How do I make the vessel point in a certain direction?

[Xyphos]

I want to make a simple mod that will hold 90,0,0 degrees but I don't know how to get/set the vessel's rotation orientation in space

[HebaruSan]

Any luck with Vessel.Autopilot.SAS.SetTargetOrientation? I've been looking at how MechJeb does attitude control, and this is the only point I can find where its PID controller system calls into KSP code.

https://github.com/MuMech/MechJeb2/blob/7aaa6241e9009265f72aaef9e87d66fc23526fea/MechJeb2/MechJebModuleAttitudeController.cs#L379

[MOARdV]

If you are willing to use the stock SAS system, it can be used to hold a heading when in Stability Assist.  See here for how I got it working.  This is currently rather messy code - I'm going to be splitting it off into its own code eventually.

The EngageAttitudePilot method starts the autopilot.

What I've found is that the SAS heading hold is tied to the inertial frame, so you have to repeatedly update it when you want a planet-relative or orbit-relative heading (I'm doing every Fixed Update, although that may be excessive) - that's what the second 'if' block in PilotFixedUpdate is doing.

[c4ooo]

On 12/29/2018 at 6:51 PM, MOARdV said:

If you are willing to use the stock SAS system, it can be used to hold a heading when in Stability Assist.  See here for how I got it working.  This is currently rather messy code - I'm going to be splitting it off into its own code eventually.

The EngageAttitudePilot method starts the autopilot.

What I've found is that the SAS heading hold is tied to the inertial frame, so you have to repeatedly update it when you want a planet-relative or orbit-relative heading (I'm doing every Fixed Update, although that may be excessive) - that's what the second 'if' block in PilotFixedUpdate is doing.

I yoinked the code and it seems to work somewhat. However there are two problems I have with it. First of all, it seems to overshoot all the time, but this should be easy to fix by adjusting the values in around line 242. Second of all though, although Rolling and Pitching seem to work fine, adjusting the Heading makes the craft/navball rotate "straight" to the left/right instead of along an arc.

For example, after setting my target pitch to 45, roll to 0, and heading to 0, the code orients the craft like this:

As Increment target heading, I expect the craft to rotate along the green line, but instead it rotates along the blue line. Do you have any idea what could be causing this? I replaced the getReferenceAttitude(activeReference) on line 235 with Quaternion.LookRotation(north, east), where "north" points to the north of the planet and "east" points east. 

 

Edit: IDK why i always find solutions soon after I post about something, but I think this code works for calculating goalOrientation: https://pastebin.com/G8LABpbm

Edited January 1, 2019 by c4ooo

[MOARdV]

19 hours ago, c4ooo said:

I yoinked the code and it seems to work somewhat

Yeah, that code is still kind of rough.  I'm ripping it out some time in the future and moving it into its own class, where I can isolate it from the rest of the MAS functional code (and focus on making it work better).  One of the things I still need to do is change it so it can use a 'don't care' value for roll, since locking roll is not always useful in orbit.

[Xyphos]

Yeah, I already know about SAS AutoPilot, I'm the Author of SASAG on CKAN :p

I wanted to rotate a vessel to point a specific direction (East, zero pitch, zero yaw) so I could automate gravity turns and circulation burns, and that's not possible with stock SAS unless it's pointing to a maneuver node.

I'll look over your code, and see if I can find anything useful. thanks

Edited January 6, 2019 by Xyphos

[Xyphos]

UPDATE: found what I was looking for, thanks. Specifically, the first and last lines in the following highlight block.

https://github.com/MOARdV/AvionicsSystems/blob/master/Source/MASVesselComputerControl.cs#L237-L258