Copyright 2003 by Syed M. Mahmud and Shobhit Sankar1 An Architecture for Intelligent Automotive Collision Avoidance Systems Syed M. Mahmud and Shobhit

Copyright 2003 by Syed M. Mahmud and Shobhit Sankar 1

An Architecture for Intelligent Automotive Collision Avoidance

Systems

Syed M. Mahmud and Shobhit Shanker Electrical and Computer Engg. Dept.

Wayne State UniversityDetroit, MI 48202

Email: [email protected]: (313) 577-3855

Webpage: http://www.ece.eng.wayne.edu/~smahmud


Outline of the Presentation

• Crash Statistics.Crash Statistics.• Active Collision Warning/Avoidance Active Collision Warning/Avoidance

Systems (ACWAS).Systems (ACWAS).• A Proposed Architecture for ACWAS.A Proposed Architecture for ACWAS.• Very Accurate Peer-to-Peer distance Very Accurate Peer-to-Peer distance

calculations without using Differential calculations without using Differential GPS receivers.GPS receivers.

• A Wireless Protocol for ACWAS.A Wireless Protocol for ACWAS.• An algorithm for ACWAS.An algorithm for ACWAS.


Crash Statistics• During the last forty years, significant During the last forty years, significant

improvements have been made in improvements have been made in automotive safety features, such as seat automotive safety features, such as seat belts, air bags, lighting, etc. belts, air bags, lighting, etc.

• As a result, the fatality rate per hundred As a result, the fatality rate per hundred million vehicle miles traveled has fallen million vehicle miles traveled has fallen from from 5.5 to 1.75.5 to 1.7 in the period from the mid- in the period from the mid-1960s to 1994. 1960s to 1994.

• Still in the United States, each year motor Still in the United States, each year motor vehicle crashes account for about vehicle crashes account for about 40,00040,000 deaths, more than three million injuries, deaths, more than three million injuries, and over and over $130 billion$130 billion in financial costs. in financial costs.


Crash Statistics (contd.)

• Crash data collected by the U.S. Crash data collected by the U.S. National Highway Traffic Safety National Highway Traffic Safety Administration (NHTSA) show that Administration (NHTSA) show that approximately approximately 88%88% of rear-end of rear-end collisions are caused by driver collisions are caused by driver inattention and following too closely.inattention and following too closely.

• Study shows that Study shows that an additional one an additional one second warningsecond warning could reduce the rear- could reduce the rear-end and intersection accident rate by end and intersection accident rate by 50 to 90%.50 to 90%. Intersection collisions Intersection collisions account for almost account for almost 30%30% of all crashes. of all crashes.


Active Collision Warning/ Avoidance Systems (ACWAS)• By continuing with the passive safety By continuing with the passive safety

technologies, it will be difficult to technologies, it will be difficult to significantly reduce further crash significantly reduce further crash costs. costs.

• Thus, people have started developing Thus, people have started developing active safety features in order to further active safety features in order to further reduce crash costs.reduce crash costs.

• The introduction of automotive The introduction of automotive Collision Warning/AvoidanceCollision Warning/Avoidance Systems Systems represents the next significant leap in represents the next significant leap in vehicle safety technology.vehicle safety technology.


ACWAS (contd.)

• Automotive Collision Warning Automotive Collision Warning systems try to warn drivers of an systems try to warn drivers of an impending collision event, impending collision event, allowing the driver little bit extra allowing the driver little bit extra time to react. time to react.

• If the collision warning systems If the collision warning systems are built in conjunction with are built in conjunction with drive-drive-by-wireby-wire technology, then the technology, then the system could try to automatically system could try to automatically maneuver the vehicle in order to maneuver the vehicle in order to avoid an impending collision. avoid an impending collision.


Technologies of Current Collision Warning Systems

• Most of the current work in collision Most of the current work in collision warning systems are related to the use warning systems are related to the use of: of:

(1)(1) long range radar or optical sensors to long range radar or optical sensors to detect potential hazards in front of the detect potential hazards in front of the vehicle, vehicle,

(2)(2) short range sensors to warn the driver short range sensors to warn the driver of nearby objects when changing traffic of nearby objects when changing traffic lanes or backing up, and lanes or backing up, and

(3)(3) a lane detection system to alert the a lane detection system to alert the driver when the vehicle deviates from driver when the vehicle deviates from the intended traffic lane. the intended traffic lane.


Technologies of Current Collision Warning Systems (contd.)

• The short and long-range radar and The short and long-range radar and optical sensors require line of site optical sensors require line of site communications.communications.

• Using radar and optical sensors, it Using radar and optical sensors, it would be difficult to detect another would be difficult to detect another vehicle that is behind an obstacle, but vehicle that is behind an obstacle, but approaching the subject vehicle.approaching the subject vehicle.

• Hence, intersection collision warning Hence, intersection collision warning systems didn’t receive enough systems didn’t receive enough attention, even though attention, even though intersection intersection crashescrashes account for almost account for almost 30%30% of all of all crashes.crashes.


Collision Warning/Avoidance Systems Using the Wireless Technology

• If the wireless communication If the wireless communication technology is used, then a vehicle can technology is used, then a vehicle can easily detect all other surrounding easily detect all other surrounding vehicles regardless of the fact whether vehicles regardless of the fact whether or not those surrounding vehicles are or not those surrounding vehicles are behind any obstacles.behind any obstacles.

• Hence, the wireless technology can be Hence, the wireless technology can be used in addition to the existing used in addition to the existing technologies in order to develop better technologies in order to develop better collision warning/avoidance systems.collision warning/avoidance systems.


Motivation for Using the Wireless Communication Technology

• During the last several years, interest in During the last several years, interest in using wireless communication using wireless communication technologies have grown significantly. technologies have grown significantly.

• Bluetooth features are becoming Bluetooth features are becoming common in cell phones, PDAs, etc.common in cell phones, PDAs, etc.

• The automotive industry has started The automotive industry has started introducing Bluetooth technologies in introducing Bluetooth technologies in vehicles. vehicles.

• The Bluetooth-enabled cellphone fitted The Bluetooth-enabled cellphone fitted in the 2003 Saab 9-3 car can access any in the 2003 Saab 9-3 car can access any other Bluetooth-enabled devices in the other Bluetooth-enabled devices in the car.car.


Motivation for Using the Wireless Communication Technology (contd.)

• Global Positioning System (GPS) Global Positioning System (GPS) technologies are also becoming technologies are also becoming popular in many applications including popular in many applications including automotive applications. automotive applications.

• More and more vehicles are coming up More and more vehicles are coming up with built-in GPS features, electronic with built-in GPS features, electronic compasses, and other electronic compasses, and other electronic devices. devices.


Our Proposed Architecture• In our architecture, a vehicle collects In our architecture, a vehicle collects

data from the GPS receiver, electronic data from the GPS receiver, electronic compass, accelerometer, speed sensor, compass, accelerometer, speed sensor, etc., and then exchanges that set of etc., and then exchanges that set of data with other neighboring vehicles in data with other neighboring vehicles in order to warn drivers about impending order to warn drivers about impending collisions.collisions.

• The successful operation of a Collision The successful operation of a Collision Warning/Avoidance system will depend Warning/Avoidance system will depend on how accurately the distance on how accurately the distance between vehicles can be measured and between vehicles can be measured and how fast the set of data can be how fast the set of data can be exchanged among the vehicles.exchanged among the vehicles.


Our Proposed Architecture


An Object Vehicle and its Restricted Boundary Around a Subject Vehicle


An Object Vehicle and its Restricted Boundary Around a Subject Vehicle


An Object Vehicle is Inside the Restricted Boundary

(A warning will be issued to both drivers)


Parameters to Detect an Impending Collision


Vehicles’ Parameters

• There are two types of parameters: There are two types of parameters: staticstatic and and dynamicdynamic..

STATIC PARAMETERS:STATIC PARAMETERS:• For Vehicle Number For Vehicle Number n n (n = 1,2,3…), the static (n = 1,2,3…), the static

parameters are parameters are Ln, Wn, bn, cnLn, Wn, bn, cn..• The static parameters indicate the size of the The static parameters indicate the size of the

vehicle and the location of its GPS receiver vehicle and the location of its GPS receiver within itself.within itself.

DYNAMIC PARAMETERS:DYNAMIC PARAMETERS:• The dynamic parameters are vehicle’s The dynamic parameters are vehicle’s

position position (xn,yn),(xn,yn), speedspeed, , accelerationacceleration, , directiondirection and the status of the and the status of the brakesbrakes, , steering wheelsteering wheel, , gas paddlegas paddle, , turn signalturn signal, etc., etc.


Vehicles’ Parameters (contd.)

• The static parameters are to be The static parameters are to be exchanged only once, when two exchanged only once, when two vehicles first form a network.vehicles first form a network.

• But, the dynamic parameters are to be But, the dynamic parameters are to be continuously exchanged after certain continuously exchanged after certain interval of time.interval of time.

• The successful operation of a Collision The successful operation of a Collision Warning/Avoidance system depends on Warning/Avoidance system depends on how accurately the vehicle’s how accurately the vehicle’s parameters can be measured.parameters can be measured.

• All parameters, except the vehicle’s All parameters, except the vehicle’s position and direction can be measured position and direction can be measured with a very high accuracy.with a very high accuracy.


Accuracy of Direction and Position Parameters

• If two vehicles are moving in the same If two vehicles are moving in the same lane, then the accuracy of the direction lane, then the accuracy of the direction parameter is not that important.parameter is not that important.

• But, if two vehicles are moving in But, if two vehicles are moving in different lanes and are approaching different lanes and are approaching each other (e.g. approaching an each other (e.g. approaching an intersection from two different roads), intersection from two different roads), then the accuracy of the direction then the accuracy of the direction parameter is important.parameter is important.

• The direction can be measured using The direction can be measured using an electronic compass as well as using an electronic compass as well as using the GPS readings.the GPS readings.


Accuracy of Direction and Position Parameters

• Readings from electronic compass Readings from electronic compass have a resolution of about have a resolution of about one degreeone degree, , which may be okay for avoiding which may be okay for avoiding intersection collisions.intersection collisions.

• Accurate measurement of distance Accurate measurement of distance between two vehicles depends on how between two vehicles depends on how accurately the positions of two GPS accurately the positions of two GPS receivers can be determined.receivers can be determined.

• Standard GPS receivers using Standard GPS receivers using Civilian Civilian GPS signalsGPS signals can give a positional error can give a positional error of several tens of feet.of several tens of feet.


Accuracy of Position Parameter• Using differential GPS receivers the Using differential GPS receivers the

positional errors can be reduced to positional errors can be reduced to several feet. But, still this error may be several feet. But, still this error may be too high for developing an effective too high for developing an effective collision warning/avoidance system.collision warning/avoidance system.

• The use of differential GPS receivers The use of differential GPS receivers for collision warning/avoidance for collision warning/avoidance systems requires an systems requires an infrastructure of infrastructure of GPS ground stationsGPS ground stations to cover all the to cover all the highways and freeways of the country.highways and freeways of the country.


Very Accurate Distance Measurement• The following figure shows a 2-D The following figure shows a 2-D

analogy of position measurement analogy of position measurement techniques using satellite signals.techniques using satellite signals.


Use Signals From The Same Set Of Satellites For Accurate Distance

Measurements


A Mathematical Proof Has Been Submitted For Publication

Syed Masud Mahmud, “Syed Masud Mahmud, “Very Very Accurate Peer-to-Peer Distance Accurate Peer-to-Peer Distance Measurements Among Intelligent Measurements Among Intelligent Vehicles Without Using Differential Vehicles Without Using Differential GPS ReceiversGPS Receivers”, ”, submitted to the submitted to the IEEE Transactions on Intelligent IEEE Transactions on Intelligent Transportation SystemsTransportation Systems..


Wireless Protocol for Collision Warning/Avoidance Systems

• If Bluetooth technology is used for the If Bluetooth technology is used for the inter-vehicle wireless links, then each inter-vehicle wireless links, then each vehicle can keep track of another seven vehicle can keep track of another seven vehicles in real-time. vehicles in real-time.

• The master device can exchange The master device can exchange information with a particular slave information with a particular slave device at least once in every 14 time device at least once in every 14 time slots, where each time slot is 625 slots, where each time slot is 625 microseconds long. microseconds long.

• Thus, the master device can exchange Thus, the master device can exchange data with a particular slave device at data with a particular slave device at least once in every 8.75 milliseconds.least once in every 8.75 milliseconds.


Wireless Protocol for Collision Warning/Avoidance Systems (contd.)

• Some messages may need to be Some messages may need to be retransmitted due to errors. Probably we retransmitted due to errors. Probably we can safely assume that the vehicles will can safely assume that the vehicles will be able to exchange messages once be able to exchange messages once every 10 msec, i.e. 100 times/sec. every 10 msec, i.e. 100 times/sec.

• A vehicle traveling at 75 mph can move A vehicle traveling at 75 mph can move only 1.1 feet in 10 msec. Thus, the only 1.1 feet in 10 msec. Thus, the message exchange rate is fast enough message exchange rate is fast enough for collision avoidance systems. for collision avoidance systems.

• The only bottleneck will be the rate at The only bottleneck will be the rate at which data can be collected from GPS which data can be collected from GPS receivers.receivers.


Predicted Positions of Vehicles

• If 10 Hz GPS receivers are used, then If 10 Hz GPS receivers are used, then the vehicles can exchange position the vehicles can exchange position information once every 100ms. information once every 100ms.

• Between two successive GPS readings Between two successive GPS readings the vehicles can exchange their other the vehicles can exchange their other dynamic information 10 times. dynamic information 10 times.

• After a new GPS reading is obtained, a After a new GPS reading is obtained, a vehicle can predict (using speed, vehicle can predict (using speed, acceleration and direction, etc.) the acceleration and direction, etc.) the next positions of the neighboring next positions of the neighboring object vehicles, every 10 msec.object vehicles, every 10 msec.


Predicted Positions of Vehicles


Predicted Positions of Vehicles (contd.)

• This way, the vehicles can also This way, the vehicles can also predict their locations at the time of predict their locations at the time of the next GPS reading. the next GPS reading.

• If there is a difference between the If there is a difference between the predicted location of a vehicle, at the predicted location of a vehicle, at the time of the next GPS reading, and the time of the next GPS reading, and the actual reading from the vehicle’s GPS actual reading from the vehicle’s GPS receiver, then some adjustments can receiver, then some adjustments can be made to refine the prediction be made to refine the prediction algorithm.algorithm.


Computational Algorithm

• Since a subject vehicle will have to Since a subject vehicle will have to keep track of several object vehicles in keep track of several object vehicles in real-time, the vehicle’s computer will real-time, the vehicle’s computer will have to do lots of computations. have to do lots of computations.

• Every 10 msec, the vehicle will have to Every 10 msec, the vehicle will have to work with new sets of data. work with new sets of data.

• However, we can efficiently use the However, we can efficiently use the vehicle’s computation power if we ask vehicle’s computation power if we ask the vehicle’s processor to do the vehicle’s processor to do computation on demandcomputation on demand..


Computational Algorithm• If a subject vehicle detects that the relative If a subject vehicle detects that the relative

speed of an object vehicle is almost zero speed of an object vehicle is almost zero and no other driving conditions is and no other driving conditions is changing, then the subject vehicle can changing, then the subject vehicle can reduce the rate of computation for this reduce the rate of computation for this object vehicle. object vehicle.

• But when certain driving conditions But when certain driving conditions change in the object vehicle, such as change in the object vehicle, such as pressing the brake, removing foot from the pressing the brake, removing foot from the gas paddle, significantly turning the gas paddle, significantly turning the steering wheel, etc., then the subject steering wheel, etc., then the subject vehicle should resume processing the vehicle should resume processing the object vehicle’s data at the normal object vehicle’s data at the normal computation rate.computation rate.


Conclusion• In this paper we studied the feasibility In this paper we studied the feasibility

of using Bluetooth devices along with of using Bluetooth devices along with GPS receivers to develop an GPS receivers to develop an Automotive Collision Automotive Collision Warning/Avoidance System. Warning/Avoidance System.

• The bandwidth available from The bandwidth available from Bluetooth devices is sufficient to Bluetooth devices is sufficient to exchange all vehicle specific exchange all vehicle specific information in real-time. information in real-time.

• We believe that if the subject vehicle We believe that if the subject vehicle and all object vehicles around it use the and all object vehicles around it use the same set of satellites, then distance same set of satellites, then distance between the vehicles can be between the vehicles can be determined with a greater accuracy.determined with a greater accuracy.


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Copyright 2003 by Syed M. Mahmud and Shobhit Sankar1 An Architecture for Intelligent Automotive Collision Avoidance Systems Syed M. Mahmud and Shobhit