Cruise Control

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  • Topic: Cruise control, Automobile pedal, Control theory
  • Pages : 10 (2408 words )
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  • Published : April 23, 2013
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Dept. of Electronics & Communication
RVCE, Bangalore

Cruise Control System

|Cruise control is a new technological development which incorporates a factor of comfort in driving. Safety is only a small benefit of this | |system. In short, cruise control can be said to be a system which uses the principles of radar to determine the distances between two | |consecutive moving vehicles in which either one or both of them is incorporated with this system. |

Lalitha Chinmayee H M 1RV11EC052
Namratha H Mahesh 1RV11EC062

Introduction

Every minute, on average, at least one person dies in a crash. Air bags and seat belts save tens of thousands of people a year. But the ultimate solution and the only thing that will save far more lives, limbs and money is cruise control system. Cruise control was commercially introduced in 1958 as an option on the Chrysler Imperial.

Cruise control is an invaluable feature on American cars. Without cruise control, long road trips would be more tiring, for the driver at least, and those of us suffering from lead-foot syndrome would probably get a lot more speeding tickets.

Cruise control is far more common on American cars than European cars, because the roads in America are generally bigger and straighter, and destinations are farther apart. With traffic continually increasing, basic cruise control is becoming less useful, but instead of becoming obsolete, cruise control systems are adapting to this new reality -- soon, cars will be equipped with adaptive cruise control, which will allow your ­car to follow the car in front of it while continually adjusting speed to maintain a safe distance.

What is Cruise Control System?

Cruise control is a system, which automatically controls the speed of an automobile. Most cruise control systems don’t allow the use of cruise control below a certain speed. The purpose of the cruise control system is to maintain a constant vehicle speed despite external disturbances, such as changes in wind or road grade. This is accomplished by measuring the vehicle speed, comparing it to the desired or reference speed, and automatically adjusting the throttle according to a control law.

The cruise control system actually has a lot of functions other than controlling the speed of your car. It can accelerate or decelerate with the tap of a button. There are also several important safety features -- the cruise control will disengage as soon as you hit the brake pedal, and it won't engage at speeds less than a particular value (usually around 25-30 mph). We all know that the things that control the speed of the car are the gas pedal and the brakes. And the brain that normally controls the speed of the car is the brain of the driver. The driver senses the speed by looking at the speedometer and then adjusting the pressure on the gas pedal or the brakes to compensate for variations in the desired speed. The cruise control system does the same thing with one exception. It only controls the gas pedal - it doesn't even know there are brakes in the car!!

A Blind inventor and mechanical engineer called Ralph Teetor, invented cruise control in 1943.

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Modelling

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 acted on by a control force, u. The force u represents the force generated at the road/tire interface. For this simplified 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, due to rolling resistance and wind drag, are assumed to vary linearly with the vehicle velocity, v, and act in the direction opposite the vehicle's motion.

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Figure 1

Summing...
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