Mechjeb and Docking Problem :\

[papershuffler]

For some reason, Mechjeb auto pilot docking keeps sending my docking port to the RIGHT of the target. I am aiming a shielded port to another shielded port.

I'm pretty sure I've been using Mechjeb correctly, since I have selected the "Control From Here" and set the target as the other docking port. Mechjeb seems adament on sending my ship slightly right of the target. :\

The only time I did get close, I did it manually after autopiloting to within 200m of the target. However, the ports only slammed together, not dock. I was going around 1.5m/s relative to the target.

Any ideas?

[Shukinen]

did you ever docked before, and w/o use of mechkeb? this is the most difficult thing to learn in this game in my opinion,and the best feeling ever when you accomplish it
i suggest that you start by learning how to do it manually if you never did, there is also docking port alignement mod that helps a bunch

there is tutorials to get to it, and also,
are you using any kind of RCS?
if you do, put them on the center of mass so it will move porperly when uding them,

tutorial by scott manley (imo god of KSP)
https://www.youtube.com/watch?v=AHkY3FusJIQ

[kabukiman]

I'd try checking the ship for symmetry issues. Usually problems like this are caused from badly placed RCS pods on your ship.

[Vandalen]

You are sure MJ isn't just navigating to a good spot to align correct? The latest MJ-Versions are normaly pretty good at docking.

Maybe you can try to go to spaceport and back, or restart the game. Sometimes, it's just a bug.

[papershuffler]

Originally posted by Shukinen:

did you ever docked before, and w/o use of mechkeb? this is the most difficult thing to learn in this game in my opinion,and the best feeling ever when you accomplish it
i suggest that you start by learning how to do it manually if you never did, there is also docking port alignement mod that helps a bunch

there is tutorials to get to it, and also,
are you using any kind of RCS?
if you do, put them on the center of mass so it will move porperly when uding them,

tutorial by scott manley (imo god of KSP)
https://www.youtube.com/watch?v=AHkY3FusJIQ

No, I have never done it manually before, and I don't intend to. My primary interest in KSP is the design of rockets, not trying to fly it. I'm an engineer by trade anyway. :p

I use Mechjeb as sort of an "ideal" pilot to test my rockets.

I am using RCS, but maybe my placement is kinda off. I am trying to dock a Science Lab + Crew Container to a refueling station I previously built, so even with RCS, the ship is sort of unwieldy. I'll take a look again.

I have seen that tutorial by Scott. Unfortunately, he kinda cuts off the end part, and you never see the docking actually take place. He just kinda squishes the ports together, and it suddenly cuts to the ships docked.

Thanks.

[papershuffler]

Originally posted by kabukiman:

I'd try checking the ship for symmetry issues. Usually problems like this are caused from badly placed RCS pods on your ship.

Yeah, now that Shuriken mentioned it, it's probably the RCS pod placement. I kinda/sorta lined the sides of the Science Lab with RCS pods, and didn't pay much attention to the alignment.

I'll take a look.

[kabukiman]

Originally posted by FGN john4valor:

Yeah, now that Shuriken mentioned it, it's probably the RCS pod placement. I kinda/sorta lined the sides of the Science Lab with RCS pods, and didn't pay much attention to the alignment.

I'll take a look.

I'd always use 4x placement with RCS with equal distance to the center of mass - 2 sets of 4 does it for me. That way you can make sure that a´n ignition will only modify a single dimension (x,y,z) instead of more than one. Also - when placing more than one set take care they are lined up - being off a bit can also make your ship behave erratically.

[Xcorps]

http://www.curse.com/ksp-mods/kerbal/220602-rcs-build-aid

That's for engineers. It shows you in real time during design how your RCS placement affects your pitch and yaw.


I suggest the following steps to dock with MJ. All using SmartASS.

1) Phase orbit of 50k above or below the target. Match inclination of target.
2) Hohmann transfer to target.
3) Fine tune approach, 200m.
4) If approach is >200, do number 3 again.
5) Match velocity at closest approach.

You are now at about 200m with zero relative velocity.

Select the docking port of your ship, control from here.

Swap to the target with the [ or ] key. Select the docking port, control from here.

Target the first ship, set smart ass to target +, wait for rotation to end.

Switch back to first ship, set smart ass to target +, wait for rotation to end, turn it off.

Now dock.

[papershuffler]

Alright fellas. IT WORKS! Right after correcting the RCS thrusters placement on both the refueling station and space lab, MJ nailed the docking in 1 go!

Thanks everybody for your help!

[Thyriel]

Originally posted by Vandalen:

The latest MJ-Versions are normaly pretty good at docking.

I wouldn't say "pretty good". MJ does its job (most times) on docking, but how it's doing it is far from optimal. Especially the fuel used is extremely high compared to manual docking

Originally posted by TWC_Xcorps:

I suggest the following steps to dock with MJ. All using SmartASS.

1) Phase orbit of 50k above or below the target. Match inclination of target.
2) Hohmann transfer to target.
3) Fine tune approach, 200m.
4) If approach is >200, do number 3 again.
5) Match velocity at closest approach.

You are now at about 200m with zero relative velocity.

or just use the "rendezvous autopilot" if you want mechjeb to do it.

[Vandalen]

Originally posted by Thyriel:

Originally posted by Vandalen:

The latest MJ-Versions are normaly pretty good at docking.

I wouldn't say "pretty good". MJ does its job (most times) on docking, but how it's doing it is far from optimal. Especially the fuel used is extremely high compared to manual docking

Better than me trying to dock manually. :D

A while age, only ORDA was able to dock even the wildest designs. The latest MJ-Version are definetly improved. I like it.

[Xcorps]

Originally posted by Thyriel:

or just use the "rendezvous autopilot" if you want mechjeb to do it.

Rendezvous doesn't unlock until late in the career mode.

[Vandalen]

You can edit the tech requierements via notepad.

[Thyriel]

Originally posted by TWC_Xcorps:

Originally posted by Thyriel:

or just use the "rendezvous autopilot" if you want mechjeb to do it.

Rendezvous doesn't unlock until late in the career mode.

could be i missed that as i installed mechjeb when i was almost done with the tree ;)

[papershuffler]

Originally posted by TWC_Xcorps:

Originally posted by Thyriel:

or just use the "rendezvous autopilot" if you want mechjeb to do it.

Rendezvous doesn't unlock until late in the career mode.

Not sure what "late" is, but I already have it, and I've only orbited/landed on Mun, Minus and orbited Eve. I've not even started looking at other planets.