**1. Introduction**

Computational Intelligence in Electromyography Analysis – 426 A Perspective on Current Applications and Future Challenges

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Electromyography (EMG) is the subject which deals with the detection, analysis and utilization of electrical signals emanating from skeletal muscles. The field of electromyography is studied in Biomedical Engineering. And prosthesis using electromyography is achieved under Biomechatronics [1]. The electric signal produced during muscle activation, known as the myoelectric signal, is produced from small electrical currents generated by the exchange of ions across the muscle membranes and detected with the help of electrodes. Electromyography is used to evaluate and record the electrical activity produced by muscles of a human body. The instrument from which we obtain the EMG signal is known as electromyograph and the resultant record obtained is known as electromyogram [2].

The human body is a wonder of nature. The functioning of human body is an intriguing and fascinating activity. Motion of the human body is a perfect integration of the brain, nervous system and muscles. It is altogether a well-organized effort of the brain with 28 major muscles to control the trunk and limb joints to produce forces needed to counter gravity and propel the body forward with minimum amount of energy expenditure [3]. The movement of the human body is possible through muscles in coordination with the brain. Whenever the muscles of the body are to be recruited for a certain activity, the brain sends excitation signals through the Central Nervous System (CNS). Muscles are innervated in groups called 'Motor Units'. A motor unit is the junction point where the motor neuron and the muscle fibers meet. A depiction of the Motor Unit is given in Figure 1. When the motor unit is activated, it produces a 'Motor Unit Action Potential' (MUAP) [4]. The activation from the Central Nervous System is repeated continuously for as long as the muscle is required to generate force. This continued activation produces motor unit action potential trains. The trains from concurrently active motor units superimpose to produce the resultant EMG

© 2012 Jamal, licensee InTech. This is an open access chapter distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2012 Jamal, licensee InTech. This is a paper distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Computational Intelligence in Electromyography Analysis – 428 A Perspective on Current Applications and Future Challenges

signal. A group of muscles are involved in a certain movement of the human body. The number of muscles recruited depends upon the activity in which the body is involved. E.g. in lifting a small weight such as a tiny pebble, fewer amount of muscles will be involved as compared to lifting a heavy mass like a 6 kg weight, where the muscles employed will be greater. In technical terms, whenever it is required to generate greater force, the excitation from the Central Nervous System increases, more motor units are activated and the firing rate of all the motor units increase resulting in high EMG signal amplitudes [4,5].

Signal Acquisition Using Surface EMG and Circuit Design Considerations for Robotic Prosthesis 429

This chapter will discuss in detail, the effective use of surface electromyography (SEMG) as a tool for achieving robotic prosthesis. An elaborate account of SEMG electrode types, signal acquisition technique, electronics circuit design considerations and the control procedure to

The bioelectrical activity inside the muscle of a human body is detected with the help of EMG electrodes. There are two main types of EMG electrodes: surface (or skin electrodes) and inserted electrodes. Inserted electrodes have further two types: needle and fine wire electrodes. The three electrodes (needle, fine wire and surface) are explained as follows. Among these three electrodes, surface EMG electrodes will be specifically discussed in

Needle electrodes are widely used in clinical procedures in neuromuscular evaluations. The tip of the needle electrode is bare and used as a detection surface. It contains an insulated wire in the cannula. The signal quality from the needle electrodes is comparatively improved from other available types. Needle electrodes have two main advantages. One is that its relatively small pickup area enables the electrode to detect individual MUAPs during relatively low force contractions. The other is that the electrodes may be conveniently repositioned within the muscle (after insertion) so that new tissue territories

Wire electrodes are made from any small diameter, highly non-oxidizing, stiff wire with insulation. Alloys of platinum, silver, nickel, and chromium are typically used. Wire electrodes are extremely fine, they are easily implanted and withdrawn from skeletal muscles, and they are generally less painful than needle electrodes whose cannula remains

drive electric motors in a robotic mechanism is provided in this chapter.

**2. EMG electrodes and its types** 

detail as it pertains to the topic of this chapter.

may be explored [5]. A needle electrode is shown in Figure 2.

**2.1. Needle electrodes** 

**Figure 2.** A Needle EMG Electrode [8]

**2.2. Fine wire electrodes** 

**Figure 1.** A Motor Unit consists of one motor neuron and all the muscle fibers it stimulates [6]

Electromyography enables us to generate force, create movements and allow us to do countless other functions through which we can interact with the world around us. The electromyograph is a bioelectric signal which has, over the years, developed a vast range of applications. Clinically, electromyography is being used as diagnostic tool for neurological disorders. It is frequently being used for assessment of patients with neuromuscular diseases, low back pain and disorders of motor control [7]. Other than physiological and biomechanical research, EMG has been developed as an evaluation tool in applied research, physiotherapy, rehabilitation, sports medicine and training, biofeedback and ergonomics research.

In the recent past, EMG has also found its use in rehabilitation of patients with amputations in the form of robotic prosthesis. EMG proves to be a valuable tool as it provides a natural way of sensing and classifying different movements of the body. A multi-degree of freedom robotic mechanism can effectively imitate the motion of the human limb. Recent advances in electronics and microcontroller technology have allowed improved control options for robotic mechanisms. One of the most vital advantages of microprocessor technology in robotic prosthetics is the advanced EMG filtering algorithms. Nowadays, control options are even available to those who were not at one time qualified for such prosthetic management.

This chapter will discuss in detail, the effective use of surface electromyography (SEMG) as a tool for achieving robotic prosthesis. An elaborate account of SEMG electrode types, signal acquisition technique, electronics circuit design considerations and the control procedure to drive electric motors in a robotic mechanism is provided in this chapter.
