Electro-Occulography Based Wheelchair for Aged and Paralyzed

Paralysis has been commonly referred to the complete or partial impairment of the body function due to the loss of mobility of the muscles or nerves of the body. The predominant causes of paralysis range from stroke, cerebral palsy, multiple sclerosis and spinal cord injury that prevails the rest. According to a study, there are 1 in 50 people living with paralysis that approximates to be around 6 million people. It means that we all know someone a brother, sister, friend, neighbor, or colleague, living with paralysis. In order to regain the function and independence following the disease, different mobility aids and medications have been brought into light in hands with the technology. In the past few decades, various classes of bio signals have been used which have contributed a key role in the rehabilitation of the disabled. From these, for the purpose of communication and control, especially for those with eye motor coordination, Electro-oculogram is considered to be the most convenient signal over the others due to many factors. EOG signal is based on the dipole within the eye. It is commonly known as the electrical signal produced from the potential difference of the cornea (positively charged) and the retina (negatively charged). A wheelchair consists of accelerometer and electrode sensor as sensing element, CC2500 transceiver module for transmitting and receiving RF signal, a microcontroller unit a decision-making device and motors to navigate the wheelchair in four directions just with your hand movement or eye movement. You just need to wear a small transmitting device in your hand which include an acceleration meter or wear electrode behind the eye. This will transmit an appropriate command to the wheel chair so that it can move into the desired direction they want. Traditional wheelchairs have some limitations in context to flexibility, bulkiness and limited functions. Our system allows the users to use hand movement or eye movement for movement and synchronize them with the movement of the Wheelchair so that they can use it with comfort. There is a steady corneal-retinal potential from the back of the eye to the front of the eye. This steady dipole may be used to measure eye potential by placing surface electrodes around the eyes. When the eyes are looking straight, the electrodes spaced equally from the eyes will be at right angles with the eye’s electric field which will result in the output to be zero. Due to movement of the eyes, there is a direct current voltage shift experienced which gives the EOG signal. The most important factor that makes EOG far better than the other modalities is a linear relationship of EOG signal over the eye movements that makes it suitable for the application. The other reasons include better face access, good accuracy and resolution, great range of eye displacements, and more importantly economical. The development and implementation of a low-cost eye movement detection device for controlling wheelchair prototype for paralyzed patients. In the proposed automated wheelchair prototype, a simple bio-potential amplifier has been used for detecting EOG signal while the source code for data acquisition and processing has been written in C. The control technique can be used to guide a wheelchair which is motorized to assist the people with severe disabilities. Appropriate devices have been incorporated to generate the control signal through the saccadic eye movement. A dc motor has been operated by the signal which in turn has been employed to regulate the wheelchair. The performance evaluation verifies the effectiveness of the proposed wheelchair prototype.