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

[LameLefty]

Some variation #2 & #3 is under consideration as the subject has had recent discussion. You're late to the party.

Having been one of those who requested this feature a few weeks ago, I say the more the merrier to this party!

[sarbian]

Some news on the docking AP work. As you can see it's going well, but if you jump to the end you'll see I still have some work to do

It move too far from the target too, but it's just that I did not take the time to fix that part yet.

Edited January 22, 2014 by sarbian

[Commissar]

I've been a fan of MJ for a while now and I wanted to thanks r4m0n, Sarbian and the other contributors for their excellent work. I also wanted to let the others here know a few tricks I've discovered over time, which you may find helpful.

• When building very long rockets, put a reaction wheel just after the first engine and another one every 2 stages - it makes the rocket respond faster to control inputs, which in turn allows MJ to make smaller corrections and you get a smoother ride.
  
• If you find that your rocket wobbles during an MJ-controlled ascent, it means that it's flexing (even if you can't see it) and you need to strengthen one or more joints. Use Kerbal Joint Reinforcement and/or struts.
  
• MJ's docking autopilot works best with symmetric spacecraft.
  
• If you notice that MJ overshoots nodes and needs to turn the craft around to do a correction (eg when circularizing), it means that the rocket engine is too powerful for the spacecraft it's pushing and you need to limit its thrust using the tweakable right-click menu the VAB. I wonder if this is something MJ could do automatically.
  
• A way to drastically reduce the number of times Jeb gets stranded is to get a delta-V map from the KSP wiki and use it with the MJ Delta-V Stats window while you're in the VAB. Remember that a good engineer always adds a bit extra - according to the map I'm using it takes 4550m/s to get to low Kerbin orbit, but in my experience it ends up being closer to 4800m/s.
  
• Related to the previous point, MOAR BOOSTARS is not always the answer to insufficient delta-V: rocket fuel is heavy, so you might actually end up with less delta-V after adding another stage! try the different rocket engines you can get from the spaceport (experiment by putting different engines in different stages) and try techniques like asparagus staging.
  

I find that, lately, after installing FAR, i'm using maybe 4k deltav, including circularization, to get to a 600km orbit. however, your last statement is quite correct. my 150t payload launcher probably uses a considerable amount of it's thrust just to lift itself, what with 7 titans under the big KW tanks in asparagus, plus 6 thor SRBs...

used to use it for 50 ton launches till today, when I found that 2 liquid boosters is plenty

Some news on the docking AP work. As you can see it's going well, but if you jump to the end you'll see I still have some work to do

It move too far from the target too, but it's just that I did not take the time to fix that part yet.

I have had few problems with the autodock, most of those are due to my not turning on the SAS on the receiving end. it docks a full 160t tanker just fine using the KW 3.5m docking ring. however, those refinements in the pathing look pretty good... and the redenvous appears to compensate pretty well for low TWRs... such as my tankers again... lol

also, suggestion: if this isn't in mechjeb already, and assuming it's possible, how about something like the SAS, that keeps a craft tidally locked when active. I can definately see some significant uses for this, particularly on satellites.

Edited January 22, 2014 by Commissar

[DerekL1963]

Some news on the docking AP work. As you can see it's going well, but if you jump to the end you'll see I still have some work to do

It move too far from the target too, but it's just that I did not take the time to fix that part yet.

Looking pretty good... that bump in the end seems to me to have been a PEBKAC error setting the maximum speed too high.

[drtedastro]

Looking GREAT...

Great work as always sarbian... Thanks.

[Galane]

Try it docking to a ship without power so it's rotation can't be held. Would have to come in carefully and get it right the first time or a bump could send it spinning.

[sojourner]

also, suggestion: if this isn't in mechjeb already, and assuming it's possible, how about something like the SAS, that keeps a craft tidally locked when active. I can definately see some significant uses for this, particularly on satellites.

Smart A.S.S. module does that.

[sarbian]

Looking pretty good... that bump in the end seems to me to have been a PEBKAC error setting the maximum speed too high.

The code should slow down enough anyway. If it does not someone will complain that MJ destroyed their station after asking for a 50m/s docking. And in other test the heavy tank did not align properly, so there is most likely some residual error in my code.

The most important point for now is that it uses less monoprop than all my previous versions.

I'll try to finish it quickly since I'm working on something else with other modders

[togfox]

Ill ask an obvious question here, is autom8 dead, buried and forgotten?

*sob*

[sarbian]

r4m0n said he was working on it but he has no eta, so don't hold your breath.

[crazyewok]

My auto dock on MEC jeb not working it just seems to be flying about the target on RCS. The docking points check out it seems.

[BARCLONE]

I had a strange incident the other day with the docking AP. The approach looked good until about 3-4 meters away, then the spacecraft began drifting off to one side. When it was within 1m of the target, MJ realized it wasn't lined up correctly, and it started to back up for another run. Instead of putting plenty of distance between the spacecraft and the target, however, it got into a tight loop of backing up and thrusting forward within that 1m space. MJ never managed to get lined up, it just looped inside that 1m gap.

[DerekL1963]

My auto dock on MEC jeb not working it just seems to be flying about the target on RCS. The docking points check out it seems.

I had a strange incident the other day with the docking AP. The approach looked good until about 3-4 meters away, then the spacecraft began drifting off to one side. When it was within 1m of the target, MJ realized it wasn't lined up correctly, and it started to back up for another run. Instead of putting plenty of distance between the spacecraft and the target, however, it got into a tight loop of backing up and thrusting forward within that 1m space. MJ never managed to get lined up, it just looped inside that 1m gap.

Sometimes MJ loses it's little simulated digital mind... maybe it's a bug, maybe it's just the game getting lost and confused. The answer to determining which is which is to quicksave before maneuvering, and to restore and try again if it goes all pear shaped.

[crazyewok]

Sometimes MJ loses it's little simulated digital mind... maybe it's a bug, maybe it's just the game getting lost and confused. The answer to determining which is which is to quicksave before maneuvering, and to restore and try again if it goes all pear shaped.

I keep resetting it all it does is do this stupid dance of circleling at 20m and refusing to dock.

I hate docking its the most tedius boring finicky part of the game!

Edited January 22, 2014 by crazyewok

[Andon]

I suspect that you may have MechJeb using the wrong control point, but I don't use the auto-docking module. I find docking to be the EASIEST thing to do in the game. Once I get the ships rendezvoused and about 200-500m apart, I go to "Control from here" from the docking port, then SmartASS to Target+, then switch to the other ship and do the same. A little bit of closing speed (Maybe 1.5 m/s tops), then when they get closer I set the target to the appropriate docking ports on both craft. SmartASS lines them up properly and I'm done in no time.

[crazyewok]

I suspect that you may have MechJeb using the wrong control point, but I don't use the auto-docking module. I find docking to be the EASIEST thing to do in the game. Once I get the ships rendezvoused and about 200-500m apart, I go to "Control from here" from the docking port, then SmartASS to Target+, then switch to the other ship and do the same. A little bit of closing speed (Maybe 1.5 m/s tops), then when they get closer I set the target to the appropriate docking ports on both craft. SmartASS lines them up properly and I'm done in no time.

Good for you..... I still hate docking lol

[Commissar]

I keep resetting it all it does is do this stupid dance of circleling at 20m and refusing to dock.

I hate docking its the most tedius boring finicky part of the game!

usually, when this happens to me, it's because the craft i'm docking TO does not have SAS on, so mechjeb has a helluva time trying to compensate for the drift of the target, in addition to the usual imbalances of the RCS jets, the intertia of the docking craft, and avoiding collisions. never done it any other time for me.

[Starwaster]

The code should slow down enough anyway. If it does not someone will complain that MJ destroyed their station after asking for a 50m/s docking.

Thrusters only while in spacedock?

[goldenpeach]

Is there a way to see the marker when the target(or landing site) is on water?

[glesage]

Hey guys,

Will there be updates for 0.23, I'm having issues...

Win 7 x64 using the Steam Install.

Thanks

PS: I tried installing it manually and using the KSPMODAdmin but no luck seing it anywhere ):

[SkyHook]

So...using the latest version of mechjeb, my craft overcontrols itself when using the ascent autopilot. It uses full control surface deflection and engine gimbal to correct any deviations in trajectory, wobbling back and forth violently. This is very reminiscent of the old SAS. I know that the problems lies with mechjeb, as using simple SAS causes normal behavior. Is there any way to stop mechjeb from doing this?

I have attached some photos of the craft:

[K3-Chris]

RCS balancer broken in latest dev builds, makes RCS not work most of the time, you get a split second puff and then nothing until you tap the key again, same result using docking AP etc.

[Galane]

So...using the latest version of mechjeb, my craft overcontrols itself when using the ascent autopilot. It uses full control surface deflection and engine gimbal to correct any deviations in trajectory, wobbling back and forth violently. This is very reminiscent of the old SAS. I know that the problems lies with mechjeb, as using simple SAS causes normal behavior. Is there any way to stop mechjeb from doing this?

Latest version on the spaceport or latest dev build linked on the first post?

[AndreyATGB]

If you don't mind extreme over corrections, go in altitude adjustment and check "use stock SAS". This will basically simulate user input and should work with any craft exactly the way it would if you control it yourself.

[acc]

mj needs definitly be fixed, i have a lot of buging things happend with it.

but it's ok, i think KSP players like challenges