INTERNATIONAL JOURNAL OF ELECTRONICS AND COMMUNICATION ENGINEERING & TECHNOLOGY (IJECET) International Journal of Electronics and Communication Engineering & Technology (IJECET), ISSN 0976 ISSN 0976 6464(Print) ISSN 0976 6472(Online) Volume 3, Issue 3, October- December (2012), pp. 187-196 IAEME: www.iaeme.com/ijecet.asp Journal Impact Factor (2012): 3.5930 (Calculated by GISI) www.jifactor.com IJECET I A E M E APPLIANCE SWITCHING USING EYE MOVEMENT FOR PARALYZED PEOPLE OMKAR S. DESHPANDE E & TC Department, PVPIT, Bavdhan, Pune, Maharashtra, India. E-Mail: deshpandeomkar10@yahoo.com Prof. B.L. MAHAJAN Lecturer, E & TC Department, PVPIT, Bavdhan, Pune, Maharashtra, India. INDRANEEL P. CHAVAN E & TC Department, PVPIT, Bavdhan, Pune, Maharashtra, India. E-mail: chavan.indraneel@gmail.com BRIJESH B. CHAUDHARY E & TC Department, PVPIT, Bavdhan, Pune, Maharashtra, India. E-mail: vijesh.chuodhary@gmail.com ABSTRACT Paralysis is loss of muscle function, loss of feeling (sensory loss) in one or more affected areas. If there is sensory damage as well as motor & such people suffer from Motor Neuron Disease. In other words these people are in near vegetative state with only their eyes moving. Such people are completely dependent on other individuals for all of their work, starting from feeding to general change in position. So, a system needs to be developed to help these people to become independent. There are systems available in the market that are developed to help paralyzed people in some way or the other, but they are limited to only those people who are only partially paralyzed, that means, fully paralyzed people have little or no use of these systems. Also, these systems are very costly, bulky & less portable. Our system will be cost effective, portable & moreover it will help even those people who are completely paralyzed with only their eyes moving. This system will be based on only the movement of the eyes hence eliminating the need of any limb or any other body movements. Keywords: Eye-Sensing mechanism, LDR, microcontroller, RF transreceiver module, LCD 187
1. INTRODUCTION Eye tracking is a technique whereby an individual s eye movements are measured so that the researcher knows both where a person is looking at any given time and the sequence in which their eyes are shifting from one location to another. The annual report of the Ministry of Public Health and Welfare states that 0.73 million people have a motor disability on the legs and arms. For people with these disabilities, many different kinds of activities like switching fan, tubelight, etc. on/off become very problematic due to restricted movements of these body parts. These people are dependent on others for switching any home devices whenever they want to. So, a solution to this using eye-motion technology is proposed by us in this paper. 2. BLOCK DIAGRAM OF TRANSMISSION SECTION Fig. 1: Block diagram of Transmission Section (A) Eye Sensing Mechanism Requirements of sensing apparatus:- The sensor should be able to detect minute changes in the movement of the iris. It should have minimum or no dependence on ambient light. Sensor placement should not depend upon the size of the iris. It should give maximum states with minimum movement of eye. It should have minimum eye fatigue, and should not harm the eye. What can we use to sense the movement of the eye? Can we use the lens of a camera which produces the image of the eye and then detect its motion? A digital camera circuit is a possible solution to the sensing problem. It has less dependence on ambient light and can detect minute movements of the eye. But the circuit is expensive to make and is complex for its requirement of rapid transmission of large data. There must be a simpler, cheaper and yet exquisite solution of the problem. LDRs are used for sensing the movement of the eye. It measures the reflected intensity of light by varying its resistance according to the light intensity incident on it. When the light intensity increases, it resistance decreases and vice-versa. LDR then converts it into voltage so that ADC of microcontroller can measure it. In reality, the normal eye movement without fatigue is the left and right movement only. The up movement of the eye, if done for more times, introduces fatigue to the eye. So it is preferable not to use the upward movement of the eye for control. In this system, we have used 2 LDRs which are positioned as- one to the left of the eyeball & another one to the right of eyeball-as shown in following figure:- 188
Fig. 2: Positions of two LDRs with respect to eye Now, we know that the visible portion of the eye has two parts namely white portion (called sclera in medical terminology) and the coloured portion (pertaining to the iris). These white and black parts of the eye have difference in the way they reflect light. The white sclera reflects most of the light falling on it, while the coloured iris will not reflect light with so much intensity. This intensity difference in the reflected light gives us our sensing mechanism. For the left-right movement of the eye, we have 2 cases:- Case 1:- When the eyeball is rotated towards left Fig. 3: Position of Focus of LDRs when eye is turned left In this case, as seen from fig. 4, the focus of LDR1 moves on the black iris area of the eye while the focus of LDR2 is white sclera region. Since, black iris will absorb much of the incident light, the intensity of light reflected towards LDR1 will be less. And the intensity of light reflected towards LDR2 will be greater. So, the o/p voltage from LDR 1 will be more & o/p voltage of LDR2 will be greater (The maximum voltage from both LDRs will be same & the threshold levels of LDRs are equal to their maximum voltages). Hence, device corresponding to LDR2 will get toggled. Case 2:- When the eyeball is rotated towards right Fig. 4: Position of Focus of LDRs when eye is turned right 189
In this case, as seen from fig. 4, the focus of LDR1 moves on the black iris area of the eye while the focus of LDR2 is white sclera region. Since, black iris will absorb much of the incident light, the intensity of light reflected towards LDR1 will be greater. And the intensity of light reflected towards LDR2 will be less. So, the o/p voltage from LDR2 will be more & o/p voltage of LDR2 will be greater. Hence, device corresponding to LDR1 will get toggled. Table 1: Truth Table for LDR1 & LDR2 (B) Conversion of Sensor Output into Digital Form:- The RF module requires data serially and it also gives back the data serially. Hence it requires some assembly which converts the three or four bits of data acquired from the conversion mechanism to a sequence of serial data. As per our requirement, it is also necessary that this data should not be corrupted by any intervention of the same frequency. This means that we also must have some pre-sequence of at least three bits which is predefined, and this sequence should be checked at the decoder side to validate the data. All this can be taken care of by the ADC (Analog-to-Digital) of microcontroller PIC16F877A. The input to this ADC is the analog voltage signal from the corresponding LDR. Since we have used 2 LDRs, there will be two voltage signals (one from each LDR) applied to the two corresponding input pins of ADC. The converter then generates a digital result of this analog level via successive approximation. The A/D conversion of the analog input signal results in a corresponding 10-bit digital number. That means the output of the ADC will be in terms of 1 s and 0 s. This output is given to RF transmitter which is CMOS compatible & hence don t require line driver like MAX232. Why LCD connected to microcontroller? The output of ADC is given to the RF transmitter as well as to the LCD. This is done so that the user could know the ADC readings of both LDRs during the trials.. Also, we have displayed which device has been toggled at the receiver end merely for the sake of convenience. The user can disconnect LCD whenever he wants to. 190
(C) Data Transmission Module After digital data has been made from the iris movement, this data needs to be transmitted without any error to a distant place, preferably near to the switchboards already installed in the room wirelessly. Wireless transmission is preferred to wired transmission here to avoid a jumble of wires spreading across the room. A point to be noted is that it is more economic to use wires if the switchboard is nearby. But wires may become inconvenient for the user in most cases. Requirements: The following are the main requirements of data transmission and reception:- The transmission and reception should be essentially error free. Any disturbance of the same frequency must not hinder. It should have high distance range. Multiple samples of the eye per second should be sent. Size of the transmitter circuit should be so small that it can be implemented in spectacles itself. The RF module, we have used, operates at Radio Frequency. The corresponding frequency range varies between 30 khz & 300 GHz. In this RF system, the digital data is represented as variations in the frequency of carrier wave. This kind of modulation is known as Frequency Shift Keying (FSK). This RF transmitter operates at a frequency of about 2.4GHz. It receives serial data in digital form from the output of microcontroller. It will convert this digital data into corresponding radio wave of the said frequency. The transmission occurs at the rate of around 250 kbps. 3. BLOCK DIAGRAM OF RECEIVER SECTION (A) RF Receiver Fig. 5: Block Diagram of Receiver Section This RF receiver will receive the RF signal at frequency 2.4 GHz from the RF transmitter. It will then convert the received signal into its equivalent digital form as it was at the input of RF transmitter. This digitally converted data is fed to the decision making section that is microcontroller PIC16F877A. 191
(B) Decision Making Section The decision making block processes on the data available to it from the RF receiver. The microcontroller PIC16F877A is used for this purpose, where the main job of the controller is to make certain decisions according to the available data and send its decisions to the relay board. In addition to data processing, the microcontroller also double checks any false triggering, takes into account the delay caused due to wireless channel and checks whether the transmission is valid or not. Depending on the intensity of light reflection from eyes, microcontroller makes the decision on which of the devices (connected at output) will toggle its state depending on the program. Here, we have program the microcontroller in such way that if LDR1 gets stronger reflections, Relay 1 will be activated whereas LDR2 gets stronger reflections, Relay 2 will be activated. (C) Output Section The output section consists of the relay driver that drives the relays at its output. Since we have used only two devices to show the final output of our system, we require only two relayseach for one device. 4. SOFTWARE DESIGN (A)Software Used for Programming PIC16F877A For programming our microcontroller PIC16F877A, we have used software known as MPLAB IDE v8.56. Software Description MPLAB Integrated Development Environment (IDE) is a free, integrated toolset for the development of embedded applications employing Microchip's PIC and dspic microcontrollers. MPLAB IDE runs as a 32-bit application on MS Windows, is easy to use and includes a host of free software components for fast application development and super-charged debugging. MPLAB IDE also serves as a single, unified graphical user interface for additional Microchip and third party software and hardware development tools. MPLAB IDE has the same user interface for all tools. MPLAB IDE has highly optimized compilers for the PIC18 series microcontrollers, high performance PIC24 MCUs, dspic digital signal controllers and PIC32MX MCUs and not for PIC16 series. So, for compiling the code for PIC16 series we require third party compiler. Compiler:- The third party compiler we have used for PIC16F887A microcontroller is Hi-tech C Compiler for PIC10/12/16 MCUs. 192
(B)Flowchart of System Programming 193
5. RESULT Here we have used red LED to represent the reflected light that will come from eye & will be incident on the LDRs. This is done merely for the sake of demonstration. The actual working & result of system is shown through photographic presentation from Fig. 6(a) to Fig. 6 (f). Fig. 6 (a): Whole Circuit after turning ON Fig. 6(b): Receiver LCD showing Device1 & Device2 initially in OFF state 194
Fig. 6 (c): LED focus on LDR1 & Receiver LCD showing Device1 in ON state Fig. 6 (d): LED refocused on LDR1 & Receiver LCD showing Device1 in OFF state Fig. 6 (e): LED focused on LDR2 & Receiver LCD showing Device2 in ON state Fig. 6 (f): LED refocused on LDR2 & Receiver LCD showing Device2 in OFF state 6. COMPARISON Our system is basically based on the system in [1]. But our system has some major differences compared to the above system. System [1] uses photodiode sensors whereas we have used LDR due to easy availability. This is done because of we already had a set of LDRs available with us. Although, using photodiodes will give good results. The signal conditioning circuit is required for system [1], but our system does not require any signal conditioning since o/p of sensor is suitable enough for further processing. Due to this, our system is less bulky. System [1] uses different modules for encoding, decoding, data transmission & reception, 195
whereas our system uses single CC2500 RF transreceiver module which performs encoding, transmission, reception & decoding. This again reduces bulkiness of system & moreover reduces programming efforts since all functions are performed by same module. Microcontroller used in system [1] is basic 89C51 which cannot be used in case of any additional functionality needs to be added. Our system uses PIC16F877A which is superior to 89C51 in terms of operation speed, functionality, etc. Also, system [1] uses GUI on computer to display output. Hence, there are limitations on its portability & requires experts to maintain the GUI. Our system uses simple 16x2 LCD panel to display the output status. Thus, it is more portable & does not require any special expertise. Hence, our system is much cheaper, portable & technically robust. 7. CONCLUSION Right from the sensor module to the output, each module is working as expected. Our endeavor of the semester is successful Light Dependent Diode (LDRs) work well for good light intensity but not in poor light conditions. A way still needs to be found to reduce the dependence on ambient light. Attempts were also made to make the output of the device more reliable. But due to lack of time, funds we are restricted to very few attempts. This system can further be made more accurate, work in real world by making some optimizations. Few are listed below:- We can use IR sensors to get more accurate output. We can create a Graphical User Interface (GUI) with visual and sound effects, so that it would be very easy and user-friendly device. We can make the data transmission more accurate & secure by using Xigbee (due to high cost of Xigbee as compared to CC2500; we have avoided using it & used CC2500 instead). 8. REFERENCES [1] Pethani Kishan V., Gor Mehul K. and Raja Jimit S. (2011), Intermediate Progress Report on ELECTRONIC SPECTACLES FOR PARALYZED PATIENTS Submitted in the partial fulfilment of ALL INDIA YOUNG ENGINEERS HUMANITARIAN CHALLENGE 2011 [2] Tim Wilmshurst (2009), Designing Embedded Systems with PIC Microcontrollers, Second Edition: Principles and Applications, Newnes Publications [3] Paul Horowitz, Winfield Hill, The Art of Electronics - 2nd Edition, Cambridge University Press. 196