1. INTRODUCTION A normal fetal heart rate (FHR) usually ranges from 120 to 160 beats per minute (bpm) in the utero period. At about 5 weeks gestation, your baby's heart begins to beat. At this point, a normal fetal heart rate is about the same heart rate as the mother's: about 80-85 beats per minute (BPM). It is measurable sonographically from around 6 weeks and the normal range varies during gestation, increasing to around 170 bpm at 10 weeks and decreasing from then to around 130 bpm at term. From this point, it will increase its rate about 3 beats per minute per day during that first month. By the beginning of the 9th week of pregnancy, the normal fetal heart rate is an average of 175 BPM. At this point it begins a rapid deceleration to the normal fetal heart rate for the middle of the pregnancy of about 120-180 BPM. Fetal heart rate monitoring is used in nearly every pregnancy at prenatal visits. It is done to check on how the fetus is doing and to look for any problems. Fetal heart rate monitoring is especially helpful if you have a high-risk pregnancy. The pregnancy will be high risk if the patient is an diabetian or have high blood pressure. It is also high risk if the fetus is not developing or growing thus the results of fetal heart rate monitoring will be less accurate. Hence continuous monitoring can ensure the safe pregnancy for the mother. MATLAB simulation is implemented to display the fetal heart rate. Here the input signals are taken from the physionet website. This website provides the 1
signals used for the research purposes. These signals are extracted as Matlab file. Then by using the fuzzy logic these signals are trained and the fetal heart rate is displayed in the LCD using Arduino. Figure 1.1: Input signal 2
2. BLOCK DIAGRAM MATERNAL AND FETAL SIGNAL MATLAB SOFTWA RE ARDUINO LCD Figure 2.1: Block diagram 3. COMPONENTS ARDUINO LCD DISPLAY 3
4. HARDWARE DESCRIPTION 4.1 ARDUINO UNO The Arduino Uno is a microcontroller board based on the ATmega328. It has 14 digital input/output pins (of which 6 can be used as PWM outputs), 6 analog inputs, a 16 MHz crystal oscillator, a USB connection, a power jack, an ICSP header, and a reset button. It contains everything needed to support the microcontroller. Simply connect it to a computer with a USB cable or power it with a AC-to-DC adapter or battery to get started. The Uno differs from all preceding boards in that it does not use the FTDI USB-to-serial driver chip. Instead, it features the Atmega8U2 programmed as a USB-to-serial converter. All Arduino boards are based around the ATMEGA AVR series microcontrollers from ATMEL which feature both analog and digital pins. Arduino also created software which is compatible with all Arduino microcontrollers. The software, also called Arduino, it can be used to program any of the Arduino microcontrollers by selecting them from a drop-down menu. Being open source and based around C, Arduino users are not necessarily restricted to this software, and can use a variety of other software to program the microcontrollers. 4.2 FEATURES Operating Voltage 5V Input Voltage (recommended) 7-12V Input Voltage (limit) 6-20V Digital I/O Pins 14 (of which 6 provide PWM output) PWM Digital I/O Pins 6 4
Analog Input Pins 6 DC Current per I/O Pin 20 ma DC Current for 3.3V Pin 50 ma Flash Memory 32 KB (ATmega328P) of which 0.5 KB used by bootloader SRAM 2 KB (ATmega328P) EEPROM 1 KB (ATmega328P) Clock Speed 16 MHz 4.1.2 INPUT AND OUTPUT Each of the 14 digital pins on the Uno can be used as an input or output, using pinmode(), digitalwrite(), and digitalread() functions. They operate at 5 volts. Each pin can provide or receive 20 ma as recommended operating condition and has an internal pull-up resistor (disconnected by default) of 20-50k ohm. A maximum of 40mA is the value that must not be exceeded on any I/O pin to avoid permanent damage to the microcontroller. The Uno has 6 analog inputs, labeled A0 through A5, each of which provide 10bits of resolution (i.e. 1024 different values). By default they measure from ground to 5 volts, though is it possible to change the upper end of their range using the AREF. pin and the analogreference() function. There are a couple of other pins on the board: AREF. Reference voltage for the analog inputs. Used with analogreference(). 5
Reset. Bring this line LOW to reset the microcontroller. Typically used to add a reset button to shields which block the one on the board. Figure 4.1.1 Pin diagram 4.1.3 MEMORY The ATmega328 has 32 KB (with 0.5 KB occupied by the bootloader). It also has 2 KB of SRAM and 1 KB of EEPROM. 6
4.1.4 POWER The Uno board can be powered via the USB connection or with an external power supply. The power source is selected automatically. External (non-usb) power can come either from an AC-to-DC adapter (wall-wart) or battery. The adapter can be connected by plugging a 2.1mm center-positive plug into the board's power jack. Leads from a battery can be inserted in the GND and Vin pin headers of the POWER connector. The board can operate on an external supply from 6 to 20 volts. If supplied with less than 7V, however, the 5V pin may supply less than five volts and the board may become unstable. If using more than 12V, the voltage regulator may overheat and damage the board. The recommended range is 7 to 12 volts. The power pins are as follows: Vin. The input voltage to the Uno board when it's using an external power source (as opposed to 5 volts from the USB connection or other regulated power source). You can supply voltage through this pin, or, if supplying voltage via the power jack, access it through this pin. 5V.This pin outputs a regulated 5V from the regulator on the board. The board can be supplied with power either from the DC power jack (7-12V), the USB connector (5V), or the VIN pin of the board (7-12V). Supplying voltage via the 5V or 3.3V pins bypasses the regulator, and can damage your board. We don't advise it. 3V3. A 3.3 volt supply generated by the on-board regulator. Maximum current draw is 50 ma. GND. Ground pins. IOREF. This pin on the Uno board provides the voltage reference with which the microcontroller operates. A properly configured shield can read 7
the IOREF pin voltage and select the appropriate power source or enable voltage translators on the outputs to work with the 5V or 3.3V. 4.1.5 COMMUNICATION The Uno has a number of facilities for communicating with a computer, another Uno board, or other microcontrollers. The ATmega328 provides UART TTL (5V) serial communication, which is available on digital pins 0 (RX) and 1 (TX). An ATmega16U2 on the board channels this serial communication over USB and appears as a virtual com port to software on the computer. The 16U2 firmware uses the standard USB COM drivers, and no external driver is needed. The Arduino Software (IDE) includes a serial monitor which allows simple textual data to be sent to and from the board. The RX and TX LEDs on the board will flash when data is being transmitted via the USB-to-serial chip and USB connection to the computer (but not for serial communication on pins 0 and 1). A Software Serial library allows serial communication on any of the Uno's digital pins. The ATmega328 also supports I2C (TWI) and SPI communication. The Arduino Software (IDE) includes a Wire library to simplify use of the I2C bus; see the documentation for details. For SPI communication, use the SPI library. 4.1.6 AUTOMATIC RESET Rather than requiring a physical press of the reset button before an upload, the Uno board is designed in a way that allows it to be reset by software running on a connected computer. One of the hardware flow control lines (DTR) of 8
the ATmega8U2/16U2 is connected to the reset line of the ATmega328 via a 100 nanofarad capacitor. When this line is asserted (taken low), the reset line drops long enough to reset the chip. The Arduino Software (IDE) uses this capability to allow you to upload code by simply pressing the upload button in the interface toolbar. This means that the bootloader can have a shorter timeout, as the lowering of DTR can be well-coordinated with the start of the upload. This setup has other implications. When the Uno is connected to either a computer running Mac OS X or Linux, it resets each time a connection is made to it from software (via USB). For the following half-second or so, the bootloader is running on the Uno. While it is programmed to ignore malformed data (i.e. anything besides an upload of new code), it will intercept the first few bytes of data sent to the board after a connection is opened. If a sketch running on the board receives one-time configuration or other data when it first starts, make sure that the software with which it communicates waits a second after opening the connection and before sending this data. The Uno board contains a trace that can be cut to disable the auto-reset. The pads on either side of the trace can be soldered together to reenable it. It's labeled "RESET-EN". You may also be able to disable the auto-reset by connecting a 110 ohm resistor from 5V to the reset line. 4.1.7 SPECIALIZED PIN FUNCTIONS Some pins have specialized functions: Serial: 0 (RX) and 1 (TX). Used to receive (RX) and transmit (TX) TTL serial data. These pins are connected to the corresponding pins of the ATmega8U2 USB-to-TTL Serial chip. 9
External Interrupts: 2 and 3. These pins can be configured to trigger an interrupt on a low value, a rising or falling edge, or a change in value. See the attachinterrupt() function for details. PWM: 3, 5, 6, 9, 10, and 11. Provide 8-bit PWM output with the analogwrite() function. SPI: 10 (SS), 11 (MOSI), 12 (MISO), 13 (SCK). These pins support SPI communication using the SPI library. LED: 13. There is a built-in LED driven by digital pin 13. When the pin is HIGH value, the LED is on, when the pin is LOW, it's off. TWI: A4 or SDA pin and A5 or SCL pin. Support TWI communication using the Wire library. 4.1.8 PHYSICAL CHARACTERISTICS The maximum length and width of the Uno PCB are 2.7 and 2.1 inches respectively, with the USB connector and power jack extending beyond the former dimension. Three screw holes allow the board to be attached to a surface or case. Note that the distance between digital pins 7 and 8 is 160 mil (0.16"), not an even multiple of the 100 mil spacing of the other pins. 10
Figure 4.1.2 Physical characteristics 4.1.9 ADVANTAGES Inexpensive Cross-platform Simple, clear programming environment Open source and extensible software Open source and extensible hardware 11
4.2 LCD DISPLAY A liquid crystal display (LCD) is a flat panel display, electronic visual display, or video display that uses the light modulating properties of liquid crystals. Liquid crystals (Fig 3.5) do not emit light directly. LCDs are available to display arbitrary images (as in a general-purpose computer display) or fixed images which can be displayed or hidden, such as preset words, digits, and 7- segment displays as in a digital clock. They use the same basic technology, except that arbitrary images are made up of a large number of small pixels, while other displays have larger elements. LCDs are used in a wide range of applications including computer monitors, televisions, instrument panels, aircraft cockpit displays, and signage. They are common in consumer devices such as video players, gaming devices, clocks, watches, calculators, and telephones, and have replaced cathode ray tube (CRT) displays in most applications. They are available in a wider range of screen sizes than CRT and plasma displays, and since they do not use phosphors, they do not suffer image burn-in. LCDs are, however, susceptible to image persistence. The LCD is more energy efficient and can be disposed of more safely than a CRT. Its low electrical power consumption enables it to be used in battery-powered electronic equipment. It is an electronically modulated optical device made up of any number of segments filled with liquid crystals and arrayed in front of a light source (backlight) or reflector to produce images in color or monochrome. Liquid crystals were first developed in 1888. By 2008, worldwide sales of televisions with LCD screens exceeded annual sales of CRT units; the CRT became obsolete for most purposes. 12
Figure 4.2.1 LCD 4.2.1 PIN DESCRIPTION The LCDs have a parallel interface, meaning that the microcontroller has to manipulate several interface pins at once to control the display. The interface consists of the following pins: A register select (RS) pin that controls where in the LCD's memory you're writing data to. You can select either the data register, which holds what goes on the screen, or an instruction register, which is where the LCD's controller looks for instructions on what to do next. A Read/Write (R/W) pin that selects reading mode or writing mode An Enable pin that enables writing to the registers 8 data pins (D0 -D7). The states of these pins (high or low) are the bits that you're writing to a register when you write, or the values you're reading when you read. 13
There's also a display constrast pin (Vo), power supply pins (+5V and Gnd) and LED Backlight (Bklt+ and BKlt-) pins that you can use to power the LCD, control the display contrast, and turn on and off the LED backlight, respectively. 4.2.2 PIN INTERFACING To wire the LCD screen to arduino board, connect the following pins: LCD RS pin to digital pin 12 LCD Enable pin to digital pin 11 LCD D4 pin to digital pin 5 LCD D5 pin to digital pin 4 LCD D6 pin to digital pin 3 LCD D7 pin to digital pin 2 Additionally, wire a 10k pot to +5V and GND, with it's wiper (output) to LCD screens VO pin (pin3). A 220 ohm resistor is used to power the backlight of the display, usually on pin 15 and 16 of the LCD connector 14
Figure 4.2.2 Arduino and LCD interfacing 15
Use of the LCD is pretty straightforward. After power-up, wait a half second or so to let the LCD run its own initialization. Since the default mode is eight bits, we ll have to reinitialize it to accept our data via the four-bit bus. When the four-bit initialization is complete, It can send our characters or commands. The RS line is set high for characters, low for LCD commands. The initialization code is required to allow the LCD to operate in four-bit mode. After setting the four-bit interface, this section of code turns the display on, turns off the underline cursor, and causes the cursor to increment after each character is written. Just to ensure that there is no garbage left from any previous operations, the Display Clear command is sent to the LCD. Writing a character or command is done in these steps: 1. Set the RS line (HIGH for character, LOW for command). 2. Place the high nibble of the character/command byte on the bus. 3. Strobe the Enable line (cause a HIGH-to-LOW transition). 4. Place the low nibble on the bus. 5. Strobe the Enable line one more time. The LCD pins are numbered from 1-16.In the case where the LCD is powered with the Arduino by the 5V USB cable, selecting the contrast resistor to be 2K ohm and the back LED resistor to be 100 ohm is a good start. Alternatively, a 5K potentiometer can be used to adjust the contrast. 16
Table 4.2.1 LCD and its interface 5 SOFTWARE DESCRIPTION 5.1 MATLAB SOFTWARE MATLAB is a high-performance language for technical computing. It integrates computation, visualization, and programming in an easy-to-use environment where problems and solutions are expressed in familiar mathematical notation. Typical uses include: Math and computation Algorithm development Modeling, simulation, and prototyping Data analysis, exploration, and visualization Scientific and engineering graphics Application development, including Graphical User Interface building 17
The name MATLAB stands for matrix laboratory. MATLAB features a family of application-specific solutions called toolboxes. Very important to most users of MATLAB, toolboxes allow you to learn and apply specialized technology. Toolboxes are comprehensive collections of MATLAB functions (Mfiles) that extend the MATLAB environment to solve particular classes of problems. Areas in which toolboxes are available include signal processing, control systems, neural networks, fuzzy logic, wavelets, simulation, and many others. 5.1.1 METHOD AND CONCEPT OF FECG EXTRACTION The method used in this project is adaptive noise cancellation (ANC) based on neuro fuzzy logic technique. ANC is a process by which the interference signal can be filtered out by identifying a non linear model between a measurable noise source (which is MECG in this case) and the corresponding immeasurable interference. This is an extremely useful technique when a signal is submerged in a very noisy environment. Usually, the MECG noise is not steady; it changes from time to time. So the noise cancellation must be an adaptive process: it should be able to work under changing conditions, and be able to adjust itself according to the changing environment. The basic idea of an adaptive noise cancellation algorithm is to pass the corrupted signal (abdominal) through a filter that tends to suppress the MECG while leaving the signal unchanged. As mentioned above, this is an adaptive process, which means it does not require prior knowledge of signal or noise characteristics. 18
Figure 5.1: Noise cancellation with ANFIS filtering In this project, x(k) represents the FECG signal that is to be extracted from the noisy signal. n(k) is the MECG which is the noise source signal. The noise signal goes through an unknown nonlinear dynamics(f) and generates a distorted d(k) which is then added to x(k) to form the measurable output(abdominal) signal y(k). During the extraction of the fetal heartbeat signal, the system input parameters (of both the maternal and the fetal heartbeat signals) were generated by codes written in matlab. These parameters were then passed to the adaptive neuro fuzzy inference system (ANFIS) for training. In the process of training, the parameters (i.e. membership function parameters) of each system input signal continues to map each other until the adaptive noise canceller (ANC) reaches a point of convergence. At this point the fetal heart rate signal is extracted. 19
Figure 5.2:Flowchart for the extraction of FECG 5.1.2 ADVANTAGES OF ANFIS Adaptive Neuro Fuzzy Inference System (ANFIS) was the proposed technique for the extraction of Fetal Electrocardiogram (FECG) signals from composite abdominal ECG recordings. The advantage of this technique over other methods is that it requires only one abdominal signal and one thoracic signal. But the other methods require many signals to validate their results. Compared to other methods, ANFIS is well suitable for non linear applications.. Since this technique uses neural network it requires fewer inputs to extract the FECG signal. Convergence time is less compared to methods using neural network alone due to the hybrid rule used in the ANFIS technique. ANFIS can separate the FECG without dividing the signals into different frames. After removing the major interference (MECG) from the FECG, it is easier to cancel the high frequency noise using digital filters. Since the morphology of the extracted FECG using this technique remains same, it can be used by the medical doctors and/or physicians to diagnose. 20
5.2 ARDUINO SOFTWARE The open-source Arduino Software (IDE) makes it easy to write code and upload it to the board. It runs on Windows, Mac OS X, and Linux. The environment is written in Java and based on Processing and other open-source software. This software can be used with any Arduino board. The Arduino Integrated Development Environment or Arduino Software (IDE) contains a text editor for writing code, a message area, a text console, a toolbar with buttons for common functions and a series of menus. It connects to the Arduino and Genuino hardware to upload programs and communicate with them. Programs written using Arduino Software (IDE) are called sketches. These sketches are written in the text editor and are saved with the file extension.ino. The editor has features for cutting/pasting and for searching/replacing text. The message area gives feedback while saving and exporting and also displays errors. The console displays text output by the Arduino Software (IDE), including complete error messages and other information. The bottom righthand corner of the window displays the configured board and serial port. The toolbar buttons allow you to verify and upload programs, create, open, and save sketches, and open the serial monitor. Verify/Compile Checks your sketch for errors compiling it; it will report memory usage for code and variables in the console area. Upload Compiles and loads the binary file onto the configured board through the configured Port. Upload Using Programmer : This will overwrite the bootloader on the board; you will need to use Tools > Burn Bootloader to restore it and be able to 21
Upload to USB serial port again. However, it allows you to use the full capacity of the Flash memory for your sketch. Please note that this command will NOT burn the fuses. To do so a Tools -> Burn Bootloader command must be executed. Export Compiled Binary : Saves a.hex file that may be kept as archive or sent to the board using other tools. Port This menu contains all the serial devices (real or virtual) on your machine. It should automatically refresh every time you open the top-level tools menu. Burn Bootloader The items in this menu allow you to burn a bootloader onto the microcontroller on an Arduino board. 6.ADVANTAGES Continuous fetal heart rate monitoring reduces the chances of seizure after the birth, a symptom of brain injury from low oxygen. It also ensures the well-being and safety of both mother and fetal during pregnancy. An abnormal fetal heart rate or pattern mean that the fetus is not getting enough oxygen or suffering from any other problems. If the fetal heart rate lies above or below 120 to 160BPM, it indicates the emergency situation. 7.CONCLUSION Thus the fetal heart rate is monitored by using the adaptive neuro fuzzy logic which is implemented by MATLAB, in which the FECG signal is extracted by comparing normal MECG signal from the MECG and the fetal heart rate signal is displayed in the LCD using Arduino. So that we ensure the wellbeing and safety of both mother and fetal during pregnancy. 22
8. REFERENCE [1] Assaleh K. (2007). Extraction of Fetal Electrocardiogram Using Adaptive Neuro-Fuzzy Inference Systems, IEEE Trans. Biomed. Eng., 54: 59-68. [2] Ibahimy M. et al. (2003). Real Time Signal Processing For Fetal Heart Rate Monitoring, IEEE Med Biol. Eng. Comput., 50: 258-261. [3] Jang J. (1993). ANFIS: Adaptive Network- Based Fuzzy Inference Systems, IEEE Trans. Syst. Man Cybern, 23: 665-683. [4] Ferrara, E. R., and Widrow, B., Fetal electrocardiogram enhancement by timesequenced adaptive filtering, IEEE Trans. Biomed. Eng. 29, pp. 458 460, 1982. [5] Jafari, M. G., and Chambers, J. A., Fetal electrocardiogram extraction by sequential source separation in the wavelet domain, IEEE Transactions on Biomedical Engineering, vol. 52, no. 3, pp.390 400,2005. [6] Widrow, B., Adaptive Noise Cancelling: Principles and Applications, Proc. IEEE, vol. 63, pp.1692-1716, Dec. 1975. [7] John, R. G. Jr., Adaptive Noise Canceling Applied to Sinusoidal Interferences, IEEE Trans. ASSP, Vol. ASSP-25, no. 6, pp. 484-491, Dec.1977 [8] V. Zarzoso and A. Nandi, Noninvasive fetal electrocardiogram extraction: blind separation versus adaptive noise cancellation, Biomedical Engineering, IEEE Transactions on, vol. 48, no. 1, pp. 12 18, 2001. [9] Physionet, the research resource for complex biomedical signals. http://www. physionet.org/. [10] R. Sameni and G. Clifford, A review of fetal ECG signal processing; issues and promising directions, The open pacing, electrophysiology & therapy journal, vol. 3, p. 4, 2010. 23