History of Mechanical Simulation

Mechanical Simulation Corporation was founded in 1996 to make simulation technology developed in the course of 30 years of research available to the automotive community.

Vehicle Dynamics

Starting in the late 1960's, the University of Michigan Transportation Research Institute (UMTRI) was a pioneer in developing knowledge about vehicle dynamic behavior and modeling. Knowledge about vehicle dynamics came from three activities:

1. experimental testing and analysis of results;
2. development of models and algorithms to try to duplicate the observed behavior; and
3. special laboratory tests and measurements to obtain the vehicle/tire properties needed to use the models.

The early research projects included many experimental tests, where modeling assumptions were validated by direct comparison with test data.

The modeling concepts and assumptions developed at UMTRI and elsewhere underlie the CarSim and TruckSim models. In addition to emphasizing the correctness of the physics and associated math, we apply the research results to include vehicle properties that are both significant and measurable.

VehicleSim Technology for Physics Models

In the late 1980's, UMTRI scientist Dr. Michael Sayers developed the world's most advanced automated code generation capability for vehicles and other multibody systems. The code generator (called AutoSim) was used at UMTRI to create new vehicle models with unparalleled computational efficiency In the past 20 years, the original AutoSim program—now called VS Lisp—has been continuously developed and maintained in order to generate equations for 3D multibody vehicle models.

Mechanical Simulation has developed a support runtime library to provide advanced capabilities such as database integration, numerical processing routines, communication with other software such as Simulink. A standard application program interface (VS API) is supported to control integration of the vehicle math models with other software, including custom programs created by customers.

Some of the symbolic algebra capabilities from VS Lisp have been duplicated in the runtime library, allowing new variables and equations of motion to be added to the model at runtime using VS commands.

VehicleSim technology supports several characteristics of our software development:

1. We can create new models and extend existing models quickly. All of the equations involving multibody dynamics are machine-generated in just minutes by VS Lisp for specific custom physics model representing unique vehicle configurations (suspension types, number of axles, trailers, etc.).
2. The custom math models run fast, as required to support real-time and optimization applications.
3. We can support new interface and operating-system requirements rapidly by extending the runtime library shared by all vehicle math models.
4. If the API or the math model architecture does not work for some new application, we can extend VS Lisp or the VS API as needed.

Other Parts of VehicleSim

The main limitation to the use of vehicle dynamics simulation is the time needed to learn how to use the software (training and education).

Extensive development was done at UMTRI in the 1990's to create a database browser for simulations, now called the VS browser, and standard data files for simulation (ERD files) that are used in our products. Since 1996, the development has continued at Mechanical Simulation. Our vehicle dynamics simulation products have become the most popular in the world, in part because they are exceptionally easy to use.

All of our VS simulation programs read standard input parameter text files (called parsfiles) and work with standard VS utilities for plotting, animation, automation, etc. The same tools for providing a GUI, managing databases, plotting, and animating are used in all VehicleSim products.

In addition to our extensive background in vehicle dynamics, the development team at Mechanical Simulation includes programmers and graphic artists from the video gaming industry. Improvements for animation, initially use for immersive driving simulators, greatly enhance the visualization of vehicle motions simularted by our physics models.

Ongoing Development and Improvements

As the ease-of-use and efficiency of CarSim, BikeSim, and TruckSim make simulation accessible to more engineers, we are working to make the software more productive for existing users, and also to provide simulation to engineers and planners who have never considered the use of vehicle math models.

Although we continue to improve the math models, we are also working to extend the ways that the models can be run and the ways the associated data can be transferred and shared.