Incorrect center of mass positioning

Discussion in 'Backlog' started by eggofevil, May 7, 2023.

  1. eggofevil

    eggofevil Ensign

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    For more information see here Bug Report Template

    Build: 4137
    Mode: Survival
    Mode: Singleplayer

    SERVER NAME:
    SEED-ID: any

    If applicable:
    MODIFIED PLAYFIELDS:

    Reproducibility: always
    Severity: critical for HV's

    Type: game mechanics

    Summary: Center of mass of any loaded cargo container is not the center

    Description: When check mass/volume difficulty option enabled, center of mass of any type of cargo container wich loaded with some cargo displaced to left - bottom - rear corner of container relative to vessel direction.
    So, for example, some HV balanced by placement of cargo containers through central line, will allways list on the left side when loaded with some massive cargo.

    Steps to Reproduce:
    1) Enable check mass/volume option and start Survival game
    2) Build simpliest vessel testbed - core + any cargo container, check 'show center of mass in debug menu
    3) While container is empty thats'ok, then load container with some massive cargo - the center of mass will be displaced to the left bottom side relative to vessel direction.

    Screenshots, Crash Logs, any other Relevant Information or Download links:
    Loaded cargo box:
    [​IMG]
    Empty cargo box
    [​IMG]
     
    #1
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  2. TSM

    TSM Guest

    reporoduced V1.9.13 Vanilla as soon as you add cargo :) , tested CV,SV and HV , also saved a bp with the pivot point reset respawned bp got same result.

    [​IMG]
    [​IMG]
     
    #2
    Last edited by a moderator: May 7, 2023
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  3. imlarry425

    imlarry425 Captain

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    Likewise container controller center of mass is in the same location and doesn't reflect the mass moment of the storage matrix- all the mass is calculated at the controller regardless. Workaround- position controller in to place the left rear at the CG to avoid issues with loading. Critical on an HV.
     
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  4. eggofevil

    eggofevil Ensign

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    Can't workaround this, center of mass is shifting when adding new extengers to controller, seems like here some way to balance even blocks wide array, but not odd.
    [​IMG]

    [​IMG]

    [​IMG]

    [​IMG]
     
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  5. imlarry425

    imlarry425 Captain

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    Ah, it was broke a release or two ago and I don't recall seeing a fix in the release notes. My bad. Always repo before posting (to) a bug report.
     
    #5
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  6. eggofevil

    eggofevil Ensign

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  7. Scoob

    Scoob Rear Admiral

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    Seems that the centre of mass for any Cargo extensions is set around the controller. I used to place the storage central to the model (be it HV or SV) and had some weird balance issues. Now I assume that only the storage controller has any mass and make that my centre point - irrespective of where cargo extensions are - and balance seems fine.

    Of course, HV's still work badly, don't follow the terrain, do weird barrel rolls / fall flat / back flip / sink (pick one) when crossing the map join and snag on things they clearly miss even if they are perfectly balanced lol.
     
    #7
  8. eggofevil

    eggofevil Ensign

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    Can't reproduce... Seems like extensions are very light, so need to install many to see their mass effect, but I see it in mode with disabled mass/volume check and in the mode with enabled check, so it seems to me there is all ok with center of mass of controller and extensions on there own, but there is issue when mass/volume check enabled and they are loaded with some cargo
     
    #8
  9. Scoob

    Scoob Rear Admiral

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    What you can do is set the container controller and a long line of extensions, then pop hover engines each end. In theory the load should be nice and even as cargo is added, in reality the weight appear to be applied only at the location of the controller. As load increases, weird anomalies start occurring, such as the craft leaning to one side even though it's symmetrical and/or a strange bouncing as the vessel sinks under the weight (which is fair enough) then suddenly springs back up. It might do it evenly front and back, or just one end might bounce, sometimes causing the vessel to flip.

    I've not checked explicitly to confirm that the reported CoM ties in with the actual CoM as load increases. Just that an otherwise perfectly balanced craft has that balance massively offset as cargo load increases, despite a perfectly even front/back and left/right distribution of extensions. The location of the Controller is essential to the crafts balance when loaded in my experience.
     
    #9
  10. imlarry425

    imlarry425 Captain

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    Just tried to do that and things seem pretty much right, I saw no difference between the loaded and unloaded state beyond a slight CG shift to starboard of a fraction of a block, destroying blocks on one side shifted the CG proportionally to reduced capacity.

    Added engines to prevent drift and saw similar behavior under power. If you can figure out a way to illustrate the glitch it's still there, but it may be fixed.

    [​IMG]

    One thing I had never noticed, while doing the destruction of container extensions on the left side it did the ejection.

    Cargo ejection is stackwise ... not sure of the criteria used, but if there is a way (weigh? :) ) to hedge it, then figuring out how to load sandbags before going into a battle might be worth the effort.
     
    #10
  11. Scoob

    Scoob Rear Admiral

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    I will check again. These issues are something I've become so accustomed to when operating HV's that I'd deliberately design around it via Controller placement location. Even with ideal placement, a heavily loaded but still under the limits HV would exhibit all sorts of weirdness. I'd be over the moon if these had been fixed since I last played. Got a game in progress at the moment, so I'll test when I am able.

    Note: My HV designs are usually 2x as long as they are wide, and they're usually no more than 5 blocks wide with the hover engines - possibly 7 including extra blocks for armour. They're very much and early-game T1 build for me, when resources are limited. Any later-game HV will be a dedicated tank or miner, and much more over-engineered so exhibit the issues less.

    In earlier designs I've made, where the Controller is at the back for ease of access, the HV would tilt backwards even if the extension blocks are even, front to back, when loaded. When it became heavily loaded - but still within limits - the HV would constantly sink at the back and it's turn MASSIVELY more quickly as another side-effect.

    As mentioned, I was observing how the HV behaved not what the CoM overlay said, which it why I suspected that CoM isn't right when an HV is loaded. Will test again though, and hopefully things have improved here.
     
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  12. Garaman

    Garaman Captain

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    When the extension chain is broken it calculates the new container volume using whatever extenders are still connected to the controller. At that point it starts ejecting stacks the opposite way they are filled: I.E. stacks fill left to right, then top to bottom as rows fill up, so it starts ejecting from bottom right up to top left. As soon as it ejects enough stacks that the remaining cargo fits in the new controller volume it stops.

    In combat ships I always split my ammo into multiple stacks (2-4 each) so if the chain gets broken it doesn't eject all of a particular ammo type and the majority of guns will continue to fire.
     
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  13. Atola

    Atola Commander

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    WORK AROUND for HV- well Mostly:
    Place your Container controllers roughly along the side to side center line of the ship.
    Place your Hover engines along the center of mass lines (after loading the Containers with lots off mass) so that you start with a diamond configuration with Hover engines at the intercection of the center of mass lines and the edge of the ship, and then add Hover engines along the mass lines as needed.

    Bonus: I actualy like how the HV operates better with the diamond configuration anyway, Mainly for tilting up the HV when going up/over an object direclty in front but not as wide as the HV, but also buecause the Hover engines are no longer competing with thrusters for the lower corners of the HV in order to maximize torque from the thrusters.
     
    #13
    Last edited: May 31, 2023
  14. Atola

    Atola Commander

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    OK - So I deleted my post where I thought this was fixed because I made my first transport and I was like WHAT??

    After playing around with it a bit... I believe the game does the following:
    1. Determines the center mass space (which does not have to be part of the container), and the algorithm for this is a little wonky, but because of the next point doesn’t matter to much.
    2. Places all the mass in the center mass space in the lower left back corner of the block. (I'm guesssing this can't be fixed due to game engine limitations?)

    As some one above has hinted at, given point 2, the only way to get the mass in the exact center of the container is to have an even rectangle container. To put it another way the height, depth and width have to be evenly divisible by 2. However, each axis is determined independently, which can be used to get us something good enough without having to balance everything.

    So how to best build the ships to take this into account? Personally i think the only one that really matters is the width. This unfortunately means you have to build your transports with the width even for the entire ship because you want to only have one container… (which i dislike, i like to build odd width).

    For HVs when your transport is fully loaded with dense blocks the center line will be between two rows of blocks, if your going with a diamond configuration of the hoover engines it means you need to have equal amounts on both sides of the line to have a perfectly balanced ship... so can't use a single row of the small hoover engine. If the large hoover puts its downward thrust in the exact middle of the 4 blocks it uses it would be a natural fit. I haven’t looked into it though.
     
    #14

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