Designing a track in Adams/Car:

Size: px

Start display at page:

Download "Designing a track in Adams/Car:"

Grace Young
6 years ago
Views:

1 Warning: Remember to change your working directory before you begin this lesson. If you do not, Adams may not work correctly. Also remember to move everything you wish to keep from the working directory before you log off. See the Opening Files tutorial for more information. Designing a track in Adams/Car: This tutorial is designed to help you understand how to use the Road Builder function inside of Adams/Car to generate a track for full vehicle simulations. Road Builder uses three dimensional points entered by the user to define the centerline of a roadway or travel surface. The user must enter X,Y, and Z coordinates for points along the path. At each point, the user must also enter a roadway width, friction values for the left and right side of the road, and a bank angle for the road. Since Road Builder requires a large list of XYZ points, it is logical to begin your roadway design using a CAD package. This will allow you to design your track visually, list out the points required to create the track, then cut and paste them directly into Road Builder. Version 1.0 6/18/2008 1

2 Creating Barber Motorsports Complex in Adams/Car: The first step in creating a track is to have a geometric layout for the travel surface. This can be anything you dream up from a skidpad or autocross track for FSAE or a hill climb or motocross track for Mini Baja. There are several ways to get started other than just dreaming up a track. The easiest way is to find an actual track that has already been built. Barber Motorsports has the exact dimensions of their track published on the internet. (and are also included in this tutorial) Other good sources are motocross track websites, SCCA forums for autocross tracks, and aerial images. Michelin has a tire test facility in South Carolina and can be seen clearly from free aerial images provided by These images can be imported into CAD software and then traced out to give the outline of a track surface. Barber Motorsports Park Track Geometry To get started, we would first open CAD software and make an outline of the Barber facility. This tutorial assumes that the user has had enough CAD experience to do this on his or her own. There is an Excel file in the tutorials folder called Barber Tutorial.xls containing the three dimensional points needed for this tutorial. Those points were created by inserting the above image into the CAD software. The centerline of the track was traced out, and a list of the X,Y, and Z coordinates of the centerline were then input into the Excel file included with this tutorial. From your CAD file, you should be able to list the X,Y, and Z coordinates from your track. One important note is that you should always begin your track at the origin (0,0,0) and if your track is a continuous loop, it should also end at the origin. ADAMS/Car always begins each simulation by placing the full vehicle model at the 0,0,0 location. This requires that you design your track to occupy that space. Version 1.0 6/18/2008 2

3 Now that we have a path of travel for our full vehicle analysis, lets open ADAMS/Car. Click on the start menu/all programs/msc.software/msc.adams 2005 r2/acar/adams Car Once ADAMS/Car opens, we need to open a full vehicle assembly. ADAMS/Car will not let us access the Road Builder function unless we have an assembly open. Version 1.0 6/18/2008 3

text entry area of the dialog box. This will automatically bring up the file browser.

4 Inside Adams/Car, click Open/Assembly Now you will be prompted for the Assembly Name. There is not a button to browse to the assembly you want, you must double click in the text entry area of the dialog box. This will automatically bring up the file browser. Double Click in the text entry area. You should see the following dialog box: Version 1.0 6/18/2008 4

5 We will open the MDI_Demo_Vehicle.asy. This is a demo vehicle which has been built and tested by the software manufacturer. By using this vehicle which we know has been built correctly, it will allow us to troubleshoot any warnings or errors much easier. Double click the MDI_Demo_Vehicle.asy file. Now click Apply You should get a popup message window like the one below: Version 1.0 6/18/2008 5

6 Once the full vehicle assembly has fully loaded, your screen should look like the following photo: Now click close on the popup message window, and then click the red X to close the open assembly dialog box. Version 1.0 6/18/2008 6

7 Now we are ready to open the Road Builder and begin to create our track. Click simulate/full vehicle analysis/road Builder This will open the Road Builder portion of ADAMS/Car. There will be a user interface that should look similar to the one below: Road Builder User Interface Version 1.0 6/18/2008 7

Now that Road Builder is open, lets get started creating the track. By default, each time you go to the Road Builder interface, the last opened track will be displayed.

8 Now that Road Builder is open, lets get started creating the track. By default, each time you go to the Road Builder interface, the last opened track will be displayed. We need to start a new Road Builder File. Click File/New This opens a clean Road Builder file, and should look like the above photo. The first thing we need to do is define the units. I like to work in feet and degrees, so we will change those units shown on the right of the screen. Click Settings/Units and a screen like this will appear: Change the units to: Feet, Pounds Mass, Pounds Force, Seconds, and Degrees, then select OK Now lets move on to the Global tab to set some of the global parameters. Click on the Global tab; You should be looking at a screen like this: Version 1.0 6/18/2008 8

Set the Forward direction to Normal Set the Search Algorithm to Fast Set Closed Road to Yes Set the Road Vertical to (Loc X = 0, Loc Y=0, Loc Z=1) Select the Road Width Check Box and enter a value of

9 Set the Forward direction to Normal Set the Search Algorithm to Fast Set Closed Road to Yes Set the Road Vertical to (Loc X = 0, Loc Y=0, Loc Z=1) Select the Road Width Check Box and enter a value of 15. (This gives your track an overall width of 15 feet. Think of this as the grassy shoulder of the road. This will be more evident later) Select the Road friction Left and Right Check boxes and set their values to 1 (This assigns a multiplier to the friction of the shoulder of the road in this case it will be the same friction as the travel surface) Your screen should look like the dialog box above. Now we want to define the centerline of our track. Click on the Road Points Tab Version 1.0 6/18/2008 9

This is what you should see under the road points tab. This is the dialog box where we will be entering all of the X,Y, and Z coordinates of the centerline of our track.

10 This is what you should see under the road points tab. This is the dialog box where we will be entering all of the X,Y, and Z coordinates of the centerline of our track. Don t worry, you wont have to type all of them in! Left click on the point number one to highlight the row. Now right click on Number 1 and select Delete Row(s) Version 1.0 6/18/

This will remove the one row of data already entered into Road Builder. Now, navigate to the Tutorial CD and open the Microsoft Excel File labeled Barber Tutorial.

11 This will remove the one row of data already entered into Road Builder. Now, navigate to the Tutorial CD and open the Microsoft Excel File labeled Barber Tutorial.xls Next, select all the cells in the Excel file containing data. The first row should contain X,Y, and Z data of (0,0,0) and the last row should also contain (0,0,0). Your selection set should be 3 columns wide and 294 rows long. Do not select any of the cells containing text, such as X, Y, or Z. Right click on the selected data in Excel and click copy Now lets go back to the Road Builder window in ADAMS/Car Left click the button near the bottom of the window that says Add Road Points You will be prompted for the number of road points to be added. Type in 294 and press ok Your screen should look like the one below. Version 1.0 6/18/

12 The 294 road points you just added correspond to the 294 rows of X,Y, and Z points you copied from the Excel file. Now we need to paste the data into Road Builder. Your screen should look like this: Version 1.0 6/18/

Right now, all of these cells should contain zeros. Now highlight all of the X, Y, and Z values in the Road Builder window just like in the above picture.

13 Right now, all of these cells should contain zeros. Now highlight all of the X, Y, and Z values in the Road Builder window just like in the above picture. To do this, point your mouse to the X value for row number 1. Hold down the left mouse button and drag to the bottom of the screen. As you are dragging, drag your mouse toward the right to encompass all three of the X, Y, and Z columns. Once all of the desired cells are highlighted in blue, you can release your left mouse button. To paste the copied data from Excel into Road Builder, hold down the control button on the keyboard and tap the V key twice. Sometimes this doesn t work right away, so you may have to try it a few times before it will work. Now that the X, Y, and Z data is entered into Road Builder, you must enter values for the rest of the data. Go back to Excel and create a column of cells that all contain the number 12. Make the column 294 rows high (this is the number of rows in Road Builder). Now on your own, copy and paste the column into Road Builder in the width column. This will make our travel surface 12 feet wide at every data point. Our track will be 12 feet wide with a 2.5 foot grass shoulder around it. (This is from the global 15 foot width we entered on the global tab) Version 1.0 6/18/

14 Also use Excel to enter values of 0.9 into Road Builder for both the Friction Left and Friction Right. (These values are for the coefficient of friction for the right and left sides of the road, respectively. Your screen should look like this: If you are not comfortable copying and pasting data into Road Builder, you can manually enter each piece of data into the cells by selecting the individual cell and typing in the value. Now, lets look at a plot of our data to make sure our track looks like we would expect it to. Click on the Show X-Y Plot button near the bottom of the Road Builder window. A window should pop up and look like this: Version 1.0 6/18/

If your window doesn t look like this, try pressing the Redraw or Fit button on the right side of the window. This will fit the plot to the window so all of the data is viewable.

15 If your window doesn t look like this, try pressing the Redraw or Fit button on the right side of the window. This will fit the plot to the window so all of the data is viewable. When you are finished looking at your track s X-Y geometry, just close the Road Point Editor X- Y window. Now let s save the road file so we don t lose all that hard work! Version 1.0 6/18/

16 From the above window, click Save As on the bottom right hand corner of the window. Navigate to a directory and save your file. Remember where you save the file so you can get to it later to run a simulation on your track. Also remember when you name the file to NOT use spaces in the name. It WILL mess up if you include spaces in any folders or file names that you may access. The final task when creating a track is to include rough areas or potholes to simulate real world roads. To do this, we will use the obstacle tab in Road Builder. Click on the Obstacle tab in Road Builder. Your screen should look like this: Version 1.0 6/18/

17 We will add a pothole obstacle for our track. There are several types of obstacles, including jumps. This feature will be very important for those of you designing and simulating Mini Baja suspensions. In the name text entry line near the bottom of the window, type the word pothole Now click the Add button next to the text entry line. The obstacle Pothole should appear like in the photo below. Version 1.0 6/18/

18 Now we need to define the location of the pothole. I entered the start of the pothole at (0,0,0) and the end of the pothole at (100,0,0). This will simulate a 100 foot long sudden drop in the road surface. Make sure your obstacle parameters are identical to those listed in the above and below photos. From this screen, you can add many different obstacles at any location along your track. Next, we need to edit some more specific obstacle parameters. Version 1.0 6/18/

19 Road Builder Obstacle parameters Left click the word pothole to highlight the data set for the pothole obstacle. Now right click the word pothole and then left click Modify with PropertyEditor Make sure you click on the Modify with PropertyEditor button highlighted in blue as in the photo below: Version 1.0 6/18/

20 Clicking Modify with PropertyEditor will bring up the following screen: Version 1.0 6/18/

21 This Property Editor will allow you to change parameters associated with your obstacle. The obstacle type drop down menu will allow you to create obstacles such as jumps, potholes, and objects in the road. I strongly encourage you to experiment with these settings so you have a feel for how they change your full vehicle simulations. These obstacles will help you more accurately simulate real world conditions. We all know that no road is completely smooth so this will help add realism to your analysis. To return to the listing of all obstacles on this track, click the back arrow located next to the obstacle name. Set the obstacle type to pothole. Your screen should look like this: Now change the parameters of the pothole to match the above photo. Now your track is complete. Save your Road Builder file and close out of the Road Builder window. Version 1.0 6/18/

22 Full Vehicle simulations with a custom created track: Now that you have created your own track, we will simulate a vehicle driving on that track. We previously loaded the MSC_ADAMS/Car demo vehicle to allow us to create our track. Ideally, you would simulate your own designs on the custom track. For this tutorial, we will use the Demo Vehicle for simplicity. We will be using the SmartDriver feature of Adams/Car to execute the simulation. From the simulate menu, click: simulate/full vehicle analysis/adams/smartdriver Your screen should look like this: Now when the ADAMS/SmartDriver interface opens, it should look like this: Version 1.0 6/18/

ADAMS/SmartDriver interface First, give the SmartDriver simulation a file name. To do this, type test_barbers_track_1 into the Output Prefix field.

23 ADAMS/SmartDriver interface First, give the SmartDriver simulation a file name. To do this, type test_barbers_track_1 into the Output Prefix field. Your filename must not contain spaces and cannot begin with a number. Input an end time of 25. This will simulate the vehicle on our track for 25 seconds of run time. Input 100 for number of steps. Keep the Mode of Simulation drop down as Interactive Course Type should be 3D Road Double click in the 3D Road Data File text entry area to delete the default 3D road. Double clicking in the text entry area will allow you to browse to the location where you saved your copy of the Barber s track created in Road Builder. Navigate to this location and select your Barbers Track file you just created. The file type should be.xml. Set the initial velocity to 50 mph. Don t forget to make sure the speed units are in MPH. Version 1.0 6/18/

Set the initial gear position to 5. We will be changing the Smart Diver Task from Vehicle Limits to User Defined. This will allow us to simulate a nice, smooth drive around the track.

24 Set the initial gear position to 5. We will be changing the Smart Diver Task from Vehicle Limits to User Defined. This will allow us to simulate a nice, smooth drive around the track. Set all of the Acceleration sliders to approximately 25. This will limit the vehicle s handling to 25 percent of its maximum. Click Apply You should get the following Question: Click on the Use Recommended button. Now your simulation will begin. This will take several minutes to run. You should see a message window pop up. This window will keep you updated on all of the processes going on with the simulation. When the simulation ends, your screen should look like this: Version 1.0 6/18/

25 Now that the simulation has ended, we can run an animation to make sure the car followed the path we wanted it to. Click on the main tool bar: Review/Animation Controls This will open an animation controller where you can play and rewind the vehicle s motion. Version 1.0 6/18/

26 You should get a window like this: Version 1.0 6/18/

27 Now, lets zoom out on the screen to view the entire track. Hold down the Z key on the keyboard then hold down the left mouse button and drag the mouse cursor up and down to zoom in and out. Hold down the T key on the keyboard then hold down the left mouse button and drag the mouse cursor up and down to translate the objects on the screen. Hold down the R key on the keyboard then hold down the left mouse button and drag the mouse cursor up and down to rotate the objects on the screen. Zoom completely out on the track and compare this view to the photo of Barber Motorsports Complex at the first of this tutorial. Did your track turn out like you expected it to? Move your screen view to your desired location by using the above methods. Now, click the play button on the Animation Controls menu to watch your vehicle maneuver around the track. The data from the simulation can now be viewed using the postprocessing window. Other tutorials can guide you through this process. To open the postprocessing window, click on the main tool bar: Review/PostProcessing Window. Internal to the postprocessing window, you can look at plots of speed vs time, suspension parameters, and hundreds of other pieces of data calculated during the simulation. This tool will be extremely useful in the determination of how well all of your vehicle s subsystems are performing together. It is important for you to vary the parameters in the SmartDriver menu to see how they affect the simulation. It is good practice to try new scenarios on your own using SmartDriver to better your understanding of how this particular simulation works. Warning: Remember to change your working directory before you begin this lesson. If you do not, Adams may not work correctly. Also remember to move everything you wish to keep from the working directory before you log off. See the Opening Files tutorial for more information. Version 1.0 6/18/

Tangents. In this tutorial we are going to take a look at how tangents can affect an animation.

Tangents. In this tutorial we are going to take a look at how tangents can affect an animation. Tangents In this tutorial we are going to take a look at how tangents can affect an animation. One of the 12 Principles of Animation is called Slow In and Slow Out. This refers to the spacing of the in