Assignment Help on Mechanized Wheel chair

INTRODUCTION

This project work describes about a wheelchair for physically disabled people with five degree of freedom to the human body. The demo or proto type module is designed by considering mechanical model, control (low level control, control by push buttons) and motors driving mechanism for the mechanical transmission section control, etc. The results of the experiments carried out on the prototype module also given in the further chapters.

The number of people, who need to move around with the help of some artificial means, whether through an illness or an accident, is constantly increasing. These means have to be increasingly sophisticated, taking advantage of technological evolution, in order to increase the quality of life for these people and facilitate their integration into the working world. In this way a contribution may be made to facilitating movement and to making this increasingly simple and vigorous, so that it becomes similar to that of people who do not suffer deficiencies. Systems already exist which respond to many of the needs of people with different degrees of incapacity. However, there are still important advances to be made in this field. This justifies the numerous research programs which are being carried out at the present time. The main reasons for their justification are as follows:

 The present high level of technology in the electronic and robotic systems permits some of the mobility problems suffered by certain people to be resolved. Electronics solves the problems very well enough for the users. This is because the electronics used is eminently suitable for coping with the needs presented.
 Unfortunately more and more people are appearing with incapacities which prevent them from carrying out normal activities. Most have serious problems related to movement.

The type of artificial aid needed by a disabled person in order to move about depends, to a large extent, on the level of his incapacity. For example, in order to guide a wheelchair, various situations can be distinguished:

 If the user is capable of controlling his head or his hands, the ideal solution is the use of a joystick.
 Where there is a high level of incapacity, solutions are basically centered on the use of other means, such as the voice or eye movements. In this case, the presence of safety sensors is justified with the object of assisting the user to guide the chair (detection of obstacles, nearness to certain places, the existence of stairs, etc.).
 Only in extreme cases it is suggested that there may be a need for the chair to cover certain distances in an autonomous manner, without the need for any intervention on the part of the user (interest in this type of wheelchair could be in the following of prefixed routes in hospitals, recreation centers, etc.). In this case the presence of external sensors is vital.

Another important requirement that a wheelchair has to fulfill is that of responding rapidly and efficiently to the commands of the user, independently of the method used for giving these commands.

The project described here is orientated towards providing solutions to the need for moving around of disabled people who have great incapacity with regard to driving and move to do their daily needs. These needs and their possible solution were put forward here for demonstration purpose in this project work. The main objectives of the project are given below:

i. To design a mechanical skeleton system that could be installed in any of the commercially produced wheelchairs.
ii. To make guiding the wheelchair possible by means of input commands by using the push buttons present on the wheel chair.

iii. The electronic interface would have to permit the chair to be further guided using other means like electro-mechanical components for various degree of freedom (the control of household electrical equipment, opening doors, etc.).
iv. The system had to be open and modular, in the sense that future additions could be made which would be related to guiding the chair through speech (voice), eyes, etc.
v. Another aspect of great importance with regard to the design was that the final prototype should be economically priced for its later manufacture and commercialization.

As this development work falls under the subject of Mechatronics, various fields of technologies must be included to fulfill the target. The integration of electronic engineering, mechanical engineering, electrical engineering and control technology is forming a crucial part in this design. Especially the control circuit designed with motor drivers plays dominant role in this project work. The term Mechatronics is used to describe this integrated approach; therefore all above subjects are described in this project report in following chapters. Most systems that provide motion and force contain a mixture of Mechanical, Electrical, Electronic and Digital Components. In fact, today most systems are mixed systems. The design of these mixed systems requires knowledge from all these fields. The purpose of Mechatronics is to provide knowledge regarding the Mechanical, Electrical, Electronics and Digital components required for the system.

To make the project work more realistic, much importance is given for practical orientation, therefore a prototype module is constructed for the demonstration purpose. This mini module simulates the real working system and based on this technology huge machine can be constructed for real applications. The machine is constructed with electronics, electrical & mechanical components. The mechanical structure is constructed with a variety of devices as they relate to robots specially gear mechanisms. The method of converting rotary to linear motion is implemented in the mechanism, for this reason DC motors with reduction gear mechanism are used to create motions in the mechanisms in a particular direction. This revolving mechanism of the DC motors can be moved in one particular direction, i.e. clockwise or anti clockwise depending on the polarities provided to the DC motor through the driver IC’s L293D (H – Bridge chip). The DC motors are controlled independently for five degree of freedom as well as the wheel chair movement through these driving IC’s. The detailed description of the project work is provided in the further chapters.