SISTer (Server for Interaction with Surfaces & Terrains) enhances tire models by accessing multipoint 3D scanned surface data; application brings new levels of simulation accuracy by separating the associated computational load from the vehicle and/or tire model.
Cruden, the simulator and simulator software manufacturer, has launched a new software application for tire and vehicle models to help automotive and motorsport vehicle dynamics engineers improve the accuracy of their simulations. It works out of the box with any vehicle simulation that has Simulink connectivity.
This new software application from Cruden is programmed to determine how the tire / road contact patch is deformed, replacing the single point tire contact patch with multiple points. It provides highly improved input to the tire model, resulting in far more detailed and precise forces and moments as well as road-normal calculations.
Working with any combination of vehicle and tire model in real time, SISTer is a separate process which frees the vehicle model from the computational load associated with evaluating 3D scanned surfaces.
The software, developed by Cruden’s in-house computer scientists, is a flexible package, working with many forms of surface data: LIDAR data represented by a triangular mesh or as a point cloud, OpenCRG files, or smooth splines enhanced with spatial properties. Based on the current wheel-position, -orientation and road surface irregularities, SISTer evaluates contact path deformation for every tire simulation timestep and returns road normal and dynamic application point within less than 2 ms to the tire model.
The use of SISTer is not limited to tire-road interaction; it can also be used for instance to detect collision between the vehicle chassis or race car plank with road surface, or as a ride height estimator for aero models.
Once loaded, SISTer holds the surface data (often tenths of Gb) in memory between simulation sessions if the road route or race track does not change. This is very effective when conducting repeated simulation runs at the same track or route, where loading time is dramatically reduced.
“SISTer has been developed as a result of our vehicle dynamics and ride and comfort work with automotive OEMs where higher quality scans and road definition are required, for example, to enable test drivers to get the precise feeling of paint strips leading up to a junction,” explains Nico Kruithof, computer scientist at Cruden.
“Racing drivers will also feel the benefit, at contact with curbs, for example, where relying on single point road contact models results in missing or misinterpreting the available road surface detail. Incorporating the data to the extent required for such a realistic vehicle model, without a package like SISTer, is currently limited due to the computational burden.