The New Landing Gear System

[njmksr]

Hey everybody!

I may be a little late to the party in asking this question, but does anybody know how to use the new landing gear .cfg module?

Thanks!

[GoSlash27]

njmksr,

I'm still puzzling it out as I go.

        name = ModuleWheelBase
        radius = n.n The collision mesh wheel's radius in m
        center = x,y,z Where the force of the wheel is applied in relation to the wheel itself.
        mass = n.n The amount of sprung mass used in the suspension. units unknown.
        groundHeightOffset = n.n Presumably in meters, but I have had no luck playing with this value.
        frictionSharpness = n.n I dunno.

        name = ModuleWheelSuspension
        suspensionDistance = n.n The amount of travel from fully extended to fully compressed in meters.
        suspensionOffset = n.n Not exactly sure, but it's in meters and affects where the wheel "lives" in relation to the surface. Negative values raise the wheel.
        targetPosition = n.n Where the wheel, as drawn, resides in it's travel. 0 is fully extended, 1 is fully compressed.
        springRatio = n.n The tightness of the spring, units unknown. It affects how rapidly the wheel moves in response to shocks. Too low causes sluggish behavior and banging into the suspension stops. Too high causes phantom forces, skittering, and terrain collisions.
        damperRatio = The drag created by movement. 0 is completely undamped, while 1 is critically damped. Exceeding 1 causes oscillations.
        boostRatio = I have no idea.

The simulation figures out how much mass is resting on the suspension, then adjusts the spring tension so that it will rest where we want it to. Then it turns up the damper based on the spring value.
        
The values in the damage module seem to work backwards from how I expected. The higher the number, the lower the threshold for damage.

HTHs,
-Slashy

Edited April 30, 2016 by GoSlash27

[nli2work]

center shifts wheelCollider from the position in the MU. can be used to adjust the wheel without reexporting, best left to default of 0,0,0
groundHeightOffset sets spawn height, basically replaces the Bounds collider from earlier WheelModule. only used when vessel is initially spawned from VAB/SPH
forceSharpness I think this determines how quickly full friction forces act on the vehicle. Higher increases responsiveness overall. Too low a value makes it very mushy; too high a value makes wheels jitter continuously. Defaults 10; I find values between 10~20 is decent. 

suspensionDistance, height of actual suspension, http://i.imgur.com/E9kYjaO.jpg

suspensionOffset moves suspensionTransform up/down the suspension vector. e.g. you set suspensionDistance to 1m; targetPosition to 1; and suspensionOffset to -1; this in effect sets suspensionTransform to move between 0 to -1 relative to suspension vector's origin. This only affects the suspensionTransform's position, not the actual suspenion interaction with terrain or other objects, actual suspension will still be between 0 to 1m from terrain. pics: http://i.imgur.com/DPHxpvf.jpg
targetPosition is where the wheelCollider will try to position suspensionTransform. 0 is fully compressed, 1 is fully extended. This is inverted from Unity's WheelCollider. Wheels generally sit around 0.5; Lander Legs sit around 1. Setting this to 0 is functionally same as setting suspensionDistance = 0
springRatio adjusts how much mass the suspension can support. Since there's dynamic adjustment and tweakable sliders in game, this will take a lot of testing for each wheel you make. Higher supports more mass, but can shoot vehicle into the air on unpack when wheelCollider becomes active. My guess is units are in kN from observing behavior in game.
damperRatio adjusts force opposing oscillation due to springRatio force. 10% to 50% of springRatio value is good starting point. takes trial and error for each wheel part.

groundHeightOffset video https://www.youtube.com/watch?v=OunIHXUWfoE
wheelClip detection video https://www.youtube.com/watch?v=E9lZD3OemrM

Big thread with lots of info on the new wheel modules.

 

 

Edited May 2, 2016 by nli2work

[Markarian421]

boostRatio seems responsible for some of the strange behavior.  I've been trying to scale up the LT-1 legs, and it appears I need to adjust:

groundHeightOffset (to keep it from shooting into the air)

springRatio (to hold up more mass)

and then damperRatio and boostRatio to try and get things back under control with the suspension once I've upped springRatio.  The boostRatio parameter almost seems like a "superball" adjustment -- I cranked it up on one try, and the legs would bounce higher with each landing.  In general I'm finding I need to reduce both damperRatio and boostRatio to keep larger landing gear stable.