Summer 2003 - Engineering Dynamics Corporation
Contents
1. Textures None Translate 0 000 Translate Y o 000 Mapping derai Rotate 1 D 000 Repeat _ j O00 Options repeat gt Repeat 1 1 000 Figure 3 Material Texture Editor dialog displaying the selected image to be applied to the surface 3 Build a surface in the 3D Editor that corresponds to the size and shape of the image that you have created If 1 inch equals 100 feet in your image and your image is 5 inches on edge make the surface 500 feet 4 After completing your surface and preparing it for editing choose 3D Edit Material Texture from the menu This will display the Material Texture Editor dialog Choose your image from the list of textures on the left hand side of the Material Texture dialog as shown in Figure 3 5 Check the appearance of the image on the sample and adjust the rotation if required Click the Accept button to attach the texture to your surface At this point if you are using a rectangular image you will need to adjust the Repeat and also the Translate settings for the image The value used for Repeat will be the longest side of your image divided by the shortest side For example 600 pixels divided by 300 pixels is a Repeat value of 2 This will shrink Scale the texture which was stretched to a square in the Material Texture dialog back to the rectangular shape you started with You need to click the Accept button to update your image displ2. SUMMER 2003 ENGINEERING DYNAMICS CORPORATION Elvis Grimes challenging Jack Beemer with HVE related questions in a round of HVE Jillionaire during Monday night social hour activities The 2003 HVE Forum once again brought HVE and HVE 2D users together to learn more about their software and to network with other users in a relaxed environment The Users Group Meeting the HVE White Paper session and all of the workshops were well attended and received excellent reviews As part of the week s activities a special guest was invited to host the Monday evening Jillionaire game The real Elvis couldn t have better hosted the game and helped contestants win HVE Dollars good towards the purchase of EDC products and services 2004 HVE Forum San Francisco CA Planning is already underway for the 2004 HVE Forum Mark your calendar for the dates of May 3 7 2004 The Crowne Plaza Union Square hotel in downtown San Francisco California will serve as the conference hotel Special room rates for attendees have been arranged with the hotel Registration forms workshop schedules and workshop descriptions will be available for download from the EDC website Please visit the 2004 HVE Forum page at www edccorp com service hveforum html Technical Newsletter 2003 HVE Forum Humans Vehicles and Elvis HVE White Paper Session This year s papers presented topics of interest ranging from scene data collectio
3. Q Earlier we said that the Wheel Force and Available Friction brake table options were not recommended It is now clear why Use of either of these methods Wheel bypasses completely the wheel spin equations of results in motion Any details related to tire spin dynamics are B Ooo o completely lost Obviously ABS simulation is also not uM Brake Torque F l spin wneei possible when either of these options is used refer to i the December 2001 Technical Newsletter for more From this wheel spin acceleration 2 is calculated details spin S contstant and Brake Torque and F xire for the current timestep are known A question sometimes asked by new 3 D users is How can tell how much pedal force to use There are a Brake Torque F couple of ways to answer this question First you have wneer your common sense and years of actual driving I sin experience Think about it You probably apply around 10 Ib during a normal brake application and maybe 50 Numerical integration is used to update the spin velocity lb Or more during heavy braking If you re the of the wheel for the start of the next timestep Using this analytical type here s a method for you First create a spin velocity and the current tire radius Ry also brake table that varies from zero force at time zero and known the linear velocity VX rire at the tire contact increases to 100 Ib at 5 seconds Start the vehicle at a patch is
4. Here are the lists from the 2003 HVE Forum HVE Users Top 10 Wish List DyMESH Tire Model Sidewall Contacts Save Camera View Accelerometer Tracer Display Key Results in Playback Window Print All Reports Heavy Truck Air Suspensions Add Vehicle to Existing Event Dynamic Payload Shift Elliptical Air Bags Attach Camera to Follow Target Tire Interaction With Other Vehicles and Humans NN NN NOGA BBR WD Retarders HVE 2D Users Top 10 Wish List 1 Path Follower 1 Create EDSMAC event from EDCRASH results like EDVAP 3 Undo Command history of last 20 or so actions 4 Include open report windows in current object list and enable minimize for all report windows in Playback 5 Are you sure message when clicking intermediate position 5 Copy and paste contents of all report windows 7 Make EDCRASH damage profile visualized like v1 33 and EDVAP 7 Lock cursors Z coordinate to zero in 3D editor or allow to pick friction zone vertices in event viewer 7 Add remove or switch vehicles in an existing event 10 Insert text into report windows 3 EOD Technical Newsletter SUMMER 2003 Using Aerial Photos as Scene Drawings Many users are working with aerial photographs as the background for their reconstructions and simulations These photographs may be from a company hired to provide a specific digital image or downloaded directly from image libraries a
5. get the environment model shown in Figure 4 Rot Roty I Zoom gt 45 0 Dolly NUM Figure 4 Roadway with unsmoothed concrete texture map A viewer of the scene gets the general idea that the Surface is comprised of concrete but the effect is not entirely realistic because of the pronounced tiling effect created by the repeated square boundaries of the applied texture This effect can be reduced by modifying the edges of the texture map so that they match better when the pattern is repeatedly applied to a surface Here s how First open the texture map within an image editing application This article will describe how to modify the texture using Adobe Photoshop 7 0 but other software packages should have similar features Before proceeding further be sure to save the file with a different name so you can experiment freely without fear of losing the original file Next use the Image Image Size command to determine the dimensions of the texture map in pixels The cement tif texture supplied in HVE is 256 pixels by 256 pixels Next engage the Filter Other Offset command In the window which appears enter the values of 128 in the Horizontal and Vertical boxes and put a check in the box labeled Wrap Around This will cause the texture to be shifted exactly half its dimension in both the vertical and horizontal directions By doing this you have just created a texture tile wh
6. software The HVE Forum also presents a great opportunity to meet other users and expand your network of resources Engineering Dynamics Corporation Training Course Schedule EDC Simulations Los Angeles CA January 2005 Miami FL November 10 14 2003 EDC Reconstruction Los Angeles CA January 19 23 2004 Miami FL November 2004 Theoretical amp Applied Vehicle Dynamics TOA ade a SS ee ee OE ards Fall 2003 2004 HVE FORUM San Francisco CA May 3 7 2004 Vehicle Dynamics Theoretical and Applied Vehicle Dynamics extends the theory of the basic SAE course and includes direct applications using several vehicle simulation programs e g SIMON EDVSM within the HVE simulation environment as well as a solid theoretical background for such simulations The course is focused towards vehicle design engineers and safety researchers with an interest in a greater understanding of vehicle dynamics and automotive chassis systems development Hands on Training Intensive hands on training on how to use your HVE or HVE 2D system software physics programs and databases is available Contact EDC Customer service for more information about bringing this two day on site course to your office Course Registration You may register for a course by contacting EDC Customer Service at 503 644 4500 or by email to training edccorp com You can also visit
7. 4 September 1999 EDC Technical Newsletterr P 2003 5 Contact EDC if you would like to receive copies of these articles ABS An ABS Anti lock Braking System system is an optional component that when present plays a major role in the calculation of brake torque See Figure 1 ABS works by reducing brake system pressure and therefore brake torque so as to prevent wheel lock up This task is accomplished by monitoring the current longitudinal tire slip actually it is the wheel spin velocity and acceleration that are being monitored by the ABS computer longitudinal tire slip may then be inferred When tire slip reaches a specified level system pressure is quickly dumped from the brake thus allowing the wheel to again spin freely Pressure is then allowed to rebuild The main goal of this process is to keep the tires rolling so the driver can steer the vehicle Reduced braking distance is a secondary benefit For more information about calculating brake torque refer to the HVE User s Manual Section Eleven HVE Brake Designer Or contact EDC Technical Support we re always glad to help 2003 HVE Forum Top 10 Wish List Each year at the HVE Forum attendees to the User s Group meetings develop a Wish List of additional functionality or enhancements for HVE and HVE 2D that they would like to have EDC implement over the next 12 months The groups suggestions are then narrowed down by voting for their Top 10 choices
8. HVE HVE 2D If you have followed all of the troubleshooting tips to try to correct your problems and are still experiencing random program crashes or not seeing all of the dialogs being displayed on your computer please contact EDC Technical Support We have heard that some notebook computers and desktop computers with ATI Radeon graphics chipsets can provide extremely sluggish reponse when running HVE or will not properly display environment models Users have typically returned these computers and bought others with different graphics cards to avoid the problem without ever telling us the make and model of the one that gave them problems With so many different configurations out there this is detailed information we really need to know Using this information we will be able to pinpoint and study the issues and then identify solutions to overcome any problems Call for Papers and Simulation Movies If you are interested in presenting a technical paper in the HVE White Paper session or contributing a simulation movie to the HVE Simulations Festival for the 2004 HVE Forum now is the time to prepare For the HVE White Paper session please submit your abstract to EDC Customer Service before October 15 2003 Please include complete contact information for the lead author with each abstract submission If you would like to discuss possible topics for your paper please call and talk them over with us For the HVE Simula
9. ayed on the surface 6 That s it Now create an event and place a vehicle on your suface to test the scale of your scene As a Side note you could use the advanced capabilities of a 3D modeling program to create a 3D terrain model and then map an aerial photograph to the surface This provides the scaled image appearance and also accounts for terrain irregularities and changes when vehicles drive on the surface EQO 4 SUMMER 2003 Technical Newsletter User Hints and Tips This section contains useful hints and tips to help HVE and HVE 2D Users make the most of their software gt Not satisfied with the image quality of your movies but don t want to change the video codec you are using Try increasing the settings for Anti Aliasing from 1 to at least 3 It is best to do this just after you set your Destination to AVI as it increases the time to refresh the screen You will see immediate improvements Some users report adjusting the setting up to 10 to achieve a very clear crisp image The only drawback to increasing your anti aliasing setting this high is the length of time your graphics card will take to refresh the screen You ll have to try and decide for yourself Remember if you do turn up your anti aliasing settings be sure to set them back down to 1 after making the movie otherwise your program will be very slow to respond HVE and HVE 2D F A Q This section contains answers to frequently asked questi
10. calculated high speed say 80 mph and execute the run Then produce a graph of Forward Acceleration vs Brake Pedal Force Voila You now know precisely how hard to press the brake to achieve a desired deceleration Q R XTiro Wheel EQO 2 Tire SUMMER 2003 Technical Newsletter HVE Brake Designer As shown earlier Brake Torque Ratio is one of the key players in the calculation of brake torque By default Brake Torque Ratio is a single lumped parameter assigned for each wheel and editable by the user However we can go a step further Brake Torque Ratio can also be calculated using the mechanical and geometrical properties in the individual brake assembly The HVE Brake Designer does exactly that Different types of brakes disc various types of drums S cams wedge etc are mechanically different from each other Free body diagrams of the forces acting between the pads and rotor or shoes and drum are used to compute the brake torque ratio for each of eight different user selectable brake types The brake torque ratio will also vary as changes in brake temperature dynamically affect lining friction Thus the model allows for a very thorough analysis of brake failure mechanisms A good example of this is the study of marginal brake adjustment on the ability of a truck driver to maintain control while traveling over a long down hill grade See the following three articles for examples SAE Paper No 200 01 129
11. ec 17 7K ITIK Figure 6 Texture map after offset filter and smoothing via the Clone Stamp tool You ve now completed the modification of the texture map Try applying the new texture to the roadway Surface you created in HVE Compare it with the surface mapped with the unmodified texture and you ll likely find that it appears smoother and more realistic as shown in Figure 7 You ll notice that there is still repetition in the surface the texture map has been smoothed but is after all still being repeated However the effect is now less noticeable Now your vehicles will appear less like they are traveling across a dance floor Good luck Rot Roty M Zoom 4 45 0 Dolly NUM Figure 7 Roadway with smoothed concrete texture map If you have any questions or would like to discuss the techniques described in this Contributors Corner article please contact the author Eric Deyerl P E 214 Main Street Suite 303 El Segundo CA 90245 310 615 2600 edeyerl sbcglobal net Suggested Computer Requirements EDC Needs Your Help We are constantly trying to offer advice to users about their choice of options and upgrades for computers they are considering purchasing for their office However it seems like there are new configurations of processor and graphics cards available every day of the year We need your help in determining if there are configurations out there that have problems with running
12. n to vehicle loss of control simulation to the study of possible injury causation of occupants during a crash The following White Papers may be downloaded directly from the EDC website WP 2003 1 Downhill Commercial Vehicle Simulations Part A Tractor Semi trailer Brake Fade WP 2003 2 Downhill Commercial Vehicle Simulations Part B Intercity Bus Equipped with an Engine Data Recorder WP 2003 3 Reconstruction of Real World Side Impact Vehicle Collisions Using HVE A Case Study of Pediatric Pelvic Fracture WP 2003 4 Investigating the Use of Simulation Model Non linear SIMON for the Virtual Testing of Road Humps WP 2003 5 Constructing Detailed Road Surfaces for Vehicle Dynamics Simulation Using 3D Laser Scanning M Techniques HVE White Paper Session Presenters posing for a quick group photo with Terry Day From left to right Larry Jackson Shresta Marigowda Terry Day Fabian Marsh Iwan Parry and Yoganand Ghati EOS Technical Newsletter SUMMER 2003 Technical Session This Technical Session explains how the brake system on a 3 D simulation model e g SIMON EDVSM works 3 D simulation users will note that the driver brake table includes the Pedal Force option 2 D simulations not having a brake system model include only the Wheel Force and Available Friction options although these options may be available in some 3 D simulation models they reduce the quality
13. of the results and EDC does not recommend their use The 3 D brake system model in the simulation works just like it does in a real vehicle It starts with the driver pressing the brake pedal in the simulation this is presented as a table of brake pedal force vs time The master cylinder converts this force to brake system pressure in the simulation this is called the Brake Figure 1 Schematic flow of 3 D brake system simulation Pedal Ratio The system pressure may then be model reduced through a proportioning valve modeled by a Threshold Pressure and Proportion Ratio Next the system pressure may be modulated at each wheel by an ABS system This modulation is controlled by a The tire longitudinal slip is then computer software algorithm in the simulation just as it is on the actual vehicle Finally the system pressure is Slip VivnooiGenton Vex converted to brake torque by the wheel brake assembly The simulation calls this the Brake Torque Ratio The entire process is shown schematically in Wheel Center The tire s friction mu vs slip data are then used to Figure 1 determine directly for the start of the next timestep the So how does the resulting brake torque actually result OMI RHEIN NOTARJA Xara in braking In addition to equations of motion for linear motion X Y Z and rotation roll pitch yaw 3 D simulations also have equations of motion for wheel spin Application of first principles to wheel spin
14. on the main collisions of my multiple vehicle crash simulation but now I want to add an additional vehicle to my EDSMAC4 event Is this possible A No When you first created the event you selected all of the objects that would be allowed in the event You cannot add or remove any vehicles from the event However you have two possible choices to consider One is to recreate your entire event and add the additional vehicle initially The other is to add an additional event with only the new vehicle and then combine the Traj Sim sequences together in the Playback Window to complete your sequence Q I have a 16 second simulation run but I only want to make a movie of the action from t 5 seconds to t 13 6 seconds Ive tried moving the slider to select the correct starting frame but when I change the Destination to AVI and press the Play button to begin recording the sequence starts from the beginning t 0 Do have to use an external movie editing program or can somehow do this within the Playback Window A You can do this within the Playback Window What you need to do is to play the sequence forward from the beginning to the point where you want it to start recording Dont try to use the slider to set it to a starting frame Press the Pause button to stop the sequence and then change your render settings if desired Change the Destination to AVI and press the Play button Your movie will begin recording from that frame f
15. ons submitted to our Technical Support staff by HVE and HVE 2D users Q I try to run HVE and immediately get an error message from Windows saying that the program failed to initialize Why can I not run HVE A The error message you received probably read something like The application failed to initialize properly Oxc000142 Click OK to terminate the application This error occurs when a Windows program often running as a service restricts access to OpenGL When HVE starts it has to access OpenGL so the restriction results in HVE failing to initialize To correct the problem you must stop the program service that has exclusive control over OpenGL Two programs that we are aware of that cause this problem are MatLab and PCAnywhere If one of these programs is running as a service change the Startup Type of the service to Manual Or you can disable the MatLab or PCAnywere program temporarily by right mouse clicking on their icon in the Taskbar Notification Area and then choosing disable or exit If you find other programs that cause this problem please contact EDC Technical Support Q Can make a QuickTime format movie directly from the Playback Window A No The Playback Window produces an AVI format movie If you need to produce a different format of movie such as QuickTime or mpeg you need to convert the movie using a movie editing program such as Adobe Premier Q I ve been working
16. orward When you reach the point where you want to stop the recording press the Pause button and change your Destination back to the Playback Window When you view your AVI you will see that you have recorded the exact sequence you wanted to F A Q s on EDC Website The EDC website provides a special section dedicated to Technical Support including answers to F A Q s from this and previous Newsletters We encourage you to visit this page to search for answers to your questions before contacting Technical Support for assistance Go to www edccorp comand follow the links to Support 5 EOD Technical Newsletter SUMMER 2003 Contributors Corner Interested in learning how to improve the appearance of the textures applied to your environment model Here is a method submitted by user Eric Deyerl for smoothing out texture maps to reduce the tiling effect which often occurs when using a texture map available Straight out of the box As an example let s look at a texture map intended to represent a concrete surface in HVE This texture map is stored as a file named cement tif which is located in the supportFiles images environments EnvTextures directory within the HVE program directory If you used HVE s 3D Editor and created a rectangular roadway surface with dimensions 50 feet by 200 feet and applied the standard cement texture to the surface at a repetition of 2 5 cycles in X and 10 cycles in Y you d
17. ose pattern will match exactly with the edges of the tiles adjacent to it on all sides when the texture is repeated Figure 5 depicts the results of the application of this filter in Photoshop compared to the original texture Figure 5 Original texture map left and texture map with offset filter applied right We re not quite done yet though As you can see the offset filter has eliminated the differences in patterns at the edges of adjacent texture maps but it has created a pair of vertical and horizontal discontinuities which run across the middle of the texture To minimize this effect click on the Clone Stamp tool in Photoshop Use this tool to copy smooth areas of the texture onto the hard discontinuities across the middle of the texture To make this effect realistic use a medium sized brush with a feathered edge from the Brushes palette a 45 pixel brush works well You may have to make multiple attempts to get the effect just right Also take care not to modify the texture near the edges of the map as the edges by definition already match perfectly from the application of the offset filter and any changes to the texture near the edges will destroy this effect Figure 6 depicts the texture after manipulation with the Clone Stamp tool EQO 6 SUMMER 2003 Technical Newsletter Adobe Photoshop CEMENT Paper Smoothed ti ade Fle Edt image Layer Select Fier yew Window Help i wows A B
18. the Training pages on our website and download a course registration form All courses are eligible for Continuing Education and ACTAR credits See you at our next course Related Training Courses Northwestern University Center for Public Safety NUCPS is no longer actively scheduling the COMPTAR and MATAR courses which used EDCRASH and EDSMAC The material previously covered in these courses is available in the EDC Reconstruction and EDC Simulations courses If you are interested in hosting one of these courses at your location please contact EDC Customer Service at 503 644 4500 Engineering Dynamics Corporation 8625 SW Cascade Blvd Suite 200 Beaverton Oregon 97008 7100 USA Phone 503 644 4500 FAX 503 526 0905 Email info edccorp com Website www edccorp com EDVAP EDCRASH EDSMAC EDSMAC4 EDCAD EDSVS EDVTS EDHIS EDVSM EDVDS EDGEN EDVDB HVE HVE 2D HVE Brake Designer and GetSurfacelnfoQ are trademarks of Engineering Dynamics Corporation All Rights Reserved SIMON and DyMESH Patent number 6 195 625 are registered trademarks of Engineering Dynamics Corporation All Rights Reserved GATB is a trademark of Collision Engineering Associates Inc EQO 8
19. tions Festival you are welcome to submit any simulation movies from previous cases or to prepare an example of your own creation Please contact us to discuss the format file tape etc that is best for submitting your movies 7 EQO Technical Newsletter SUMMER 2003 EDC Training Courses EDC Reconstruction amp EDC Simulations EDC offers an excellent training course on the use of the EDC reconstruction program EDCRASH Both new and long time users of EDCRASH agree that the EDC Reconstruction course is extremely beneficial and challenging EDC also offers an excellent training course on the use of EDC simulation programs such as EDSMAC EDSMAC4 EDSVS and EDVTS The EDC Simulations course offers the fastest way to learn what you really need to know how to efficiently use the program and get the right results These one week courses are designed to fully investigate the program s inner workings Lectures are full of helpful hints gained from years of experience During the course students will use the programs e g EDCRASH EDSMAC4 in either the HVE or HVE 2D simulation environment to complete several workshops highlighting the capabilities of the programs HVE Forum The HVE Forum is an excellent opportunity for HVE and HVE 2D users to jump to a new level of ability By participating in workshops attendees brush up on their present skills learn new techniques and learn how to use the latest advancements in the
20. vailable on the internet as shown in Figure 2 Figure 2 Example aerial photograph of a crowded intersection obtained from a company specializing in providing aerial images over the Internet There are different techniques for using these images but the basic concepts are similar You may need to manipulate the image in a photo drawing editor program Then you can use the capabilities of the 3D Editor to apply a material texture to a surface and create your scaled site Here are two approaches that you might consider Approach 1 You may find it easiest to match a square image to a square surface in the 3D Editor You will need to add background area or crop your image to make its dimensions a perfect square Approach 2 You may choose to work with a rectangular image and use the translation and repeat sliders on the Material Texture dialog to match your image to the surface For either approach follow these general steps 1 Determine the size of the image in inches or pixels and also the scale of the image in feet per inch or pixel 2 Make sure your image is saved in the proper location of supportFiles images environments EnvTextures It must be in this location to be available as a texture in the 3D Editor Texture Editor green marble 2 rgb greer tile rgb hillside rgb HVEtcon tif intersection jpg Intersection square tit Woy gb oak rgb PayvementH appyy alley rgb
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