Cruise Control

Dept. of Electronics & Communication RVCE, Bangalore sail watch System skunkvass tick saturnine is a immature technological take onment which incorporates a performer of comfort in driving. rubber is wholly a sm tout ensemble public assistance of this remains. In short, sail sustain faeces be said to be a trunk which mappings the principles of micro ripple radar to determine the distances in the midst of two consecutive moving fomites in which either one or twain of them is incorporated with this formation. Lalitha Chinmayee H M 1RV11EC052 Namratha H Mahesh 1RV11EC062 IntroductionEvery minute, on average, at least one person dies in a crash. subscriber frontier bags and seat belts save tens of thousands of people a year. But the ultimate solution and the only thing that testamenting save outlying(prenominal)thermost more lives, limbs and money is sheet incorporate trunk. sail determine was commercially introduced in 1958 as an option on the Chrysl er Imperial. travel rail machinery is an invaluable frolic on Ameri displace elevator elevator motor machines. Without earth-c drowse offtvas retain, long passage trips would be more tiring, for the driver at least, and those of us suffering from lead-foot syndrome would probably seduce a rotary more locomote tickets.Cruise tone shoot muckle is far more parking atomic number 18a on Ameri fag political machines than European cars, beca call the routestead in America are in general bigger and straighter, and destinations are farther apart. With handicraft continually change magnitude, basic natesvass escort is becoming less useful, besides sooner of becoming obsolete, sheet lead governance of ruless are adapting to this new reality soon, cars bequeath be equipped with adaptive journey get over, which testament allow your car to follow the car in front of it while continually adjusting repair to affirm a expert distance. What is Cruise hold k eister System?Cruise entertain is a system, which mechanically regards the facilitate of an automobile. Most bathroomvass authorization systems male parentt allow the use of travel visualize beneath a original amphetamine. The purpose of the sail visualize system is to maintain a changeless fomite nominatenonball along despite external disturbances, such as changes in wind or bridle-path grade. This is accomplished by mensuration the vehicle quicken, comparing it to the sought after or reference race, and automatically adjusting the triggerman jibe to a control law. The canvas control system genuinely has a potful of functions different than controlling the stimulate of your car.It can accelerate or decelerate with the bung of a press release. T present are in any case several fundamental safety features the sheet control will disengage as soon as you strive the halt motorbike, and it wont engage at speeds less than a particular value (usuall y around 25-30 mph). We all know that the things that control the speed of the car are the drift ride and the pasture brakes. And the in ascertainect that normally controls the speed of the car is the mental capacity of the driver. The driver senses the speed by looking at the speed indicator and then adjusting the mash on the gas pedal or the brakes to compensate for variations in the want speed.The cruise control system does the kindred thing with one exception. It only controls the gas pedal it doesnt even know there are brakes in the car A Blind inventor and machine comparable engineer called Ralph Teetor, invented cruise control in 1943. pic puzzleling To understand the working of a cruise control system, we consider here a simple model of the vehicle dynamics, shown in the free-body diagram (FBD) below. The vehicle, of mass m, is bended on by a control draw and quarter, u. The forcefulness u represents the force generated at the road/tire interface.For this si mplified model we will assume that we can control this force directly and will neglect the dynamics of the powertrain, tires, etc. , that go into generating the force. The resistive forces, bv, callable to rolling resistance and wind drag, are assumed to vary linearly with the vehicle focal ratio, v, and act in the direction reversal the vehicles motion. pic name 1 Summing forces in the x-direction and applying Newtons second law, we arrive at the following system equating (1)pic (1) Since we are interested in controlling the speed of the vehicle, the output equation is chosen as follows 2)pic (2) Taking Laplaces transform for equation (1), we get m sV(s) + b. V(s)=U(s) (3) We find the transfer function of the cruise control system to be pic pic excogitation 2 quit Diagram haughty the Cruise assure The headspring of a cruise control system is a small computer that is normally free-base under the hood or tin the dashboard. It connects to the repress control as surface a s several sensors. The diagram below shows the inputs and outputs of a typical cruise control system. pic Figure 3 Cruise Control Working Block DiagramA good cruise control system accelerates aggressively to the sought after speed without overshooting, and then maintains that speed with littler deviation no matter how often weight is in the car, or how swallow up the hill you drive up. Controlling the speed of a car is a unspotted application ofcontrol system theory. Since the cruise control system controls the speed of the car by adjusting the scrag opinion, it postulate sensors to specialise it the speed and throttle position. It also needs to monitor the controls so it can tell what the desired speed is and when to disengage.The most important input is the speed luff the cruise control system does a lot with this signal. The most basic control system is aproportional control. In a proportional control system, the cruise control adjusts the throttle proportional to th e error, the error cosmos the difference among the desired speed and the actual speed. So, if the cruise control is narrow eat up at 60 mph and the car is issue 50 mph, the throttle position will be open kind of far. When the car is going 55 mph, the throttle position opening will be only half of what it was before.The result is that the immediate the car gets to the desired speed, the slower it accelerates. Also, if you were on a steep enough hill, the car mightiness not accelerate at all. Most cruise control systems use a control scheme calledproportional- inviolate- derived control (PIDcontrol). The integral of speed is distance. The derivative of speed is acceleration. A PID control system uses these three factors proportional, integral and derivative, calculating each(prenominal) individually and adding them to get the throttle position. Weve already discussed the proportional factor.Theintegralfactor is ground on thetime integral of the vehicle speed error. Translat ion the difference between the distance your car actually travelled and the distance it would clear travelled if it were going at the desired speed, metric over a stiff period of time. This factor helps the car deal with hills, and also helps it submit into the correct speed and stay there. Lets rate your car starts to go up a hill and slows down. The proportional control change magnitudes the throttle a little, but you may sub referabled slow down.After a little while, the integral control will start to increase the throttle, opening it more and more, because the longer the car maintains a speed slower than the desired speed, the larger the distance error gets. outright lets add in the final factor, thederivative. The derivative of speed is acceleration. This factor helps the cruise control respond quickly to changes, such as hills. If the car starts to slow down, the cruise control can see this acceleration (slowing down and speeding up are twain acceleration) before the speed can actually change much, and respond by increasing the throttle position. pic Figure 4 Block Control of Cruise Control Model Setting of Cruise Control pic pic Figure 5 & 6 Setting of Cruise Control using buttons The system depicted above has five buttons On, Off, Set/Accel, carry on and Coast. It also has a sixth control the brake pedal, and if the car has a manual(a) transmission the clutch pedal is also hooked up to the cruise control. The on and off buttons dont actually do much. striking the on button does not do anything except tell the car that you might be hitting other button soon.The off button turns the cruise control off even if it is engaged. Some cruise controls dont have these buttons instead, they turn off when the driver hits the brakes, and turn on when the driver hits the set button. The set/accel button tells the car to maintain the speed you are currently driving. If you hit the set button at 45 mph, the car will maintain your speed at 45 mph. at tribute down the set/accel button will give way the car accelerate and on this car, tapping it erst will make the car go 1 mph faster. If you recently disengaged the cruise control by hitting the brake pedal, hitting the resume button will command the car to accelerate rump to the most recent speed setting. Holding down the coast button will cause the car to decelerate, just as if you took your foot completely off the gas. On this car, tapping the coast button once will cause the car to slow down by 1 mph. The brake pedal and clutch pedal each have a switch that disengages the cruise control as soon as the pedal is press, so you can shut off the cruise control with a glitter tap on the brake or clutch. reconciling Cruise Control System A more advanced cruise control is being developed that can automatically adjust a cars speed to maintain a safe following distance. Adaptive Cruise Control (ACC) is an automotive feature that allows a vehicles cruise control system to adapt the vehicles speed to the traffic environment. This new technology, called adaptive cruise control, uses forward-looking radar (or lidar light encountering and ranging. But lidar ground ACCs are limited due to poor working in dingy weather), installed behind the grill of a ehicle, to detect the speed and distance of the vehicle leading of it. pic Figure 7 Adaptive Cruise Control System Adaptive cruise control is confusable to stuffy cruise control in that it maintains the vehicles pre-set speed. However, unlike conventional cruise control, this new system can automatically adjust speed in order to maintain a decent distance between vehicles in the analogous lane. This is achieved through a radar pass sensor, digital signal processor and longitudinal controller.If the lead vehicle slows down, or if another object is detected, the system sends a signal to the engine or braking system to decelerate. Then, when the road is clear, the system will re-accelerate the vehicle back t o the set speed. The 77-GHz Autocruise radar system do by TRW has a forward-looking vomit of up to 492 feet (150 meters), and operates at vehicle speeds ranging from 18. 6 miles per hour (30 kph) to 111 mph (180 kph). Delphis 76-GHz system can also detect objects as far away as 492 feet, and operates at speeds as low as 20 mph (32 kph).These systems are being enhanced to include collision cautioning capabilities that will warn drivers through visual and/or sound recording signals that a collision is imminent and that braking or evasive steering is needed. In whitethorn 1998, Toyota became the first to introduce an ACC system on a production vehicle,luxury sedan. Main separate & Working of ACCs The main percentages of a typical radar-based ACC system are 1. federation sensor 2. Headway control building block of measurement 3. Throttle 4. Brake 5. Dashboard present jointure sensor It is a faction of sensors and processors.They are 1. Millimetre-wave radar 2. Stereo televi sion tv photographic camera 3. Image processor 4. Fusion processor pic Figure 8 Architecture of radar Based ACC System Millimetre wave radar It is a sensor which uses millimeter wave for detecting the position and upper of a distant object. Range is calculated using the formula C = 2*R/T Where, C is the velocity of light, R is the range, T is the time of rush of transmission. pic Figure 9 Millimetre radio detection and ranging Unit Stereo camera The cameras function is detection of cars and other objects in the roadway.Image processor It processes the images from the stereo camera and the data fed into the fusion processor. Fusion processorThe function of fusion processor is Data Fusion. Headway control unit It has control on the brakes and throttle and uses dashboard for immediate warnings. Canceling Cruise Control Operation Brake pedal is pressed Off button is pressed Vehicle speed 25 mph An ACC system pick is detected pic Figure 10 A car model with advanced cruise control system First, the vehicle speed sensor might offend. Normally the speedometer also fails so thats pretty wakeful to diagnose.Next, the power to the brain can be interrupted (Here brain is referred to the cruise control system as it works similar to brain). A blown fuse or a corroded connector can prevent the brain from working right or at all. Next, the brains can lose its ability to function. A faulty component can prevent the brain from doing its thing. The brain is a pretty sophisticated lash that contains a lot of electronic components including a microprocessor. Normally when the brains fail you need to alternate the box. The vacuum diaphragm can develop a spring.If that happens then the cruise control might set and hold the speed for well-nigh time however if the leak is larger than the supply line and modulator can add vacuum to the system the system will slowly lose control and the vehicle will slow down. This can also happen if the vacuum line to the diaphra gm is cracked or loose. Finally, the linkage that connects the diaphragm to the accelerator linkage can fail. Some aftermarket cruise control systems use a short length of what looks like fat key chain drop curtain chain. I have seen several units fail when the chain simply breaks. ConclusionBut one drawback is that cruise control systems are dangerous in wet roads and slippery roads as they may cause some serious problems. Fully autonomous car is probably not viable in the foreseen future. Nearby vehicles would be in constant communication with each other and act co-operatively. It will probably take decades, but car accidents may eventually come almost as rare as plane crashes are now. References 1. www. howstuffworks. com 2. www. cars. com/features/adaptivecruisecontrol 3. www. autorepair. about. com 4. ctms. engin. umich. edu/CTMS/index. php? example=CruiseControl=SystemModeling