Semiautomatic wheelchair

1. Semi Automatic Wheel Chair
Presented by
Group A Group B
Stavan Dholakia Dhwanil Desai
Ankit Gothi Vatsal Patel
Guide (s) :- Funding Provided by :-
1. Dr. P.R. Upadhyay
Gujarat Council of Science &
Ex Professor, Elect Engg. Dept.
Technology
2. Mr. V.B. Pandya
Lecturer, Elect Engg. Dept
InstItute Of technOlOgy,
nIrma unIversIty

2. Contents
•Introduction
•Survey Details
•Physical Structure
•Components used
•Motors
• Driving
• Steering
• Reclining
•Drive Circuits
•Gear Box
•Applications, Advantages and Limitations
• References
• Finance Break Up
•Photo Gallery

3. Introduction :-
The project is entitled Semi - Automatic Wheel Chair. It is a semi-automatic
locomotive which will be helpful to carry patients and physically challenged
people. Over and above the task is not just restricted to designing a drive
system by fixing an electric motor to a wheel chair and running it with two
degrees of freedom. On the contrary, the wheel chair is being designed with four
degrees of freedom. Here, even the back and the support for leg-room is motile
and this would help the wheel chair to get converted into a stretcher. An
important point here is that, this task will also be achieved by electric drives,
which facilitate the speed control and braking mechanism. That is, a fully user
friendly mechanism. Advanced Electric Machines will be used in driving the
above mentioned system to get a smooth, accurate and highly efficient
governing. The project topic covers and rather tests all the fundamentals on
Engineering Mechanics, Electrical Machines, Advanced Electrical Machines,
Control Theory, Electronics and Electric Drive Systems.

4. An outline of survey :-
• Hospitals visited :-
 SAL Hospital, Ahmedabad
 Sterling Hospital, Ahmedabad.
 Civil Hospital, Sola.
 Shalby Hospital, Ahmedabad.
 Jivaraj Mehta Chariyable Hospital, Ahmedabad.
 Thakershy Charitable Hospital, Ahmedabad.
 Apollo Hospital,Gandhinagar
 Medilink hospital, Ahmedabad
 Private Clinics

5. Doctors Speak :-
Feasible Points Suggested By Doctors:
•The chair must overcome 30 degrees ramp up to 15 ft
.
•There must be joysticks on both the sides of arm rest.
•High cost should not be the limitation.
•Alarm system must be incorporated.
•Height variation of the chair must be possible.
•Lesser amount of joints.
•Ergonomics concept must be included.
•Belts to avoid jerks on pelvis. Not Feasible:
•Provision for toileting.
•Battery must have a safe clearance from the patient. •‘Control by feet’ module has to be
added
•There must be a mechanism so as to reduce the jerks

6. Physical Dimensions of the Wheel Chair

7. Components Needed
•Wheels
•Rods
•Bearings
•Gear Boxes
•Gears (rack & pinion , spherical)
•Motors
•Transistors (2N5671/72, 2N5683/84)
•Resistors (1Ω, 47Ω, 470Ω, 1kΩ)
•Wires
•Joystick Circuit
•Wooden Sheets
•Sponge & Clothing

8. Motors Used :
•Driving Motor
PM DC motor ( Dyna Flux, 0.75 hp,24 V, 23.3 A, 1500 rpm
Available torque T = 25.2 kg cm.
Torque = T * gear ratio = 176.4 kg cm.
Cost : Rs. 7300

9. Steering Motor :-
DC series motor (0.1 hp, 24 V, 12 A )
Reclining Motors :- Cost :- Rs. 4150 * 2 (taxes extra)
Hybrid Stepper Motor ( DPM ,34 kg cm, 24 V, 3 A )
“A stepper motor is a brushless DC
motor whose rotor rotates in discrete
angular increments when its stator
windings are energized in a
programmed manner. Rotation occurs
because of magnetic interaction
between rotor poles and poles of the
sequentially energized stator winding.”

10. Drive Systems
• Hybrid Stepper Motor
The hybrid stepping motor is a synchronous motor excited by AC
current supplied by the power converter. It is usual for the power
converter to incorporate a phase current sensor so that the
excitation level can be controlled to suit the motor rating and load
conditions. The controller is responsible for generating the phase
excitation sequence such that the drive acts according to the
requirements given by the user input.
Cost = Rs. 2750 * 2 (taxes extra)

11. Drive Systems
• PMDC motors
A driver circuit is needed to run
the PMDC motor smoothly and
to bring the required speed as
low as 200 rpm. The current is
controlled by the circuit.

12. Gear Box:-
A gear box is used to increase the torque of the motors used for back
rest and foot rest movement.
.

13. Applications :-
1. Aged people
2. Physically challenged persons
3. Patients of arthritis and rheumatism
4. People suffering from paraplegia and quadriplegia
5. Hospitals (major application)
Advantages & Limitations:-
• A unique feature of module of a stretcher
• Innovative development
• Lower cost compared to conventional motorized
wheel chair (highly economic)
• Great demand
• Highly user friendly
• Can withstand 150 kg mass
• PM material undergoes wear and tear
• Battery capacity is bit low
• Bulky

14. References / Bibliography
•Beer & Johnston----- “Engineering Mechanics”.
•Tayal, A.K “ Dynamics for Engineers “
• Bridger, R.S “Introduction to Ergonomics”.
•Ogata “ Control System Engineering”
•Prof. Patel, U.A, “Control Theory”.
•Ratan, S.S, “ Automotive Mechanics TMH Publishers, 1978,
•Singh, K. N , “A course in Automobile Engineering Vol 1“, Standard Publishers, New
Delhi, 1999.
•R. Drzewoski, J. Jelonkiewicz and E.A. Med, “Gearless drive for electric
vehicles with disc motor”, Electrical News 1999, no. 4, pp.188- 193.
•G. Atkin and J. Storey, Electric Vehicles- Prospects for battery-, fuel cell.
•J. F. Gieras and M. Wing, PM motor technology –Design and Applications Second
Edition, Revised and Expanded, Marcel Dekker, Inc., New York, Basel.

15. Finance Break Up :-
1. Dynaflux PMDC driving motor Rs 7300
2. Hybrid Stepper Motors + Drivers Rs.15,700
3. Steel Rods Rs. 1303
4. Reports & Stationery Rs. 500
5. Travel Expenditure Rs. 500
Rs. 25,303

17. •Photo Gallery

18. Department of Electrical Engineering
Institute Of Technology,
Nirma University .