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.  
 

 

wishbone
McPherson Double wishbone
4link
Trailing links Semi-trailing arm
 
Tri-link strut  

 

Tire models


The module includes two 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.

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.