[1.12.x] Anatid Robotics / MuMech - MechJeb - Autopilot - [2.14.3] [4th March 2023]

[MikeO89]

8 minutes ago, maja said:

In the Ascent Guidance window are two fields, where you can enter degrees of rotation after a launch and at the start of a gravity turn. Enter into both of them 90 degrees and your craft will not turn.

That does not work unless you have already re-oriented the craft (or root part) in the VAB 90°

[maja]

17 minutes ago, MikeO89 said:

That does not work unless you have already re-oriented the craft (or root part) in the VAB 90°

It does work without reorienting the root part (usually a pod), unless something changed in MJ lately.

[TeslaPenguin1]

After using CKAN, it says it's incompatible. Is there a way to tell CKAN to use the correct version?

[Nik Power]

People, HI!

Need help, in version 1.3... there was a mod, that was showing fuel remaining in tanks of a vessel in seconds.

Was very usefull to understand, how much DeltaV you have (for example, to understand, is there enough fuel for redevous maneuver and deorbit)

Can anyone remind me, what mod it was?

 

UPD: found what I seeked in MechJeb Stage Info. Question closed.

Edited November 17, 2018 by Nik Power

[LameLefty]

I have question re MJ's landing guidance. I understand the difficulties with atmospheric entry, descent and landing, but thankfully my question is about landing on vacuum bodies. 

Way back when I started playing KSP (version 0.19, over 5-1/2 years ago), it seems to me that MJ was more aggressive when landing on, say, the Mun or Ike. Just last night I was landing a plenty-powerful lander (TWR of nearly 5/1 on Ike) yet MJ (latest dev version)  basically jockeyed the throttle between 25% - 50% most of the way through the descent and wasted a huge amount of dV fighting gravity losses all the way to the surface. Is there an option or setting buried somewhere to toggle a more "aggressive" vacuum landing profile?

There's already a suicide burn timer display  (which I have enabled via a custom window to use for manual landings), but it seems to me like that a more aggressive suicide burn landing profile might be an option some people would like to use automatically. And with a couple of settings fields for "tolerance" you could satisfy a lot of folks: e.g., an option to set the target height for zero velocity (much like the landing guidance now uses 500m for vertical descent), another to allow timer padding to allow for slow throttle response, maybe a couple other things I haven't thought about in great detail.

 

[Catto]

I'm downloading it the right way i think, But it still says i'm downloading it incorrectly.

[Kroslev Kerman]

Maybe a Good suggestion would be SSTO Spaceplane ascent Guidance

Edited November 20, 2018 by Kroslev Kerman

[Xd the great]

2 hours ago, Kroslev Kerman said:

Maybe a Good suggestion would be SSTO Spaceplane ascent Guidance

The ascent guidance is good enough, if you know how to tweak.

[Kroslev Kerman]

8 hours ago, Xd the great said:

The ascent guidance is good enough, if you know how to tweak.

i cant set up a god damn SSTO guidance with the current "Rocket Guidance"

[Jim DiGriz]

On 11/3/2018 at 5:50 PM, Papa BullDust said:

@Jim DiGrizI specifically came to the forums today to write about this issue, only to find user @dmsilev has nicely summarised the problem with the new Bi-impulsive. It can, in certain situations "waste" dV by performing the plane change at the same time as the acceleration burn whilst deep within a gravity well. I would like to add a simple request to add back into MechJeb the true Hohmann (co-planar) fuctionality. This would allow once again, the plotting of a later plane change manoeuvre at a more optimal time. I realise that this may well clutter up the interface a little, but MechJeb (I would argue) is a learning tool also; it may also encourage new users to seek out the differences between the two modes.

TLDR; please add the old Hohmann transfers back in!

@dmsilev @Papa BullDust dev build #819 has a checkbutton to do the old coplanar transfer

[GeneCash]

On 11/7/2018 at 2:41 PM, Jim DiGriz said:

Possibly, I found some bugginess when I was investigating the prior reports, but real life has intruded on KSP time.

So what the heck do you do for a living??

The reason I ask is I had a very interesting higher-math teacher at my community college back in the mid-'80s. Now I've been a space nut since I saw Apollo 11 launch on my 4th birthday, so when he started to talk about guidance state vectors in his (IIRC) Diff-Eqn class, I got very interested, and even more so when he started talking about how they applied to the Apollo guidance and navigation problems. He offhand mentioned he worked at Charles Draper labs, and when he retired, he wanted a sleepy backwater college to teach mid-level math.

Unfortunately I was too star-struck and introverted to ask further questions, and since that was 30+ years ago, there's no info on him on the Internet.

So I've learned to ask these things...

[Jim DiGriz]

On 11/22/2018 at 12:38 AM, GeneCash said:

So what the heck do you do for a living??

Software developer.  Server configuration management software.  Dayjob has gotten a bit boring.

In college I was a physics-astronomy double major before dropping out -- mostly because I spent too much time in the library and at the computer labs working on stuff that was interesting to me rather than always going to classes...

And I'm kinda jealous, I would kill to pick the brain of someone who worked at CSDL on guidance...

Edited November 24, 2018 by Jim DiGriz

[GeneCash]

6 hours ago, Jim DiGriz said:

Software developer.  Server configuration management software.  Dayjob has gotten a bit boring.

In college I was a physics-astronomy double major before dropping out -- mostly because I spent too much time in the library and at the computer labs working on stuff that was interesting to me rather than always going to classes...

And I'm kinda jealous, I would kill to pick the brain of someone who worked at CSDL on guidance...

The guy was so good at teaching, he almost made me change my major from computers to math, which would be about like getting Einstein to switch from physics to political science. I remember he made Laplace Transforms seem like 3rd grade math. "well now that you know how to do 'em, here's the theory... wouldn't you have been horribly confused if I taught that first...?" I kind of held him in complete awe, so unfortunately I never got the courage to talk to him.

His son designed jet engines at Palm Beach, and so one day he took 10 minutes to go over the math of "tolerance stacking" where you don't want to have the tolerances of 40 parts all add up so you're an inch off at the other end, which is a big concern in jets.

He had an interesting idea on tests, which were all take-home: "well your job lets you look at anything, and they pay for a big library, so you should use it. The only thing you can't do is talk to someone else in your class, since I'm testing YOUR knowledge" and one of his big difficult questions actually had the complete solution in the textbook... where he was disappointed only one person got it correct. He'd also sneak in little gotchas like integrating across a discontinuity to remind the class "that basic stuff doesn't go away just because it was 4 classes ago, but hey, Fields Medal guys get bit like that too..."

His name was "Bill Carpenter" but no useful hits. I swear though, I saw him in a CSDL staff picture once, and I didn't keep track of it.

Unfortunately, I got killed by electrical physics at UCF and dropped out myself. I missed something fundamental and it doesn't gel for me. And large database s/w development pays the bills, but since I've been moved around so much, I'm kinda phoning it in these days.

Ah well, time to rejoin the currently scheduled thread in progress...

[Papa BullDust]

On 11/21/2018 at 4:00 AM, Jim DiGriz said:

dev build #819 has a checkbutton to do the old coplanar transfer

Awesome job Jim, thank you VERY much indeed

 

[dmsilev]

On 11/20/2018 at 11:00 PM, Jim DiGriz said:

@dmsilev @Papa BullDust dev build #819 has a checkbutton to do the old coplanar transfer

Wonderful, thank you. I don’t usually mess with the dev builds, but I think I’ll make an exception here. 

[Eugene Moreau]

So I'm having this problem with MechJeb.  It's over steering like crazy on ascent.  Using the Classic Ascent Mode, but shortly after launch it start to push me over and then back and then the other way inducing an oscillation.  Eventually it starts doing the same thing on the roll axis, but this seems to dampen the other oscillation and correct it.  I've tried turning various options off and on with no luck.  I tried doing the ascent manually and the rocket flies pretty straight if left to it's own devices.  

Are there any obvious things I should be checking for?  Is there compatibility with FAR?  

[LameLefty]

1 hour ago, Eugene Moreau said:

So I'm having this problem with MechJeb.  It's over steering like crazy on ascent.  Using the Classic Ascent Mode, but shortly after launch it start to push me over and then back and then the other way inducing an oscillation.  Eventually it starts doing the same thing on the roll axis, but this seems to dampen the other oscillation and correct it.  I've tried turning various options off and on with no luck.  I tried doing the ascent manually and the rocket flies pretty straight if left to it's own devices.  

Are there any obvious things I should be checking for?  Is there compatibility with FAR?  

I was noticing this as well with dev version 819. I haven't tested any earlier versions to see exactly when this behavior started. I was able to help minimize (but not eliminate) the problem by tweaking the deadzone settings in the "Attitude Adjustment" window but a lander design I've used since darn near forever (since about KSP verison 0.21 actually!) now climbs like a drunken duck. 

[Loren Pechtel]

(Note that I hit this on 1.4, but I don't see anything about it being fixed in 1.5)

Advanced transfer to another planet--I got the porkchop showing values that I expected, tried to create the node and it failed.  After a moment's thought I realized what was up--I was in a polar orbit (science mission going from the Mun to Minmus.)  Obviously the porkchop was drawn without actually looking at my orbit but the node creator didn't know how to cope with my orbit as I was never pointed in the right direction.  I wonder if this might be related to some wacky burns it's tried to set up in the past.

[Loren Pechtel]

And another one from 1.4:

The third stage of this rocket is Nerva.  On the pad it showed about 3000 m/s in it.  By the time it lit off in orbit it showed about 5000 m/s in it, which is what it showed in the VAB.  The atmosphere and vacuum numbers were always the same.

[Alexoff]

On 11/29/2018 at 3:19 AM, Eugene Moreau said:

So I'm having this problem with MechJeb.  It's over steering like crazy on ascent.  Using the Classic Ascent Mode, but shortly after launch it start to push me over and then back and then the other way inducing an oscillation.  Eventually it starts doing the same thing on the roll axis, but this seems to dampen the other oscillation and correct it.  I've tried turning various options off and on with no luck.  I tried doing the ascent manually and the rocket flies pretty straight if left to it's own devices.  

Are there any obvious things I should be checking for?  Is there compatibility with FAR?  

This oscillation and rotation started at 1.3 as I remember. It happened with big rockets everytime. I suppose that the problem is PID regulator, maybe it use FPS in calculation and when you has significant drop of frame rate SAS module work wrong. There is one possible and stupid way to repair ascending - you can start fast clicking Q and E buttons during ascending. It helps mechjeb by some way. Maybe there is another way - fixing of mechjeb PID regulator, but Sarbian still ignoring this issue.

[sarbian]

7 minutes ago, Alexoff said:

Sarbian still ignoring this issue.

I love it when people dismiss an issue like this. There have been multiple patch to the controller and you can even choose one of the 3 available controller to find what suits your rocket best. 

If you can do better then write a freaking patch. I would love a amazing controller that can handle whatever freak build you throw at it. But I get more amateur hours analysis (FPS dependant, lol) than  contributions. 

[The_Franconian]

On 11/29/2018 at 1:19 AM, Eugene Moreau said:

Are there any obvious things I should be checking for?

Any chances that your rocket ist structurally unstable, or that the mechjeb part that controls the rocket is off angle with the engine parts of the rocket? This happens to me only, when i haven't fortified the connections between parts enough and the controling part is not instantly following the rest of the rocket, when the course changes. The rocket starts to oscilate in itself and the wobbling mechjeb is unable to keep the contraption on a straight course. This also happens, when the mechjeb part is not facing the right direction.

[El Sancho]

40 minutes ago, sarbian said:

I love it when people dismiss an issue like this. There have been multiple patch to the controller and you can even choose one of the 3 available controller to find what suits your rocket best. 

If you can do better then write a freaking patch. I would love a amazing controller that can handle whatever freak build you throw at it. But I get more amateur hours analysis (FPS dependant, lol) than  contributions. 

Apologies for that, Sarbian. You shouldn't have to put up with such ****ty little comments, but some people's children don't seem to understand that you volunteer your time to support a free program, or perhaps they never heard that old saw about "never look a gift horse in the mouth".

Your efforts are deeply appreciated by the vast majority of us.

[Loren Pechtel]

3 hours ago, Alexoff said:

This oscillation and rotation started at 1.3 as I remember. It happened with big rockets everytime. I suppose that the problem is PID regulator, maybe it use FPS in calculation and when you has significant drop of frame rate SAS module work wrong. There is one possible and stupid way to repair ascending - you can start fast clicking Q and E buttons during ascending. It helps mechjeb by some way. Maybe there is another way - fixing of mechjeb PID regulator, but Sarbian still ignoring this issue.

In my experience the MechJeb oscillation problem is a derivative of the underlying game oscillation problem.  You need more control authority.  What happens is that it does not correctly figure out when to start countering a turn and overshoots the target--so now it goes in the other direction.  If the control authority is low enough it overshoots by more each time.

I have seen this is stock with an EVA kerbal.  Turn the jetpack way down and tell the Kerbal to stabilize.

[Tonka Crash]

On 11/28/2018 at 5:19 PM, Eugene Moreau said:

So I'm having this problem with MechJeb.  It's over steering like crazy on ascent.  Using the Classic Ascent Mode, but shortly after launch it start to push me over and then back and then the other way inducing an oscillation.  Eventually it starts doing the same thing on the roll axis, but this seems to dampen the other oscillation and correct it.  I've tried turning various options off and on with no luck.  I tried doing the ascent manually and the rocket flies pretty straight if left to it's own devices.  

Are there any obvious things I should be checking for?  Is there compatibility with FAR?  

It helps to see a picture of your rocket. Does it look like a realistic rocket or is it a silly looking thing only a Kerbal would fly? I design my launches to have a 1.4 starting TWR. I also turn off roll control on any control fins assuming reaction wheels will handle roll and fins are only for pitch and yaw. If you don't have control fins, you need them. If it's tumbling or overheating in the lower atmosphere, set the ascent guidance profile for a steeper initial climb.

What works for me for other options is:

• Limit Q on 20000 (default)
• Force Roll climb at whatever roll attitude you climb out at.
• Corrective Steering Gain On (0.6) 
• Classic Ascent Profile (Altitude & Velocity sliders all the way to the left) 
• Classic Ascent Profile Turn Shape 60%

On 11/28/2018 at 7:03 PM, LameLefty said:

I was noticing this as well with dev version 819. I haven't tested any earlier versions to see exactly when this behavior started. I was able to help minimize (but not eliminate) the problem by tweaking the deadzone settings in the "Attitude Adjustment" window but a lander design I've used since darn near forever (since about KSP verison 0.21 actually!) now climbs like a drunken duck. 

My "drunken duck" landers generally use multiple engines around the central core. If the CoG is laterally offset from the thrust line at all it's always trying to induce a rotation while thrusting. When I first started playing I tried thrust limiters to balance it, but then I found a checkbox for Differential Throttle under MechJeb Utilities. The Differential Throttle setting lets MechJeb balance the throttles to keep the thrustline and CoG in line. When I found that setting it was night and day for lander performance and even some of my boosters if the payload is asymmetric.

Overall I leave MechJeb settings at their defaults unless noted above. 

Edited to add: My only real gripe with MechJeb is the lack of up to date documentation on what all the settings are supposed to do. As a tool it's really impressive that this was put together by a couple volunteers.

Edited December 2, 2018 by Tonka Crash