder (ver. 1.0.2) and I've lost the some functionality. When automatically executing a node MechJeb will control the ship but it won't activate the throttle. I can make it work with manual throttle control. It all worked fine with the previous version of MechJeb. I checked all the settings but I haven't found anything obvious. Any ideas?

Known issue. He needs logs. Logs are a good thing to attach to any bug report.

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Capt. Hunt

Capt. Hunt

Posted
Posted (edited)

What broke the ascent guidance?

I just updated to the latest mechjeb, 2.5.1, and now anything I launch under guidance starts somersaulting uncontrollably when it reaches terminal velocity. (I know it starts at terminal velocity because the engine shuts off right before it starts flipping if I have it set to limit to that). I also noticed that regardless of where I set it to start the gravity turn, it starts at 800 meters, and if my ship is lucky enough to survive the somersaults, the guidance doesn't correct to put me in the right orbit, I end up way low and off trajectory, and the circularization burn doesn't seem to correct for the orbit either, it doesn't fully circularize. I tried the latest dev build too, and it had the same problem.

Meanwhile, if I roll back to the last pre-1.0 mechjeb build, it launches fine, but docking is janky, if I set the docking autopilot, half the time it either goes off course and plows the ship into the station I'm trying to dock with or it randomly just starts jetting away from the target until it either runs out of mono or gets out of range and loses the target lock.

I first noticed the glitches with the KSO, but I've gotten them with other mods and all stock ships too.

Edited by Capt. Hunt
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billkerbinsky

billkerbinsky

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One glitch I've observed several times: if you enable the attitude control debug arrows that show various vectors (control pod direction, orbital velocity, surface velocity, maneuver node direction, etc.) and go into time warp, the arrows can be seen flying away (think " I must go! My people need me!".. ). The reverse happens as you come out of warp.

if this is intentional, it's entertaining. if it's unintentional I'm curious about why...

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smjjames

smjjames

Posted
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One glitch I've observed several times: if you enable the attitude control debug arrows that show various vectors (control pod direction, orbital velocity, surface velocity, maneuver node direction, etc.) and go into time warp, the arrows can be seen flying away (think " I must go! My people need me!".. ). The reverse happens as you come out of warp.

if this is intentional, it's entertaining. if it's unintentional I'm curious about why...

I've seen that a number of times too. Not sure if sarbian can do anything about that one.

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futrtrubl

futrtrubl

Posted
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I also noticed that regardless of where I set it to start the gravity turn, it starts at 800 meters, and if my ship is lucky enough to survive the somersaults...

Please look back a few pages and change the turn start speed.

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Capt. Hunt

Capt. Hunt

Posted
Posted (edited)
Please look back a few pages and change the turn start speed.

By the way, it was doing that before I even started messing with the ascent profile, and I never messed with the speed. What speed would you suggest I set it to?

Ok, I reinstalled the dev build -463 to test changing the turn start speed, but before I could do that, I ran into a completely different problem. Now, as soon as the gravity turn starts, before the ship even tips below vertical, mechjeb just cuts out. It starts the force roll (which I had set to 0), rolls about 45 degrees and stays there, the rocket then continues to power straight up at full throttle until it runs out of fuel (regardless of having the terminal velocity limiter checked). No amount of tweaking mid flight or changing of settings before launch seems to correct this behavior.

The strange thing is when I was testing before, this build didn't have this issue, mechjeb controlled the ship through the entire ascent (albeit with the flip problem discussed above).

Here is my output log from that series of flights:

https://www.dropbox.com/s/xcstvdgyx5xi4kv/output_log.txt?dl=0

Will try 2.5.1 again next.

Edited by Capt. Hunt
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AgentMOO

AgentMOO

Posted
Posted (edited)
Dev #4​64 should fix the node problem. Please test and report.

Tested. No autowarp when it should.

5tgf1tE.jpg

If I use warp helper it WILL do the burn but it does it wrong. Note the angle, it should be level.

4J75Ej8.jpg

Output log: http://www./view/ghv07lurc2dh7gd/output_log.txt

Craft file: http://www./download/773pgba671mrv38/newb6.craft

I may have used the warp helper incorrectly. I only gave it a *10 second lead. It might not have realigned properly.

Edited by AgentMOO
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Capt. Hunt

Capt. Hunt

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Posted

ok, this is where it gets wierd, that cut out behavior happened in 2.5.1 too, but it only occurred in the sandbox save I was using to test, when I switched to my main career save file, mechjeb worked. but I was still getting flips. I've tried tweaking the turn start speed all over the place, and I'm just not sure if it's getting anywhere. What's worse is when I change the speed, it turns at the altitude, when I change the altitude it turns at the speed. :huh:

And landing guidance doesn't seem to be working either, After one of the tests, I hit Abort, just to see if my capsule's LES would work, and then turned on mechjeb's landing guidance to put it into a powered landing, the capsule just fell like a rock, it never fired the retro rockets to slow the descent or even lower the landing gear.

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Galane

Galane

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ok, this is where it gets wierd, that cut out behavior happened in 2.5.1 too, but it only occurred in the sandbox save I was using to test, when I switched to my main career save file, mechjeb worked. but I was still getting flips. I've tried tweaking the turn start speed all over the place, and I'm just not sure if it's getting anywhere. What's worse is when I change the speed, it turns at the altitude, when I change the altitude it turns at the speed. :huh:

And landing guidance doesn't seem to be working either, After one of the tests, I hit Abort, just to see if my capsule's LES would work, and then turned on mechjeb's landing guidance to put it into a powered landing, the capsule just fell like a rock, it never fired the retro rockets to slow the descent or even lower the landing gear.

Have you checked that the center of lift is lower than the center of mass in the VAB? 'Course the problem with that is what KSP needs to show for rockets, and to use in its aerodynamic simulation, is center of pressure instead of lift.

If you put no parts with lift properties on a rocket it will show the center of lift sitting on the VAB floor.

Center of pressure is found by finding the center of mass of a flat sheet cut to the shape of a silhouette of the rocket. That point has to be behind the center of mass of the actual rocket in order for it to be stable.

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Jim DiGriz

Jim DiGriz

Posted
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I just updated to the latest mechjeb, 2.5.1, and now anything I launch under guidance starts somersaulting uncontrollably when it reaches terminal velocity.

You shouldn't really be hitting terminal velocity. Build rockets with lower TWR and/or clip the max acceleration to 18-22 m/s or so. You'll actually get to orbit with more fuel because you were fighting less drag. At 25,000-35,000m or so you can remove the acceleration limit and let the mainsails roar, but at the surface you're just wasting fuel fighting drag. Terminal velocity is now too fast. If you get mach effects or heating effects that's also too fast. The aero model changed.

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sarbian

sarbian

Posted
Posted
One glitch I've observed several times: if you enable the attitude control debug arrows that show various vectors (control pod direction, orbital velocity, surface velocity, maneuver node direction, etc.) and go into time warp, the arrows can be seen flying away (think " I must go! My people need me!".. ). The reverse happens as you come out of warp.

if this is intentional, it's entertaining. if it's unintentional I'm curious about why...

The method that updates some of the values used for the arrows is not running while in warp. So the position of some is not updated. I should hide them or tether them to the ship while in warp.

I've seen that a number of times too. Not sure if sarbian can do anything about that one.

And why would I not be able to do a thing about code I wrote myself ? This pattern is getting more than annoying.

I had 2.5.1 installed and version checker told me it was incompatible so I DLed MechJeb2-2.5.1.0.zip and installed.

Now KSP stops loading.

Seems to get stuck at /Parts/MechJeb2_AR202

any ideas?

Delete outdated mod files from <KSP>/part and <KSP>/plugins ? Better even do a clean install of KSP if you have such old files in here. All MJ files should be in <KSP>/GameData/MechJeb2

Tested. No autowarp when it should.

NaN in DeltaV windows :(

At least I fixed on of the case...

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edemlama

edemlama

Posted
Posted
That terminal velocity looks about right to me. You are going about mach 1 so your drag coefficient is at it's maximum and you are only getting about 1/5g (2.2m/s2) drag. Your craft is pointy so your drag coef will drop significantly after transonic so your terminal velocity (where drag =1g) should be at least 2.2x your current speed and very likely more than 5x your current speed, so >700m/s for sure and probably more than 1500m/s.

Do not base your assumptions on pre-1.0 ksp.

Thanks for the explanation, appreciate it. :cool:

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acc

acc

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Posted
I am seriously considering removing that option. It causes more problem than it solves. It is disabled in the current default.

maybe just bind it to the AoA feature. I like to activate it later (~45km) to correct inclined launches a bit. btw inclined launches are not the strong side of the ascent guidiance at all :D

but thanks anyways for your good work.

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Gfurst

Gfurst

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Posted
I shamelessly copied over the config file for MechJeb for all (in CKAN), and made some alterations.

Thing is I want to use certain aspects of MechJeb with every ship, such as the ascent profile guide, auto pilot for probes and such.


@PART[*]:HAS[@MODULE[ModuleCommand]]:Final
{
	%MODULE[MechJebCore]
	{
		MechJebLocalSettings
		{
			// MechJebModuleCustomWindowEditor { unlockTechs = flightControl }
			MechJebModuleSmartASS { unlockTechs = start }
			MechJebModuleManeuverPlanner { unlockTechs = start }
			MechJebModuleNodeEditor { unlockTechs = start }
			// MechJebModuleTranslatron { unlockTechs = advFlightControl }
			MechJebModuleWarpHelper { unlockTechs = start }
			MechJebModuleAttitudeAdjustment { unlockTechs = start }
			// MechJebModuleThrustWindow { unlockTechs = advFlightControl }
			// MechJebModuleRCSBalancerWindow { unlockTechs = advFlightControl }
			MechJebModuleRoverWindow { unlockTechs = start }
			MechJebModuleAscentGuidance { unlockTechs = start }
			MechJebModuleLandingGuidance { unlockTechs = start }
			MechJebModuleSpaceplaneGuidance { unlockTechs = start }
			MechJebModuleDockingGuidance { unlockTechs = start }
			//MechJebModuleRendezvousAutopilotWindow { unlockTechs = advUnmanned }
			MechJebModuleRendezvousGuidance { unlockTechs = start }
		}
	}
}

My idea was that if I hide certain parts of the module it wouldn't show, but apparently everything is showing up. How could I do what I want? Permanently hide certain of the MJ utilities?

Plus, I've noticed that if you enable the ascent guidance and close the window, the target pointer doesn't update.

So I've tried assigning some of these modules to the "hidden" tech (which some seem to use to hid parts), bit it didn't quite work. Any hints?

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Capt. Hunt

Capt. Hunt

Posted
Posted
Have you checked that the center of lift is lower than the center of mass in the VAB? 'Course the problem with that is what KSP needs to show for rockets, and to use in its aerodynamic simulation, is center of pressure instead of lift.

If you put no parts with lift properties on a rocket it will show the center of lift sitting on the VAB floor.

Center of pressure is found by finding the center of mass of a flat sheet cut to the shape of a silhouette of the rocket. That point has to be behind the center of mass of the actual rocket in order for it to be stable.

yes the center of lift is below the center of mass.

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