Internatio nal Jo urnal o f Sc ientific & Eng ineering Researc h, Vo lume 3, Issue 2, February -2012 1 ISS N 2229-5518 IJSER © 2012 http://www.ijser.org ———— ——— ——— ——— ———  Taslim Reza has obtained his Masters degree in Biomedical Engineering from Tamper University, Finland and Bachelor degree in Electrical and Electronic Engg from Islamic University of Technology, Bangladesh. Currently he is serving as Lecturer in Dept. of EEE of American Interna- tional University of Bangladesh (AIUB), Dhaka, Bangladesh. E-mail: taslimreza@gmail.com  S.M.Ferdous has obtained his Masters and Bachelor degree in Electrical and Electronic Engg from Islamic University of Technology, Bangladesh. Currently he is serving as Lecturer in Dept. of EEE of American Interna- tional University of Bangladesh (AIUB), Dhaka, Bangladesh. E-mail: tanzir68@gmail.com  Md. Nayeemul Hasan is currently serving as Lecturer in Dept. of EEE of American International University of Bangladesh (AIUB), Dhaka, Bangladesh. E-mail: nayeem01@yahoo.com  Md. Rokonuzzaman is currently serving as Lecturer in Dept. of EEE of University of Asia Pacific (UAP), Dhaka, Bangladesh. E-mail: rokon_iut@gmail.com  Kazi Firoz Ahmed is currently serving as Lecturer in Dept. of EEE of American International University of Bangladesh (AIUB), Dhaka, Bangladesh. E-mail: k.firoz@aiub.edu  A.Z.M Shahriar Muttalib is currently serving as Lecturer in Dept. of EEE of American International University of Bangladesh (AIUB), Dhaka, Bangladesh. E-mail: sadi_eece@yahoo.com A Low Cost Surface Electromyogram (sEMG) Signal Guided Automated Wheel Chair for the Disabled Taslim Reza, S.M.Ferdous, Md. Nayeemul Hasan, Md. Rokonuzzaman, Kazi Firoz Ahmed, A.Z.M.Shahriar Muttalib Abstract— This paper discusses the exploratory research of a simple, effective and low cost design of a microcontroller based wheelchair using the sEMG signal collected from the neck muscles w hich w ill allow a disabled person to control the wheelchair only by using the movement of his neck. Among the different neck muscles, upper trapezius muscle has been chosen for collection of the sEMG signals which are used to move, control and navigate the wheel chair. The main purpose of the w ork is to design a cost-effective, easily affordable and accessible w heel chair for the disabled general masses where advanced attachments like on board computer, digital cameras , sophisticated sensors etc. are not being used, rather concentration has been paid on designing a more practical and simple but effective system using an electrically controlled differential drive with only two wheels . Index Terms—Automated Wheel Chair, Bio-Electric Amplifier, Differential Drive controller, F/V converter, Myoelectric Signal processing, PID control, sEMG signal. ——————————  —————————— 1 INTRODUCTION ver the years, the neurophysiology and biomechanics of muscle systems have been investigated quite extensively based on the research of surface EMG signal. Surface Electromyography (EMG) signals represent the electrical activ- ity of a muscle during contraction [1]. The surface EMG sig- nals are complex and non stationary time sequence that can be considered as direct reflection of the muscle activity [2]. In this work EMG signals collected from the muscles responsible for two types of movements of neck medically termed as – flexion (the movement in which the chin is lowered down toward the chest) and lateral rotation (rotation to the left or to the right towards the shoulder); are used as the controlling signal for the wheelchair movement. In the past decade, a number of simple yet effective hands-free human machine interfaces (HMI) are brought into applications using human physiologi- cal signals such as electromyography (EMG), electrooculogra- phy (EOG) and electro-encephalography (EEG). As can be seen in literature [1, 2], HMIs developed from these signals are used for hands-free control of electric-powered Wheelchairs. Li and Tan [3] propose a bimodal wheelchair control approach by integrating vision and speech controls. Matsumoto and Ino et al. [4] apply the recognition of head motion and eye gaze onto a locomotive wheelchair system. Ferreira and Silva et al. [5] proposed an HMI structure to con- trol a robotic wheelchair by scalp EMG and EEG signals. This paper presents a solution for those kinds of disabled people who are unable to spend a lot of money to buy a fancy wheelchair that requires on board computer and other expen- sive instruments. A simple structure and user friendly control system are used to control the wheelchair movement using only the movements of neck muscles. Generally this type of design would suit most to the people those who are totally disabled, that means completely unable to move their hand or leg. First part of the paper shows the extraction of EOG signal by elaborately analyzing the anatomy of the eye muscles and processing of those signals to make it compatible to use in con- junction with a microcontroller. Second part shows the struc- ture and control mechanism of the wheelchair. 2 S ENSING AND ACQUISITION OF SEMG SIGNALS Myoelectric signals or surface electromyograms (sEMG) are produced during muscle contraction when ions flow in and out of muscle cells. When a nerve sends the signal to initiate muscle contraction a potential is developed across the muscle due to the movements of electrolytes. This ionic current can be converted into electronic current with Ag-AgCl electrodes placed on the surface of the skin of the contracting muscle. A typical EMG signal has an amplitude level of 0-5mV with a frequency range of 0-500Hz where the dominating frequency lies in the range of 50-150 Hz. O