2010-03-30

Shelley, Stanford's Autonomous Car

Shelley, Stanford's robotic car, goes before the cameras

Stanford's automous car Shelley did a workout at the Santa Clara County Fairgrounds in San Jose on Thursday, and members of the media were there to watch.


FOX News.com

VW, Stanford Build High Performance Robot Racecar

It takes a certain kind of driver with skilled hands to brave the bumpy flats and sharp turns that mark Colorado's Pikes Peak Hill Climb...a 12-mile stretch of mountain switchbacks, rough terrain, and steep curves bordered by sheer drop-offs. But engineers from Stanford University and Volkswagen Group will soon attempt the feat with no hands on the wheel at all, in an effort to improve vehicle safety.


Their unique racecar is a modified Audi TTS coupe called "Shelley." Standard equipment on this autonomous coupe includes GPS sensors, a digital roadmap, and an array of computers that control the navigation and steering. Shelley is also linked to base stations that emit radio signals to improve the accuracy of the GPS. In most tests, the prototype has managed to stay on course to within a few inches.




Shelley - Vehicle Dynamics Control at the Handling Limits




How the car drives herself

Shelley knows exactly where she is on the road by using a differential GPS. Unlike a standard GPS system, hers corrects for interference in the atmosphere, showing the car's position on the Earth with an accuracy of about 2 centimeters. Shelley measures her speed and acceleration with wheel-speed sensors and an accelerometer, and gets her bearings from gyroscopes, which control equilibrium and direction.

"The computer puts all this information together and then compares it to a digital map to figure out how close the car is to the path that we want it to take up Pikes Peak," Gerdes said.

Many control features already exist on the stock Audi. For example, the computers in Shelley's trunk will plug into the car's existing electric steering system. The car moves into action with stock automatic gear shifting and brakes with an active vacuum booster, a feature that normal cars use for emergency braking.

The researchers have programmed Shelley to handle like a racecar by using a set of computer calculations called algorithms. For example, as the car approaches a turn, it calculates a best guess on steering and acceleration. Audi's steering system normally responds to the steering wheel, but since there is no driver, it responds to algorithms that combine information such as the GPS path and inertial movement picked up from its sensors.

As the car approaches a corner, another set of calculations corrects the handling through the turn and prepares for what might happen next.

Sources:
  1. Shelley, Stanford's robotic car, goes before the cameras
  2. FOXNews.com - VW, Stanford Build High Performance Robot Racecar
  3. Mechanical Engineering
  4. YouTube - Stanford's Autonomous Car Gets A Workout
  5. Stanford's robotic Audi to brave Pikes Peak without a driver
Related:
  1. Driverless car - Wikipedia, the free encyclopedia
  2. Shelley, Stanford's robotic car, goes before the cameras (w/ Video)
  3. Stanford Automotive
  4. IEEE Spectrum: Stanford and Volkswagen Unveil An Autonomous Race Car
  5. A robotic car goes for a spin (Video) - SmartPlanet
  6. YouTube - DARPA Grand Challenge: Stanford
  7. YouTube - Stanford teams wins robot car race