Cruise controller and collision avoidance
For electric cars
Introduction.
Electric car .
An electric car is an automobile which is propelled by electric motor(s), using electrical energy stored in batteries or another energy storage device. Electric cars were popular in the late-19th century and early 20th century, until advances in internal combustion engine technology and mass production of cheaper gasoline vehicles led to a decline in the use of electric drive vehicle. The energy crises of the 1970s and 80s brought a short lived interest in electric cars, but in the mid-2000s took place a renewed interest in the production of electric cars due mainly to concerns about rapidly increasing oil prices and the need to curb greenhouse gas emissions
Electric cars have several potential benefits as compared to conventional internal combustion automobiles that include a significant reduction of urban air pollution as they do not emit harmful tailpipe pollutants from the onboard source of power at the point of operation (zero tail pipe emissions); reduced greenhouse gas emissions from the onboard source of power depending on the fuel and technology used for electricity generation to charge the batteries and less dependence on foreign oil, which for the United States, other developed and emerging countries is cause of concerns about their vulnerability to price shocks and supply disruption. Also for many developing countries, and particularly for the poorest in Africa, high oil prices have an adverse impact on their balance of payments, hindering their economic growth.
Despite their potential benefits, widespread adoption of electric cars faces several hurdles and limitations. As of 2011 electric cars are significantly more expensive than conventional internal combustion engine vehicles and hybrid electric vehicles due to the additional cost of their lithium-ion battery pack. Although battery prices are coming down with mass production and expected to drop further. Other factors discouraging the adoption of electric cars are the lack of public and private recharging infrastructure and the driver's fear of the batteries running out of energy before reaching their destination (range anxiety) due to the limited range of existing electric cars. Several governments have established policies and economic incentives to overcome existing barriers, to promote the sales of electric cars, and to fund further development of electric vehicles, more cost-effective battery technology and their components. The U.S. has pledged US$2.4 billion in federal grants for electric cars and batteries. China has announced it will provide US$15 billion to initiate an electric car industry within its borders. Several national and local governments have established tax credits, subsidies, and other incentives to reduce the net purchase price of electric cars and other plug-ins.
Electric Cars What Is an Electric Car?
An electric car is powered by an electric motor instead of a gasoline engine. The electric motor gets energy from a controller, which regulates the amount of power—based on the driver’s use of an accelerator pedal. The electric car uses energy stored in its rechargeable batteries, which are recharged by common household electricity
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Unlike a hybrid car—which is fueled by gasoline and uses a battery and motor to improve efficiency—an electric car is powered exclusively by electricity. Historically, EVs have not been widely adopted because of limited driving range before needing to be recharged, long recharging times, and a lack of commitment by automakers to produce and market electric cars that have all the creature comforts of gas-powered cars. That’s changing. As battery technology improves—simultaneously increasing energy storage and reducing cost—major automakers are expected to begin introducing a new generation of electric cars.
Electric cars produce no tailpipe emissions, reduce our dependency on oil, and are cheaper to operate. Of course, the process of producing the electricity moves the emissions further upstream to the utility company’s smokestack—but even dirty electricity used in electric cars usually reduces our collective carbon footprint.
Another factor is convenience: In one trip to the gas station, you can pump 330 kilowatt-hours of energy into a 10-gallon tank. It would take about 9 days to get the same amount of energy from household electric current. Fortunately, it takes hours and not days to recharge an electric car, because it's much more efficient. Speaking of convenience, let's not forget two important points: charging up at home means never going to a gas station—and electric cars require almost none of the maintenance, like oil changes and emissions checks, that internal combustion cars require.
Electric motors develop their highest torque from zero rpms—meaning fast (and silent) zero-to-60 acceleration times.
AUTO-CRUISE CONTROL SYSTEM DIAGNOSIS
INTRODUCTION TO AUTO-CRUISE CONTROL SYSTEM DIAGNOSIS
The auto-cruise control system allows driving without stepping on the accelerator pedal by setting a random speed between 40 km/h (25 mph) and 200 km/h (124 mph).
The concept of the feedback loop to control the dynamic behavior of the system: this is negative feedback, because the sensed value is subtracted from the desired value to create the error signal, which is amplified by the controller.
What is Cruise control?
. Cruise control is an automatic speed control mechanism. It relieves the car driver of having to maintain speed manually by pushing the accelerator pedal. Once the cruise control is activated, besides maneuvering duties, the driver need not worry about acceleration control. This mechanism is very useful while driving on long routes and high ways that stretch for hundreds of miles. Besides the ease in driving, this mechanism increases fuel efficiency of the car. By setting the cruise control pace to lesser than the speed limit, you can ensure that you do not land up with speeding tickets!
The control over speed is achieved through control over throttle valve of the engine, which decides the volume of gasoline consumed at a time. The cruise control settings are within reach of the driver and usually have 'on/off', 'resume', 'set', 'accelerate' and 'coast' buttons. Once the driver has manually accelerated the car above a certain minimum speed, the cruise control mechanism can be activated when you set a speed limit. This leaves the accelerator on autopilot and you need not push down the accelerator any more. Even if you push on the pedal and accelerate above the set value, the speed will lower down to the set value, once you release the accelerator pedal. The mechanism stops working in event of braking or tapping of the clutch. The control over speed is achieved by pulling of the throttle cable by a vacuum operated servomechanism. The cruise control module (CCM) monitors the overall functioning of the mechanism through a feedback and relay mechanism
Common Cruise Control Problems
Cruise control mechanism, being a mechanical contraption, is vulnerable to certain problems due to failure of components or failure of coordination between them. Here are the most common cruise control problems that you could face
Vehicle Speed Sensor Failure
Vehicle speed sensor (VSS) is the eye of the cruise control module, that monitors the speed of the vehicle by sending alternating current signals, whose frequency is directly proportional to speed. When the vehicle speed sensor fails, it can no longer receive signal information about vehicle speed, rendering it blind and useless. VSS failure is one of the most common cruise control problems that you could face. How can you know that cruise control not working is a result of VSS failure? Look at the speedometer, as it is dependent on the VSS too. If the cruise control and speedometer stop working simultaneously, you are facing VSS failure. In such a case, the only way out is to repair or replace the VSS.
Cruise Control Module Problems
The cruise control module is the brain of the cruise control mechanism. It processes the signals it receives from the VSS, compares it with set speed value and prods the actuator to accordingly control the throttle through vacuum mechanism. A blown fuse and broken wires can be the bane of a CCM mechanism, leading to functional failure and consequently complete speed control failure. In such a case, repairing or replacing the CCM is the only way to restore back functionality.
Actuator Vacuum Diaphragm Leak
The actuator is the device that actually controls throttle through a vacuum mechanism. If the vacuum diaphragm inside the actuator develops a leak, the cruise control mechanism will fail. This is also one of the most common cruise control problems. The only way out is fixing the leakage, and restoring vacuum inside the actuator.
Throttle Linkage Breakdown
Throttle linkage is the connector between the actuator and the throttle. These linkages are usually metal chains. If they fail or break down, cruise control will stop working. Replacing the linkage will solve the problem
Collision avoidance system
A collision avoidance system is a system of sensors that is placed within a car to warn its driver of any dangers that may lie ahead on the road. Some of the dangers that these sensors can pick up on include how close the car is to other cars surrounding it, how much its speed needs to be reduced while going around a curve, and how close the car is to going off the road. The system uses sensors that send and receive signals from things like other cars, obstacles in the road, traffic lights, and even a central database are placed within the car and tell it of any weather or traffic precautions. A situation that provides a good example of how the system works is when a driver is about to change lanes, and there is a car in his blind spot. The sensors will detect that car and inform the driver before he starts turning, preventing him from potentially getting into a serious accident
Significant applications
Collision avoidance systems are especially useful in bad weather conditions. The sensors in the car would be capable of detecting the poor conditions and would inform the driver on how to drive in them. For example, because fog affects visibility, the sensors would recognize this and alert the driver of any dangers that lie ahead, like a windy turn or another car, giving the driver enough time to slow down, allowing him to escape from what could have been a bad accident. Ongoing research focuses also on collision avoidance during night with
Current Trends in Collision avoidance systems
Collision is something to be avoided. Humans had been researching on the issue, and various developments were made in the field through the years. Vehicles are born in high numbers today and the accidents are also increasing. Present collision avoidance system is based on the sensors placed in vehicles which help in danger situations like how closer are other vehicles from ours, parking assistance, curve guidance etc. Recently, this system has been on an evolution with several gadgets advancing up with the capacity to show weather and traffic conditions on highways. The sensors in our cars can detect signals from other cars, obstacles and traffic lights etc. and save the driver and passengers from potential collisions
Need for Change
Expectations regarding the current collision avoidance system were high that they would reduce accidents to the minimum. But the reality shows a different story. Effectiveness of the present system is not up to the mark. It demands an update in the technique. In the context of alarming increases in accidents, we need a far better system for collision avoidance
New developments
The research for a better system is in progress across the world led by Japan, the U.S. and Europe, indeed the prime victims of hazardous traffic and disastrous road accidents. Many advanced models are developed in the laboratories, yet their effectiveness can be fully assessed only after on-road tests. The range of technical and behavioral issues involved in many models is such that practical applicability of the concepts requires a well-controlled traffic situation, which has a relatively low casualty reduction potential. Some of the latest developments in the field are listed below.
Forward Collision Warning System:
Forward Collision Warning is a system for visual and audible warning on the objects or vehicles in front of a vehicle. Even drivers can see what are in front of their vehicle they are mostly misunderstood about the distance between the vehicles. This system assists the driver find the distance between the vehicles. The status will change from “safe” to “critical” as the distance decreases.
What difference will it make?
Time to Contact (TTC) is the key technique used in the Forward Collision Warning, which detects whether a collision is imminent or not. The system examines the speed of host vehicle, relative speed and relative acceleration by learning the variation in size of the image of the vehicle in front. Consequently, the driver will be warned of the dangers.
Problems:
Excessiveness is the disadvantage of anything. In case of Forward Collision Warning, the system gives out excessive warning even if the driver is intending to stop the vehicle. This creates irritation to the driver and passengers.
Reverse Collision Warning System
In times, the Reverse Collision Warning System has gained popularity and is now an essential part of every vehicle. This system also emits video and audio signals when the vehicle approaches an obstacle, but at the rear. The sensors are normally placed on the rear bumper to avoid a collision.
What difference will it make?
Apart from FWC system, which warns the host driver, the Reverse Collision Warning System alarms the driver of the vehicle which follows. When the distance between the vehicles decreases, The driver behind is given with a warning through flashing brake lights or other warning lights.
Problems:
The problem of excess warning signals pertains in the system of Reverse Collision Warning also. This causes distraction and irritation to drivers
Adaptive Cruise Control (ACC)
It is a recent development in the automatic cruise control found in vehicles today. In Adaptive Cruise Control (ACC), radars and lasers are used to analyse the speed of the vehicle ahead. Whenever there is a variation in the speed of the preceding vehicle, the ACC adjusts the velocity of the host vehicle and maintains a safe distance.