DS-100 Virtual Reality Driving Simulator

Figure 1. Typical Computer-generated Driverís Scene

The DS-100 is a virtual reality driving simulator in which the computer generated scenery appears on a rugged, see-through, head-mounted display as a bright image against the black background. A typical computer generated DS-100 image is shown in Figure 1. The interior of the vehicle, including the instrument panel gages and indicators, the rear view mirror, and a front seat passenger can all appear in the display. The driverís hands and the real driver controls (steering wheel, gearshift lever, and column-mounted controls) are viewed by looking through the displayed imagery and are therefore not seen in the computer-generated image.

The DS-100 simulator incorporates a number of innovative features aimed at driving down the cost of driving simulators while maintaining high fidelity. Key features include:

The head-mounted display requires only a single channel of computer graphics to support a total field-of-view of more than 180 degrees in both the horizontal and vertical directions as the driver moves his head from right to left and from up to down. Conventional driving simulators using projection displays typically require three graphics channels and three projectors and screens for the scenery, another channel for the rear view mirror, and a detailed mockup of the car interior Ė all very expensive. Using projection screens or monitors also takes up considerable floor space. The use of virtual reality limits the required floor space for the DS-100 system to about 25 square feet. There are two units, the driver trainer and the computer system. They can be arranged to fit available space. The system includes an optical tracker for head position which, unlike magnetic trackers, works without interference from other nearby simulators or equipment.

Using the see-through mode of the head-mounted display eliminates the need to track the user's hands and to recreate them in the graphics imagery. However, effective use of the see-through mode requires careful control of ambient lighting. To achieve the required ambient lighting condition, the DS-100 utilizes a high-intensity directional light to illuminate the driver controls and the driverís hands. The tasteful yellow striping on the steering wheel helps it show up through the display. The DS-100 hardware is shown in Figure 2.
 
 

Figure 2. DS-100 System

How does the driver trainer work?

Before the simulation exercise begins, the computer keyboard and mouse are used to select the database to be used, the weather effects, the driving conditions, visibility range, other traffic, and distractions. Once the desired conditions are selected, the simulation exercise can begin.


Figure 3. Hardware Block Diagram

During the simulation, the optical tracker monitors the driverís head position. To track the driverís head position, the optical tracker electronics causes the four infrared light emitting diodes (LEDís) located on the helmet-mounted display to illuminate in sequence. Two sensors located above the steering wheel then triangulate the position of each LED and compute the position and attitude of the driverís head. The computer also monitors the position of all driver controls via the data acquisition card to control progress through the simulation database. Using this head and vehicle position and attitude data, the computer system generates a 3-D image corresponding to the current head and vehicle position that is displayed on both the driverís helmet-mounted display and the local monitor. The local monitor is used for simulation setup and also allows other people to watch the progress of the simulation.

Should the driver "crash" into something during the simulation, the car will stop - it will not run through the object as in some simulations. To recover from a crash, the driver must back up and then steer around the object.

Steering Wheel Mechanism

The DS-100 utilizes a force feedback steering wheel to provide road feel to the driver. Effects such as running into a curb are simulated, as is the force needed to make a turn.

CGSD also offers a "flight mode" steering wheel as an option. The flight mode steering wheel control mechanism can be unlocked for game applications. When unlocked, pulling back on the steering wheel causes the simulator to climb into the air and pushing forward causes the simulator to descend. Besides being an ideal feature for games, it also provides an easy-to-use interface for applications such as urban visualization or architectural walk-throughs.

Sound Simulation

A stereo sound card located in the computer provides audio cues to the driver via the HMD earphones. The sound system is used to create a variety of sounds. Sounds from the driverís car horn, engine, wind, wipers, and turn signals are heard.

Suspension and Motion Model

The DS-100 uses a high-fidelity real time vehicle dynamics model developed by Realtime Technologies, Inc. and marketed by Hyperion Technologies, Inc. The General Vehicle Dynamics System (GVDS) is capable of representing a variety of four-wheel vehicles.

The physics-based motion model comprises four wheel & suspension models that are coupled to the 6 degree-of-freedom vehicle equations of motion. Each wheel/suspension model encompasses spring and damping rates, bump stops, anti-sway bars, anti-squat anti-dive geometry, and the roll axis height. The unsprung mass is modeled as a separate body connected by a translational joint to the base body. A tire model is used to predict the tire forces at each wheel.

A power train model calculates the torque at each wheel based on brake pedal, gear, and accelerator pedal inputs. The power train contains complete engine, transfer case, differential, and torque converter models. The engine model is based on a torque lookup map. Parameters such as torque converter efficiency, shift maps, and gear ratios can be specified in the data file. The brake model includes models of the master cylinder, prop valves, wheel cylinders, pad friction, and rotor and wheel diameters.

User selection of input data files allows easy switching between multiple vehicle models. New vehicle models can be developed simply by editing the data file. Expert help will usually be required to closely model a specific new vehicle.

Weather Effects

Weather effects are selected at the keyboard. The choices for weather conditions are Clear, Fog, Rain, and Snow. The color of the sky, haze color, visibility range, and percent of direct vesus ambient illumination change depending on the selected weather condition. This provides realistic weather simulation for most weather conditions.

In rainy conditions, a droplet pattern appears on the windshield and the side windows, and the area under the windshield wipers is swiped clean when the wipers are turned on. The visual database is modified to include reflective puddles in the roadway. If the weather is chosen to simulate snow, the visual database is modified to show snow on roofs, trees, fences and roadways. Visibility is reduced.

Windshield Wiper Simulation

The windshield wiper is modeled with a blade and arm, and moves realistically. The wipers settle to the bottom of the windshield when the wipers are OFF. The rate at which the wiper moves depends on the position of the wiper control; LO or HI. When the wipers are activated, a clear wiped area appears on the windshield.

Databases

The DS-100 database is rich in detail and variety. This vivid database is made possible through CGSDís own Parametric Planets software*, and our RealTexture Tools*, and RealTexture Library* patterns. The database offers a variety of driving environments: city, highway, and country. Collectively, these environments should meet the needs of most users. Four versions of the database are provided; summer right-hand drive, winter right-hand drive, summer left-hand drive, and winter right-hand drive. Each version provides highly detailed imagery suitable for a variety of simulation tasks: Figures 1, 4, 5a, and 5b show scenes in the DS-100 database.

*Parametric Planets™ automatic culture generation software, RealTexture Tools™, and RealTexture Library™ are CGSD products that may be purchased separately.

Figure 4. Database Overview

Note the detail and variety of building types shown in Figure 4.

Figure 5a. Summer Scene

Figure 5b. Winter Scene

Figures 5a and 5b are similar except for the time of year being simulated and the type of tree in the front yard. Note the snow on the roofs, fence, and at the edge of the road.

 

Click on the image at the left to view a demo of our DS 230 Driving Simulator. The demo includes a drive-through of several blocks of a virtual Berkeley CA. Download times vary depending on the speed of your connection.

For PC users, the RealOne Player is recommended to view the 8MB MPEG-4 video.

Mac users can get DivX for MAC OS, available for 8.6 or higher.

 

 

For further information please see our Frequently Asked Questions page and the Product Specification.



Please inquire via e-mail to Roy Latham at rlatham@cgsd.com   Copyright CGSD Corporation 1999