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

[rottielover]

I'm having a few issues that someone may be able to help out.The biggest one is trying to orbit mun. I've got the orbit of kerbal down pat and using the rendezvous module I can even make it to mun however it makes me crash into mun every single time. I believe the rendezvous is ment more so with meeting with an object that is already in orbit and not for getting to planets though I am not 100% sure on that. Any advice? My next issue is with career mode. I have unlocked mech jeb2 in the tech tree and successfully used it 3 times. Now when I attach it it no longer gives me the ascent control options, landing options, rendezvous nothing. The only thing it shows delta v orbit info and ship info. Did I miss something here?

Try using manuver planner and the Holhman transfer to target function. It will put you on an intercept course as well, but then setup a correction burn using the other manuver planning functions to fine tune whatever Pe you want etc.

As for functions availible, read the post above yours, sounds like you need to unlock some more tech tree nodes?

[sarbian]

Ok, I've played enough for now. Back to coding.

I have pushed change for MJ #104. This allow for external module to interact with some part of MJ. This is just the start and implementation is subject to change.

BUT it allow me to release the first version of the FAR compatibility.

For those who want to test get MJ2 dev #104 and add this dll in the same folder as MechJeb2.dll : www.sarbian.com/sarbian/MechJebFARExt.dll

FAR 10+ is required

Code: https://github.com/sarbian/MechJebFARExt

Licence is GPL3.

For now the only thing it adds is torque from control surface. It let MJ know how fast it can turn when FAR is used. This is important for the attitude control.

FAR drag change are not used in any way yet, so don't expect the landing AP to hit the target on planet with atmosphere.

Edit : change version to #104. 103 works too, just a minor change.

Edited November 18, 2013 by sarbian

[scorchdestroya]

Right, remember that problem of the ascent guidance not allowing roll? Well, i seem to have found a fix that works for me. Below ascent guidance, there is attitude adjustment. Within it, it has the option to use stock SAS, disableing this completely solved it for me.

[Galane]

I'm having a few issues that someone may be able to help out.The biggest one is trying to orbit mun. I've got the orbit of kerbal down pat and using the rendezvous module I can even make it to mun however it makes me crash into mun every single time. I believe the rendezvous is ment more so with meeting with an object that is already in orbit and not for getting to planets though I am not 100% sure on that. Any advice?

To get to Mun from Kerbin Orbit.

Click on Mun in Map view to set it as target.

Use maneuver planner to do a Hohmann transfer to target.

Time warp until you cross the node that pops up Mun encounter. (You'll want to be ready to click on 1x warp when you get there.)

Use Maneuver planner to Circularize. You can use the timed option to set when, or leave it at 0 to do it right now. Or you can use the altitude option. If your path is aimed to impact the Mun you cannot use the Periapsis option. The other option that works is the altitude one. If the path is missing Mun and has a Pe marker you can use that option, though be certain it's high enough.

To get to Minmus, do all the same steps but as the second step after setting the target you must use match planes with target. If you don't you won't enter Minmus SOI, you'll fly above or below the moon's orbit unless the encounter happens at one of the two points where Minmus orbit crosses the Kerbin equatorial plane.

[MD5Ray01]

I've kind of noticed a problem with MechJeb. Whenever I try to have it dock with my cargo hauler (which uses parts from B9 Aerospace, Novapunch, Remotetech 2 Lite, and Ion Hybrid Electric Engines), my satellite wants to run right into the outer side of the hauler's cargo bay. Is there anything I can do?

Edited November 19, 2013 by MD5Ray01
Forgot an addon.

[Starwaster]

I've kind of noticed a problem with MechJeb. Whenever I try to have it dock with my cargo hauler (which uses parts from B9 Aerospace, Novapunch, Remotetech 2 Lite, and Ion Hybrid Electric Engines), my satellite wants to run right into the outer side of the hauler's cargo bay. Is there anything I can do?

need more data!

maybe a picture of the craft involved?

how you go about docking and when/where you ran into trouble?

[Virtualgenius]

Would it be possible to add the dll number to the version of mechjeb like you used to, it makes it easier to see what dll your using eg:2.1.0.104 last three digits designates dll build number

[sarbian]

I'll speak to r4m0n to see if he can configure jenkins so the build number is shown.

[rosenkranz]

To get to Mun from Kerbin Orbit.

Click on Mun in Map view to set it as target.

Use maneuver planner to do a Hohmann transfer to target.

Time warp until you cross the node that pops up Mun encounter. (You'll want to be ready to click on 1x warp when you get there.)

Use Maneuver planner to Circularize. You can use the timed option to set when, or leave it at 0 to do it right now. Or you can use the altitude option. If your path is aimed to impact the Mun you cannot use the Periapsis option. The other option that works is the altitude one. If the path is missing Mun and has a Pe marker you can use that option, though be certain it's high enough.

To get to Minmus, do all the same steps but as the second step after setting the target you must use match planes with target. If you don't you won't enter Minmus SOI, you'll fly above or below the moon's orbit unless the encounter happens at one of the two points where Minmus orbit crosses the Kerbin equatorial plane.

Actually getting to the Mun or minmus is about the same procedure. Once in LKO, target the Mun and from the maneuver planner do the Hohmann xfer to target as Gal said. This will actually put you on a collision course. Now you want to (from the maneuver planner again) do 'fine tune to target' with a 100km final Ap. You should now have two nodes. Do 'Execute all nodes' from the maneuver planner and let MJ do it's thing. The warp helper is good for not over shooting the SOI once MJ is done executing burns. Once in the Mun's SOI, do circularize at Pe from the planner and execute node and you should be golden.

This works for minmus as well. Correcting for the inclination isn't absolutely necessary as the that fine tuning node will correct for that with a minimum dV cost. It's cheaper to correct for inclination en-route than prior to the inital xfer burn. A 6 degree change in LKO runs you about 230dV while the fine tune burn will only cost 10-50dV depending on where minmus is in its orbit. Alternately if you're using MJ just target minmus prior to launch and 'Launch into target plane' on the ascent AP.

[LORDPrometheus]

I've kind of noticed a problem with MechJeb. Whenever I try to have it dock with my cargo hauler (which uses parts from B9 Aerospace, Novapunch, Remotetech 2 Lite, and Ion Hybrid Electric Engines), my satellite wants to run right into the outer side of the hauler's cargo bay. Is there anything I can do?

Check to make sure your command pod isn't upside down

[NotCoach]

I've kind of noticed a problem with MechJeb. Whenever I try to have it dock with my cargo hauler (which uses parts from B9 Aerospace, Novapunch, Remotetech 2 Lite, and Ion Hybrid Electric Engines), my satellite wants to run right into the outer side of the hauler's cargo bay. Is there anything I can do?

I don't like MechJeb auto-docking because it just doesn't seem to work for me. It is beyond painfully slow, and even when I'm very close to my target docking port the auto-docking sends me off into space away from my target. I think you'll have more luck utilizing Smart A.S.S. and switching between ships to dock.

Procedure that works for me:

1.) Get within a comfortable distance of your target (I do 50m for small craft, and 100m for large craft).

2.) I am going to assume you know how to select control from docking ports, and set as target target ports. Switch between crafts using the '[' ']' keys to do the same for both craft.

3.) On both craft select the 'TGT' tab in Smart A.S.S., and select the '+TGT' button. Wait for them to line up with each other.

4.) Select 'Kill Rot' in Smart A.S.S. on the target craft after they have lined up with each other.

5.) Switch to your approaching craft and select '+RELV', or '-RVEL' (depending on which will take less time to line up with). I suggest RCS be off at this point if it isn't. Once the approaching craft is lined up with the prograde reticle or the retrograde reticle click 'Kill Rot' in Smart A.S.S. Turn RCS on and tap the 'H' or 'N' keys until your relative velocity is as close to zero as you can get it.

6.) Turn RCS off (I found turning using RCS adds relative velocity to my craft. Probably improper RCS balance on my craft builds. I only worry about RCS balance on the forward and backwards axis ('H', 'N' buttons). Press '+TGT' on Smart A.S.S.

7.) When approaching craft is lined up on the target reticle swtich back to target craft and press '+TGT' on Smart A.S.S.

8.) When both craft are aligned with each other turn RCS back on approaching craft and press 'H' until relative velocity is approximately 0.5m/s.

9.) Now watch your target reticle and your prograde reticle. The prograde reticle should remain mostly inside the target reticle as you approach your target. If it starts to drift from the target reticle return to step 4 and repeat process. Just remember your relative velocity is now 0.5m/s, so you'll have to kill all of that velocity as well.

10.) At 5 meters from target I switch to target craft and select 'Kill Rot' in Smart A.S.S. I switch back to approaching craft and watch the magic happen.

After much practice the above method works 9 out of 10 times for me. If I bounce off I usually just have to do a retrograde (because I'm now traveling away from target) RCS burn to get back to target. Make sure you switch to target and select '+TGT' in Smart A.S.S. if this happens, though wait until approaching craft is more than 5m away before doing so. Repeat steps 7 thru 10 until successful.

I hope the above helps. Docking was a huge pain in the arse for me until much practice and experience. I don't know why the auto-docking module is almost useless for me (probably something I am doing wrong myself), but I can't use it the way it currently works for me.

[SergeiKorolev]

Hey I'm kind of new to KSP and I wondering if MechJeb 2.1 can be integrated with the tech tree in KSP .22 and if so, how can I do this?

[Nibb31]

Hey I'm kind of new to KSP and I wondering if MechJeb 2.1 can be integrated with the tech tree in KSP .22 and if so, how can I do this?

It's already integrated. It's already been explained several times in this thread.

[Starwaster]

Hey I'm kind of new to KSP and I wondering if MechJeb 2.1 can be integrated with the tech tree in KSP .22 and if so, how can I do this?

It's already integrated. It's already been explained several times in this thread.

To expand on that answer, the two MJ parts already have tech tree integration. you have to do nothing else but unlock the flight techs. the more you unlock the more mj functionality you get. if you want to integrate mj with other parts like command pods, look just a page or two back.

[Duke-49th]

Ascent guidance seems to have a bug wherein it starts trying to face the rocket retrograde, or at least 90 degrees off from the correct direction. This happens even when there is only one command pod on the ship plus a mechjeb case, and the mechjeb case is facing up. Ascent guidance points in the correct direction for awhile, but at some point after starting the gravity turn it suddenly goes crazy and starts steering the ship wildly in the wrong direction. This only happens on some ships, and only some of the time. Most ships work perfectly. When my large first stage separates, the behavior stops immediately.

SAS or controlling manually easily keeps the rocket on track.

I caught it in action. At the first screenshot, things are going normally. Note the prograde marker is close to the navball guidance marker; everything is pretty much on track. In subsequent screenshots, note the direction MJ is attempting to thrust in: the opposite of what it should.

Mods: RealSolarSystem, KW, StretchyTanks, Engineer, FAR, etc.

MechJeb 2.1.0 downloaded from this thread.

Edit: I tried without corrective steering and got the same effect.

Hahaha..good to know this problem is not only on my side

Yes..known problem (for me, at least) with huge rockets. Whenever a rocket is too tall I launch it maunal. No way to get MJ handle it correct. I dont know that the problem is...

[BigD145]

I've shipped a hundred tons into LKO, many that are very tall, with mechjeb and the only times things went wrong were when my designs were unbalanced OR I set the wrong control pod/probe core.

[Damaske]

Still no word back on the space plane auto-landing function and then rework of the auto-landing function? I am getting sick of not being able to land a space plane on the runway, and have my rockets attempt to slow down from 1000+ M/s when trying to do a no parachute landing. I can not fly a space plane to save me life and the auto-land function of the space planes would be very helpful. Might need to take a look into the landing location for both the runway and what ever the vertical target is.

I've not tested it out on other planets and i don't have FAR installed.

[Galane]

I'm going back to build 102. The landing guidance in 104 is quite flaky. Here's the mission update for tonight's work at Duna.

http://forum.kerbalspaceprogram.com/threads/58167-Duna-mission-planning-and-R-D?p=791859&viewfull=1#post791859

Hopefully 102 will use less fuel in the Kethane landers so I won't be there 20 years refueling the return ship. The manned lander is going to sit on the surface until refueling is done. During ascent, it will dump the three side tanks (when empty) with 909's and continue up on the single Poodle engine. With build 102 I know it can do that with enough fuel left to rendezvous. With 104? Don't know.

Ascent guidance with the Kethane landers seems to work the same in both builds. Uses nearly all the fuel getting up to 45KM then will not completely shut down the engines after the circularization burn. It's not a problem with the landers turning speed causing nodes to be missed. They're short and have big reaction wheels so they can spin around fast to aim for the burns. It's not a lack of thrust, they have the same engines as on some much heavier Kethane landers I've built.

[Neutrinovore]

Still no word back on the space plane auto-landing function and then rework of the auto-landing function? I am getting sick of not being able to land a space plane on the runway, and have my rockets attempt to slow down from 1000+ M/s when trying to do a no parachute landing. I can not fly a space plane to save me life and the auto-land function of the space planes would be very helpful. Might need to take a look into the landing location for both the runway and what ever the vertical target is.

I've not tested it out on other planets and i don't have FAR installed.

Hmm... I agree that in the past the spaceplane autoland feature was worse than useless, I'm convinced it was actively trying to kill my Kerbals. However, more recently - I'm using build #98 - it works like a dream for me. I've discovered, however, a few things: First, you don't want to be just anywhere on Kerbin, at any random heading and altitude, and just engage autoland and expect it to fly you all the way to the runway. No, you need to be somewhere between 100km to 300km out, at about 10,000 to 15,000 meters altitude. Then bring up the spaceplane guidance window, but don't choose 'autoland' just yet. First order of business is to set the 'autoland glide slope' to AT LEAST 7 degrees. The default of 3 degrees is, frankly, suicidal. It'll put you in the ocean if you're coming in east-to-west, and it'll DEFINITELY fly you into a mountain if you're coming in west-to-east. In fact, for a landing heading of 90 deg. I recommend a glide slope of more like 10 to 12 degrees. This is for the main KSC runway, btw, but it's pretty similar for the island airstrip too, just be aware that there's a ridge directly EAST of the island runway, so again set a slightly steeper glide slope to clear it. Anyway, now select 'show navball autoland guidance'. Use this to get your plane headed in generally the right direction. With me this can sometimes be an ugly affair, but as long as I'm high enough I can usually recover from a spin before any lithobraking occurs. Or, as I've recently learned from another forum user, if you want MJ to fly that's fine, but don't use the crappy spaceplane 'altitude and heading hold' things, instead bring up Smart A.S.S., select SURF, and now you can control your pitch, heading and roll with total precision. Just be sure to set your roll to zero most of the time, 15 degrees at most if you're banking, and your pitch slightly nose-up, you'll have to experiment with your individual craft to see what generates level flight. Btw, negative roll is left, positive roll is right.

Okay, now, once you have your yellow prograde indicator somewhat close to the purple target circle, and are flying fairly level at a MINIMUM of 10,000 meters, now you can engage autoland. At first the plane will dive a few thousand meters for some reason, but then it'll come back on track and put the prograde indicator right on the target circle. Now, regarding speed. For time savings I'll generally keep full throttle, or close to it, until I'm fairly close to the runway, maybe 10 - 15km or so. Then throttle back to just enough to keep headway without stalling, but you want to be sure to do this AT LEAST 10km before the runway, because MJ can be slow to react to your throttle changes (autoland doesn't control your throttle, btw, you have to do that manually. FYI.), and it can porpoise up and down for a bit before settling back down, so you want to set the throttle at your final landing position fairly early. Erm, this is predicated on a powered landing, obviously, I haven't tried doing this with a glider like the REAL Space Shuttle yet, lol!

So that's about it, at this point you should be able to ride the autopilot all the way down until the wheels touch the runway. Finally, you need to do three things in quick succession once you are on the ground. Hit 'abort' on the autopilot so it doesn't keep trying to 'land' once it's already landed; cut your throttle; and engage your brakes. Hopefully your spaceplane landing gear is designed & constructed so as to track straight without any input.

Bleh, sorry for the wall of text, I'm just trying to help.

As for the rocket/vertical 'land at target', I've been having good success with that as well. Except... Well, there are lots of people on this thread saying that this feature is now TOO accurate, that if they target a ship to land close to on, say, the Mun, that MJ will now literally land them right on top of the target ship. Well, I've NEVER had that happen to me! When doing the de-orbit burn, it always stops doing corse correction burns as soon as it breaks 150 meters on the predicted landing site, and only rarely does it ever even land that close, it's usually more like 300 - 400 meters. Not a huge problem, I just think it'd be nice to be able to get within 50 meters more often than not.

Alright, 'nuff said, more than enough I'm sure, lol. Again, I hope this helps, Damaske.

[sarbian]

I'm going back to build 102. The landing guidance in 104 is quite flaky. Here's the mission update for tonight's work at Duna.

102=>104 change nothing at all if you don't use the "API" I added. Your landing problem are not related to the version.

[Starwaster]

Ascent guidance seems to have a bug wherein it starts trying to face the rocket retrograde, or at least 90 degrees off from the correct direction. This happens even when there is only one command pod on the ship plus a mechjeb case, and the mechjeb case is facing up. Ascent guidance points in the correct direction for awhile, but at some point after starting the gravity turn it suddenly goes crazy and starts steering the ship wildly in the wrong direction. This only happens on some ships, and only some of the time. Most ships work perfectly. When my large first stage separates, the behavior stops immediately.

SAS or controlling manually easily keeps the rocket on track.

I caught it in action. At the first screenshot, things are going normally. Note the prograde marker is close to the navball guidance marker; everything is pretty much on track. In subsequent screenshots, note the direction MJ is attempting to thrust in: the opposite of what it should.

Mods: RealSolarSystem, KW, StretchyTanks, Engineer, FAR, etc.

MechJeb 2.1.0 downloaded from this thread.

Edit: I tried without corrective steering and got the same effect.

I've had suspicions that MJ might behave like that myself, but there's too much unknown about your pictures to consider it damning evidence. At worst, it might only be guilty of poor responses to forces that are already acting to throw your rocket off course. You're at a critical point in your ascent where depending on your velocity and heading, you could go severely off course beyond MJ's ability to compensate for (considering, FAR and RSS)

Also, What FAR corrective features are enabled if any? FAR does provide control inputs to the rocket and they can fight each other.

[sarbian]

Each time I had this problem (resulting most of the time in a nice looping) it was not MJ but the rocket design. All MJ did was make the problem more obvious because the transition from straight ascent to gravity turn can be quite step with the default 40% turn => MJ turn a bit too hard, top heavy rocket do a loop.

Having FAR without my small extension make thing even worse since MJ think it can't turn the ship fast and it will push the control to the maximum.

Try with a different turn shape %.

Not saying that I am sure there is no bug, but I don't think there is one.

[B787_300]

the only issue i have with 2.1 is that it will try to spin some of my rockets 180 degrees upon lift off, which has cased some rockets to crash...

[I.O.M.]

the only issue i have with 2.1 is that it will try to spin some of my rockets 180 degrees upon lift off, which has cased some rockets to crash...

It's possible that the part controlling your rocket is oriented upside-down. Before you launch you should check the navball. if the navball orange that means the command part thinks the rocket is facing downwards. When on autopilot the rocket will try to "correct" its orientation by flipping... and crashing.

Edited November 21, 2013 by I.O.M.

[MOARdV]

It's possible that part controlling your rocket is upside-down. Before you launch you should check the navball, if it's orange that means the command part thinks the rocket is facing downwards. When on autopilot the rocket will try to "correct" its orientation by flipping... and crashing.

Or does B787_300 refer to the roll problem? That is, sometimes, during launch, I've seen MJ want to do a 180 degree roll around the vertical axis for some reason or another. When it happens right off the launch pad, results can be pretty bad. It'd be nice if MJ would have a "dead zone" during rocket launch where all it does is try to keep the nose pointed up, and not apply rolls or anything else until there's enough speed or altitude to make the maneuver safer.