Dr. Achmad Arifin, ST., M.Eng.

Profil Dosen

NIP   197103141997021001
Nama   Dr. Achmad Arifin, ST., M.Eng.
Email   arifin[at]bme.its.ac.id
arifin[at]ee.its.ac.id
Pendidikan   S1: ITS, Elektro/Elektronika (1990-1996)
S2: Tohoku University, Electronic Eng./ Biomedical Electronics (2000-2002)
S3: Tohoku University, Electronic Eng./ Biomedical Electronics (2002-2005)

Penelitian dan Publikasi

Research

1997-1998, IIR filter untuk pengolahan sinyal ECG, Penelitian Dosen Muda, DIKTI, DEPDIKBUD

1998-1999, Sistem Analisa Arrhtymia Digital, Penelitian Dosen Muda, DIKTI, DEPDIKBUD

2000-2002, Feedback Control of FES Gait, Tohoku University

2002-2005, Gait Database for Rehabilitation Purpose, Tohoku University

2002-2005, Cycle-to-cycle FES Gait Control, Tohoku University

2006-2007, Closed-loop FES system for lower limb, TPSDP, ITS

2007-2008, Adaptive Fuzzy FES Controller, ITS & Tohoku University

2009-2011, Stimulasi Elektrik untuk penyembuhan luka, ITS

2011-2012, Pengembangan Portable FES System, ITS

2011-2012, Multichannel Wearable Movement Sensor, Program Penelitian Unggulan ITS

2012-2013, Heartsound signal processing, ITS

2012-2013, Multijoint FES control, Program Penelitian Unggulan ITS

2014-2015, Wearable FES System, ITS

 

Journal Articles

2017

[1] Basith, Aidatunisadina Linazizah; Setiawan, Stanley; Arifin, Achmad; Arrofiqi, Fauzan; Nuh, Muhammad, "Design and Tests of A Wearable Functional Electrical Stimulation (FES) System for Knee Joint Movement Using Cycle-To-Cycle Control Method", Journal of Theoretical and Applied Information Technology, 15th June 2017. Vol.95. No 11. pp. 2523-2571.

Paralysis has became more widespread nowadays. Mostly caused by stroke, spinal cord injury, and multiple
sclerosis, the growing number of paralysis case also implied for a better treatment for its bearer. Some of
the main problems for individual with paralysis is to improve health problems related to paralysis and to
decrease the dependence to other people by regaining muscle function. In this study, a wearable functional electrical stimulation with cycle-to-cycle control system for knee joint movement restoration was developed. The system consists of sensor system, electrical stimulator, and fuzzy logic controllers. The controller was developed as Single Input Single Output (SISO) controller for knee flexion movement and Multi Input Single Output (MISO) controller for knee extension movement. Sensor system was used to measure angle of knee joint. A combination of two inertial sensors, accelerometer and gyroscope, made up the sensor system. The angle measured by sensor system was also used as feedback to realize closed-loop control. The data from the system could be monitored and saved as database using user interface program in a PC/laptop. Tests with neurologically intact subjects was done to test the performance of the system designed. It resulted in small number of RMSE and Settling Index for both maximum knee flexion and maximum knee extension control. The system designed was expected to be developed further to provide a full wearable FES system for lower limb motoric restoration.
Keywords: Functional Electrical Stimulation, Cycle-to-cycle Control, Knee Joint, Fuzzy System

[2] Setiawan Rachmad; Arifin Achmad; Budiman Fajar; Soeprijanto Adi;, "Programmable Amplitude of Portable Electrical Stimulator for Multi-Channel Functional Electrical Stimulator (Fes) System", Journal of Theoretical and Applied Information Technology, Vol. 95, No. 9, pp. 1974-1982, 2017

2016

[1] Hendradi, Rimuljo; Arifin, Achmad; Shida, Hiro; Gunawan, Suhendar; Purnomo, Mauridhi Hery; Hasegawa, Hideyuki; Kanai, Hiroshi;, "ANALYSIS AND METHODS TO TEST CLASSIFICATION OF NORMAL AND PATHOLOGICAL HEART SOUND SIGNALS", Journal of Theoretical and Applied Information Technology, Vol. 90, No. 1, pp. 222-236, 2016

An acute shortage of cardiologists and many rural clinics were run by nurses in Indonesia. We proposed to develop of a screening technique based on artificial intelligence that classifies of normal and pathological heart sound signals of human subjects due to signs important and symptoms for heart diagnosis based on knowledge of auscultation experts. Heart sound signal analysis system consisted of three stages. Firstly, preprocessing. Secondly, feature extraction with respect to the cardiac cycle based on wavelet analysis to differentiate normal and pathological heart sounds. Feature reduction using PCA was also carried out to reduce the dimension of the heart sound feature vectors for classification. Thirdly, three classifiers: ANN MLP-BP, FCM clustering and HCM clustering to classify normal, systolic murmur, diastolic murmur, and continuous murmur, respectively. The performance of each classifier was evaluated with statistical validation method. From our experimental results, the three classifiers that showed significant potential in their use as an alternative diagnostic tool were compared. The ANN achieved the best performance as an automated classifier rather than FCM and HCM methods. Its performance was 100% for sensitivity, specificity, and accuracy, respectively, of input 20,000 features. Furthermore, for input 300 features, the performance was 98.90%, 99.37%, and 99.03% for sensitivity, specificity, and accuracy, respectively. The heart sound signal analysis system was suitable to classify of normal and pathological cases. The proposed method was considered very important for objective screening and very useful as an alternative diagnostic tool that complies with the requirements for rural clinics. We hoped that the method would be beneficial in study of auscultatory technique for medical students. Surrogate data modeling of pathological heart sounds signals as an alternative tool of the heart sound simulator and for classification purpose was further study. Keywords:

[2] Hendradi, Rimuljo; Arifin, Achmad; Shida, Hiro; Gunawan, Suhendar; Purnomo, Mauridhi Hery; Hasegawa, Hideyuki; Kanai, Hiroshi;, "Signal Processing and Extensive Characterization Method of Heart Sounds Based on Wavelet Analysis", International Review of Electrical Engineering (IREE), Vol. 11, No. 1, pp. 55, Praise Worthy Prize, 2016

One of the valuable methods of cardiac valve diagnosis can be performed by auscultation. We proposed a signal processing and extensive characterization method based on wavelet analysis to investigate important characteristics of heart sounds of normal and pathologic systolic murmur human subjects. Time-scale maps yielded by wavelet transform calculation were solved using magnitude thresholding operation and centre of gravity to restrict temporal and frequency-related of valvular activities. From our experimental results, temporal and frequency-related parameters of S1, S2, and their components could be characterized precisely. Application of our method was adequate to characterize the heart sounds objectively, clearly, systematically, and comprehensively. The method was considered valuable to explain mechanisms of cardiac valves functions. We expected that the method would be helpful for clinical diagnosis as well as developing of heart sound modelling and educational purpose. Next topic of our study was addressed for classification of the heart sounds.
link: www.praiseworthyprize.org

2015

[1] Fitrianto, Idil; Fitrianto, Idil; Arifin, Achmad; Nuh, Mohammad; Fitrianto, Idil; Nuh, Mohammad;, "Rancangan Kontroler Perangkat Keras EH1 Milano Dengan Modul Wireless Electronics", Jurnal Teknik ITS, Vol. 4, No. 1, pp. A53--A58, 2015

Teknologi dalam dunia robot medis perkembangannya sangat pesat sekali, salah satunya adalah EH1 Milano yang dimiliki oleh salah satu laboratotium yang ada di kampus ITS Surabaya. Modul lengan robot EH1 Milano sebelumnya telah di riset oleh mahasiswa teknik elektro. Kekurangan dari riset tersebut, sistem perangkat keras masih terlalu rumit karena interface antara robot dan user masih menggunakan kabel. Sistem yang dirancang menggunakan modul Wireless Electronics untuk mengatasi masalah pengkabelan dan modul yang digunakan adalah modul Bluetooth model HC dengan jarak jangkauan sampai dengan 50 meter dan waktu pairing rata-rata 8 detik. Sensor flex dengan karakteristik sensor yang linier, dengan error percentage terkecil sebesar 0,58% sedangkan terbesar 15,13% terhadap garis linier dapat menggantikan sensor yang sebelumnya digunakan. Untuk penelitian berikutnya dapat ditambahkan EMG sebagai pembanding impuls dari sensor flex dengan sinyal electromyogram dari tiap-tiap jari.
link: www.ejurnal.its.ac.id

[2] Fuad, Muhammad Faris Zaini; Arifin, Achmad; Nuh, Mohammad;, "Perbaikan Sistem Kendali Robot Tangan EH1 Milano Menggunakan Sistem Kendali Loop Tertutup", Jurnal Teknik ITS, Vol. 4, No. 1, pp. A59--A64, 2015

Teknologi robotika sangat berkembang pesat dan penggunaanya semakin luas. Prensilia EH1 Milano dikembangkan sebagai organ buatan untuk menggantikan peranan tangan manusia yang cacat atau diamputasi. Robot EH1 Milano dilengkapi satu buah motor untuk masing-masing jari, sensor proximity untuk mendeteksi jari terbuka atau tertutup penuh, dan sensor arus yang digunakan untuk mengatur kekuatan genggaman dari robot tangan. Sebelumnya telah dibuat sistem mikrokontroler untuk mengendalikan robot tangan EH1 Milano, dengan sensor gerak berupa sarung tangan yang dilengkapi potensiometer, akan tetapi belum dapat melakukan gerakan menggenggam benda. Dalam penelitian ini dirancang sistem untuk mengendalikan robot EH1 Milano menggunakan sensor gerak berupa sebuah sarung tangan yang diengkapi flex sensor, yang berfungsi untuk mendeteksi gerakan tangan manusia dengan menggunakan kendali PID. Flex sensor digunakan karena lebih sensitif terhadap perubahan gerakan tangan dan memudahkan untuk mengendalikan robot untuk melakukan gerakan menggenggam benda. Dari pengujian yang dilakukan menunjukkan bahwa dengan sistem kendali yang diterapkan, robot tangan EH1 Milano dapat melakukan gerakan menggenggam benda dengan diameter lebih dari 5 cm. Performansi yang dihasilkan sistem kendali yang dibuat cukup baik dengan RMSE rata-rata tertinggi sebesar 0.102%± 0.016%. Untuk penelitian selanjutnya perlu perbaikan pada sensor gerak untuk ibu jari, agar pergerakan pada ibu jari dapat dilakukan dengan maksimal.
link: ejurnal.its.ac.id

2014

[1] Nurmadyansyah, Rizky; Nurmadyansyah, Rizky Fauzy; Arifin, Achmad;, "Perancangan dan Implementasi Sistem Kendali Robot Tangan Prensilia", Jurnal Teknik ITS, Vol. 3, No. 1, pp. F1-F6, 2014

Teknologi robotika pada bidang medis terus berkembang dan penggunaannya semakin luas. Pada tugas akhir ini sistem kendali loop tertutup untuk robot tangan telah dikembangkan dan dievaluasi. Sistem kendali dengan komponen utama mikrokontroler untuk mengendalikan robot tangan IH2 Azzurra mampu bekerja secara real-time. Sistem yang dibuat memiliki antarmuka UART dengan baud rate sebesar 115,2kbps yang dapat menerima masukan dari sensor gerak berupa sarung tangan dan menghasilkan keluaran berupa suatu perintah sebagai masukan robot tangan. Perintah ini mampu mengatur kecepatan motor pada masing-masing jari robot tangan sesuai dengan gerakan tangan melalui sensor gerak. Metode sistem kendali yang digunakan adalah sistem kendali PID diskrit berbasis mikrokontroler ATMEGA8. Performansi dari sistem kendali yang dirancang dapat dilihat secara langsung menggunakan perangkat lunak berbasis PC yang telah dibuat. Selain itu, perangkat lunak PC dapat memperbaharui firmware pada mikrokontroler secara langsung dan parameter-parameter penting pada sistem dapat ditampilkan dalam bentuk grafik, atau disimpan pada media penyimpanan berbasis PC sehingga lebih mudah untuk dianalisa lebih lanjut. Performansi yang dihasilkan sistem cukup baik, dilihat dari nilai error steady state tertinggi sebesar 3,137%, settling time tertinggi sebesar 3,8 detik, overshoot tertinggi sebesar 3,529%, dan RMSE rata-rata tertinggi yang dihasilkan sebesar  0,0595%±0,0119%. Kebutuhan daya pada sistem relatif rendah yakni 111,9mW. Sehingga catu daya baterai li-ion berkapasitas standar dapat digunakan untuk mencatu sistem selama kurang lebih 29,4 jam atau 1,225 hari. Tingkat portabilitas dari sisi kebutuhan daya sudah terpenuhi untuk sistem ini.
link: ejurnal.its.ac.id

2011

[1] Arifin, Achmad; Budiarmoko, Alfian;, "Aplikasi Bioelectrical Impedance Untuk Mengukur Gerakan Sendi Lutut Pada Bidang Sagital", Jurusan Teknik Elektro – FTI, Institut Teknologi Sepuluh Nopember : Surabaya, 2011

Jaringan tubuh manusia tersusun dari berbagai material kompleks yang memiliki sifat-sifat listrik yang berbeda. Bioelectrical Impedance (BI) mengacu pada perlawanan aliran arus yang melalui jaringan tubuh tersebut. BI ini memiliki nilai yang bervariasi tergantung dari perubahan komposisi material pada jaringan tubuh. Perubahan tersebut dapat terjadi akibat adanya gerakan atau karena suatu penyakit tertentu. Tugas Akhir ini bertujuan untuk mengembangkan rangkaian pengukuran BI serta aplikasinya untuk menganalisa perubahan BI terhadap perubahan sudut dari sendi lutut / knee joint pada bidang sagital. Metode yang digunakan untuk mengukur perubahan BI terhadap gerakan knee joint ialah dengan menginjeksikan arus sinusoidal yang konstan dengan amplitudo 250µA dan Frekuensi 50KHz pada bagian kanan abdomen dan telapak kaki bagian atas, serta mencatat perubahan drop tegangan diantara dua titik tertentu pada kaki. Perubahan drop tegangan ini diproses pada rangkaian Instrumentasi BI, yang terdiri dari rangkaian Instrumentasi Amplifier sebagai penguat sinyal, rangkaian High Pass Filter untuk menghilangkan noise pada frekuensi rendah, serta rangkaian Demodulation Amplitudo untuk mendapatkan tegangan eksak dari BI. Data BI yang diperoleh kemudian diubah dalam bentuk digital menggunakan ADC mikrokontroler ATMega32 dan dikirim ke komputer melalui komunikasi serial untuk diolah pada program khusus. Dengan penguatan 194.35 kali pada rangkaian instrumentasi amplifier, hasil nilai BI berubah antara ±2.3V hingga ±1.5V untuk perubahan sudut knee joint dari 0° hingga 120°. Ketidaklinearan antara BI dengan sudut knee joint mengakibatkan error yang cukup besar yaitu 64o, dimana minimum error yang terjadi sebesar 0o. Pengaruh posisi penempatan elektroda sangat vital terhadap kelinearan hasil pengukuran ini. Oleh karena itu, penelitian lebih lanjut tentang penempatan elektroda ini sangat diperlukan untuk pengembangan kedepannya. Hasil pengukuran sudut menggunakan sistem pengukuran BI ini dapat diaplikasikan untuk berbagai keperluan, salah satunya ialah sebagai pengganti electro-goniometer dalam sistem rehabilitasi FES. I.

2009

[1] WATANABE, Takashi; MASUKO, Tomoya; ARIFIN, Achmad;, "Preliminary Tests of a Practical Fuzzy FES Controller Based on Cycle-to-Cycle Control in the Knee Flexion and Extension Control", IEICE TRANSACTIONS on Information and Systems, Vol. E92-D, No. 7, pp. 1507-1510, The Institute of Electronics, Information and Communication Engineers, 2009

2008

[1] WATANABE, Takashi; MASUKO, Tomoya; ARIFIN, Achmad; YOSHIZAWA, Makoto;, "A Feasibility Study of Fuzzy FES Controller Based on Cycle-to-Cycle Control: An Experimental Test of Knee Extension Control", IEICE TRANSACTIONS on Information and Systems, Vol. E91-D, No. 3, pp. 865-868, The Institute of Electronics, Information and Communication Engineers, 2008

2006

[1] Arifin, A.; Watanabe, T.; Hoshimiya, N.;, "Design of Fuzzy Logic Controller of the Cycle to Cycle Control for Swing Phase of Hemiplegic Gait Induced by FES", IEICE Trans. Inf. & Syst., Vol. E89-D, No. 4, pp. 1525-1533, The Institute of Electronics, Information and Communication Engineers, 2006

The goal of this study was to design a practical fuzzy controller of the cycle-to-cycle control for multi-joint movements of swing phase of functional electrical stimulation (FES) induced gait. First, we designed three fuzzy controllers (a fixed fuzzy controller, a fuzzy controller with parameter adjustment based on the gradient descent method, and a fuzzy controller with parameter adjustment based on a fuzzy model) and two PID controllers (a fixed PID and an adaptive PID controllers) for controlling two-joint (knee and ankle) movements. Control capabilities of the designed controllers were tested in automatic generation of stimulation burst duration and in compensation of muscle fatigue through computer simulations using a musculo-skeletal model. The fuzzy controllers showed better responses than the PID controllers in the both control capabilities. The parameter adjustment based on the fuzzy model was shown to be effective when oscillating response was caused due to the inter-subject variability. Based on these results, we designed the fuzzy controller with the parameter adjustment realized using the fuzzy model for controlling three-joint (hip, knee, and ankle) movements. The controlled gait pattern obtained by computer simulation was not significantly different from the normal gait pattern and it could be qualitatively accepted in clinical FES gait control. The fuzzy controller designed for the cycle-to-cycle control for multi-joint movements during the swing phase of the FES gait was expected to be examined clinically. Keywords:

[2] Arifin, Achmad; WATANABE, Takashi; Hoshimiya, Nozomu;, "Design of fuzzy controller of the cycle-to-cycle control for swing phase of hemiplegic gait induced by FES", IEICE transactions on information and systems, Vol. 89, No. 4, pp. 1525-1533, The Institute of Electronics, Information and Communication Engineers, 2006

The goal of this study was to design a practical fuzzy controller of the cycle-to-cycle control for multi-joint movements of swing phase of functional electrical stimulation (FES) induced gait. First, we designed three fuzzy controllers (a fixed fuzzy controller, a fuzzy controller with parameter adjustment based on the gradient descent method, and a fuzzy controller with parameter adjustment based on a fuzzy model) and two PID controllers (a fixed PID and an adaptive PID controllers) for controlling two-joint (knee and ankle) movements. Control capabilities of the designed controllers were tested in automatic generation of stimulation burst duration and in compensation of muscle fatigue through computer simulations using a musculo-skeletal model. The fuzzy controllers showed better responses than the PID controllers in the both control capabilities. The parameter adjustment based on the fuzzy model was shown to be effective when oscillating response was caused due to the inter-subject variability. Based on these results, we designed the fuzzy controller with the parameter adjustment realized using the fuzzy model for controlling three-joint (hip, knee, and ankle) movements. The controlled gait pattern obtained by computer simulation was not significantly different from the normal gait pattern and it could be qualitatively accepted in clinical FES gait control. The fuzzy controller designed for the cycle-to-cycle control for multi-joint movements during the swing phase of the FES gait was expected to be examined clinically.
link: search.ieice.org

[3] 柴田聡; 渡邉高志; ARIFIN, Achmad; 吉澤誠; 星宮望;, "片麻痺者の歩行遊脚期の cycle-to-cycle 制御に基づく FES 制御法: 床反力を考慮したモデルシミュレーション", 生体医工学, Vol. 44, No. 4, pp. 687-695, Japanese Society for Medical and Biological Engineering, 2006

2005

[1] Arifin, Achmad; WATANABE, Takashi; Hoshimiya, Nozomu;, "Computer Simulation Test of Fuzzy Controller for the Cycle-to-Cycle Control of Knee Joint Movements of Swing Phase of FES Gait", IEICE TRANSACTIONS on Information and Systems, Vol. E88-D, No. 7, pp. 1763-1766, The Institute of Electronics, Information and Communication Engineers, 2005

2004

[1] Arifin, Achmad; Watanabe, Takashi; Yoshizawa, Makoto;, "A test of fuzzy controller of cycle-to-cycle control for controlling three-joint movements of swing phase of FES gait", バイオメカニズム学術講演会予稿集, Vol. 25, pp. 43-46, バイオメカニズム学会, 2004

2003

[1] Arifin, A; Watanabe, T; Hoshimiya, N;, "A Test of Fuzzy Controller for Cycle-to-Cycle Control of FES-induced Hemiplegic Gait: Computer Simulation in Single-joint Control", 生体医工学: 日本エム・イー学会誌, Vol. 41, No. 1, pp. 68, 社団法人日本生体医工学会, 2003

[2] Arifin, Achmad; Watanabe, Takashi; Hoshimiya, Nozomu;, "Design of Fuzzy Controllers for Cycle-to-Cycle Control of Swing Phase of FES-induced Hemiplegic Gait", バイオメカニズム学術講演会予稿集, Vol. 24, pp. 199-202, バイオメカニズム学会, 2003

2002

[1] ARIFIN, Achmad; WATANABE, Takashi; HOSHIMIYA, Nozomu;, "Cycle-to-Cycle Control of Swing Phase of FES-induced Hemiplegic Gait : A Computer Simulation with Different Controllers", IEICE technical report. ME and bio cybernetics, Vol. 102, No. 481, pp. 1-4, The Institute of Electronics, Information and Communication Engineers, 2002

Conference Proceedings

2017

[1] Aliansyah; Achmad Nur, Arifin; Achmad, Purwanto; Djoko , Fatoni; Muhammad Hilman, "Extraction of Brain Signal during Motor Imagery Task for Wheelchair Control Command", International Conference on Research & Innovation in Computer, Electronics and Manufacturing Engineering (RICEME-17), Feb. 2-3, 2017. Bali (Indonesia). pp. 25.

Abstract—Paralysis is a disease that causes loss of function from one or more muscle. When someone is paralyzed, the brain still works to obtain information about body activities. While doing or imagining movement, the similar response occurs in the brain. The purpose of this study was to detect any change the value of Event Related Desynchronization/Event Related Synchronization (ERD/ERS) during event. Time-frequency domain analysis was used to determine the frequency dominant when it occurred. This
information would be used as a Band Pass Filter for calculating the value of ERD/ERS. In this research, EEG signals were acquired from channel C3, C3-F3, C4, and C4-F4 base on international system
10/20 from EEG. The findings show that the range of frequency dominant from selected channels on all subject is 8-12Hz. The value of ERD/ERS was changed 64.43% in channel C3 and 60% in channel
C3-F3 whereas in channel C4 was 64.43% and 66.67% in channel C4-F4. The change of value of ERD/ERS would be used as control command for wheelchair in the next research topic.

2016

[1] Arifin, A; Arrofiqi, F; Watanabe, T; Nuh, M; Basith, A. L.;, "Embedded Fuzzy Logic Controller for Functional Electrical Stimulation System", 2016 International Seminar on Intelligent Technology and Its Application, pp. 89-94, 2016

Functional electrical stimulation (FES) is one of the most common techniques used to improve motor function in individuals with paralysis. In this study, fuzzy logic controller implemented in embedded system for wearable FES was developed. The controller was designed as Single Input Single Output (SISO) and Multi Input Single Output (MISO) controllers to manage electrical stimulation for seven muscles in thigh and shank and to induce certain joint movements. The system was realized in two steps utilizing 32-bit ARM microcontrollers, STM32F429 and STM32F103C8T6, respectively. Closed-loop control was used in the system and realized using feedback from the sensors. Serial communication was utilized for data transmission between embedded system and PC/laptop as monitoring station. Experiments done to test the performance of SISO controller of knee flexion proved that the system was able to adjust burst duration and to control joint movement induced. The system designed was expected to be helpful for clinical application of motor function improvement

[2] Hikmah, Nada Fitrieyatul; Arifin, Achmad; Sardjono, Tri Arief; Suprayitno, Eko Agus;, "A sequential hypothesis testing of multimodal cardiac analysis", Asea Uninet Scientific and Plenary Meeting 2016, pp. 63-77, 2016

Focus of our research group is development of integrated cardiac analysis system. A measurement and analysis system of cardiovascular system can be realized in an integrated system that includes all cardiac vital signs [1]. We have tested a signal processing framework of multimodal cardiac signals, electrocardiogram, carotid pulse, and phonocardiogram of normal subjects [2]. This paper describes a follow up effort in analysis and classification of heart conditions. Multimodal cardiac signals were recorded from 20 normal and 3 abnormal subjects. The measurements were performed after obtaining the consent of subjects. The data were recorded using a special instrument designed by our group, and digitized with 1 kHz sampling frequency. The recordings were performed in 10 trials, with 5 second for each trial. Parameters of the cardiac signals were extracted. Sequential hypothesis testing [3] was used in classification stage to produce a diagnosis of normal and abnormal heart based on the extracted parameters. The overlapping problem was solved by selecting two thresholds, upper and lower, resulted in no decision taken while the value of data tested was in the overlapping zone. The results of normal subjects showed that 90% of the data were identified in the 3rd test and 100% of the data could be identified after the 4th test, while the abnormal subjects showed that 80% of data were identified in the 3rd test and 100% of the data could be identified after the 4th test. The classification result recommended the proposed method should be realized in clinical use.

[3] Mujibtamala, Arizal; Imron, Nanda; Arifin, Achmad; Purwanto, Djoko;, "Realisasi Kontrol Hirarki Untuk Pengaturan Kecepatan Kursi Roda Elektrik Berdasarkan Subject Intension Menggunakan Bioelectrical Impedance", SEMINAR NASIONAL INOVASI DAN APLIKASI TEKNOLOGI DI INDUSTRI (SENIATI) 2016, pp. 1-7, 2016

Makalah ini menjelaskan metode kontrol kecepatan kursi roda elektrik, yang didedikasikan untuk orang dengan keterbatasan alat gerak tangan dan kaki. Pada penelitian sebelumnya, bioelectrical impedance digunakan sebagai perintah kontrol kecepatan kursi roda elektrik. Penelitian ini dikembangkan kontrol kecepatan yang dapat direalisasikan pada jalan datar, berdasarkan keinginan subjek. Instrumentasi bioelectrical impedance digunkanan sebagai sistem untuk membaca keinginan pengguna kursi roda elektrik melalui perubahan impedasi pada otot trapezius, 3 elektroda disposable digunakan sebagai interface antara tubuh subjek dan instrumentasi bioelectrical impedance, dimana masing-masing elektroda diletakkan pada bahu kanan, bahu kiri dan tepat di bagian tulang belakang, perubahan impedansi pada masing-masing bahu akan diterjemahkan oleh konrol hirarki sehingga dapat dibaca oleh sistem mikrokontroler untuk menggerakkan kursi roda elektrik. Perintah kontrol belok kanan, belok kiri, maju dengan kecepatan 1, kecepatan 2 dan kecepatan 3 masing masing didapat ketika ada perubahan impedansi yang melebihi threshold pada bahu kiri, bahu kanan dan kedua bahu digerakkan ke depan secara trigger untuk meningkatkan kecepatan kursi roda elektrik saat berjalan maju. Variabel kecepatan maju masing- masing sebesar 20, 30 dan 40 RPM, sedangkan untuk perintah kontrol berhenti, dilakukan dengan menggerakkan kedua bahu ke depan dan ditahan selama 1,5 detik. Hasil percobaan menunjukkan persentase keberhasilan sebesar 75% pada pengujian jalan datar. Percobaan dilakukan pada 4 orang subjek normal dengan masing-masing subjek melakukan percobaan sebanyak 5 kali.

2015

[1] Arrofiqi, Fauzan; Arifin, Achmad; Indrajaya, Benicditus;, "Design of wearable system for closed-loop control of gait restoration system by Functional Electrical Stimulation", 2015 International Seminar on Intelligent Technology and Its Applications, ISITIA 2015 - Proceeding, pp. 131-136, IEEE, 2015

This paper describes design and test of a wearable FES system for the purpose of improving the performance of gait in patients with post-stroke. The prototype system that was developed includes electrical stimulator and sensor systems. Electrical stimulator was designed to generate pulse train that was realized using non-isolated boost converter. Sensor system was designed to measure gait phases that was realized using FSR sensors and to measure lower limb joint angles that was realized using a fusion of gyroscope and accelerometer-based tilt angle sensor. In order to remove measurement error due to bias error of the gyroscope and fluctuation of tilt sensor, Kalman filter was used to estimate true lower limb joint angles. Each system was tested separately. Testing was done by measuring the stimulator's output on the tibialis anterior muscle stimulation in normal subjects. The characteristics of pulse train in accordance with the desired specifications and capable of producing contractions in the tibialis anterior muscle. Sensor system was tested to measure gait parameters in subjects who walk normally. Comparison of the measured data with existing research data, showed the same pattern of the signal, the magnitude value is still in the standard deviation value of comparative data.
link: ieeexplore.ieee.org

[2] Hikmah, Nada Fitrieyatul; Arifin, Achmad; Sardjono, Tri Arief; Suprayitno, Eko Agus;, "A signal processing framework for multimodal cardiac analysis", 2015 International Seminar on Intelligent Technology and Its Applications, ISITIA 2015 - Proceeding, pp. 125-130, IEEE, 2015

The heart is a complex organ in the cardiovascular system which its measurement and analysis system in clinical level should be realized in an integrated system including all cardiac vital signs. A previous study combined ECG and PCG analysis could detect murmur symptom. However, the heart mechanical activity could not be described. This study developed a multimodal analysis of cardiac signals consisting of ECG signals, carotid pulse, and PCG. The purpose of this study was to develop and test an appropriate signal processing framework to facilitate parameter extraction and to enhance understanding of underlying mechanisms in the cardiac physiology. Frequency and time-frequency domain analysis of cardiac signals were performed to design sophisticated digital filters. Recursive digital filters were chosen in realizing segmentation methods and the advanced signal processing techniques were performed in parameter extraction. Results show the proposed method was able to detect QRS complex, P and T waves in ECG signal with 88% sensitivity and also percussion wave with 85.62% sensitivity. Sistolic (S1) and diastolic (S2) heart sound also could be separated. Classification of normal and the disease type of heart based on the cardiac parameters resulted by the presented signal processing framework would be next research topic.
link: ieeexplore.ieee.org

[3] Arifin, Achmad; Budiman, Fajar; Arrofiqy, Fauzan; Indrajaya, Bededictus Mawar; Ma'ar;, "Wearable Gait Measurement for Two Sensors and Force Sensing Resistor", International Conference on Sensor, Sensor System and Actuator (ICSSSA), 2015

2014

[1] Nurmadyansyah, Rizky Fauzy; Arifin, Achmad;, "Discrete PID Control System Performance for IH2 Azzurra Hand Robot", Seminar on Intelligent Technology and Its Applications 2014, 2014

Robotic technology for various application keep growing and widely used. In this research, a closed loop control system for a robot prosthetic hand was developed and evaluated. Control system with microcontroller as a main component to controlling an IH2 Azzurra hand robot capable to run in real time. It has UART interface with 115,2kbps baud rate which be able to get an input from moving sensor and produce output that is command as input for hand robot. It can control motor speed for each finger referenced to hand posture through moving sensor. Discrete PID control based microcontroller is control system method that be used in this system. System performance that be designed can be seen directly using made PC software. Moreover, the important parameters can be made to chart or stored to storage based on PC, so advanced analysis can be obtained easily. System performance that be obtained is good enough, referenced to maximum RMSE is 0,0496% for ring-little finger control system. For further application, this control system can be developed for medical application such as neuroscience and prosthetic or industrial application such as telecontrol system.

2013

[1] Madona, Putri; Arifin, Achmad; Sardjono, Tri Arief; Hendradi, Rimuljo;, "Segmentasi Suara Jantung S1 dan S2 Menggunakan Kurva Amplop", The 13th Seminar on Intelligent Technology and Its Applications, pp. 109-114, 2013

Proses segmentasi suara jantung adalah tahapan yang penting dalam analisa suara jantung. Mengetahui lokasi dan interval dari suara jantung S1 dan S2 serta komponen-komponennya yang didapatkan melalui proses segmentasi dapat menjadi informasi tentang kondisi kerja jantung. Salah satu metode segmentasi yang bisa digunakan adalah wavelet transform dan kurva amplop. Dalam penelitian ini digunakan Discrete Wavelet Transform (DWT), serta 2 algoritma kurva amplop yaitu Moving Average Filter dan Normalized Average Shannon Energy untuk segmentasi 28 data suara jantung yang terdiri dari normal dan 3 murmur. Perhitungan pada kedua algoritma kurva amplop tersebut menghasilkan kurva amplop yang bergeser dari sinyal aslinya. Semakin lebar window yang digunakan semakin besar pergeseran yang terjadi. Dari hasil segmentasi menunjukkan bahwa periode sistolik mempunyi durasi yang lebih pendek dan lebih konstan dibandingkan periode diastolik. Dan interval suara jantung S1 murmur sistolik lebih panjang dibandingkan suara jantung normal sementara interval suara jantung S2 murmur diastolik lebih panjang dibandingkan suara jantung normal. Algoritma segmentasi yang digunakan telah menunjukkan kemampuan dalam segmentasi suara jantung S1, S2 dan komponen-komponennya dengan tingkat keberhasilan 71.43%. Sebagai langkah selanjutnya perlu dilakukan ekstraksi ciri pada suara jantung S1 dan S2 hasil segmentasi untuk mengetahui kandungan frekuensi dari masing-masing suara jantung tersebut. Kata

2012

[1] Arifin, Achmad; Arrofiqi, Fauzan; Setiawan, Rachmad; Supeno, Bambang; Tasripan; Pujiono; Tasripan, Pujiono;, "A Wearable Human Movement Measurement System: ~ Sensor Fusion and Signal Processing Method ~", The 13th Seminar on Intelligent Technology and Its Applications, pp. 189-193, 2012

We studied a method of joint angle measurement during movements using wearable sensor for rehabilitation purpose. The method utilized fusion of two types of inertial sensors, gyroscope and accelerometer-based tilt angle sensor. In order to remove measurement error due to bias error of the gyroscope and fluctuation of tilt sensor, Kalman filter was used to estimate true joint angle. The method was tested experimentally in measuring knee joint angle during cyclic movements using a physical model of knee joint. The measured joint angle data in 24 trials were assessed statistically comparing to the joint angle data measured by the electronic goniometer instrumented in the physical knee joint model. The designed Kalman filter reduced measurement error significantly. The method of sensor fusion and Kalman filtering showed high accuracy reflected by low RMSE: 2.66±0.64 degree, and high correlation coefficient: 0.97±0.05. By utilizing the Kalman filter, fusion of the gyroscope and tilt sensor would be applicable as a wearable, low-cost human movement measurement system, or in realizing a wearable control system for human movement rehabilitation.

[2] Hakim, Luqman; Arifin, Achmad; Sardjono, Tri Arief;, "Identifikasi Suara Serak Berbasis Transformasi Wavelet Dan Algoritma Jaringan Syaraf Tiruan", The 13th Seminar on Intelligent Technology and Its Applications, pp. 119-124, 2012

Paper ini membahas identifikasi suara serak berbasis transformasi wavelet dan algoritma jaringan syaraf tiruan (JST). Serak merupakan indikator gangguan pada pita suara, sehingga identifikasi jenis suara normal dan serak yang sistematis dapat membantu diagnosa gangguan pita suara. Continous Wavelet Transform (CWT) dengan fungsi morlet digunakan untuk mengeksplorasi karakter sinyal suara dalam domain waktu dan frekuensi secara simultan Data objek penelitian berupa suara vokal “A”, “E”, “I”, “O”,”U” normal dan serak karena radang tenggorokan.Topologi JST terdiri 900 neuron pada layer input, 40 neuron pada hidden layer 1 dan 2, dan 10 neuron layer output. Hasil CWT menunjukan perbedaan karakter waktu-frekuensi antara sinyal suara normal dan serak. Pengujian menggunakan yang sudah dilatih (50 data, terdiri atas 5 sampel dari setiap vokal normal dan serak) 100% teridentifikasi dengan tepat. Kemampuan JST mengenali data baru diuji secara online dengan suara normal dan suara serak secara random. Didapatkan nilai sensitifitas 84%, spesifisitas 86%, dan efisiensi rata–rata 85% untuk kelima jenis suara vokal. Dengan hasil tersebut dapat diketahui bahwa CWT dan JST dapat digunakan untuk mengidentifikasi jenis suara normal dan serak. Hasil penelitian ini diharapkan dapat dikembangkan hingga terealisasi sisitem identifikasi jenis penyakit daerah pita suara berdasarkan analisa suara pasien.

[3] Hendradi, Rimuljo; Arifin, Achmad; Hery Purnomo, Mauridhi; Gunawan, Suhendar;, "Exploration of cardiac valvular hemodynamics by heart sound analysis of hypertensive cardiac disease background patients", Proceeding - 2012 IEEE International Conference on Computational Intelligence and Cybernetics, CyberneticsCom 2012, pp. 153-157, IEEE, 2012

Heart sounds reflect heart valve activities, cardiac muscle contractions, and hemodynamics of heart. Auscultation technique is one of valuable methods for diagnosis. There are limitations in traditional auscultation stimulate utilization of signal processing methods to extract important characteristics of the heart sounds. We proposed Continuous Wavelet Transform (CWT) as time-frequency analysis for exploration of cardiac valvular hemodynamics of two normal subjects with hypertensive heart disease history. Decimation and a wavelet denoising were used for filtering. A normalized average Shannon energy was used for heart sound signal segmentation. Time-scale maps resulted by calculation of CWT were processed using thresholding method to localize temporal and frequency-related information of valvular activities of each cardiac sub-cycle. The temporal and frequency-related parameters were spaced time between systolic (S1) and diastolic (S2), activities of mitral (M1) and tricuspid (T1) valves during systolic period, aortic (A2) and pulmonary (P2) valves during diastolic period, and split time between valve activities in each cycle. Results of this study were considered to be valuable to explain the cardiac valvular hemodynamics of heart sounds precisely. The results indicate the benefit of the developed method to be applied in analyzing heart sound characteristics. The results are very helpful information for clinical use. Next topic of our research was addressed to expand the analytical method to other pathological background. The research work would be finalized by development of software analysis of cardiac pathology diagnostic system.
link: ieeexplore.ieee.org

[4] Indrajaya, Benedictus; Setiawan, Rachmad; Arifin, Achmad;, "Penentuan Lower Limb Joint Angles Berdasar Respon Akselerometer dalam Pengembangan Wearable Sensor untuk FES", The 6th Electrical Power, Electronics, Communications, Controls, and Informations Seminar, 2012

Banyaknya pasien yang mengalami kelumpuhan, misal, akibat stroke memerlukan rehabilitasi kelumpuhan anggota geraknya. Functional Electrical Stimulation (FES) dapat secara efektif dalam membantu restorasi kelumpuhan fungsi motorik. Untuk sistem FES terinduksi gait (gaya berjalan), memerlukan sistem sensor untuk memonitor lower limb joint angles sebagai feedback. Pada paper ini kami mengusulkan penggunaan sensor akselerometer dan giroskop untuk mengukur lower limb joint angles, yaitu sudut sendi heap, knee dan ankle. Pengunaan sensor berteknologi MEMSs dengan ukuran yang kecil bertujuan agar sistem sensor mudah dipakai dan nyaman bagi pasien. Dijabarkan bagaimana penentuan persamaan lower limb joint angles berdasar vektor akselerasi akselerometer yang terpasang pada segmen tubuh, paha, betis dan telapak kaki, untuk mengukur sudut tilt tiap segmen. Pengujian dilakukan dengan menggunakan model kaki dari seorang subyek dengan skala 1:1 didapat hasil yang linier dengan nilai RMSE sudut heap = 0,96o, RMSE sudut knee = 1,25o dan RMSE sudut ankle = 1,81o. Dengan metode yang diusulkan peletakan posisi sensor lebih mudah dilakukan. Berdasar hasil penelitian ini, kedepan akan dilanjutkan penelitian tentang penentuan lower limb joint angles pada subyek yang berjalan dengan normal gait

[5] Lutfi, Fuad; Arifin, Achmad;, "Klasifikasi Sinyal Elektrokardiografi Menggunakan Wavelet Transform dan Neural Network", The 13th Seminar on Intelligent Technology and Its Applications, Vol. 62, pp. 136-140, 2012

Elektrokardiografi (EKG) merupakan metode yang umum digunakan untuk mengukur kinerja jantung manusia melalui aktivitas elektrik jantung. Pada penelitian ini telah direalisasikan sebuah sistem yang mampu menganalisis dan mengklasi-fikasikan kelainan sinyal EKG. Continuous Wavelet Transform (CWT) dengan fungsi Morlet digunakan untuk mengeksplorasi karakteristik time-frequency sinyal EKG. Klasifikasi sinyal EKG dilakukan dengan Artificial Neural Network (ANN) metode algoritma backpropagation. Konfigurasi ANN adalah 20.000 neuron pada lapisan masukan, 50 neuron pada lapisan tersembunyi, dan 3 neuron pada lapisan keluaran. Sinyal EKG yang digunakan diambil dari database MIT-BIH Arrhythmia, termasuk sinyal denyut normal dan sinyal denyut bundle branch blok (BBB). Hasil komputasi CWT menunjukkan perbedaan karakteristik time-frequency yang signifikan antara sinyal normal dan sinyal BBB. Dalam pengujian kinerja klasifikasi ANN dengan data yang sebelumnya telah dilatih (sejumlah 25 data untuk 3 kelas : normal, left bundle branch block, right bundle branch block), masing-masing kelas 100% dikenali. Pengujian dengan data yang belum dilatih, ANN mengenali data dengan akurasi 87,04%. Dalam pengujian dengan validasi silang, ANN menunjukkan kinerja yang baik dengan sensitivitas 87% dan spesifisitas 95%. Hasil pengujian menunjukkan efektivitas pengenalan pola sinyal EKG menggunakan CWT dan ANN. Oleh karena itu, metode yang diusulkan ini diharapkan dapat diwujudkan dalam pengembangan Sistem Cerdas Diagnosa Jantung untuk aplikasi klinis.

[6] Madona, Putri; Arifin, Achmad; Tri, Arief; Hendradi, Rimuljo;, "Analisa Suara Jantung Berbasis Complex Continuous Wavelet Transform", Conference Paper, 2012

Penyakit jantung merupakan salah satu penyakit berbahaya yang masih menjadi penyebab utama kematian di seluruh dunia. Penyakit jantung valvular merupakan salah satu jenis penyakit jantung yang disebabkan ketidaknormalan fungsi katup-katup jantung. Teknik auskultasi tradisional yang masih umum dijalankan hingga saat ini mengandung kelemahan yang utama, yaitu faktor variabilitas intra- subjek dan inter-subjek, sehingga dapat mengakibatkan perbedaan hasil diagnosa. Dalam rangka mengembangkan sistem auskultasi modern diperlukan suatu metode yang mampu menganalisa suara jantung dengan baik. Oleh karena itu diusulkan sebuah metode analisis data suara jantung menggunakan Complex Continuous Wavelet Transform. Data yang digunakan adalah 28 data suara jantung yang dikumpulkan dari database publik serta 16 data dari pengambilan sampel suara jantung normal dari subjek normal menggunakan stetoskop digital. Prosedur pemrosesan sinyal untukmengekstrak fenomena fisik tersembuyi dari sinyal suara jantung terdiri dari 3 tahap. Pertama, Discrete Wavelet Transform, digunakan untuk mengurangi background noise pada sinyal asli. Kedua, sinyal disegmentasi menggunakan Normalized Average Shannon Energy. Ketiga, karakteristik dari sinyal akan diekstrak menggunakan Complex Continuous Wavelet Transform (CWT). Metode CWT yang telah diusulkan ini, menunjukkan kemampuan dalam mengekstrak dan mengidentifikasi suara jantung pertama S1, suara jantung kedua S2 dan komponen- komponennya. Hasil kontur time-frekuensi yang merefleksikan aktifitas mekanik dari katup maupun otot jantung diharapkan dapat digunakan dalam mendiagnosa kelainan jantung manusia.

[7] Puspasari, Ira; Arifin, Achmad; Hendradi, Rimuljo;, "Ekstraksi Ciri Komponen Aortik dan Pulmonari Suara Jantung Diastolik dengan Menggunakan Analisis Nonstasioner", The 6th Electrical Power, Electronics, Communications, Controls, and Informations Seminar, pp. 1-5, 2012

-Dalam rangka mengembangkan sistem diagnosa suara jantung secara elektronik, bagian ekstraksi ciri menjadi bagian yang sangat penting. Oleh karena itu, perlu dipelajari metode ekstraksi ciri yang efektif untuk menggali dinamika yang terkandung dalam data suara jantung. Pada penelitian ini telah dipelajari lebih spesifik dari beberapa metode ekstraksi ciri, dengan metode pengolahan sinyal non stasioner: Short Time Fourier Transform dan Wavelet Transform. Dari hasil penelitian durasi S2 suara jantung normal sebesar 0.071 ± 0.01017, durasi A2 sebesar 0.021 ± 0,0096 detik dari total data, dan durasi P2 sebesar 0.016 ± 0,0039 detik. Dari hasil suara mitral regurgitasi, tampak bahwa countour yang dihasilkan dari S2 tidak terpisah sedurasi S2 sebesar 0.02537 ± 0.00115 detik. Hasil penelitian ini menunjukkan bahwa terdapat time split pada komponen A2 dan P2 yaitu sebesar 0.03 ± 0.0144 detik untuk jantung normal. Penelitian selanjutnya adalah pemodelan suara jantung yang diharapkan mampu lebih mendiskripsikan dan memberikan informasi tentang karakteristik suara jantung secara objektif.

[8] Supeno, Bambang; Setiawan, Rachmad; Arifin, Achmad;, "Disain Wireless Functional Electrical Stimulator Menggunakan X-Bee Pro", The 6th Electrical Power, Electronics, Communications, Controls, and Informations Seminar, 2012

Secara garis besar semua jenis gerakan itu dapat dikelompokkan menjadi dua bagian besar, yaitu gerakan tubuh bagian atas (upper limb) dan bawah (lower limb). Semua jenis gerakan, termasuk berjalan, merupakan hasil dari sebuah proses rumit yang melibatkan otak, sumsum tulang belakang, saraf perifer, otot, tulang dan sendi. Paralyzed lower limbs adalah suatu kondisi klinis pada pasien yang berupa kelumpuhan anggota tubuh bagian bawah. FES (Functional Electrical Stimulator) adalah merupakan salah satu divais yang dipergunakan sebagai metode terapi restorasi gerakan pasien dengan paralyzed lower limbs untuk mengaktifkan jaringan motoriknya, sehingga pasien dapat berjalan. Harapan utama dari penelitian ini adalah adanya disain sistem FES dengan komunikasi data tanpa kabel. Dengan Wireless FES yang menggunakan X-Bee Pro, diharapkan dapat semakin memudahkan dan mempercepat proses restorasi kelumpuhan pasien bagian bawah. Kata

[9] Suprayitno, Eko Agus; Arifin, Achmad;, "Sistem Instrumentasi Sinyal Electrocardiography Untukanalisa Dinamika Jantung", Seminar Nasional Fisika Terapan III , Departemen Fisika, FST, Universitas Airlangga Surabaya,15, 2012

Klasifikasi sinyal jantung sangat penting untuk mengetahui penyakit jantung yang seringkali datang secara tiba-tiba. Untuk mendukung pentingnya klasifikasi sinyal jantung, maka beberapa pekerjaan pendahuluan terkait pembuatan instrumentasi pendeteksian sinyal jantung (Electrocardiography) dihasilkan informasi bahwa hasil penguatan rata-rata instrumentasi Diferensial Amplifier ECG didapatkan sebesar (279.65 ± 14.66) kali. Untuk Low Pass Filter Analog Orde 4 dengan frekuensi cutoff 100 Hz dihasilkan penguatan -3 dB di area frekuensi 120 Hz. Hasil uji Notch Filter 1 dan Notch Filter 2 menghasilkan tegangan output (Vout) terkecil di frekuensi 50 Hz dengan besar Vout masing-masing (0.14 ± 0.00) volt dan (0.094 ± 0.009) volt serta Quality factor (Q) keduanya sama yaitu 6.28. Analisa sinyal jantung (ECG) dengan menggunakan DFT memberikan informasi bahwa pada sinyal jantung, area frekuensinya terjadi di area 3 Hz sampai 26 Hz. Penelitian ini selanjutnya akan dikembangkan pada Multimodal Cardiac Analysis dengan menampilkan sinyal ECG, sinyal Phonocardiography (PCG) dan sinyal Tekanan Darah (diwakili sinyal Carotid Pulse) secara simultan untuk mendapatkan informasi anatomi dan fisiologi jantung yang lebih kompleks.

[10] Suprayitno, Eko Agus; Hendradi, Rimuljo; Arifin, Achmad;, "Analisa Sinyal Electrocardiography dan Menggunakan Continuous Wavelet Transform", The 6th Electrical Power, Electronics, Communications, Controls, and Informations Seminar, pp. 1-6, 2012

Pada paper ini telah dikembangkan sistem analisa aktivitas jantung berdasarkan sinyal suara jantung (PCG) dan sinyal jantung (ECG) yang ditampilkan secara simultan dan di analisa menggunakan CWT. Sinyal suara jantung yang diambil pada empat titik jantung (Left Ventricle (LV), Right Ventricle (LV), Pulmonary Artery (PA), dan Aortic (AO)) secara simultan dengan sinyal jantung menghasilkan informasi suara jantung frekuensi dominannya banyak berada pada bunyi suara jantung pertama (S1) dan pada sinyal jantung frekuensi dominannya berada pada area glombang QRS kompleks. Ditinjau dari waktu kejadian, frekuensi suara S1 ada pada range 188 Hz - 229 Hz dengan range waktu 0,2 detik - 0,32 detik; suara jantung S2 pada 197 Hz - 535 Hz dengan range waktu 0,52 detik - 0,69 detik; suara jantung S3 ada pada 141 Hz - 212 Hz dengan waktu 0,8 detik; suara jantung S4 ada pada 169 Hz - 273 Hz pada waktu ke 0,16 detik. Sinyal QRS kompleks frekuensinya ada pada 94 Hz - 134 Hz dengan range waktu ke 1,2 detik - 1,3 detik. Ini menunjukkan bahwa suara S1 terjadi hampir bersamaan dengan timbulnya QRS kompleks. Penelitian selanjutnya akan dikembangkan lagi pada Multimodal Cardiac Analysis.
link: https:

[11] Wardana, P Susetyo; Arifin, Achmad;, "Instrumentasi dan Pendeteksian Sinyal EMG Dinamik selama Elbow Joint Bergerak", The 6th Electrical Power, Electronics, Communications, Controls, and Informations Seminar, pp. 1-5, 2012

Sinyal Electromyograph adalah salah satu sinyal penting yang menunjukan aktifitas otot manusia, sedangkan untuk merekam data sinyal EMG yang mempunyai karakteristik amplitude cukup kecil (0 – 10 mV) dan frekuensi pada range 20 – 500 Hz diperlukan rangkaian pendukung seperti penguat differential, filter low pass, high pass dan notch filter. Sinyal EMG yang dihasilkan oleh sebuah instrumentasi EMG memerlukan beberapa analisa yang membuktikan bahwa yang diperoleh adalah sinyal EMG bukan noise. Untuk menganalisa sinyal EMG dalam kawasan frekuensi digunakan (Discrete Fourier Transform) DFT dan (Mean Power Frequency) MPF. Dari penelitian ini diperoleh nilai MPF pada otot Triceps brachii untuk gerakan Elbow Flexion sebesar 75,156 Hz sedangkan gerakan Elbow Extension sebesar 65,069 Hz, gerakan Elbow Supination sebesar 27,627 Hz, gerakan Elbow Pronation sebesar 47,659 Hz. Dari keempat data MPF diatas membuktikan bahwa Instrumentasi EMG telah berfungsi merekam data sinyal EMG yang berada pada frekuensi 20 – 500 Hz

[12] Yasak, Abdul; Arifin, Achmad;, "Ekstraksi Parameter Temporal Sinyal ECG Menggunakan Difference Operation Method", The 13th Seminar on Intelligent Technology and Its Applications, 2012

Sinyal ECG merupakan salah satu sinyal yang dapat digunakan untuk mendeteksi kelainan jantung. Tiap-tiap komponen sinyal ECG menggambarkan proses fisiologis selama satu siklus aktivitas jantung. Deteksi ketidaknormalan jantung dapat dilakukan dengan mengetahui parameter temporal dari sinyal ECG. Pada penelitian ini dilakukan eksperimen metode ekstraksi parameter temporal sinyal ECG dengan menggunakan metode Difference Operation Method (DOM)untuk ekstraksi fitur sinyal ECG. Parameter temporal yang diekstrak meliputi interval R-R, durasi kompleks QRS, dan laju detak jantung. Metode ini diuji dengan menggunakan data ECG dari ECG MIT database dengan tiga kondisi, normal, right bundle branch block (RBBB) dan left bundle branch block (LBBB). Hasil penelitian menunjukkan metoda DOM dapat mengekstrak parameter temporal ECG. Masing-masing kondisi jantung mempunyai ciri yang khas dari parameter temporal yang diekstrak. Kami mendeteksi ada kasus tertentu dimana batas antara satu kondisi dengan yang lain mempunyai batas yang fuzzy. Hal ini akan ditindaklanjuti dengan metoda klasifikasi yang sesuai dengan karakter data sesuai hasil penelitian ini. KataKunci:Difference

2011

[1] Firdaus, Sukma; Arifin, Achmad;, "Analisa Nonstasioner Pada Auditory Evoked Responses", Conference Paper, 2011

Auditory evoked responses (AER) adalah representasi dari proses neurofisiologi di dalam otak akibat stimulus suara pada sistem pendengaran. Sinyal AER merupakan sinyal nonstasioner, hal ini disebabkan karena otak selalu menghasilkan respons dengan frekuensi yang tidak konstan disetiap waktu. Salah satu metode analisa yang dapat digunakan untuk sinyal nonstasioner adalah analisa time-frequency. Analisa time-frequency yang digunakan dalam penelitian ini adalah continuous wavelet transform (CWT). Dalam penelitian ini, dilakukan analisa terhadap rentang skala dengan magnitudo yang lebih besar. Rentang skala tersebut adalah 20x10-2 hingga 80x10-2. Nilai magnitudo pada rentang skala tersebut lebih besar dari pada sebelum dan sesudah stimulus. Hal tersebut juga terjadi pada subyek yang dikondisikan dengan mata terbuka. Terdapat perbedaan pada kondisi mata tertutup dan mata terbuka, perbedaan tersebut adalah nilai magnitudo pada mata tertutup lebih besar dari pada mata terbuka. Perubahan nilai magnitudo pada mata tertutup jauh lebih tegas berada pada daerah VI dan VII dalam gambar plot hasil perhitungan CWT. Sedangkan pada mata terbuka, nilai magnitudo direntang tersebut lebih melebar. Waktu respon tercepat terdapat pada perekaman ke-10 subyek 1 untuk kondisi mata terbuka dengan waktu tempuh sebesar 0.045 detik, sedangkan waktu respon paling lama terdapat pada perekaman ke-8 subyek 1 kondisi mata tertutup dengan waktu tempuh sebesar 0.220 detik. Dari penelitian ini diperoleh, bahwa pendekatan analisa nonstasioner dengan menggunakan CWT, mampu menunjukkan sifat kenonstasioneran dari sinyal AER.

[2] Lutfi, Fuad; Arifin, Achmad;, "Karakterisasi Sinyal Elektrokardiografi menggunakan Transformasi Wavelet Kontinyu", Konferensi Nasional Forum Teknik Elektro 2011, 2011

2009

[1] Saito, Hiroki; Watanabe, Takashi; Arifin, Achmad;, "Ankle and knee joint angle measurements during gait with wearable sensor system for rehabilitation", IFMBE Proceedings, Vol. 25, No. 9, pp. 506-509, Springer Berlin Heidelberg, 2009

A method of joint angle measurement during gait using wearable sensors for rehabilitation was studied in this paper. The method corrected joint angles measured by gyroscopes using joint angles measured by accelerometers with Kalman filter. Although gyroscopes could measure joint angles, their offset drift caused error in measurement of joint angles. At first, we made up small sensor units consist of a gyroscope and an accelerometer. Then, the method was validated with the developed sensor units in measurement of ankle and knee joint angles of three healthy subjects under walking on short distance pathway and on treadmill for long time. The measured joint angles were compared with reference joint angles measured with optical motion measurement system simultaneously. The result for short distance walking showed low RMS errors and high correlation coefficients (3.19deg and 0.918 for the ankle joint, 2.98deg and 0.993 for the knee joint in average). The result for treadmill walking also showed low RMS errors and high correlation coefficients (3.04deg and 0.960 for the ankle, 4.19deg and 0.994 for the knee in average). Although the measurement accuracy decreased in some of trials of a specific subject because of sensor attachment position, the experimental results suggested that joint angle could be measured with good accuracy independent of measurement period of time, walking speeds and subjects. © 2009 Springer-Verlag.
link: link.springer.com

2008

[1] Arifin, Achmad; Saito, Hiroki; WATANABE, Takashi;, "An error reduction method of portable, low-cost joint angle sensor system for human movement measurement and control (ME とバイオサイバネティックス)", 電子情報通信学会技術研究報告. MBE, ME とバイオサイバネティックス, Vol. 108, No. 314, pp. 31-34, 一般社団法人電子情報通信学会, 2008

2007

[1] Watanabe, Takashi; Arifin, A.; Masuko, T.; Yoshizawa, M.;, "An Experimental Test of Fuzzy Controller Based on Cycle-to-Cycle Control for FES-induced Gait : Knee Joint Control with Neurologically Intact Subjects", 11th Mediterranean Conference on Medical and Biomedical Engineering and Computing 2007, pp. 2007-2007, Springer Berlin Heidelberg, 2007

Functional Electrical Stimulation (FES) can be effective in assisting or restoring paralyzed motor functions caused by the spinal cord injury or the celebrovascular disease. The purpose of this study was to develop a control method of gait induced by FES. We had proposed a fuzzy control system based on cycle-to-cycle control for controlling hip, knee and ankle joints during the swing phase of FESinduced gait and evaluated it in computer simulation studies. In this report, the fuzzy controller was tested experimentally in controlling maximum knee extension angle stimulating the vastus muscles using surface electrodes with neurologically intact subjects. The fuzzy controller worked properly in regulating stimulation burst duration time and the maximum knee extension angle was controlled well. The experimental results suggested that the fuzzy controller would be practical in clinical applications for the control of FES-induced gait. However, it was also suggested that electrical stimulation with large burst duration time or muscle fatigue caused a change in muscle response.
link: link.springer.com

2006

[1] Arifin, Achmad; Watanabe, Takashi; Yoshizawa, Makoto; Hoshimiya, Nozomu;, "A Test of Stimulation Schedules for the Cycle-to-Cycle Control of Multi-joint Movements in Swing Phase of FES-induced Hemiplegic Gait", バイオメカニズム学会誌, Vol. 30, No. 1, pp. 31-35, 2006

This paper described a computer simulation test of six different stimulation schedules for the cycle-to-cycle control of swing phase of functional electrical stimulation (FES) induced hemiplegic gait. The stimulation schedules were evaluated in controlling the hip, the knee and the ankle joint movements on the point of view of acceptable quality of the gait that was similar to the natural gait pattern. Five stimulation schedules were knowledge-based stimulation schedules and one stimulation schedule was an EMG-based stimulation schedule. Two acceptable stimulation schedules were found by the evaluation. Results of this study showed that combination of the timing pattern of muscle activation and knowledge of joint movements and muscle function is necessary in design of stimulation schedule for FES gait. Co-activation of the ilopsoas, the hamstrings and the vastus muscle at the beginning of swing phase and that of the tibialis anterior and the soleus at the end of swing phase were found to be effective in controlling swing phase. The knowledge-based generation of stimulation schedule would be effective and necessary in clinical application.

[2] Arifin, Achmad; Yoshizawa, M;, "A Computer Simulation Study on the Cycle-to-Cycle Control Method of Hemiplegic Gait Induced by Functional Electrical Stimulation", RECORD OF ELECTRICAL AND COMMUNICATION ENGINEERING CONVERSAZIONE TOHOKU UNIVERSITY, Vol. 74, No. 2, pp. 58, TOHOKU DAIGAKU DENTSU DANWAKAI, 2006

2003

[1] Arifin, A; Watanabe, T; Hoshimiya, N;, "Computer simulation study of the cycle-to-cycle control using fuzzy controllers for restoring swing phase of FES-induced hemiplegic gait", Proc. Symp. on Med. & Biol. Eng, pp. 131-139, 2003

[2] Arifin, A.; Watanabe, T.; Hoshimiya, N.;, "Fuzzy controller for cycle-to-cycle control of swing phase of FES-induced hemiplegic gait: a computer simulation in two-joints control", Proceedings of the 25th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (IEEE Cat. No.03CH37439), Vol. 2, pp. 1519-1522, IEEE, 2003

This paper described a test of fuzzy controller for controlling knee and ankle movements of swing phase of FES-induced hemiplegic gait. We developed five fuzzy controllers to control electrical stimulation for the hamstrings, the quadriceps, the gastrocnemius medialis, the tibialis anterior and the soleus muscles. The fuzzy controllers regulated burst durations of stimulation pulse trains to maintain certain maximum angles of knee flexion, knee extension, ankle plantar flexion, and ankle dorsiflexion and to prepare good initial contact. Capabilities of fuzzy controller in automatic generation of stimulation burst duration and compensating muscle fatigue were tested by computer simulation using musculo-skeletal model. The fuzzy controller generated standard burst duration in automatic generation of stimulation burst duration in a few cycles and compensated muscle fatigue fast.
link: ieeexplore.ieee.org