Knock detecting door lock. Group members D.G.U.I Wickramarathna 100590G D.G.C.D Wijerathna 100596F Y.M.S.N Wijayarathna 100597J W.M.N.C Wijebandara 100598M
AbstractThe project idea was to build a knock detecting In building knock detecting door lock we useddoor lock which can identify the specific knocking micro controllers, pattern detecting algorithms,pattern and unlock the door if the pattern is touch sensor circuit and password detect system.correct. This door locking system provides much At the first we use a Guitar Pick (microphonesecurity than systems which are currently using. used in guitars) and detect the sound appearsWhen there are many users who use the door, when knocking the door, but later we change it soproblems may occur because there is only one key it detect pattern by touch sensing.to open the door. But here in this door lockingsystem this kind of problems may not occurbecause the users who know the knocking patterncan open the door any time without a key.IntroductionBackground ProblemDoor lock is use in doors to lock the door, it is asecurity strategy use for avoiding to open the Key door lock is the most common door lock wedoor. Only rightful person can open the door. see in homes and many other buildings. MostlyThere are many type of door locks currently use one key is use for one door so when many usersin the world. Key door lock is the most common use door problems may occurs. And alsoone among them. In high security systems it uses security problems may occur if the keys can beelectronic door locks. Electronic door lock is duplicated.If the key is lost door can’t be openedlocking device which operate with the means of by the user and it can be found by someone else.electricity. More often electronic door locks are And also door opening should be very simpleconnected to an access control.The advantages and user doesn’t like to spend more time in frontof an electric lock connected to an access control of the door opening the door. So facesystem include: key control, where keys can be recognition, eye detecting door lock also haveadded and removed without re-keying the lock some problems. Passcode door locks havecylinder; fine access control, where time and security problems in if someone can fetch theplace are factors; and transaction logging, where password by looking user typing the password.activity is recorded. Numerical codes,passwords, passphrase, Security tokens, Objectivebiometrics, Finger prints, Face recognition etc. We thought about the above mentioned problemare some types of electronic locks. and try to find a solution and a way to improve the security. So knock detecting door lock is the idea we came up. Here door user can assign specific knocking pattern to the door lock (can be a music pattern of a song or a simple pattern) so only the person who know the pattern and who can knock that pattern in certain accuracy can open the door. So only having one key
trouble may not occur with this door lock. Research Because any user who use the door should know the knocking pattern and they can open the door As mentioned in Introduction first we identified any time they want. Further development and the need of a door locking system that reacts to higher security we thought about having a knocking. password or face recognition. But it will take In our research period first we studied about much money for the equipment so we decide how to get sound of knocking. Getting noise free only to build the knock detecting part. And also sound, how to recognize patterns using suitable we thought about farther development by algorithms, connecting system with users mobile connecting the door lock with a mobile phone phone via internet, Arduino Programming are via blue tooth. It increase the security and if user the thing we researched in this period in purpose forgot the knock pattern only the specific user is of coming up with a better solution for the able to connect the door lock. problem we identified. Then we identified the most suitable way to Methods reach our solution. march April May June 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4Identifyin Designg theProject The first design we came up with is to identifyResearch correct knock by identifying sound made at the knock. This is the design we came up to giveMaking that kind of solution.the projectProposaland cost MicrophoneestimationDesign SignalMaking AmplifierPrototypeImplement Analog toation Digital ConverterTestingand Finish SignalProject Processing UnitDocumentation Door Lock
In this first design we used a guitar pick- output will be send in to the door lock whichup(microphone used in guitars) (Figure 1) as the will be opened only if the knock has accepted.microphone. We used it because it can beattached to wood, here to door so it only get the There were few drawbacks of this design.sound come along the timber without any noise. 1. The PIC we planned to use 16F877AThis microphone doesn’t accept any sound other has less performance than we expected.than sound of knocking. 2. Pattern recognition algorithms are too much complex. 3. Even though we use a Guitar Microphone which reduces the noise, noise still have a big impact on results. Because of these issues we had to go to an alternate solution to the problem. To avoid these problems we do certain changes in our design. We decided get pattern of the knock by using touch sensing other than getting sound input. This avoids problems occurred due to noise. Figure 1 :Guitar pick-up We replaced PIC with an Arduino Mega 2560From microphone we get a current signal that is development kit. Since it has more processingproportional to the energy of the sound wave power and memory, we could solve thereceived by the microphone. problems occurred due to law performance ofThen this signal is send to the signal amplifier. PIC.This circuit amplifies the weak signal from Touch- triggeredmicrophone so it can be used in processing. switchThen the amplified signal is send into the SignalAnalog to Digital Converter circuit. In that part Processing Unitanalog signal is sampled at foscillator/64 rate. Thenaverage voltage of each sample is compared Door Lockwith reference voltage and output 1 or 0 for eachsample. Then the output from ADC is a 1, 0 bitpattern. ImplementationThis bit stream is send into the processing unit. Touch triggering switchIn processing unit this bit pattern is comparedwith the saved bit pattern, which is Touch-triggering switch is a circuit which givescorresponding to the correct knock. If the digital output, it returns +5V when touch isdifference between 2 bit patterns is less than pre- present and 0V when no touch present. So thedefined percentage, the knock is accepted as output of this part will be a digital signalcorrect. Otherwise it is considered as wrong. An depending on knock.
We identified three types of touch switches. We identified that this type of switch is more suitable for our device so we designed a switch Resistance touch switch using this type. Hum touch switch Capacitive touch switch So we used ne555 touch circuit which is a type of Hum touch switch also have some deviationResistance touch switch (Figure 2) is the most from it.basic type of touch switch it is based on the factthat human tissues,have a great amount of water This circuit returns a digital signaland salt, something that makes it conductive. corresponding to the knock made. This signal is send into the signal processing unit. Figure 2 :Resistance touch switchThis is not very flexible design and it needs twoelectrodes, and not suitable for exposed toenvironment very much because it can make aconductivity between two electrodes with thetime. Figure 4 : ne555 touch circuitHum touch switch(figure 3) is An Hum touchsensor uses a high gain amplifier such as aDarlington pair to amplify this parasitic voltage.Here is a basic circuit with such a sensor:Figure 3: Hum touch switch
Signal Processing Part is given a priority value according to how many saved patterns it matched with. If it is a correct knock it is saved with its priority value. So when number of times knocks has made is increased, the accuracy of the algorithm will also increase. Door lock Electronic door locks use magnets, solenoidsFigure 4 : Circuit Schematic diagram and motors to actuate the lock by either supplying or removing power. Operating the lock can be as simple as using a switch, for example an apartment intercom door release, orIn signal processing unit, digital signal as complex as a biometric based accesscorresponding to knock made at door is control system.compared with knock patterns which are saved. In Magnetic Lock a large electro-magnet isSignal processing is done by ATMEGA328 mounted on the door frame and a correspondingmicro controller. We used Arduino Uno circuit armature is mounted on the door. When thewhich ATMEGA328 is connected. magnet is powered and the door is closed, the armature is held fast to the magnet. Mag locksProgramming are simple to install and are very attack resistant.Arduino board was programmed using C But the problem with this lock is this needs alanguage. large current and it cannot be supplied by a battery. This current has to be given in mainIn the program, first we save 3 sample knocks in supply, and when there is a power cut this lockprocessing unit. We have to knock 3 times while will not work.pressing a button, so 3 knocks will be saved.What is saved here is the time gaps between two In our design we used motor actuated door lock.+5V pulses in the signal. It is a quality depends In this door lock there is a motor which canon the pattern of the knock. When somebody rotate both ways. The lock is connected via aknocks the door its pattern is compared with lever to this motor. When motor is rotated to athese saved patterns. If it is matched with any of one side, door lock locks and when motorthe saved patterns it will be considered as a rotated to other side it will unlock.correct knock and signal is send to lock to open. Here we used a servo motor for the door lock.Even though in beginning there are only 3samples, when times goes on number of samplesis increased up to 20. When door knock occur it
Bluetooth module We used Blue tooth module in order to advance the security of the door lock. Here a specific person can unlock the door using his phone. This facility can be provided as the interest of the customer. If it is very high security door , door is unlock when the both knock pattern is correct and correct phone is near the door. And also it can be provided as if the specific person forgot the knock pattern he can unlock the door using his phone. Phone has a specific Bluetooth app and it sends serial data which attach the MAC address of theFigure 5: Servo motor phone and receiving the data Bluetooth module check that MAC address with saved MAC address if both are the same door will bePower Supply unlocked.Power is supplied to the system is by a 12Vpower pack. And also here we have used abackup power plan that will work under a powercut using a 9V rechargeable battery. Figure 7: Bluetooth module Figure 6 Results Knock detecting door lock is an advance doorHere 12V supply and 9V supply has connected via 2 lock which can identify specific knock patterndiodes. When 12V supply is present D2 will reverse and figure out it is correct or not. If the knockbiased and no current will be taken from battery. D2 pattern is correct lock will be opened. Specificwill be forward biased only when 12V power supply knock pattern is assigned by the user.is unavailable and then current will be taken frombattery. There is a metal plate in the door where we should knock and only the finger should use to knock because as earlier mentioned in the methods when the finger touches the metal small current is grounded through the body and it is appears as a digital 1 voltage.
User can press and hold the assign button and hand. If the knock is made by wood or anyknock the door in whatever pattern he likes and insulator it won’t work properly.it should be remembered very carefully by allusers who use the door. It is very hard to knock Also user has to make knock on the circuit part,in specific pattern 100% exactly twice. So we if it is made on wrong place of the door it won’thave to save same knock pattern 3 times. Those recognize as a knock. There is an advantage ofare three sample patterns.. That knocking pattern this also. Unauthorized person who is trying towill be saved in the EEPROM. Saved pattern open the door must know the correct place of thewill not be erased even the power is not in the door to know with the correct knock pattern.system. And we use the concept of learning In the earlier design with knock detection byalgorithm. When the user knocks the door it is sound, these problems were not present.compare with the saved samples and calculatethe similarity percentage if it is more than 95%user can open the door. And that knock patternwill be saved as a sample pattern so when thisimplement door lock pattern is adopt to the userspattern changes. And these changes are not bigdifferences with the original samples but verysmall changes which can’t be figure by ears.DiscussionWe thought about how to develop this door lockwith more features. For farther security here wecan assign more than one knock pattern so everymember who use the door has specific knockpattern for each of them. And there may have amain user. Each member should well rememberthere knock pattern and they can open the door.When someone opens the door automaticallySMS is sent to the main user’s mobile phone viaa GSM module informing which user opens thedoor at the time. And also we can assign apassword for the user so he have to knock thedoor correctly and if it is accepted SMS is sentto particular user’s mobile phone requesting thepassword , user have to give the correctpassword to open the door. This will increase thesecurity level much high.There are few limitations of this design too.Touch triggered switch is working by leakingsome current through human body. So to properworking, knock should be only made by human
AcknowledgmentFirst on foremost, we would like to thank Miss. Ashanthi Maxworth who guided us through doing thisproject. Provided important advices, helped us in difficult periods and giving us necessary information.And motivate us to do the project well.And honorable thanks to Prof. (Mrs.) Indra Dayawansa for spend her valuable time forguide us toimprove the device and solving its problems. Provide important advices.We also thank Mr. ArunaUpul Undergraduate at Department of Electronic and TelecommunicationEngineering for helping us with his knowledge to successfully finish our project.Also an honorable mention goes to our families and friends for their understandings and supports on us incompleting this project. Without helps of the particular that mentioned above, we would face manydifficulties while doing thisAt last but not in least we would like to thank all who helped and motivatedus.Referencehttp://en.wikipedia.org/wiki/Touch_switchhttp://www.arduino.cc/en/Main/ArduinoBoardMega2560http://en.wikipedia.org/wiki/Servo_motor