9.2 Performing a Single Lane-Change Analysis

Now that you opened a full-vehicle assembly, you can submit a single lane-change analysis.

1. Setting Up the Analysis

You can now specify the inputs for the full-vehicle analysis and perform a single lanechange maneuver. A single lane-change maneuver indicates that the steering input goes through a complete sine cycle in the amount of time you specify as the maximum steer value parameter.

To set up the analysis:

1) From the Simulate menu, point to Full-Vehicle Analysis, point to Open-Loop Steering Events, and then select Single Lane Change.

2) Fill in the dialog box as shown next, and then select OK.

Represent the duration and

the resolution of the analysis

3) When the analysis is complete, select Close.

You are now ready to animate and plot the results.

2. Animating the Results

In this section, you view the analysis you just ran. ADAMS/Car has already loaded the analysis results files for you.

1) From the Review menu, select Animation Controls.

2) Select the Play tool .

3) If you want the vehicle to always be in the center of the screen, do the following:

• Toggle Fixed Base to Base Part.

• Right-click the text box under Base Part, point to Body, and then select Browse.

The Database Navigator appears.

• From the list under MDI_Demo_Vehicle, double-click TR_Body, and then double-click ges_chassis.

4) If you want to see the path the vehicle takes, do the following:

• Toggle No Trace to Trace Marker.

• Right-click the text box under Trace Marker, point to Marker, and then select Browse.

The Database Navigator appears.

• Double-click TR_BODY.

• Double-click ges_chassis.

• Double-click cm.

5) To run another animation with either of the options presented in Steps 3 or 4, select the Play tool.

ADAMS/Car animates the vehicle.

6) To return the assembly to its initial configuration, select the Reset tool .

3. Plotting the Results

In this section, you create two plots that represent the following:

• Vehicle lateral acceleration as a function of time

• Roll angle of the vehicle as a function of the lateral acceleration

To create a plot of the lateral acceleration with respect to time:

1) From the Review menu, select Postprocessing Window.

2) Verify that Source is set to Requests.

3) From the Simulation list, select fveh_test_sin.

4) From the Filter list, select user defined.

5) From the Request list, select chassis_accelerations. You might have to scroll to see this option.

6) From the Component list, select lateral.

7) Set the Independent Axis to Time.

8) Select Add Curves.

ADAMS/PostProcessor displays the plot you requested, as shown next:

Figure 9.1 Plot of Lateral Acceleration versus Time

Note: Although the y-axis shows NO UNITS, acceleration is expressed in Gs.

9.3 Performing a Step Steer Analysis

To set up the analysis:

1) From the Simulate menu, point to Full-Vehicle Analysis, point to Open-Loop Steering Events, and then select Step Steer.

2) Set up the analysis as follows:

• Full-Vehicle Assembly: fveh_assy

• Output Prefix: tst

• End Time: 4

• Number of Steps: 100

• Initial Velocity: 70 (take the default of km/hr)

• Gear Position: 3

• Initial Steer Value: 0

• Final Steer Value: -45

• Step Start Time: 1

• Duration of Step: 1

• Steering Input: Angle

3) Keep the defaults for Cruise Control (off) and Quasi-Static Straight Line Setup (on).

4) Select Apply, so the dialog box stays open for the analysis you will run in the next section.

The SDI test rig applies to the assembly the inputs you specified and performs a dynamic analysis.