Final Cruise Control Ppt.

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Transcript of Final Cruise Control Ppt.

A PROJECT REPORT ON

(MATLAB IMPLEMENTATION)

SUBMITTED BY :-

JYOTI & ANJALI KASHYAPB.TECH. III YEAR (EC)

PROJECT INCHARGE: (Er. ACHAL MITTAL)

ACKNOWLEDGEMENTWe pose our copious gratitude and like to thanks the entire staff of CETPA INFOTECH PVT. LTD., LUCKNOW for their help and kind

cooperation during our entire project preparation. We are extremely thankful to them for providing us with vital information about the topic. We take this opportunity to pay our sincere thanks to Er. ACHAL MITTAL, PROJECT GUIDE. At last but not the least, we would like to thank our parents and all our peers who have been a constant source of encouragement and inspiration in every walk of life.

CERTIFICATETO WHOMSOEVER MAY IT CONCERNThis is to certify that the work which is being successfully presented in the project report entitled CRUISE CONTROL SYSTEM by us during one month course on MATLAB from CETPA INFOTECH PVT. LTD. LUCKNOW .

DATED:

This is to certify that the above statement made by the candidate is correct to the best of my knowledge.

SUBMITTED BY :JYOTI & ANJALI KASHYAP B.TECH. III YEAR (EC) PROJECT INCHARGE: (Er.ACHAL MITTAL)

INDEXy y y y y

Introduction History Theory of operation Electronic Cruise Control System Modeling a Cruise Control System Physical setup and system equations Design requirements MATLAB representation1. 2.

Transfer Function State-Space

Open-loop response Closed-loop transfer function

y Modeling a Cruise Control System in Simulink Physical setup and system equations Building the model Open-loop response Extracting the Model Implementing PI control Closed-loop response

INTRODUCTIONCRUISE CONTROLCruise control is a system that automatically controls the speed of a motor vehicle . It is sometimes known as speed control or autocruise. The system takes over the throttle of the car to maintain a steady speed as set by the driver.

HISTORYThe technology was invented by James Watt and Matthew Boulton in 1788 to control steam engines. Modern cruise control (also known as a speedostat) was invented in 1945 by the blind inventor and mechanical engineer Ralph Teetor. His idea was born out of the frustration of riding in a car driven by his lawyer, who kept speeding up and slowing down as he talked. The first car with Teetor's system was the Chrysler Imperial in 1958. This system calculated ground speed based on driveshaft rotations and used a solenoid to vary throttle position as needed.

THEORY OF OPERATIONThe cruise control may need to be turned on before use in some designs it is always "on" but not always enabled (not very common), others have a separate "on/off" switch, while still others just have an "on" switch that must be pressed after the vehicle has been started. Most designs have buttons for "set", "resume", "accelerate", and "coast" functions. Some also have a "cancel" button. Alternatively, depressing the brake or clutch pedal will disable the system so the driver can change the speed without resistance from the system. The system is operated with controls easily within the driver's reach, usually with two or more buttons on the steering wheel spokes or on the edge of the hub like those on Honda vehicles, on the turn signal stalk like in many older General Motors vehicles or on a dedicated stalk like those found in, particularly, Toyota and Lexus. The driver must bring the vehicle up to speed manually and use a button to set the cruise control to the current speed. The cruise control takes its speed signal from a rotating driveshaft, speedometercable, wheel speed sensor from the engine's RPM or from internal speed pulses produced electronically by the vehicle. Most systems do not allow the use of the cruise control below a certain speed (normally around 25 mph). The vehicle will maintain the desired speed by pulling the throttle cable with a solenoid, a vacuum driven servomechanism or by using the electronic systems built into the vehicle (fully electronic) if it uses a 'drive-by-wire' system. All cruise control systems must be capable of being turned off both explicitly and automatically, when the driver depresses the brake and

often also the clutch. Cruise control often includes a memory feature to resume the set speed after braking and a coast feature to disengage the system without braking. When the cruise control is engaged, the throttle can still be used to accelerate the car, but once the pedal is released the car will then slow down until it reaches the previously set speed.

ELECTRONIC CRUISE CONTROLDaniel Aaron Wisner invented Automotive Electronic Cruise Control in 1968. His invention described in two patents filed that year (#3570622 & #3511329), with the second modifying his original design by debuting digital memory, was the first electronic gadgetry to play a role in controlling a car and ushered in the computer-controlled era in the automobile industry. Two decades lapsed before an integrated circuit for his design was developed by Motorola Inc. as the MC14460 Auto Speed Control Processor in CMOS.

Modeling a Cruise Control Systemy y y y y Physical setup and system equations Design requirements MATLAB representation Open-loop response Closed-loop transfer function

y Physical setup and system equationsThe model of the cruise control system is relatively simple. If the inertia of the wheels is neglected, and it is assumed that friction (which is

proportional to the car's speed) is what is opposing the motion of the car, then the problem is reduced to the simple mass and damper system shown below.

Using Newton's law, the modeling equations for this system become:

(1) where u is the force from the engine. For this example, let's assume that m = 1000kg b = 50Nsec/m u = 500N

y Design requirements The next step in modeling this system is to come up with some design criteria. When the engine gives a 500 Newton force, the car will reach a maximum velocity of 10 m/s (22 mph). An automobile should be able to accelerate up to that speed in less than 5 seconds.

Since this is only a cruise control system, a 10% overshoot on the velocity will not do much damage. A 2% steady-state error is also acceptable for the same reason. Keeping the above in mind, we have proposed the following design criteria for this problem:Rise time < 5 sec Overshoot < 10% Steady state error < 2%

MATLAB representation

1. Transfer FunctionTo find the transfer function of the above system, we need to take the Laplace transform of the modeling equations (1). When finding the transfer function, zero initial conditions must be assumed. Laplace transforms of the two equations are shown below:

Since our output is the velocity, let's substitute V(s) in terms of Y(s): The transfer function of the system becomes:

To solve this problem using MATLAB, copy the following commands into an new m-file: m=1000; b=50; u=500; num=[1]; den=[m b]; cruise=tf(num,den); These commands will later be used to find the open-loop response of the system to a step input. But before getting into that, let's take a look at the state-space representation.

2. State-SpaceWe can rewrite the first-order modeling equation (1) as the state-space model.To use MATLAB to solve this problem, create an new m-file and copy the following commands: m = 1000; b = 50; u = 500; A = [-b/m]; B = [1/m]; C = [1]; D = 0; cruise=ss(A,B,C,D)

y Open-loop responseNow let's see how the open-loop system responds to a step input. Add the following command to the end of your m-file and run it in the MATLAB command window:

step(u*cruise)

From the plot, we see that the vehicle takes more than 100 seconds to reach the steady-state speed of 10 m/s. This does not satisfy our rise time criterion of less than 5 seconds

y Closed-loop transfer functionTo solve this problem, a unity feedback controller will be added to improve the system performance. The figure shown below is the block diagram of a typical unity feedback system.

The transfer function in the plant is the transfer function derived above {Y(s)/U(s)=1/ms+b}. The controller will to be designed to satisfy all design criteria.

Modeling a Cruise Control System in Simulink Physical setup and system equations Building the model Open-loop response Extracting the Model Implementing PI control Closed-loop response

Physical setup and system equationsThe model of the cruise control system is relatively simple. If the inertia of the wheels is neglected, and it is assumed that friction (which is proportional to the car's speed) is what is opposing the

motion of the car, then the problem is reduced to the simple mass and damper system shown below:

Using Newton's law, modeling equations for this system becomes:

where u is the force from the engine. For this example, let's assume that m = 1000kg b = 50Nsec/m u = 500N

Building the ModelThis system will be modeled by summing the forces acting on the mass and integrating the acceleration to give the velocity. Open Simulink and

open a new model window. First, we will model the integral of acceleration.

y Insert an Integrator Block (from the Linear block library) and draw lines to and from its input and output terminals. y Label the input line "vdot" and the output line "v" as shown below. To add such a label, double click in the empty space just above the line.

Since the acceleration (dv/dt) is equal to the sum of the forces divided by mass, we will divide the incoming signal by the mass. y Insert a Gain block (from the Linear block library) connected to the integrators input line and draw a line leading to the input of the gain. y Edit the gain block by double-clicking on it and change its value to "1/m". y