final report.doc

AUTOMATIC RAIN OPERATED WIPER

A PROJECT REPORT

Submitted by

PARTH PATEL (080010102028)

AMRITESH MISHRA (080010102015)

PRIYEN PATEL (080010102032)

VRAJ MISTRY (080010102018)

In fulfillment for the award of the degree

of

BACHELOR OF ENGINEERING

in

AUTOMOBILE ENGINEERING

A D Patel Institute of Technology Vallabh Vidyanagar

Gujarat Technological University, Ahmedabad

CERTIFICATE

Date: 20-04-2011

This is to certify that the dissertation entitled “Automatic Rain Operated

Wiper” has been carried out by “Parth Patel, Amritesh Mishra , Vraj Mistry

and Priyen Patel” under my guidance in fulfillment of the degree of Bachelor

of Engineering in <AUTOMOBILE ENGINEERING> (8th Semester) of

Gujarat Technological University, Ahmedabad during the academic year

2011-12.

Faculty Guide: Head of The Dept. :

Prof. Nikunj S Yagnik Dr. A D Patel

ABSTRACT

The automated windshield wiper system is a system used to automatically detect rainfall and activate the windshield wipers without driver interaction. This product will be developed to mitigate driving distractions and allow drivers to focus on their primary task: driving. The major distraction eliminated with the development of this product is the manual adjustment of windshield wipers when driving in precipitation. The few seconds that a driver takes their attention off the road to adjust a knob while driving in sub par conditions could potentially lead to car accidents. Car manufacturers would readily purchase such a design to incorporate in their vehicles. There are similar autonomous windshield wiper systems on the market today, but no existing system includes speech recognition to switch from manual to automatic modes. The windshield wiper system will detect precipitation with an erroneous detection rate of less than 5 percent. A prototype system will first be developed before the system is mass produced. The windshield wiper system will detect precipitation through optical and impedance sensors that will activate a control unit; speech recognition will be integrated into the system through additional hardware.

Acknowledgement

It would be very difficult to complete the study without corporation and instance of number of

individual and our institution. We take this opportunity to express my sense of gratitude to them.

This project would not be seen the light of day without support, opportunity, environment

provided by institution. We also heart fully thankful to Mr. Nikunj Yagnik, our guide to have the

best presentation of our project. Lastly we would like to take an opportunity to thank all the

people who helped us in collecting necessary information and making of the report. We are

greatful to all of them for helping us with their energy and wisdom.

TABLE OF CONTENTS

Executive Summary......................................................................................................................ii

1. Introduction............................................................................................................................1

1.1. Objective...........................................................................................................................1

1.2. Motivation........................................................................................................................1

1.3. Background......................................................................................................................2

2. Product Description and Goals..........................................................................................2

3. Technical Specifications........................................................................................................3

4. Design Approach and Details..............................................................................................4

4.1. Design Approach..............................................................................................................4

4.2. Codes and Standards.......................................................................................................9

4.3. Constraints, Alternatives, Tradeoffs............................................................................10

5. Schedule, Tasks, and Milestones........................................................................................11

6. Project Demonstration.........................................................................................................12

7. Marketing and Cost Analysis.............................................................................................13

7.1. Marketing Analysis........................................................................................................13

7.2. Cost Analysis..................................................................................................................14

8. Summary..............................................................................................................................16

9. References.............................................................................................................................17

1. INTRODUCTION

The team developed an autonomous windshield wiper system for automobiles using IR and

impedance sensors, a microcontroller, and signal conditioning circuitry. The sensors send an

input signal to the microcontroller that controls the wiper motor through interfacing with the

automobile wiper control circuitry. The motivation of the project centered on developing a

reliable automatic windshield wiper system that is commercially available to a large market of

automobile owners. Research was done on similar products in the market and articles from

academic sources for the foundation of our design approach.

1.1. Objective

The project aims to develop an automatic windshield wiper system that automates the

process of the driver’s manual response to rain on the windshield. Car manufacturers will be

the primary customers for system integration into their future automobile lines, and the

secondary customers will be individual automobile owners, using the system as an after-market

product

Motivation

The National Highway and Transportation Safety Association reports that twenty-six

percent of all car accidents are caused by distractions due to talking on cell phones, eating while

driving, and other similar distractions that take a driver’s focus off the road . The distraction

considered in this project is the adjustment of wiper speed based on the intensity of precipitation

falling. By eliminating the need for drivers to adjust wiper speed while driving, the number of

accidents caused by distraction can be slightly reduced.

Similar systems are currently installed in some luxury vehicles , but such systems have not

reached the massive economy vehicle market. The low-cost solution proposed by the design will

most importantly satisfy the safety and performance requirements needed for the driver at a more

reasonable price. The windshield wiper system will manage to do this by combining the

performance of an inexpensive infrared sensor and impedance sensors. The project

demonstration will determine how our system performs against existing systems, and the cost

analysis will compare against the cost of existing products.

1.3 Background

There are products similar to the MARE systems that are currently on the market.

Existing comparable products on the market include the Rain Tracker system by Opto-

Electronic Design, Inc. and the TRW rain sensor. Both the TRW rain sensor and the

Rain Tracker detect rain through IR sensors that are located behind the rear view mirror

and interpret changes in light patterns that are caused by the precipitation on the

windshield.

The improvement of existing windshield wiper systems is still an area of interest for

researchers. In 2001, researchers presented a report at an IEEE conference that

concentrated on the design and implementation of a rain sensing system. In 2005, they

proposed a windshield wiper system that used small cameras installed in cars’

windshield to detect rain.

2. PRODUCT DESCRIPTION AND GOALS

The product goals are given by the following criteria:

Detect rainfall on windshield

Detect intensity of rainfall

Activate windshield wipers automatically once rainfall is detected

Avoid adverse effects of extraneous and environmental factors

Meet or exceed the response time of the driver

Make adaptable to all vehicles

Develop high reliability (less than five percent intensity detection errors)

Create with ease of installation

The primary goal of MARE is to automatically detect rainfall and activate the windshield

wipers without driver interaction. This system should respond to rainfall in a similar manner as

if the driver were manually controlling his or her windshield wipers. In the project proposal, the

team included a voice-activation feature as a project goal. During prototype development it

became evident to the team that the inclusion of the speech recognition feature would require

more development hours than available, thus adversely affecting the project deadline; therefore,

this feature was not included in the prototype. The automated windshield wiper system consists

of the following:

sensors that detect rain and its intensity

a microcontroller that outputs a control signal to the motor control circuitry

signal-conditioning circuitry to interface with all the components in system

3.1 Need for Automation

3.2 Types of Automation:

In the past, automakers have tried to either eliminate the wipers or to control their speed automatically. Some of the schemes involved detecting the vibrations caused by individual raindrops hitting the windshield, applying special coatings that did not allow drops to form, or even ultrasonically vibrating the windshield to break up the droplets so they don't need to be wiped at all. But these systems were plagued by problems and either never made it to production or was quickly axed because they annoyed more drivers than they pleased.However, a new type of wiper system is starting to appear on cars that actually do a good job of detecting the amount of water on the windshield and controlling the wipers. One such system is made by TRW Inc., here is a PDF describing their rain sensor system. TRW Inc. uses optical sensors to detect the moisture. The sensor is mounted in contact with the inside of the windshield, near the r earview mirror .The sensor projects infrared light into the windshield at a 45-degree angle. If the glass is dry, most of this light is reflected back into the sensor by the front of the windshield. If water droplets are on the glass, they reflect the light in different directions -- the wetter the glass, the less light makes it back into the sensor.The electronics and software in the sensor turn on the wipers when the amount of light reflected onto the sensor decreases to a preset level. The software sets the speed of the wipers based on how fast the moisture builds up between wipes. It can operate the wipers at any speed. The system adjusts the speed as often as necessary to match with the rate of moisture accumulation.The TRW system, which is found on many General Motors cars, including all  Cadillac models, can also be overridden or turned off so the car can be washed.

4. Rain Detection Unit

4.1 Impedance Sensors

The system detects rain by using two sorts of sensors. One of them is the impedance grid

sensor shown in Figure. The grid is made of two comb-like copper plates separated by a

minimum distance of in. The sensor is glued to the windshield glass with the help of a strong

adhesive material. The thin configuration of the plates allows the wiper to slide over without

peeling them off. When the plates are dry, the resistance between the two plates is very high, but

when water is between the plates, current can flow between the plates, thus decreasing the

resistance. This operation allows this design to be used as a rain sensor. The sensor becomes

Operational when one plate is connected to a power source and the other plate is taken as the

sensor output.

Figure: Impedance Grid Sensor with Water Varying Electrical Conduction

A common design challenge consists of finding the sensitivity that minimizes the detection

failure rate. In other words, the separation between the plates is strongly related to the sensors’

sensitivity and its detection rate. Increasing the distance between the plates decreases the failure

rate but it also decreases the sensitivity of the sensor which is inversely related to the system

response time. Another design issue with the impedance grid sensor is the fact that it can act as

an antenna and produce a floating voltage which can trigger a false detection. A solution to the

problem consists of reducing the sensor’s size and grounding the output signal appropriately.

Two other issues of concern are copper oxidation (rust) and physical deformation caused by the

frictional motion of the wipers over the grid sensor. The grid sensor in figure is effective at

detecting rain, but it does a poor job relaying how much water is on the windshield glass at any

point in time. Since the system should be fully automatic, there is a need to develop a way to

measure the average distribution of water falling on the glass in order to control the wiper’s

speed. A modified version of the impedance sensor was designed to provide better intensity

measurements. The new design consists of spacing isolated vertical plates from a single power

plate as shown in Figure. Measuring the voltage at these different plates provides a more

accurate way of determining the rate of rainfall. The sensing device can be mounted anywhere

on the windshield where there is no contact with the wipers. This upgraded version of rain

sensor suffers from the same issues as its predecessor, but it provides more functionality.

Figure: Three-channel

Rain Sensor for Speed

Control.

The sensor works by outputting a voltage, which is a function of how much water is in between

the teeth. The closer the teeth, the more sensitive the sensor becomes. For the prototype, the

separation distance will be adjusted between 0.10 mm and 1.0 mm to the desired sensitivity. At

least two sensors will be made and placed at different locations on the glass to increase

reliability.

Figure : Grid Sensor with varying electrical conduction due to water

A problem with this particular approach is that sometimes rain water is not very conductive;

therefore, the output voltage will be very small and undetectable. One way around this problem

is to use another impedance sensor that monitors capacitance instead of conductance. The

sensor represented in Figure is made of two thin copper plates placed around a glass, thus

forming a capacitor. The presence of water changes the permittivity of the capacitor. The

sudden change results in a detectable current/voltage that is fed into a special input signal

module for amplification and standardization.

Obviously, the reliability and accuracy of the two impedance sensors discussed above

can be improved by combining a multitude of them. However, they are vulnerable to corrosion,

dirt, and other kinds of deposits.

4.2 Optical Sensors

The optical sensors are used to bounce beams of light through the windshield, and look for

disturbances in the beams caused by raindrops at the outside surface of the windshield. The rain

sensor has an emitter that emits pulses of light, coupled into the windshield with a lens. These

beams travel through the windshield at about 45 degrees. Through research it was anticipated

that the infra-red beams were to be totally reflected by the outside surface of the windshield into

the receiver. However, when testing the analog IR sensor supplied by Optek Inc., it was

determined that the infra-red beams were not totally reflected by the windshield, but that the

infra-red beams were approximately 30% reflected by the outside surface of the windshield.

Troubleshooting this issue included using different types of glass to reflect the IR beams and

comparing that output with the results of reflecting the IR beams off a white sheet of paper. In

conclusion, it was determined that the light beams from the IR sensors were not totally reflected

by any type of glass and therefore the design approach was modified. Although the glass did not

reflect 100 percent of the light emitted, there was enough light reflected by the glass to detect the

change in reflectivity due to a raindrop. The downfall is that the rain threshold for the sensor

was lowered and it was not as easy to determine when moisture was present. If rain drops are

present on the outside surface of the windshield, some of the beams escape and this reduces the

intensity of the beams. The detector will measure this reduction in intensity and communicate

that to the rest of the system that actuates the windshield wipers. Figure on page 15 shows a

diagram of the operation.

Figure: Diagrams of IR Sensor

5. Data Processing Unit

The data processing unit is composed of a microcontroller and an output signal module.

The AVR Atmega8 microcontroller was finally selected over the initial TI MSP430

because of its higher output power and number of analog-to-digital channels. The

communication between the computer programmer and the microcontroller is done via

serial peripheral interface bus (SPI). The program executed by the microcontroller is

shown in figure.

Summary of System Control Logic

Once the system is enabled, the system initialization block checks if the sensors are

operational, sets the corresponding input and output pins, and determines if the power

is high enough to keep the microcontroller running. After performing all the necessary

checks, the program reads voltages from the impedance grid sensor and IR sensor in a

sequential order. If water is detected, the microcontroller sends a signal to a power

relay so that the wiper motor is activated at its lowest speed. Afterward, the

microcontroller reads the speed control sensor and determines the appropriate motor

speed by powering other relays. The additional relays affects change the amount of

power going to the motor. The loop continues as long as all the sensors detect water on

the windshield.

6. Windshield Wipers

5.1. Introduction

Windshield wipers are important because they permit driving during rainy and snowy

conditions. Figure showing history of wipers. Note that the last remarkable

development was that of electric wipers. Intermittent wipers are convenient when it is

drizzling or just after it has stopped raining have recently been developed. In addition.

Stepless intermittent wipers, the interval which can been freely selected by driver, and

speed following wipers, the interval of which automatically changes in response to the

vehicle speed, are becoming popular. In addition some wiper system uses rain sensor to

control the interval in response to rainfall and vehicle speed variations are beginning to

appear. This is because there is an increasing demand for windshield wipers, using

latest electronic technology to meet drivers.

3. MARKETING AND COST ANALYSIS

3.1. Marketing Analysis

The MARE windshield wiper system unique blend of dual sensor technologies

enables redundancy in moisture detection. The impedance sensors and IR sensor work in

conjunction to provide optimal wiper actuation. Competitor wiper systems, such as the

TRW Rain tracker, implement a single sensor topology for rain detection. While this

topology lowers the product price, the system is bound by single point failure. If the IR

sensor malfunctions, the tracker system is inoperable. The dual sensor topology of

MARE allows the system to maintain operability in the event that either sensor, IR or

Impedance, malfunction. Herein lays the competitive advantage of the MARE system.

The team believes that this competitive advantage justifies the slightly higher price of the

MARE system over its competitors.

The marketing strategy for MARE focuses on its appeal to two primary clientele:

luxury automobile owners and elderly drivers. Luxury automobile owners would enjoy

the accentuation of their driving experience; elderly drivers the ease of use of the system.

The team will make use of product demonstrations at AARP (American Association of

Retired Persons) Conventions and Automobile shows to market to the primary target

consumers. This approach mitigates the costly advertising scheme and passes on those

savings to the consumer in the form of a lower product price.

REFERENCES

[1] NHTSA Data Sheet, 2001, Available HTTP:

http://www-nrd.nhtsa.dot.gov/departments/nrd-12/809-716/pages/longdesc.htm

[2] “The Rain Tracker Makes Driving More Enjoyable,” [Online Document], Available

HTTP: http://www.raintracker.com/ProductInfo.htm

[3] “TRW Automotive Electronics: Rain Sensor,” 2007, [Online Document], Available

HTTP: http://www.trw.com/images/rain_sensor.pdf

[4] M. Ucar, H. Ertunc, and O. Turkoglu, “The Design and Implementation of Rain

Sensitive Triggering System for Windshield Wiper Motor,” In IEEE IEMDC, 2001,

pp. 329-336.

[5]H. Kurihata, T. Takahashi, I. Ide, Y. Mekada, H. Murase, Y. Tamatsu, and T.

Miyahara, “Rainy Weather Recognition from in-Vehicle Camera Images for Driver

Assistance ,” In IEEE Intelligent Vehicles Symposium, 2005, pp. 205-210

[6] HM Data Sheet, 2007, Available HTTP:

http://www.tranzistoare.ro/datasheets/2300/499674_DS.pdf

[7] National Fire Protection Association, 2007, [Online Document], Available HTTP:

http://www.nfpa.org/

[8] “SAE Standards Development,” Sep 2007, [Online Document], Available HTTP:

http://www.sae.org/standardsdev/

[9] “CAN Specification”, 1991, [Online Document], Available HTTP:

http://esd.cs.ucr.edu/webres/can20.pdf

[10] G. Muller, “Windshield Wiper System with Rain Detector,” U.S. patent no.

5015931, issued June 11, 1991