Science & Technology - Posted by Christine Blackman-Stanford on Tuesday, February 9, 2010 11:19 - 1 Comment
Driverless car to scale Pikes Peak
STANFORD (US)—A re-engineered Audi TTS will attempt to ascend the 14,000-foot summit of Pikes Peak in Colorado Springs without an essential ingredient: a driver.
“Our first goal is to go up Pikes Peak at speeds resembling race speeds, keep the car stable around the corners, and have everything work the way we want it to,” says Chris Gerdes, program director of the Center for Automotive Research at Stanford University (CARS) and leader of the graduate research team.
“We’re not going to put it on the mountain until we can do it safely.”
The car, which has reached speeds of 130 miles per hour without a driver on testing grounds at the Bonneville Salt Flats in Utah, “knows” exactly where it is on the road by using a differential GPS, that corrects for interference in the atmosphere, showing the car’s position on the Earth with an accuracy of about 2 centimeters.
The car measures speed and acceleration with wheel-speed sensors and an accelerometer, and gets 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 says.
Many control features already exist on the stock Audi. For example, the computers in the 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 the car to handle like a race car by using a set of computer 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.
Other autonomous cars have crossed the finish line of the Rocky Mountain road, but only at about 25 miles per hour. The 12.4-mile paved and gravel track has 156 turns and a climb of 4,720 feet.
“Our goal is to show that we can do this,” Gerdes says. “There are some sheer drops at Pikes Peak in which any sort of self-preservation kicks in and you slow down a bit. We want to go up at the speed that few normal drivers would ever think of attempting.”
The team has developed almost all of the algorithms needed to climb the hill successfully and will test them before trials at Pikes Peak.
They have gathered data from the course with a similar car and have tested the car on comparable terrain, but not yet on large hills. If anything goes wrong on the summit, someone on the team can flip the “kill switch,” the car’s only remote control feature.
The road test, which will take place in September, is far more than just fun and games, Gerdes says. Research at Stanford’s Dynamic Design Lab may lead to safer cars that respond to human error.
“We hope this project demonstrates that the technologies of stabilizing the car and helping the car stay in its lane will work with each other all the way up to the very limits of the vehicle.”
The project is funded by Volkswagen, Bosch, Honda, Toyota, and Nissan.
Stanford University news: http://news.stanford.edu/