Chapter 1INTRODUCTIONFrom the quotes of the science giant Albert Einstein, It is appallingly obvious that the technology has exceeded our humanity. This reflects the tremendous growth and influence of technology in Human culture. In the modern era, technology is the biggest sword and aid that enumerates the human power and knowledge. It is found that the thoughts are propagating from our brains in the form of cosmic waves. Of course it is an interesting fact to know that, these waves can do a lot in connection with the wishes of others. Artificiality, a word very far from Reality, is the emerging trend that pace the way for many inventions. Robot is the product which replaces emptiness with fulfilment in this regard. The urge of man to conquer the world started from the very beginning itself. With the advancements in technology, new products and possibilities came into existence. Electronic equipment are the most important gadgets well known today. These products change the world into another scenario. Now, the world is controlled with the help of advanced microcontrollers and digital signal processors.Abilities and disabilities create partialities among human into abled persons and disabled persons. The loss of a limb is a tragic event and artificial limbs are used to substitute for this loss. Early artificial limbs were crude, consisting of peg legs and hook-hands. However, with the developments in surgery and technology better limbs became available. In the sixteenth century, surgeons who carried out the amputations recruited the help of craftsmen to provide their patients with artificial limbs which were functionally useful and resembled the shape of normal limbs.Significant advances in the development of limb fitting services have been prompted by the two World Wars. Rapid progress has been made since the 1940s. This is due to the collaboration of surgeons, engineers and prosthetistto employ new developments in technology and materials to the rehabilitation of amputees.Modern technology allows people who have lost limbs to regain normal functions through use of artificial limbs or prosthetics. Patients have multiple options that allow them to walk, climb steps and run as well as before their injury. Recent researches and studies in neurology have shown the importance of brain in every aspect of technology. Intelligence is the key factor. The study regarding the Brain as the most powerful system has brought great changes in technology.

Fig 1.1. A man with artificial legs1.1 HISTORYProsthetic care goes back to the fifth Egyptian Dynasty (2750-2625 B.C.) archaeologists have unearthed the oldest known splint from that period. The earliest known written reference to an artificial limb was made around 500 B.C., Herodotus wrote of a prisoner who escaped from his chains by cutting off his foot, which he later replaced with a wooden substitute. An artificial limb dating from 300 B.C., was a copper and wood leg unearthed at Capri, Italy in 1858.In 1529, French surgeon, Ambroise Pare(1510-1590) introduced amputation as a lifesaving measure in medicine. Soon after, Pare started developing prosthetic limbs in a scientific manner. In 1863, Dubois L Parmelee of New York City made an improvement to the attachment of artificial limbs. He fastened a body socket to the limb with atmospheric pressure. He was not the first person to do so, but he was the first person to do so with satisfactory results. In 1898, Dr.Vanghetti invented an artificial limb that could move with through muscle contraction.In 1946, a major advancement was made in the attachment of lower limbs. A suction sock for the above-knee prosthesis was created at University of California (UC) at Berkeley. In 1975, Ysidro M. Martinez' invention of a below-the-knee prosthesis avoided some of the problems associated with conventional artificial limbs. Martinez, an amputee himself, took a theoretical approach in his design. He did not attempt to replicate the natural limb with articulated joints in the ankle or foot which is seen by Martinez as causing poor gait. His prosthesis has a high center of mass and is light in weight to facilitate acceleration and deceleration and reduce friction. The foot is considerably shorter to control acceleration forces, reducing the friction and pressure.Robotic legs plays very important role in the artificial legs.in the recent years there have been significant advancements in artificial limbs. The use of electronics has become very common in artificial legs. Myoelectric limbs control the limbs by converting muscle movements to electrical signals, have become much more common than cable operated limbs.1.2 BRAIN-COMPUTER INTERFACE (BCI)Brain computer interface(BCI), often called amind-machine interface(MMI), or sometimes called adirect neural interfaceor abrainmachine interface(BMI), is a direct communication pathway between the brain and an external device. In this definition, the word brain means the brain or nervous system of an organic life form rather than the mind. Computer means any processing or computational device, from simple circuits to the complex microprocessors and microcontrollers. BCIs are often directed at assisting, augmenting, or repairing human cognitive or sensory-motor functions. Research on BCIs began in the 1970s at theUniversity of California Los Angeles(UCLA) under a grant from theNational Science Foundation, followed by a contract fromDARPA.The papers published after this research also mark the first appearance of the expressionbraincomputer interfacein scientific literature.The field of BCI research and development has since focused primarily on neuro prosthetics applications that aim at restoring damaged hearing, sight and movement. Thanks to the remarkablecortical plasticityof the brain, signals from implanted prostheses can, after adaptation, be handled by the brain like natural sensor or effector channels.Following years of animal experimentation, the first neuro prosthetic devices implanted in humans appeared in the mid-1990s. The history of braincomputer interfaces (BCIs) starts withHans Bergersdiscovery of the electrical activity of the human brain and the development ofelectroencephalography(EEG). In 1924 Berger was the first to record human brain activity by means of EEG. By analysing EEG traces, Berger was able to identifyoscillatory activityin the brain, such as thealpha wave(812Hz), also known as Berger's wave.An interesting question for the development of a BCI is how to handle two learning systems: The machine should learn to discriminate between different patterns of brain activity as accurate as possible and the user of the BCI should learn to perform different mental tasks in order to produce distinct brain signals. BCI research makes high demands on the system and software used. Parameter extraction, pattern recognition and classification are the main tasks to be performed in a brain signals. In this paper it is assumed that the user of this system has one leg which is functioning fully and the system is designed accordingly. This system can be extended for both the legs and it is not limited to the basic operation of human legs such as walking, running, climbing stairs etc. It can also perform operations like cycling, hopping etc. 1.3 ADVANTAGES This system is advantageous in such a way that, it is easy to construct and have simple control unit. The system occupy very less space since it have ultra-slim design. The chance of occurring of an error is less in this system. The idea of brain controlled artificial leg can be extended for both legs and both legs can be made to do operations like walking, running etc. simultaneously. This semi-automatic system does not need the use of sensors. This brain controlled artificial leg is very cost effective.

Chapter 2BRAIN AND BRAIN WAVESThe field of neuroscience encompasses all approaches that seek to understand the brain and the rest of the nervous system.Psychologyseeks to understand mind and behaviour, andneurologyis themedical\discipline that diagnoses and treats diseases of the nervous system. The brain is also the most important organ studied inpsychiatry, the branch of medicine that works to study, prevent, and treatmental disorders.Cognitive scienceseeks to unify neuroscience and psychology with other fields that concern themselves with the brain, such ascomputer science(artificial intelligenceand similar fields) and philosophy.The oldest method of studying the brain isanatomical, and until the middle of the 20th century, much of the progress in neuroscience came from the development of better cell stains and better microscopes. Neuro anatomists study the large-scale structure of the brain as well as the microscopic structure of neurons and their components, especially synapses. Among other tools, they employ a plethora of stains that reveal neural structure, chemistry, and connectivity. In recent years, the development ofimmuno stainingtechniques has allowed investigation of neurons that express specific sets of genes. Also, functional neuroanatomyusesmedical imaging techniques to correlate variations in human brain structure with differences in cognition or behaviour.Fig 2.1. Brain A Powerful systemNeurophysiologists study the chemical, pharmacological, and electrical properties of the brain: their primary tools are drugs and recording devices. Thousands of experimentally developed drugs affect the nervous system, some in highly specific ways. Recordings of brain activity can be made using electrodes, either glued to the scalp as inEEGstudies, or implanted inside the brains of animals forextracellularrecordings, which can detect action potentials generated by individual neurons.Because the brain does not contain pain receptors, it is possible using these techniques to record brain activity from animals that are awake and behaving without causing distress.Electrical activity emanating from the brain is displayed in the form of brainwaves. There are four categories of these brainwaves ranging from the most activity to the least activity. When the brain is aroused and actively engaged in mental activities, it generates beta waves. These beta waves are of relatively low amplitude, and are the fastest of the four different brainwaves. The frequency of beta waves ranges from 15 to 40 cycles a second.

Table 2.1 Comparison table-Comparison of EEG bandsThe next brainwave category in order of frequency is Alpha. Where beta represented arousal, alpha represents non-arousal. Alpha brainwaves are slower and higher in amplitude. Their frequency ranges from 9 to 14 cycles per second. The next state, theta brainwaves, is typically of even greater amplitude and slower frequency. This frequency range is normally between 5 and 8 cycles a second. A person who has taken time off from a task and begins to daydream is often in a theta brainwave state. The final brainwave state is delta. Here the brainwaves are of the greatest amplitude and slowest frequency. They typically centres in a range of 1.5 to 4 cycles per second. They never go down to zero because that would mean that you were brain dead. But, deep dreamless sleep would take you down to the lowest frequency. Typically, 2 to 3 cycles a second. In the proposed system alpha waves and beta waves are used from the brain for signal processing. It is assumed that the person is in alpha state and beta state (which is the case normally) and these waves are taken out from the human brain and converted in the form of electrical signals with the help of electrode caps. The following figure shows the different types of waves and also the mental state of the person. Those waves usually vary from a frequency of 1Hz to 40 HZ. 2.1 ELECTROENCEPHALOGRAPHY (EEG)Electroencephalography(EEG) is the recording ofelectricalactivity along thescalp. EEG measures voltage fluctuations resulting from ionic current flows within theneuronsof thebrain.In clinical contexts, EEG refers to the recording of the brain's spontaneous electrical activity over a short period of time, usually 2040 minutes, as recorded from multipleelectrodesplaced on thescalp.2.2 ELECTRODESElectrodes are types of medical equipment places on certain parts of your body that send electrical pulses to your muscles to stimulate them.Diagnostic applications generally focus on thespectral contentof EEG, that is, the type ofneural oscillationsthat can be observed in EEG signals. Inneurology, the maindiagnosticapplication of EEG is in the case ofepilepsy, as epileptic activity can create clear abnormalities on a standard EEG study. A secondary clinical use of EEG is in the diagnosis ofcoma,encephalopathies, andbrain death. A third clinical use of EEG is for studies of sleep and sleep disorders where recordings are typically done for one full night, sometimes more. EEG used to be a first-line method for the diagnosis oftumours,strokeand other focal brain disorders,but this use has decreased with the advent of anatomical imaging techniques with high (