Intelligent Transportation Systems-Intersection Collision Avoidance






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forward collison avoidance

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What is it?
System description
Systems in Development

Forward Collision Avoidance with Active Breaking

WHAT IS IT?

Often, forward collisions occur when the driver is distracted, making a safe driving situation dangerous. A Forward Collision Avoidance system measures the closing speed, and if it looks like a collision will occur, the system warns the driver.

27% of all accidents (USA 1997) were rear-end collisions. This shows the potential of forward collision avoidance (FCA) systems.

SYSTEM DESCRIPTION

A collision avoidance system generally operates in the following manner: a sensor installed at the front or back end of a vehicle constantly scans the road for vehicles or obstacles. When one is found, the system determines whether the vehicle is in imminent danger of crashing, and if so, a warning is issued or a collision avoidance maneuver is undertaken, depending on the system.

Systems are predominantly autonomous, where detection is independent of whether other vehicles on the road are equipped with collision avoidance devices; but can be cooperative, where detection relies on vehicle-to-vehicle or vehicle-to-infrastructure communications to exchange information on the vehicle’s presence, location, lane of travel, and speed, among other factors.

The information sources that are used for FCA systems come from one or more of the following sensors:
-Millimeter radar measuring bearing, range and range
rate.
-IR Radar measuring bearing, elevation, range and
range rate.
-Camera with image processing algorithms computing
bearing and elevation. reference

The typical criteria for activation of collision avoidance are:

Time-to-collision: the system determines whether a collision is likely to happen at prevailing speeds and distances within a certain time interval. In a car-following situation, the time-to-collision is the time taken for the two vehicles to collide if they maintain their present speed and heading and
Worst-case scenario: the system assumes that the lead vehicle could brake at full braking power at any time. In essence, it maintains a "critical clearance," the minimum distance necessary to come to a stop in the event the leading car suddenly brakes.

Researchers describe two main challenges:

1. Developing an effective user interface and

2. Creating a system that distinguishes between real and false alarms.

Distracted drivers are less likely to be aware of a visual alert. They need an audible or kinesthetic alert.

Warning devices include:

Visual heads-up displays on the windshield in the driver's field of view, so that their content can be assimilated in conjunction with the driving scene ahead. These displays are intended to minimize distraction from driving tasks, in addition to ensuring that the warning does not go undetected.
Audio signals: in comparison to visual signals, auditory signals appear to be less intrusive. They also can operate even if lighting is poor or the windshield is obscured.
Haptic devices, which use tactile cues, such as vibrations or stiffening of the speed controls.
LED displays: these have been pilot tested in 2003 on a system devised for bus drivers.

Early research was done on a variety of sensor technologies, including passive infrared, laser radar, and video detection. One of the more promising avenues seems to be combining various technologies into what is called "sensor fusion."

SYSTEMS and PRODUCTS

GM/Delphi Delco: Sensor Fusion

In March 2003, GM and Delphi Delco launched a 10-month field test, carried out by the University of Michigan Transportation Research Institute, in which a group of Michigan drivers tested 10 Buick LeSabres equipped with collision warning systems. The testing used sensor fusion. This entailed the use of a GPS digital map to locate the vehicle and its direction of travel on a map, a forward-looking machine-vision system using lane markings to estimate the road geometry ahead of the vehicle, and radar tracking that uses the trajectories of tracked vehicles ahead to determine if there is a pattern that may indicate the upcoming road geometry. The system also included a heads-up display, which issued visual and audible warnings the closer the car came to a potential impact.

The forward collision warning system includes the radar sensor mounted at the front of the car to detect objects in its path. If the lane ahead is clear, the system maintains the set speed, akin to conventional cruise control. When a vehicle is detected directly ahead of the car, the system adjusts vehicle speed to maintain a driver-selected clearance from the vehicle ahead.

This technology is now offered in select models.

Eaton Vorad Company
The Eaton Vorad Company has been selling a forward collision warning system (CWS) and a side-object detection system that may help warn drivers of imminent crash situations. Little independent research has been conducted regarding the effectiveness of the side-object detection systems. As part of the IVI, NHTSA evaluated the effectiveness of the forward CWS on a fleet of 100 trucks. Driver responses to the warning alerts were measured and collected to assess the extent to which the drivers adjust their driving after receiving warnings. Forward-looking video on some trucks provided data on near misses as a complement to the rest of the stored parametric data. All of these data will be analyzed to determine the effectiveness of the CWS and driver behavioral changes.

A possible negative effect of introducing new technologies into vehicles is that they may be a source of distraction for the driver. While most of the research and concern about driver distraction has focused on passenger vehicle drivers, CMVs are often the first to adopt new technologies with could impact the drivers’ attention to the roadway. To explore the extent to which such technologies may be increasing the safety risk for truck drivers, FMCSA and NHTSA initiated a study to examine the issue. The investigators examined a sample of truck devices and conducted focus groups with drivers. The researchers found that device manufacturers provide the capability to limit driver use of the systems while driving, but some fleets and drivers do not implement this capability. Most of the drivers and others interviewed do not perceive distraction from in-vehicle devices to be a significant safety problem compared with other issues, such as fatigue. Future research efforts need to quantify objectively the incidence of distraction as a causal factor in crashes. Existing crash databases do not capture the extent of the truck driver distraction problem because of its likely underreporting.

Honda: Collision mitigation brake system

Honda Motor Company has developed a Collision Mitigation Brake System that predicts rear-end collisions and assists brake operation to reduce the impact. The system determines the likelihood of a collision based on driving conditions, distance to the vehicle ahead, and relative speeds, and uses visual and audio warnings to prompt the driver to take preventive action. It can also initiate control assistance, braking to reduce the vehicle's speed. Honda will offer the system in one model on the Japanese market in June 2005.

References

"Advance Collision Avoidance Field Test Launched in Michigan," IVSource.net, March 29, 2003.

Balvanyos, Tunde, et al. "SmartBRT: A Set of Planning, Analysis and Evaluation Tools for Bus Rapid Transit: Final Report Year 1 of 2." California Partners for Advanced Transit and Highways research report. http://www.its.berkeley.edu/publications/UCB/2003/PRR/UCB-ITS-PRR-2003-07.pdf

Bonnet, C. et al. "Fuel Consumption Reduction Experienced by Two PROMOTE-CHAUFFEUR Trucks in Electronic Towbar Operation." Report from ITS Benefits and Costs Database (US DOT). http://www.benefitcost.its.dot.gov/its/benecost.nsf/0/80B3FD71200FCBBD85256AE70044B0F2

"Chauffeur Shows Off: Demos of Electronic Tow-Bar Functions Dazzle Crowd in Italy." IVSource.net. June 14, 2003.

Frye, Cathy. "International Cooperation to Prevent Collisions at Intersections," Public Roads Magazine, July/August 2001. Vol. 65. No. 1

"Honda Introduces World’s First Collision Avoidance Mitigation System," IVSource.net, June 20, 2003.

"Hitachi Unveils New Radar for Next Generation Eaton VORAD ACC," Ivsource.net, October 9, 2000.

Shladover, Steven E. "PATH Demonstrates Automated Bus Rapid Transit Technologies," California Partners for Advanced Transit and Highways, Online report "Featured Research," Spring 2004. http://www.path.berkeley.edu/PATH/Research/Featured/102803/san-diego.html (accessed April 16, 2004).

Authors: Terri O'Connor and Marika Benko

April 2004

Last updated July 2007

Author:

Hosted by the Institute of Transportation Studies at
the University of California at Berkeley and Caltrans