Vehicle Dynamic Simulation Laboratory

1- TruckSim

Mechanical Simulation Corporation (MSC) has developed this software, which has been used extensively by the Pennsylvania Transportation Institute (PTI). TruckSim uses detailed nonlinear tire models, nonlinear spring models, and includes the major kinematics and compliance effects in the suspensions and steering systems in trucks, busses, and other highway vehicles with solid-axle suspensions and an asymmetric steering system. The kinematics and dynamical equations are valid for full nonlinear 3D motions of rigid bodies.

Using separate programs for each axle configuration ensures simulations that are both computationally efficient and numerically robust.

For control inputs, TruckSim accepts time histories of brake input and steering wheel angle (open-loop control). TruckSim also has closed-loop controller options for steering and speed control.

You can view simulation results as wire-frame animations or as plots of output variables. You can generate these plots automatically for any combination of the many variables calculated during the simulation.

2- Yaw/Roll model

The UMTRI Yaw/Roll Model was developed for the purpose of predicting the directional and roll response of single and multiple articulated vehicles engaged in steering manoeuvres, which approach the rollover condition. It should be noted that the model does not permit the simulation of braking manoeuvres. However, it does permit the analysis of unconventional heavy vehicles, such as straight trucks (up to 4 axles), tractor/semitrailer ((up to 8 axles), doubles (up to 11-axle) and triples (up to 11-axles).

In the model, the forward velocity of the lead unit is assumed to remain constant during the manoeuvre. The longitudinal motion of each sprung mass is therefore not allowed to vary, and so each is treated as a rigid body with five degrees of freedom: lateral and vertical translation, and yaw, roll, and pitch rotation. The axles are treated as beam axles that are free to roll and to bounce with respect to the sprung mass to which they are attached. The non-linear cornering force and aligning torque characteristics of the tires and suspension are represented using a tabular format. This simulation model is equipped with a post processor allows a quick analysis of the truck dynamic performance measures.

3- Phase-4 Simulation Model

Phase 4 model is developed by UMTRI and is a time-domain mathematical simulation of straight trucks, tractor-semitrailers, doubles, and triples. It is a comprehensive computer model for simulating the braking and steering dynamics of commercial vehicles. The mathematical model incorporate up to 71 degrees of freedom. For the simulation of the lateral dynamic behaviour, the model incorporate sate-the-art representation of truck tire cornering force and aligning moment characteristics and vehicle non-linear suspension properties of significance to cornering behaviour. The program can be operated in open-loop or closed-loop, and on roads of specified grad or cross-slope. Braking performance and brake fad characteristics can be also simulated, since the program incorporate a detailed thermal brake model.

4- Static Rollover Simulation Model

This model was developed by UMTRI and able to calculate the rollover threshold of articulated vehicles during steady state turning manoeuvres. This model incorporates the effects of the torsion compliance that exists in the tractor frame, fifth wheel and trailer structure compliance. This model is very sophisticated and proven to be accurate in comparison with the tilt table tests and yaw/roll model predictions of the static rollover threshold.

5- Simplified Offtracking Models

As with the Yaw/Roll Model, the simplified offtracking models were developed by UMTRI (in 1988). These models examine three different aspects of offtracking performance of multiple-unit vehicles, namely: (a) low-speed steady-state offtracking; (b) low-speed transient offtracking, and; (c) high-speed steady-state offtracking.

Each of these aspects is examined in a constant-radius-turning manoeuvre where the user defines the radius. For the steady-state options, the vehicle is assumed to be turning continuously and to have achieved a steady-state response. For the low-speed transient option, the manoeuvre includes a straight line "entry" and straight line "exit" to the constant-radius turn. The user defines the total arc, or angle, of the turn. The model determines the paths of the centreline of each axle and of the rearmost extremity of the vehicle.

In these models several assumptions are made, most notably:

(a) The cornering forces and aligning moments generated at the tire/road interface are linear functions of the slip angle of the tire.
(b) The motion of the vehicle takes place on a horizontal surface with uniform friction characteristics.
(c) Pitch and roll motions of the sprung masses are sufficiently small to neglect.
(d) The various axles within a given suspension are lumped together forming an equivalent single axle.

6- Frequency Response Simulation Model

Frequency response analysis is an evaluation of system dynamics in terms of the "steady-state" portion of the response solution to harmonic input of a constant amplitude and frequency. Applied to highway vehicles, the technique can be used to evaluate the magnitude of a vehicle's lateral acceleration response or yaw rate response to the magnitude of a steering input. The nature of the technique limits the vehicle modelling to a linear system of equations, but it allows the rapid computation of frequency response across a wide frequency spectrum, and is generally applicable to highway vehicles operating in situations where they are not too close to rolling over. It thus provides a powerful tool for estimating regions of a vehicle's operating envelope where sensitivities may exist, and where further, more detailed, modelling may be warranted.

7- Straight-line Braking Performance Model

Braking efficiency of multi-articulated vehicles can be evaluated using this simplified straight-line braking model, whose calculation is based on the repetitive close-form solution of a set of quasi static linear equations defining a steady-state braking condition (constant deceleration) for the vehicle combination. The equations are solved at 1.0 psi increments of brake application pressure, with linear or non-linear pressure gains specified for the vehicle brakes. The gains used in the Vehicle Weights and Dimensions Study were 1000 in-lb/psi for each brake on the front steering axle, and 1500 in-lb/psi for each brake on a load-carrying axle. The braking efficiency measure is determined for deceleration of 0.4 g, which illustrates braking performance in nominal high-level braking condition. The University of Michigan Transportation Research Institute develops this model.

8- Logging Trucks Simulation Models

The National Research Council of Canada developed these computer simulation models in collaboration with Victoria University for studies performed by the Forest Engineering Research Institute of Canada. These models are non-linear have the capabilities to predict the steady-state and transient dynamic responses and the rollover dynamics of the following logging truck configurations:

- Tractor/Pole Trailer
- Tractor/Jeep/Pole Trailer
- Tractor/Triaxle Trailer
- Tractor/Quadaxle Trailer (single and dual loads)
- Doglogger
- Double Doglogger
- Tractor/Jeep/Triaxle Trailer
- Tractor/Jeep/Quadaxle Trailer

9- Truck-Full-Trailer Simulation Model

Simplified four DOF vehicle model is developed in house and used in the design of various control strategies. For a linear analysis, the forward speed is assumed to be a constant and the angular displacements occurring during the maneuver is assumed to be small. This model is equipped with active control systems, such as LQR and Sliding Mode controllers, able to control the yaw motion of a truck full-trailer to enhance its rollover stability during sever maneuvers.

10- TBS Model

A simplified four-DOF tractor/semitrailer (upto 5-axle) model. In this model both longitudinal and lateral load transfers have been taken into account to determine a tire vertical load. A non-linear tire model is used to represent the longitudinal and cornering tire characteristics. The model includes five control devices models which are able to enhance vehicle stability during sever steering and braking maneuvers by controlling wheels lockup (antilock brakes) or the growth of the articulation angle (Anti jack-knife).

11- CarSimEd

Mechanical Simulation Corporation (MSC) has developed the software, which has been used for several years as part of ME452 Vehicle Dynamics Course. CarSimEd combines advanced simulation models allowing users to rapidly visualize effects of changes in vehicle properties. CarSimEd is used as part of ME452 Vehicle Dynamics Course as a tool for students to learn about vehicle dynamics and simulation. The capabilities of this software can be summarized as follows:

Handling and Braking Simulation

· Based on a nonlinear 18 degree-of-freedom (DOF) 3D mathematical model.
· Includes independent front and rear suspensions, nonlinear tire model, major suspension effects, steering system gain, and major sources of compliance.
· Very good predictor of linear handling and limit braking performance.
· Fair predictor for nonlinear handling and combined braking and handling.
· Limited to flat level surfaces, linear springs and dampers, and linear suspension kinematics.

Ride Simulation

· 4-DOF 2D model.
· Parameters compatible with 18-DOF model. However, not all 18-DOF model
parameters are used in the 4-DOF model.

Suspension Kinematics

· 3D kinematics model for wheel with 5-link suspension.
· Can simulate short- long-arm (SLA) suspension with tie-rod.
· Can simulate 5-link suspension.

12- HVOSM Computer Simulation Model

This computer simulation model was developed by Calaspan and subjected to comprehensive validation. The model is suitable for study the complex passenger car dynamics resulting from avoidance evasive maneuvers. HVOSM includes a detailed model of the braking and engine-deriveline systems and an empirically based definition of the longitudinal and lateral tire characteristics. The rotational degrees of freedom of the four vehicle wheels are also included in this model.

13- Artificial Neural Networks Based Tire Models (Neuro-Tires Models)

A set of the artificial neural networks (ANN) tire models is available to be trained and predict the steady state and transient response of passenger car or truck tires. These ANN tire models were tested on a stochastic road profile, which was generated by a first-order filter from a normal distributed Gaussian white noise process. The neural network was trained at 40 m/s longitudinal speed and up to 12 degs slip angles for wide range of vertical loads. In the operation mode, a quarter car model generated the randomly varying vertical load.

In addition, Four models are developed by PTI and available at both FHWA and Penn State to predict the contact stress distribution at the tire/pavement contact patch for 1R22.5 Radial-Ply and a 10.00X20 Bias-Ply truck tire. Furthermore, the corresponding contact area can be also predicted.

14- Dynamic Analysis and Design System (DADS)

PTI used the commercial software package Dynamic Analysis and Design System (DADS) model the interactive rigid body system of a bicycle, its rider, and the road surface. This simulation model is available to study the dynamics of the rider-bicycle-road surface system.

DADS also used to develop ride quality analysis model for a 5-axle tractor/semitrailer. This model able to predict the vertical dynamics at the driver body and seat. The suspensions, cabin mounts, seat and driver body were modeled in reasonable details. The road roughness is developed to simulate varieties of road conditions. It is planed to add ADAMS to extend the multi-body modeling capabilities.

DADS Model of 30' and 40' Transit Buses

DADS Model of 45' Coach Bus

DADS Model of 52' 5-Axle Tractor/Semitrailer

Rider, bicycle, and road surface (rumble strips) could be considered as an interactive rigid body system, where spring force and damping force are introduced between bicycle tire and road surface and between rider's hip and the seat of bicycle. The commercial software package Dynamic Analysis and Design System (DADS) is used to model and solve the above problem. Basically, DADS will generate a set of constraint equations to specify the kinematics relationship and a set of differential equations to specify the dynamics connection among the rider-bicycle-road system using energy method and solve it numerically.

DADS Model of Rider, bicycle, and road surface

15- Road Simulator

Heavy Duty Four-Post Shaker Table