UM Automotive

UM Automotive

Click to play animation.UM Automotive is the new additional module for program package Universal Mechanism, which is intended for simulation of road vehicle dynamics. UM Automotive widens the functionality of UM Base configuration and includes program tools for description of a road plan and road excitations, mathematical models of tires and drivers and a library of maneuvers, suspensions, steering systems and elements of transmission.

  

 
 Simulation of road vehicle dynamics

 

Click to play animation.

Click to play animation.

Click to play animation.

Click to play animation.

Model and animation was developed by Marcus Coleman, www.tigerspider.com.au
 To compare and determine if there is acceptable agreement between simulations from Universal Mechanism and other computer-based modeling packages special verification was done. Two test models of heavy vehicles were created in different modeling programs and results of simulation their dynamics were obtained. National road transport commission of Australia carried out numerical experiments in ADAMS/CAR, UMTRI’s constant velocity Yaw/Roll program and AUTOSIM and our laboratory did the same in Universal Mechanism.

Computer models of a truck/trailer and a B-double are considered. In total four simulations were devised that would test and compare a range of features in the models. Pulse steer and step steer inputs were used in the two simulations that employed open-loop steer control, and closed-loop control was used in path following tasks of a high-speed lane change and a low-speed 90° turn.

Detailed description of both models, all of maneuvers and comparative results of numerical simulations for ADAMS/CAR, UMTRI,s constant velocity Yaw/Roll program and AUTOSIM were published in a report of National road transport commission of Australia. This report was released into the public domain and available for downloading here.

In our laboratory identical simulations using the same test maneuvers comprising a pulse steer, step steer, standard SAE lane change and a low-speed 90° turn were performed. Results of these tests are available here.

Comparison of reports shows very good agreement between Universal Mechanism and other modeling packages.

Links for downloading:
- Report for ADAMS/CAR, UMTRI,s Yaw/Roll and AUTOSIM;
- Report for Universal Mechanism.  
 

 

Library of Car Suspensions


The module includes a library of automotive suspension. The library contains the most common types of suspensions for cars and trucks. The following suspension models are available:
• axle suspension,
• double wishbone suspension,
• semi-trailing arm suspension,
• MacPherson suspension,
• torsion suspension,
• multi-link suspension,
• typical steer and drive spring suspensions for trucks.

Models of suspensions from the library are parameterized uniformly and designed so as to provide the easiest way to create car models based on these suspensions. Key suspension properties are parameterized for easily tuning for every specific car model.

MacPherson suspension Double wishbone suspension
Axle suspension Semi-trailing arm suspension
Multi-link suspension Torsion suspension

 

  Pneumatic suspensions

 

The UM Pneumatic Systems module is used for simulation of pneumatic suspensions of trucks, buses and cars. The module allows including the main elements of pneumatic suspension into a multibody model for dynamic modeling. The following pneumatic elements are used in the suspensions:

  • air springs
  • auxiliary chamber
  • reservoir with compressed air
  • compressor
  • height control valve
  • pneumatic lines

The uses can model the truck, bus or car dynamics for different interconnections of air springs. In particular, a process of a leveling valve operation for supporting the desired suspension height can be analyzed when the truck or a bus load is changed.

Example of a pneumatic system
Example of a pneumatic system
 
Suspension with HCV
 
 
Tire models


The module includes four tire models, which describe dynamical forces and torques between a wheel and a road. Implemented models are widely used for simulation of vehicle dynamics and provide accurate solution in the case of adequate setting their parameters. UM Automotive includes the following tire models:

  • Magic formula;
  • Fiala;
  • Table / experimental dependence;
  • FTire model.
     

FTire


The interface with cosin FTire model is implemented in UM. FTire (Flexible Structure Tire Model) is a full 3D nonlinear tire model. It is used by engineers and researchers in the vehicle and tire industry worldwide.

FTire model

FTire is designed for vehicle comfort simulations and prediction of road loads on road irregularities even with extremely short wave-lengths. It can also be used as a structural dynamics based, highly nonlinear and dynamic tire model for handling studies without modifications of input parameters.

FTire explains most of the complex tire phenomena on a mechanical, thermodynamical, and tribological basis, with very good correlation to measurements. For more information, please visit www.cosin.eu

 

istory Road plan


UM Automotive contains a special tool for description of macro geometry of a road: turning, hill, hillside, etc.

 

istory Road excitation


UM Automotive contains a tool for description of a road profile, which supports several ways to describe the irregularities

 - pointwise input (for measured data);
 - analytical expressions;
 - synthesis of the road profile based on its spectral power density;
 - superposed pointwise/analytical/generated by spectral power density road profile.

Several files with spectral power density of typical road surfaces and corresponding road profiles are included in the module. They are: concrete, asphalt in good and satisfactory condition, and cobblestone road.

istory Maneuvers


Several mathematical models of driver and a set of typical maneuvers such as straight-ahead braking, double lane-change, braking in a turn, power-off reaction of a vehicle in a turn, power-off in turn, steady-state circular driving behavior and others (including ISO standards) are available. Analysis of vehicle dynamics with the help of such wide set of typical maneuvers helps you have a clear idea of dynamical behavior of the vehicle.