INTRODUCTION TO ACCELEROMETER CONTROLLED WHEEL CHAIR

The increase in human-machine interactions in our daily lives has made user interface technology progressively more important. Physical gestures as intuitive expressions will greatly ease the interaction process and enable humans to more naturally command computers or machines. For example, in tele robotics, slave robots have been demonstrated to follow the masters hand motions remotely. Other proposed applications of recognizing hand gestures include characterrecognition in 3-D space using inertial sensors, gesture recognition to control a television set remotely [4], enabling a hand as a 3-D mouse, and using hand gestures as a control mechanism in virtual reality. In todays fast world, everyone is busy and there are less people to care for the increasing number of elderly and the physically challenged people. Also these people find it tough to even navigate inside the home without external aids. The elderly people find automated wheelchairs as an easy way for locomotion. Having known about these facts, we have designed automated wheelchair which can be used by both the elderly and the physically challenged people in a user friendly manner using hand gestures for operationWheel Chair is a mobility device designed for shifting patients, moving physically challenged people from one place to another with the help of attendee or by means of self-propelling. The wheel chair is divided into two different types based on the power used for mobility: 1. Manually powered wheelchairs. 2. Electric powered wheelchairs (automated). Manual powered wheelchairs are driven by manual power. Electrical powered wheel chairs runs with electric power and operation of chair depend upon the instruction given by the patient hand gestures. Robots are generally controlled by remote or cell phone or keyboard connection. But limitations of these robots are that they are much more complex and are difficult to operate . Moreover their cost are high even for low application activities. So we decided to design a robot which can serve as wheelchair for disabled and which can be controlled by the accelerometer which will be driving itself according to position of it. Hardware required is very less.This wheelchair consists of mainly three parts. First is sensor, which works as vision of robot. We have used accelerometer that act as sensor for our robot.second is arduino uno which act as brain of robot and last is motor driver which takes signals from arduino according to the motion of accelerometer and controls the position of wheels of wheelchair. A Gesture Controlled robot is a kind of robot which can be controlled by slight hand gestures not by old buttons. You just need to wear a small transmitting device in your hand which includes an accelerometer.ACCELEROMETER SENSOR is a Micro Electro Mechanical Sensor which is a highly sensitive sensor and capable of detecting the tilt. This sensor finds the tilt and makes use of the accelerometer to change the direction of the wheel chair depending on tilt. For example if the tilt is to the right side then the wheel chair moves in right direction or if the tilt is to the left side then the wheel chair moves in left direction.As user makes movements of his hand in front of it, it senses and according to that it sends the signal for decision. Output from accelerometer is gathered for process by arduino uno. As per sensor output, the controller on arduino is made to work according to the program written inside it and it sends the respective signal to third part which is motor driver. This is the last part which drives the wheels of our Robot. It controls two dc motors to make movement.All things are mounted on metal chassis.

LITERATURE SURVEYSeveral approaches [2-3] have been presented on the concept of the wheelchair with different ideas. The various approaches were done in [2] which were as it shares the vehicle control decisions by joystick, obstacle avoidance by ultrasonic sensor, safe object approach protection for the patient includes security of the patient on the wheel chair, the maintenance of a straight path and other navigational issues.Accordingly to study a dynamic model and design a suitable dynamic controller is useful for increasing the tracking performance in a real situation. [2] It consists of a navigation system of line tracer. This application of the technology it is used for the blind person by selecting the destination and the patient can reach the destination. [2] This proposal consists of two mode; (1) Manual mode (2) Automatic mode. In manual mode joystick is used to navigate and relocate in left and right direction. In Y direction will result in the variation of speed. In Automatic mode two camera are used to sense the width of the corridors. This proposal has drawback as it consist of a color cameras which obtains images and transmits them to an on-board laptop computer. So the wheelchair tends to be very bulky and hence it is costly. [4] Used Voice control system to control the locomotion of the wheelchair. They store the default commands in the PIC IC (micro controller) by the usage this commands the wheelchair can move. Change in the words restricts the wheelchair movement. They used eyebrow muscle activity to obtain required signal. By using the signal the wheelchair movement has been controlled as the movement of the eyebrow was not easier so it had some difficulties. [5] Used head and finger movement for wheelchair locomotion. In finger movement they use flex sensor, placed on the finger. It is analog resistors usually in the form of strip long vary resistance. Due to the bending of finger the resistance varies which controls the locomotion of the wheelchair.

MATHEMATICAL MODELING

3.1 BLOCK DIAGRAM

Fig.3.1 BLOCK DIAGRAM OF ACCELEROMETER CONTROLLED WHEELCHAIRBlock diagram consist of three parts namely1. Sensing Unit2. Controlling Unit3. Driving Unit Sensing Unit comprises of the most important component that is Accelerometer(ADXL335),which reads the data from the person based on hand gestures. Controlling Unit comprises of microcontroller board that is Arduino uno which reads and process the analog readings given to it by ADXL335 and gives output to motor driver that is L298D. Driving Unit comprises of motor driver and two DC motors which gets input from controlling unit and the entire unit is powered up by external power supply.

3.2 ALGORITHMAlgorithm for ADXL335 controlled wheelchair will be as follows:1. Start the system2. Arduino reads data from ADXL3353. If ADX335 gives the reading which are in the range given to arduino for moving forward then Arduino will give respective signal to L298D motor driver and wheelchair will move in forward direction.4. Else if ADX335 gives the reading which are in the range given to arduino for moving backward then Arduino will give signal to motor driver for moving backward.5. Else if ADX335 gives the reading which are in the range given to arduino for moving right then Arduino will give signal to motor driver for moving right.6. Else if ADX335 gives the reading which are in the range given to arduino for moving left then Arduino will make the wheelchair to move in the left direction.7. Else wheelchair will be in stop condition for all other conditions and signals given by ADXL335 to Arduino and the entire system will be at step 1.

3.3 RANGE OF VALUES GIVEN BY ACCELEROMETER FOR DIFFERENT POSITIONS

TABLE 3.3.1 RANGE OF VALUES OF x,y,z FOR DIFFERENT POSITION OF ADXL335 POSITION OF ADXL335ANALOG VALUES GIVEN BY ADXL335

FORWARDy