INTELLIGENT SPEED ADAPTATION & ACCIDENT AVOIDANCE SYSTEM

Intelligent Speed Adaptation (ISA), also known as Intelligent Speed Assistance, is any system that constantly monitors vehicle speed and the local speed limit on a road and implements an action when the vehicle is detected to be exceeding the speed limit. This can be done through an advisory system, where the driver is warned, or through an intervention system where the driving systems of the vehicle are controlled automatically to reduce the vehicle’s speed.

Intelligent speed adaptation uses information about the road on which the vehicle travels to make decisions about what the correct speed should be. This information can be obtained through use of a digital maps incorporating roadway coordinates as well as data on the speed zoning for that roadway at that location, through general speed zoning information for a defined geographical area (e.g., an urban area which has a single defined speed limit), or through feature recognition technology that detects and interprets speed limit signage. ISA systems are designed to detect and alert a driver when a vehicle has entered a new speed zone, when variable speed zones are in force (e.g., variable speed limits in school zones that apply at certain times of the day and only on certain days), and when temporary speed zones are imposed (such as speed limit changes in adverse weather or during traffic congestion, at accident scenes, or near roadworks ). Many ISA systems will also provide information about locations where hazards may occur (e.g., in high pedestrian movement areas, railway level crossings or railroad grade crossings, schools, hospitals, etc.) or where enforcement actions is indicated (e.g., speed camera and red light camera locations). The purpose of ISA is to assist the driver in keeping to the lawful speed limit at all times, particularly as they pass through different speed ‘zones’. This is particularly useful when drivers are in unfamiliar areas or when they pass through areas where variable speed limits are used.

Most motorists do not appreciate the extra risks involved in travelling just a few km/h over the speed limit.[citation needed] Most think that the risk of a casualty crash is doubled if you are travelling at least 25 km/h over the speed limit. Research has found that that, in urban areas, the risk of a casualty crash is doubled for each 5 km/h over the limit. So travelling at 70 km/h in a 60 km/h zone quadruples the risk of a crash in which someone is hospitalised. As a result, it is estimated that about 10% of casualties could be prevented if the large group of motorists who routinely travel at up to 10 km/h over the limit were encouraged to obey the speed limits. About 20% of casualties could be prevented if all vehicles complied with the speed limits. Savings in fatal crashes would be larger."Minor" speeding therefore makes up a large proportion of preventable road trauma. It is difficult for enforcement methods alone to have an effect on this minor speeding. An added problem is that even motorists who want to obey the speed limits (to keep their life, licence or livelihood) have difficulty doing so in modern cars on city roads. This is where an ISA system comes into its own.

Types of ISA (Active/ Passive)

The two types of ISA systems, passive and active, differ in that passive systems simply warn the driver of the vehicle travelling at a speed in excess of the speed limit, while active systems intervene and automatically correct the vehicle’s speed to conform with the speed limit. Passive systems are generally driver advisory systems: They alert the driver to the fact that they are speeding, provide information as to the speed limit, and allow the driver to make a choice on what action should be taken. These systems usually display visual or auditory cues, such as auditory and visual warnings and may include tactile cues such as a vibration of the accelerator pedal. Some passive ISA technology trials have used vehicle modified to provide haptic feedback, wherein the accelerator pedal becomes more resistant to movement (i.e., harder to push down) when the vehicle travels over the speed limit. Active ISA systems actually reduce or limit the vehicle’s speed automatically by manipulating the engine and/or braking systems. Most active ISA systems provide an override system so that the driver can disable the ISA, if necessary, on a temporary basis.

An often unrecognised feature of both active and passive ISA systems is that they can serve as on-board vehicle data recorders, retaining information about vehicle location and performance for later checking and fleet management purposes.

Speed and location determining/ verification technology

There are four types of technology currently available for determining local speed limits on a road and determining the speed of the vehicle. These are:

1.      GPS

2.      Radio Beacons

3.      Optical recognition

4.      Dead Reckoning

Global Positioning System (GPS) Receiver based systems

GPS is based on a network of satellites that constantly transmit radio signals. GPS receivers pick up these transmissions and compare the signals from several satellites in order to pinpoint the receiver’s location to within a few meters. This is done by comparing the time at which the signal was sent from the satellite to when it was picked up by the receiver. Because the orbital paths of the satellites are known very accurately, the receiver can perform a calculation based on its distance to several of the orbiting satellites and therefore obtain its position. There are currently 24 satellites making up the GPS network, and their orbits are configured so that a minimum of five satellites are available at any one time for terrestrial users. Four satellites is the minimum number of satellites required to determine a precise three-dimensional position.

The popularity of GPS in current ISA and in car navigation systems may give the impression that GPS is flawless, but this is not the case. GPS is subject to a number of fundamental problems. Many of these problems relate to the accuracy of the determined position. The receiver still gets the signal from the satellites, but due to satellites' ephemeris uncertainties, propagation errors, timing errors, multiple signal propagation path, and receiver noises, the position given can be inaccurate. Usually these inaccuracies are small and range from five to ten meters for most systems, but they can be up to hundreds of meters. In most situations this may not matter, but these inaccuracies can be important in circumstances where a high speed road is located immediately adjacent to roads with much lower speed limits (e.g., residential streets). Furthermore, because GPS relies upon a signal transmitted from a satellite in orbit, it does not function when the receiver is underground or in a tunnel, and the signal can become weak if tall buildings, trees, or heavy clouds come between the receiver and the satellites. Current improvements being made to the GPS satellite network will help to increase GPS reliability and accuracy in the future but will not competely overcome the fundamental shortcomings of GPS. In order to be used for ISA systems. e.g., schools,banks,etc. should be there in ISA GPS map.

Radio Beacons

Roadside radio beacons, or bollards, work by transmitting data to a receiver in the car. The beacons constantly transmit data that the car-mounted receiver picks up as it passes each beacon. This data could include local speed limits, school zones, variable speed limits, or traffic warnings. If sufficient numbers of beacons were used and were placed at regular intervals, they could calculate vehicle speed based on how many beacons the vehicle passed per second. Beacons could be placed in/on speed signs, telegraph poles, other roadside fixtures, or in the road itself. Mobile beacons could be deployed in order to override fixed beacons for use around accident scenes, during poor weather, or during special events. Beacons could be linked to a main computer so that quick changes could be made.

The use of radio beacons is common when ISA systems are used to control vehicle speeds in off road situations, such as factory sites, logistics and storage centres, etc., where occupational health and safety requirements mean that very low vehicle speeds are required in the vicinity of workers and in situations of limited or obscured visibility.

Optical recognition systems

So far, this technology has been focused solely on recognizing speed signs. However, other roadside objects, such as the reflective "cats eyes" that divide lanes could possibly be used. This system requires the vehicle to pass a speed sign or similar indicator and for data about the sign or indicator to be registered by a scanner or a camera system. As the system recognizes a sign, the speed limit data is obtained and compared to the vehicle’s speed. The system would use the speed limit from the last sign passed until it detects and recognizes a speed sign with a different limit. If speed signs are not present, the system does not function. This is a particular problem when exiting a side road onto a main road, as the vehicle may not pass a speed sign for some distance.

Dead Reckoning

Dead reckoning (DR) uses a mechanical system linked to the vehicle’s driving assembly in order to predict the path taken by the vehicle. By measuring the rotation of the road wheels over time, a fairly precise estimation of the vehicle’s speed and distance traveled can be made. Dead reckoning requires the vehicle to begin at a known, fixed point. Then, by combining speed and distance data with factors such as the angle of the steering wheel and feedback from specialized sensors (e.g., accelerometers, flux gate compass, gyroscope) it can plot the path taken by the vehicle. By overlaying this path onto a digital map, the DR system knows approximately where the vehicle is, what the local speed limit is, and the speed at which the vehicle is traveling. The system can then use information provided by the digital map to warn of upcoming hazards or points of interest and to provide warnings if the speed limit is exceeded. Some top-end GPS-based navigation systems currently on the market use dead reckoning as a backup system in case the GPS signal is lost. Dead reckoning is prone to cumulative measurement errors such as variations between the assumed circumference of the tyres compared to the actual dimension (which is used to calculate vehicle speed and distance traveled). These variations in the tyre circumference can be due to wear or variations in tyre pressure due to variations in speed, payload, or ambient temperature. Other measurement errors are accumulated when the vehicle navigates gradual curves that inertial sensors (e.g., gyroscopes and/or accelerometers) are not sensitive enough to detect or due to electromagnetic influences on magnetic flux compasses (e.g., from passing under power lines or when travelling across a steel bridge) and through underpasses and road tunnels.

Limitations Of Intelligent Speed Adaptation

An initial reaction to the concept of ISA is that there could be negative outcomes, such as driving at the speed limit rather than to the conditions, but numerous ISA trials around the World have shown these concerns are unsubstantiated.

A particular issue is that most ISA systems use a speed database based purely on information regarding the posted maximum speed limit for a roadway or roadway segment. Obviously, many roads have features such as curves and gradients where the appropriate speed for a road segment with these features is less than the posted maximum speed limit. Increasingly, road authorities indicate the appropriate speed for such segments through the use of advisory speed signage to alert drivers on approach that there are features which require a reduction in travelling speed. It is recognised that the speed limit databases used in ISA systems should ideally take account of posted advisory speeds as well as posted maximum speed limits. The New South Wales ISA trial, underway in the Illwarra region south of Sydney currently, is the only trial that is using posted advisory speeds as well as posted maximum speed limits.

Some car manufacturers have expressed concern that some types of speed limiters "take control away from the driver". This is also unsubstantiated, firstly because ISA systems do have provision for over-ride by the driver in the event that the set speed is inappropriate and secondly, the claim is somewhat hypocritical given that cruise control has been in use on vehicles for many years and forces the vehicle to travel at a minimum speed unless there is driver intervention.

For some traffic safety practitioners, active intelligent speed adaptation is thought to be an example of 'hard automation', an approach to automation that has been largely discredited by the Human Factors community. An inviolable characteristic of human users is that they will adapt to these systems, often in unpredictable ways. Some studies have shown that drivers 'drive up to the limits' of the system and drive at the set speed, compared to when they are in manual control, where they have been shown to slow down. Conversely, the experience of some drivers with driving under an active ISA system has been that they find they can pay more attention to the roadway and road environment as they no longer need to monitor the speedometer and adjust their speeds on a continuing basis.

There is also concern that drivers driving under speed control might accept more risky headways between themselves and vehicles in front and accept much narrower gaps to join traffic (this fact drawing particular criticism from motorcycling groups).

Wider criticism also comes from the insistent focus on speed and that road safety outcomes could be better achieved by focusing on driving technique, situational awareness, and automation that 'assists' drivers rather than 'forces' them to behave in particular ways. Intelligent speed adaptation has also been held as an example of a technology which, like speed cameras, can often alienate the driving public and represents a significant barrier to its widespread adoption.

Some studies which pre-date the development of ISA systems indicated that drivers make relatively little use of the speedometer and instead use auditory cues (such as engine and road noise) to successfully regulate their speed. These studies, however, remain unverified. There is an argument in the literature that suggests that as cars have become quieter and more refined speed control has become more difficult for drivers to perform. Thus an alternative 'soft-automation' approach is simply to re-introduce some of those cues that drivers naturally use to regulate speed (rather than incur the expense and unexpected behavioral adaptations of ISA).

Benefits Intelligent Speed Adaptation

Real and perceived benefits of ISA are a reduction of accident risks [citation needed] and reductions of noise[citation needed] and exhaust emissions.

Commercial use

Strategic thinking in traffic safety acknowledges that Intelligent Transportation Systems (ITS), and in-vehicle technologies in particular, hold promise as safety measures to counter the risk of road crashes and the trauma arising from crashes. However, road safety practitioners have been hesitant in embarking on vigorous pursuit of emerging technologies in crash avoidance and occupant protection. This is perhaps best described as a combination of appropriate caution, bureaucratic reluctance, tinged perhaps with historical bias and lack of knowledge. It is recognized that it is difficult indeed to identify just which of a number of future or proposed technologies will prove to be viable, and to identify those future or proposed technologies that will not, as time progresses, result in significant commercial

Implementation

Perhaps it is because of such concerns that the development of ISA systems under research and development programs funded by governments has remained at the prototype or trial stages, despite positive experiences and strong endorsement of ISA technologies for more than a decade.

It is thus not surprising that the commercialisation of ISA systems occurred outside of the mainstream traffic safety community and with only very limited governmental support.

In Australia in 2007 two ISA products emerged in the marketplace and have since established commercial success. Some road safety researchers are surprised that Australia is leading the world with this technology.

         

SpeedAlert is a passive ISA product marketed by Smart Car Technologies, based in Sydney NSW. It offers full national speed zoning information embedded within a GPS-based navigation system, providing drivers with information on speed limits and vehicle speed, as well as related information on locations such as schools, railway level crossings, speed camera sites, etc.. The software is easily affordable for both fleet and private drivers, typically selling for about A$200.

SpeedShield is an active ISA product marketed by Automotion Control Systems, based in Melbourne, Vic. It offers speed zoning information embedded within a GPS-based navigation system, providing drivers with information on speed limits and vehicle speed and is combined with technology that intervenes and controls the vehicle speed to no faster than the posted speed limit for that section of roadway. The technology is generally transferrable across vehicle manufacturers and models, but must be configured for an individual make and model. As the cost is variable (estimated to be A$1–3,000 depending on vehicle type and number of vehicles to be fitted), its commercial use has tended to be into vehicle fleet operations rather than private owners.

Coredination ISA is a passive ISA product marketed by Coredination, based in Stockholm, Sweden. This product is build as a smartphone-application for Android and iPhone. It offers full national speed zoning information, providing drivers with information on speed limits and vehicle speed. The product is very lightweight and no separate hardware or fixed installations are necessary.

ACCIDENT AVOIDANCE SYSTEM :-

1.      Emergency Brake Assist

2.      Traction control system

3.      Electronic Brakeforce distribution

4.      Anti-lock braking system

5.      Blind Spot Information System

Emergency Brake Assist

Emergency Brake Assist (EBA) is a safety system in motor vehicles designed to ensure maximum braking power is used in an emergency stop situation. By interpreting the speed and force with which the brake pedal is pushed, the system detects if the driver is trying to execute an emergency stop, and if the brake pedal is not fully applied, the system overrides and fully applies the brakes until the Anti-lock Braking System (ABS) takes over to stop the wheels locking up.

Research shows that drivers can react too slowly in emergency braking situations. Many drivers are not prepared for the relatively high efforts required for maximum braking, and nor are they prepared for the "buzzing" feedback through the brake pedal during ABS operation. If an emergency develops, a slow reaction and less than maximum braking input could result in insufficient time or distance to stop before an accident occurs.

EBA is designed to detect such ‘panic stops’ and apply maximum braking effort within milliseconds – quicker than the blink of an eye. It interprets braking behaviour by assessing the rate that the brake pedal is activated.

If the system identifies an emergency, it automatically initiates full braking faster than any driver can move their foot. Emergency stopping distances can be shortened, reducing the likelihood of accidents – especially the common ‘nose to tail’ incident.

An electronic system designed to recognise emergency braking operation and automatically enhance braking effort improves vehicle and occupant safety. Can reduce stopping distances by up to 70 ft (21 m) at 125 mph (201 km/h)

If the system identifies an emergency, it automatically initiates full braking faster than any driver can move their foot. Emergency stopping distances can be shortened, reducing the likelihood of accidents – especially the common ‘nose to tail’ incident.

An electronic system designed to recognise emergency braking operation and automatically enhance braking effort improves vehicle and occupant safety. Can reduce stopping distances by up to 70 ft (21 m) at 125 mph (201 km/h)

1.      Reduces or suppress spark sequence to one or more cylinders

2.      Reduce fuel supply to one or more cylinders

3.      Brake force applied at one or more wheels

4.      Close the throttle, if the vehicle is fitted with drive by wire throttle

5.      In turbo-charged vehicles, a boost control solenoid can be actuated to reduce boost and therefore engine power.

Typically, traction control systems share the electro-hydraulic brake actuator (but does not use the conventional master cylinder and servo), and wheel speed sensors with the anti-lock braking system.

Overview

The basic idea behind the need of a traction control system is the difference between traction of different wheels evidencing apparent loss of road grip that compromise steering control and stability of vehicles. Difference in slip may occur due to turning of a vehicle or differently varying road conditions for different wheels. At high speeds, when a car tends to turn, its outer and inner wheels are subjected to different speed of rotation, that is conventionally controlled by using a differential. A further enhancement of the differential is to employ an active differential that can vary the amount of power being delivered to outer and inner wheels according to the need (for example, if, while turning right, outward slip (equivalently saying, 'yaw') is sensed, active differential may deliver more power to the outer wheel, so as to minimize the yaw (that is basically the degree to which the front and rear wheels of a car are out of line.) Active-differential, in turn, is controlled by an assembly of electromechanical sensors collaborating with a traction control unit.

Operation

When the traction control computer (often incorporated into another control unit, like the anti-lock braking system module) detects one or more driven wheels spinning significantly faster than another, it invokes ABS ecu to apply brake friction to wheels spinning with lessened traction. Braking action on slipping wheel(s) will cause power transfer to wheel axle(s) with traction due to the mechanical action within a differential. All-wheel drive AWD vehicles often have an electronically controlled coupling system in the transfer case or transaxle engaged (active part-time AWD), or locked-up tighter (in a true full-time set up driving all wheels with some power all the time) to supply non-slipping wheels with (more) torque.

This often occurs in conjunction with the powertrain computer reducing available engine torque by electronically limiting throttle application and/or fuel delivery, retarding ignition spark, completely shutting down engine cylinders, and a number of other methods, depending on the vehicle and how much technology is used to control the engine and transmission.

Use of traction control

    In road cars: Traction control has traditionally been a safety feature in premium high-performance cars, which otherwise need sensitive throttle input preventing spinning driven wheels when accelerating, especially in wet, icy or snowy conditions. In recent years, traction control systems have become widely available in non-performance cars, minivans, and light trucks.

    In race cars: Traction control is used as a performance enhancement, allowing maximum traction under acceleration without wheel spin. When accelerating out of turn, it keeps the tires at optimal slip ratio.

    In motorcycles: Traction control for a production motorcycle was first available with the Honda ST1100 in 1992. By 2009, traction control was an option for several models offered by BMW and Ducati, and the model year 2010 Kawasaki Concours 14 (1400GTR).

    In off road vehicles: Traction control is used instead or in addition to the mechanical limited slip or locking differential. It is often implemented with an electronic limited slip differential, as well as other computerized controls of the engine and transmission. The spinning wheel is slowed down with short applications of brakes, diverting more torque to the non-spinning wheel; this is the system adopted by Range Rover models in the mid 1990's, for example. This form of traction control has an advantage over a locking differential, as steering and control of a vehicle is easier, so the system can be continuously enabled. It creates less stress on drive-trains, particularly important to vehicles with an independent suspension, generally weaker compared to solid axles.[citation needed] On the other hand, only half of the available torque will be applied to a wheel with traction, compared to a locked differential, and handling is less predictable.

Traction control in cornering

Traction control is not just used for improving acceleration under slippery conditions. It can also help a driver to corner more safely. If too much throttle is applied during cornering, the drive wheels will lose traction and slide sideways. This occurs as understeer in front wheel drive vehicles and oversteer in rear wheel drive vehicles. Traction control can prevent this from happening by limiting power to the wheels. It cannot increase the limits of grip available and is used only to decrease the effect of driver error or compensate for a driver's inability to react quickly enough to wheel slip.

Automobile manufacturers state in vehicle manuals that traction control systems should not encourage dangerous driving or encourage driving in conditions beyond the drivers' control.