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  1. version 0.3.7.8

    by
    DrowsySam
    , 1 Day Ago at 11:48 AM


    Features:
    • Added beam stress & deform debug that will help content creators a lot:
    • Improved jbeam collision debug visuals - you can now see the direction of coltris much better in order to fix problems (orange being the underside)
    • AI control app added - App to control the more advanced AI (WIP)
    • In-game controller mapping added - You can now add new controllers, edit & re-map the bindings in-game (WIP)
    • Early implementation of remote controller app, the APK will be published later on after we improved the discovery phase of the device
    • Work on pressure approximation and fidelity - Here's an example of a pressurized mat with no internal beams
    • Progresses on AI and on route creation - Waypoints generated from decal roads, merged with user created waypoints, merged and optimized. Also decreased the performance burden by moving the collision with the waypoints to the physics side instead of using T3D collision.
    • Added collision quads - a more advanced way of specifying triangles


    Bugfixes:
    • Fixed debug color flickering
    • Force feedback "buildup" of old forces when reloading vehicle/changing part/etc. / FF should be much more deterministic now
    • Parts configuration: Part doesn't change on first time selection
    • Main menu options not letting user return to main screen
    • added missing texture: wheel_04a_n.dds was missing
    • Switching to full-screen with 'alt+enter' lowers refreshing rate


    Content:
    • Added buoyancy to Steel Barrel
    • Disabled self collision on T-Series mudflaps & front wheels to reduce sticking
    • Added optional dynamic reflections to vehicle materials, enable them in the options menu
    • Fixed minor coltri problems on pickup and van
    • Fixed basetex issue on East Coast USA
    • 200BX Interior and Jbeam progress - engine model and textures (not included in this update)
      Click image for larger version. Click image for larger version. Click image for larger version.
    • Global tire tuning
    • Civetta Bolide handling improvements
    • Cannon texture, model & jbeam tweaks
    • Progress on the Gavril Roamer (not included in this update):
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    You can find more changes in this version in our previous progress report: March-2015-Progress-report-Upcoming-version-0-3-7-8

    About the release of the game in the steam store: we hit some technical problems that will delay this for 4 to 8 weeks, stay tuned.

    Updated 23 Minutes Ago at 01:57 PM by tdev

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  2. A look at tire development in BeamNG (Part 2)

    by
    Goosah
    , 2 Weeks Ago at 12:01 AM
    Hi everybody, I'm back again to talk some more about progress on tires and vehicle handling. Since the new year there have been some big changes to the way our tires work. First, we replaced our tire physical model with something we call the pressureWheel, and second, we revamped the underlying friction code. These changes have brought about a big change in vehicle handling that we are still in the process of fine tuning.

    The previous physical model, called the hubWheel, used precompressed beams to inflate the tire as a simulation of air pressure. While it worked to a fashion, it wasn’t very elegant, and made the tire very difficult to tune. It seemed no combination of parameters could get me the behavior I was looking for in a tire. Believe me, I tried!

    Luckily, about the time I was at my wits end, Estama revealed a new experimental tire, called the pressureWheel. The pressureWheel does away with all of these precompressed beams and actually uses air pressure physics laws to apply forces to the surfaces of the tire. Aside from being a more elegant solution, it brings huge improvements to the problems encountered with the hubWheel. With the introduction of the pressureWheel, we also upped the polygon density of the wheel from 12 rays to 16, which primarily helps smooth out low speed rolling and improves the look of tire deflection. After months of struggling with the hubWheel, Gabe and I were able to come up with a decent pressureWheel tune in just a few days.

    However, just the pressureWheel alone was not going to cut it. After the pressureWheel, Estama produced a succession of experimental friction models for the team to test, and we found one that was more reliable in holding nodes in place with static friction. As a result, we could now make our tires physically “softer”, while still getting sharper handling. This gave us better tire deformation and transient steering response. It also increased the physics stability margin, giving us more headroom to make each tire type more unique. The result of these changes is a huge transformation in test results and driving feel.

    Test Results

    In my first tire blog I described the tests I have used so far to quantify tire behavior. This time around I am going to show some actual results. Something I'd like you to bear in mind, the curves I am showing you are measured from a machine built in the “physical” BeamNG environment. The BeamNG environment is one of mass, stiffness, vibration, and uncontrolled variables, and so, much like real life, measurements are subject to some error, and the curves aren't going to look as smooth as an empirical curve fit that you might be used to seeing. It really comes down to the fundamental difference between BeamNG and most simulators. In BeamNG we are creating an almost purely physical tire model that operates in and obeys all the universal laws of the physics "sandbox", in comparison to most simulators which create a special set of empirical relations specifically for their tires. Anyways, just keep it in mind

    Lateral (Cornering) Force Vs. Slip Angle

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    In thick blue, you can see what our old hubWheel was like. The complete lack of a peak meant the cars had very vague handling with a lot of yaw (drifting). Now, in thick red, with the new pressureWheel and friction model, we have a nice smooth curve with a peak. For comparison I’ve added a curve from an empirical (Pacejka 96) model representing a “real” tire. It turns out “real” data is not so easy to find or produce, so for now I am using some of these curves as a visual guide. As you can see our curve is still peaking a bit late, but there is still room for tuning in the physical model. I also don’t have any data for a tall and skinny 70 aspect ratio touring tire at the moment, so maybe I’m not too far off after all?

    Longitudinal (Traction/Braking) Force Vs. Slip Ratio

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    Again, what was going on with that hubWheel? The initial slope and peak looked ok, but then there was a strange increase at high slip ratio. We’ve fixed that with the new tire and friction model. Yes, it is still peaking a little bit late, but that again is a matter of tuning. As in the lateral case I think there is still some room to fix that up by stiffening certain beams in the tire.

    Combined Lateral and Longitudinal Forces

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    Most vehicle simulators these days use an empirical mathematical tire model to determine tire slip and force generation. They run into the challenge of “mixing” lateral and longitudinal curves like those shown above, so that the car behaves properly with combinations of brake/throttle and steering. Because we have a real time physical tire model with unidirectional node friction, our “mixing” and friction circle behavior comes out of the simulation naturally. I haven’t had a chance to redo the test yet for the new pressureWheel and friction model (it’s a bit tricky to do on my current test rig), but here’s a result from the hubWheel. Even with the old hubWheel’s flawed slip curves, the graph still turned out similar in nature to the published data.

    Normal Load Sensitivity

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    Load sensitivity is vital to simulating the effects of weight and weight transfer in vehicle handling. The plot above shows that our tire’s cornering stiffness decreases as load increases, as it should. This behavior is responsible for producing subtle under and oversteer behavior. Ideally, the peak lateral force coefficient should also decrease as load gets higher, but currently it does not. We will need to implement some improvements to the friction model to achieve this in the future.

    Speed Sensitivity

    One of the biggest hurdles I’ve had to wrap my head around while working on this project is the topic of speed sensitivity. Most vehicle simulators, to my knowledge, ignore the effect of speed on basic tire behavior. This is probably because they are somewhat based on the empirical Magic Formula model, which conveniently ignores speed. However, research into the science of rubber friction shows that as a viscoelastic material, its friction properties are highly dependent on slip velocity. As well, a tire spinning at high speed has all sorts of inertial effects that are speed dependent. Because we have a physical tire model that obeys newtons laws, and a speed dependent rubber friction model, we have all sorts of speed dependent behaviors coming out of our tires. But what effects are correct, and what are not? We can’t look to other vehicle simulators, or even to the most common tire and vehicle dynamics literature, as it typically ignores speed altogether.

    What I have gathered so far is this:

    1. Due to the interplay between adhesion and hysteresis, at very low speed, tires have a much different slip curve than at running speeds. Maximum force coefficient is higher, and may not have a peak at all, but rather a plateau.

    2. Because of the velocity dependence of rubber friction, sliding friction should decrease at high slip velocity, which means tires should produce less friction at high speed than at low speeds.

    3. Cornering stiffness should remain the same or perhaps slightly increase as tire speed increases, due to the inertial effect of the tread elements moving at high velocity. I have read conflicting opinions and conflicting plots on this subject!

    Now, with that in mind, let’s look at some lateral force vs. slip angle vs. speed surface plots. If you take a look at the axes, you will see these plots are much like the lateral force vs. slip angle plot shown up above, only with an extra axis representing the speed. At different speeds, the tire behaves slightly differently, and a surface plot is in my opinion the easiest way to see that.

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    Here is our old hubWheel and friction model. This surface plot shows some problems. There is no increase in grip at very low speed, and although friction decreases at higher speeds, cornering stiffness is also dropping off. Due to the lack of a peak in the friction curve, it’s difficult to see what might be causing the problem. The weakness at high speed is really where I think the "floaty handling" problem was coming from. Not too much use dwelling on this though, let’s check out the newest plot:

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    Quite a change! Aside from the much higher cornering stiffness and nice rounded peak to the curves, we can also see an increase in grip at very low speed. Cornering stiffness is not dropping nearly as much as before. Sliding friction is dropping off with speed, but perhaps drops off too early. Overall, this plot shows a huge improvement over the previous, especially for high speed handling. Bolide drivers, rejoice!

    Now, with this huge change in our tire behavior, nuance in the handling of the vehicles is starting to become apparent, and we find ourselves now going back to retune the tires, suspension, and structure of the vehicles to achieve better behavior out on the road.

    That's all for now. I hope that this blog post has been informative, and that it will serve as a benchmark for future improvement to the tire model. I look forward to reading feedback and discussion on tire development, either here in the comments or in the forum.

    Updated 2 Weeks Ago at 08:34 AM by Goosah

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  3. March 2015: Progress report / Upcoming version 0.3.7.8

    by
    DrowsySam
    , 3 Weeks Ago at 01:29 PM
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    Here are our changes over the last few weeks, some exciting things coming along.

    Features:

    • Dynamic reflections on vehicles: We also added in-game options for dynamic reflections so you can adjust the quality settings in real time.

    • Waypoints for AI, AI basics, Navigation system basics. Sneak preview of some pickups trying to get somewhere:


      Bolide driving on ECA:

      Same with debug information enabled:
    • Added indicated airspeed app:
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    • Separate full-screen and windowed vsync settings
    • Warn when disabling vsync in windowed mode with aero running


    Bugfixes:
    • Fix vsync setting not being applied when changing in full-screen mode
    • Wind sound now takes wind flow into account
    • Fixed JSON parser having problems with specific jbeam special cases(empty lists and string escapes)
    • Vehicle selector "Remove Filter" button works but doesn't hide the selection
    • Fixed hangup on T3D LUA crash
    • Better error reporting for JSON errors
    • Options menu reverted to previous working state
    • Improved tire deflation behavior
    • Improved AI Display and visualization
    • Reduced skid mark threshold to 15m/s, this allows skid marks from burnouts in first gear
    • Fixed issues with the new BC5 texture normals


    Content:
    • Added a working cannon, T to fire, signals for elevation angle
    • Tweaked overDarkFactor on Puregrid for smoother vehicle shading
    • Fixed missing clouds on Hirochi Raceway
    • Fixed wheels offset in Hirochi Sunburst
    • Minor fixes in East Coast USA and Hirochi Raceway
    • Updates in East Coast for Town, Forest and Bridge
    • Improved sky on Small Island
    • Improved support for debug draw
    • Distanced the external camera for Large spinner
    • T-Series interior finished
    • AI paths added in East Coast USA
    • 200bx texture and model progress(WIP)
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    • Separate car customization to set up car, configure parts and choose color
    • Updated angular materials in newer version of UI
    • Improved base model for Ibishu Covet from tire test tester results
    • fixed internal turn signal for Moonhawk


    Above changes are work in progress and might not be released at this point but will be released within the next updates.

    Updated 2 Weeks Ago at 04:13 PM by tdev

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  4. Update 0.3.7.7 released

    by
    DrowsySam
    , 02-20-2015 at 12:31 PM
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    Note: You will need to delete the "vehicles" folder in "My Documents\BeamNG.drive\" in order for everything to work properly. We also recommend clearing the contents of your cache folder in there. Your mods are not gone - they have simply been moved. See here: My-Mods-Are-Gone

    Features:
    • Friction subsystem update. The friction graphs are better now
    • Reduced latency for crashing sounds
    • Improved user folder: new directory structure, cache now version dependant as well as other improvements
    • Integrity checking: runs each time the game is updated to prevent conflicts and content breaking errors
    • New logging subsystem: now with improved format and ability to set it up better. (See settings/base.ini file)
    • Frame rate limiter now configurable via text file (See settings/base.ini file)
    • Globally improved and more accurate vehicle handling as a result of new friction code and extensive tire tuning
    • Optimizations for non-collidable pressureWheel triangles
    • support for BC5 normal maps for all vehicles to greatly reduce artifacts
    • putting zip files into the mods folder will automatically mount them


    Bugfixes:
    • Fixed script warnings and errors
    • Fixed crashes to desktop when returning to the menu
    • Temporarily removed other audio providers to prevent muted audio
    • Fixed positioning of crash sound
    • Fixed parts configurator bug allowing only one part removal at a time
    • Zero size warning removed for hubcaps
    • Fixed bug in soundsource ordering
    • Fixed lots of possible crashes
    • Improved logging origins so one can always tell where the error came from
    • disabled ancient GFX profile loading
    • Fullscreen mode fallbacks improved: if the game fails to switch to fullscreen, it falls back to windowed mode now
    • Fixed bugs with incorrect window resolutions resulting in startup errors
    • Fixed CPU name reporting in logs
    • Fixed crashs: on vertex buffer locking, missing lighting datablock, missing decal datablock
    • Improved D3D Crash Handling


    Content:
    • Extensive tire and suspension tuning to improve handling and FFB corresponding with new friction code
    • Softened and increased damping on all tie rods to reduce vibration and improve FFB
    • Revised most vehicles' external cameras and some internal cameras
    • Various minor fixes and corrections to all vehicles
    • Tuned all tire friction coefficients
    • Lightbars added to the H-Series, Grand Marshal, and D15
    • Pushbar finished and textured for the Grand Marshal
    • New 17" sport wheels for the D15 Sport and Grand Marshal Sport
    • Added 16" rally wheels to the Covet
    • Added barriers to the Large Spinner
    • B-pillar tweaks on most vehicles
    • Fixed mesh spikes on the Moonhawk when wheels detach
    • Fixed wrongly triggered flares on Moonhawk
    • Reduced Bolide bodywork panel attachment strength
    • Brighter gauges when not lit on the D15, H-Series, Grand Marshal, and Moonhawk
    • Turquoise gauge glow added for Covet when headlights are on
    • Fixed instability on the T65
    • T65 flatbed added
    • T65 short frame fifth wheel upfit added (much easier on FPS)
    • Added ability for T-Series transmission to detach from the engine
    • Added seats to T-Series with soft mounts
    • More T-Series interior progress
    • Reduced vehicles' metal friction coefficient from 0.7 to 0.5
    • Increased Covet skidplate friction from 0.2 to 0.5 to improve driveability
    • Added steering axis inclination (SAI) to Bolide to improve handling and FFB
    • Fixed lack of SAI on Sunburst causing strange FFB and incorrect suspension geometry
    • Breakable driveshafts on the Sunburst
    • Strengthened rear strut top on Sunburst to reduce unwanted deformation over jumps
    • Added rally suspension to the Sunburst with stronger components
    • Sunburst RS and Race damping increased
    • Retuned exhaust deformation and detaching for Sunburst
    • Fixed zero offset on Sunburst hubcaps creating zero-length beams
    • More work on 200BX (almost ready for public testing)
    • Added larger flipramp variant that matches up with T65 cargo box
    • Dry Rock Island vegetation tweaks
    • Fix for bridges dropping FPS
    • Fixes based on feedback to East Coast
    • Added another trail to East Coast
    • Improved some roads on East Coast
    • Improved jump on Industrial
    • Global groundmodel tweaks
    • Fixed some erroneous flares/spotlights
    • Gas station added to East Coast
    • Skidpads Added to Gridmap

    Updated 02-21-2015 at 02:01 AM by gabester

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  5. A look at tire development in BeamNG (Part 1)

    by
    Goosah
    , 02-06-2015 at 12:20 AM
    Hello everybody, welcome to my first blog post for BeamNG! My aim with this post is to introduce a project I am undertaking, applying a unique approach to testing and tuning the tire models in the game. I’m a mechanical engineer by education, and I’m being encouraged to get as technical as I want for these posts, so get ready for heavy reading!

    One of the things that gives BeamNG so much potential as a vehicle simulator is that it takes a bottom-up approach to simulation. Instead of defining a car body or tire as a basic object in the game and applying some physics equations, it creates these complicated structures from networks of nodes and beams. This bottom-up approach to simulation is incredibly versatile, but it means that the subtle nature of vehicle handling is dependent on not just the core physics but also the physical tire and vehicle models created within it. To date the dev team has made improvements to the vehicle handling through a test and tune method, where improvements to physics and models are made based on driving tests. However, to truly validate the handing and find new areas to improve, one needs the ability to test individual aspects of the physics and vehicles more objectively, and compare tests to real life data. This is what I have been working towards.

    My first project has been to create a tire testing machine within the game. This machine takes the tire and wheel from any of the vehicles and drives it along the ground at controlled speeds, loads, and angles. The design parallels those that tire researchers use to test real tires. In operation, the tire tester can continuously log force data from the wheel axle. One can also modify any tire or friction model parameter and see the change in tire behavior graphed in real time, independent of factors like the vehicle’s suspension geometry or chassis rigidity. With this data logged, I can then create plots that compare empirical results; in-game vs. real life, or, old tire model vs. new tire model.

    My first use of this machine was to characterize the hubWheel, which is the now deprecated tire model that has been replaced in version 0.3.7.5. I spent many hours logging data, coming up with plotted curves to show some of the most important tire behaviors. I am now using it to perform tests on the new pressureWheel, using the old hubWheel data as a benchmark. Here is a short video showing the testing machine in motion:



    Thank you CarlosAir for sharing your lua skills, creating more advanced controls and data logging abilities for the Tire Tester.

    Tire Terms

    Before we go any further, I’d like to do a basic definition of some terms used to describe tires. If you are already familiar you can skip this part.

    Slip Angle
    - The angle between the direction the tire faces and the direction it travels. As a tire rolls forward, elements of the tread in the contact patch can be imagined to flex and “walk” over each other, allowing the tire to also move sideways, without actually sliding. This happens when the wheel is steered in an attempt to turn. Turn hard enough, and the slip angle will increase as the tire contact patch starts to slide.

    Slip Ratio – Similar to slip angle, this is a relation between the speed of the tire compared to the ground. A locked up tire skidding on the ground is a slip ratio of -1, whereas a tire spinning twice as fast as the ground has a slip ratio of +1. Parts of the tire tread can compress and expand as they touch and leave the ground, allowing the tire to travel a bit faster or slower than the ground without sliding. Apply too much power or brake and the slip ratio grows as the tire begins to slide.

    Normal Force – The gravitational force holding the tire against the ground.

    Lateral Force – Defined as the force developed along the wheel axis. Essentially, this is the cornering force developed when turning.

    Longitudinal Force – Defined as the force developed parallel to the tire tread, perpendicular to the axle. Essentially, this is the acceleration or deceleration force caused by throttle or brake.

    Cornering Stiffness
    – A tire’s size, construction, and air pressure determine how much slip angle is developed for a given amount of lateral force. A stiffer, wider tire, with more pressure, tends to have a greater cornering stiffness, causing less lateral movement and a more direct feeling to the steering.

    Slip Stiffness – Similar to cornering stiffness, but acting longitudinally. More slip stiffness means more direct response to power or brake.

    Ok, those were not very rigorous definitions, mainly just meant to give an intuitive sense. There are plenty of great resources on the internet if these were too brief. On to the tests!

    Tire Tests

    Lateral (Cornering) Force Vs. Slip Angle
    This is the most common test performed on tires. Data sets from this type of test are often provided to vehicle manufacturers and race teams. The shape of the curve determines the behavior of the tire (and vehicle) when performing a pure cornering manoeuvre (no throttle or brake). To do this test, I choose a speed for the machine to travel, and cycle the tire through each increment of angle from 0 to 40 degrees, recording the data as I go.

    Longitudinal (Traction) Force Vs. Slip Ratio
    This test determines how the tire responds to brake and engine torque loads. My tire tester has an engine that creates gobs of torque, and the gear ratios are carefully chosen to represent fixed percentages of the forward speed. All I have to do is set the data to log, start the machine moving forward and cycle up and down through the gears.

    Combined Lateral and Longitudinal Forces
    One of the most important aspects of a tire simulation is not just how the tire performs in the above two tests, but how the tire works with a combination of the two. After all, people usually drive using combinations of gas, brake, and steering. To accomplish this test, I set the wheel to a given slip angle and then run the transmission through the gears. Then pick the next slip angle and do the same. This test takes much longer than the other tests, but the results are very telling.

    Normal Load Sensitivity
    In high school physics class you might have been taught the basic friction formula, and been told that the friction coefficient is some constant independent of normal force. This is quite far from true on real tires. A tire develops proportionally less peak lateral force as its normal force increases. For example, a tire that can deliver a peak grip of 1g on a car weighing 2000lb may only be able to deliver 0.8g on a 4000lb car. Higher normal forces also deform the tire more, leading to lower cornering stiffness. This behavior is the primary reason it is important to manage weight transfer in a car! This test is pretty simple; I just change the node weight of the test carriage to see the effect on any of the above tests.

    Speed Sensitivity
    Speed sensitivity is a tricky one. Very little is said about speed sensitivity in papers and textbooks, and tires are rarely tested at high speed because the tire gets heated/destroyed too quickly. It is generally assumed for basic simulations that tires are not speed sensitive. I can run any above test at any speed within reason (things get a little shaky beyond 350km/h!) Particularly this type of test is good for finding any dips in response from the tire due to resonances, an important step in the final tweaking of the tire parameters.

    Results

    With these tests I have formed a decent picture of what needs to improve in BeamNG’s tire model. In the next blog I will be using the tests and terms explained here to compare the hubWheel with the new and improved pressureWheel! For now, here is a surface plot of the old Ibishu Covet hubWheel to show as an example. I leave it as an exercise for you to infer what you can!


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    Updated 2 Weeks Ago at 12:05 AM by tdev

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