Figure from:IRJET- Advanced Voice Operating Wheelchair using Arduino

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Table -2: Wheelchair motion- The table below shows the direction of rotation of the Wheelchair based on the direction of rotation of the two motors. — Table 2 -2: Wheelchair motion- The table below shows the direction of rotation of the Wheelchair based on the direction of rotation of the two motors.

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Table -1: Power wheelchair control interfaces used. Research from University of Notre Dame, 2000, suggests that the current power wheelchair control interfaces used may not, be adequate to provide truly independent mobility for substantial number of people with disabilities. The Respondents to the survey reported on average that approximately ten percent of the patients trained to operate a power wheelchair cannot use the chair upon completion of training for activities of daily living or can do so only with extreme difficulty (Linda Fehr,2000). The data of the patients is as the table below-

Fig -1: Catia Model of Wheel Chair The challenge for engineering is to provide safe and effective mobility in a dynamic environment. Through thoughtful research and design, power wheelchair control will progress along safe and effective pathways towards providing users independent and self-guided mobility. This project will give the severely disabled people an innovative solution to control their wheelchair using voice interfacing.

Fig -2: Block diagram of System Mechanism 4. SYSTEM BLOCK DIAGRAM AND COMPONENTS

The speech recognition system is a completely assembled and easy to use programmable speech recognition circuit. Programmable, in the sense that you train the words (or vocal utterances) you want the circuit to recognize. This board allows you to experiment with many facets of speech recognition technology. It has 8 bit data out which can be interfaced with any microcontroller for further development.

Fig -6: Specifications of Arduino Arduino projects can be stand-alone or they can communicate with software running on a computer (e.g. Flash, Processing, MaxMSP). The machine part is open source, which means that anybody can make their own version of an Arduino machine for free.

When voltage is applied, current begins to flow from negative power supply terminals through the series winding and armature winding. The armature is not rotating when voltage is first applied, and the only resistance in this circuit will be provided by the large conductors used in the armature and field windings. Since these conductors are so large, they will have a small amount of resistance. This causes the motor to draw a large amount of current from the power supply. When the large current begins to flow through the field and armature windings, it causes a strong magnetic field to be built. Since the current is so large, it will cause the coils to reach saturation, which will produce the strongest magnetic field possible.

Fig -10: Moment of Wheel Chair In our model, voice recognition system is used as user interface. The block diagram of the smart wheelchair system is shown in figure 1. Here we are creating a speech recognition based wheel chair for handicapped patients. The patients who cannot walk and have to use a wheel chair can steer the wheel chair by their voice. Here in our project there is one input device i.e., mic which takes input from the user

A switched mode power supply (SMPS) offers the same end results as a commonly used 12V DC supply but at a lower cost and higher efficiency. For a given output power, an SMPS is lighter and smaller. This is because, if the frequency of operation is increased, one can get away with using a smaller core cross-sectional area. Besides, an iron-core transformer works only up to about 10 kHz, and if we need something in 50-100kHz range, we need a ferrite core.

The figure bellow demonstrates the connection of the drive circuit: Fig -11: Motors' drive circuit schematic. Four BJT transistors were used as switches for the H-Bridge. They take their signals from the microcontroller through resistors and transmit it to the four relays that control the power supply of the motors, thus deterring the direction of rotation of the motors and consequently the direction of the wheelchair's motion.

One popular type of motor drive circuits is the H-Bridge (sometimes called: The Full Bridge). It has been named that because it looks like the letter H when viewed on the discrete schematic. An H-Bridge is an electronic circuit that allows the voltage to be applied on the load in either direction. It is used to allow DC motors to operate in two opposite directions i.e. forward and Backward. The direction of rotation of aseries motor can be changed by changing the polarity of either the armature or field winding.: The four sides of the H-Bridge represent four switches that are activated in pairs; (1) High left and Low right, (2) High right and low left. This will result in controlling the current flow direction and therefore the direction of rotation of the motor. In this project two H-Bridges were used; one for each motor.

Fig -12: PWM digital output and average output.

The figure below demonstrates a schematic of the series DC motor:

The figure bellow shows the speed profile of the wheelchair. The speed profile is obtained from the assumption that the wheelchair will accelerate from 0 to 0.5 m/s speed in 1 second. Then it will continue its motion in a constant speed equals to 0.5 m/s. Chart -1: Speed profile of the wheelchair