Basic Dynamics of Ground Vehicles

Publish Date: Jun 08, 2011 | 0 Ratings | 0.00 out of 5 |  PDF

Overview

In this tutorial, a basic dynamics of ground vehicles on an incline will be discussed. We will start by assessing ground vehicle forces and motions and deriving equations of motion. Using LabVIEW Control Design and Simulation Module and LabVIEW MathScript RT Module, students can simulate the dynamic response of the given vehicle model.

1. Two-Axle Vehicle Model

A simple two-axle longitudinal vehicle model is shown in Figure 1. Notice that the body-fixed axis is placed at the center of gravity of the vehicle with y-axis pointing out of the page. We can understand all the various forces acting on the vehicle by drawing the free-body diagram.

Fig 1. Two-Axle Longitudinal Model

Fig 2. Free-Body Diagram of the Vehicle

Table 1. Vehicle Parameters

2. Equations of Motion

Let us assume that for a passenger car,ha hd  ≈ h and the vehicle does not leave the ground with only motion along the longitudinal axis.

From Euler's Equations for a rigid body

with the following assumptions

so

3. Vehicle Dynamics Simulation

Given the traction forces above, we can implement the dynamics model in LabVIEW MathScript RT module and simulate the dynamics using the LabVIEW Control Design and Simulation Module. The overall model is shown in Figure 3.

Fig 3. Block Diagram of Longitudinal Vehicle Model

We can simulate the vehicle response for various road grades and drive configuration. As shown in Figure 4, the front panel provides vehicle responses for two difference road grades.

Fig 4. Vehicle Dynamics Simulation for grade 0% (Left) 25%(Right)

4. Conclusion

This article briefly introduces the concepts of basic vehicle dynamics. The kinematic equations are implemented using LabVIEW Control Design and Simulation Module and LabVIEW MathScript RT Module.

LabVIEW Control Design and Simulation Module

LabVIEW MathScript RT Module

NI LabVIEW Robotics Starter Kit

NI Automotive Applications

Hybrid Vehicle Test and Simulation using NI's Hardware-In-The-Loop (HIL) Platform

6. Reference

ME 390: Vehicle Dynamics and Controls (Spring 2011)

Prof. Raul. G. Longoria, ME, University of Texas, Austin

http://www.me.utexas.edu/~longoria/VSDC/

Ratings

Rate this document