Head Controlled Wheelchair with Patient Monitoring System (Jawaharlal Nehru Technological University-Hyderabad [Padmasri Dr.B.V.Raju Institute of Technology])

Akhila Veerubhotla, Nitin Menon

ABSTRACT: Loss of mobility due to an injury is usually accompanied by a loss of self-confidence. For many individuals, independent mobility is an important aspect of self-esteem. Quadriplegics are limited in their motion due to damage to their spinal cord.The main goal of our project is to help the quadriplegic patients to move independently from one place to another by the tilt movement of their head which in turn moves the wheel chair without the assistance of another person..The head controlled wheelchair is designed such that the wheelchair moves in accordance with the movement of the patient’s head. A patient monitoring system consisting of heartbeat and temperature monitoring modules is provided such that it can constantly monitor these two important parameters and if any changes are seen, send a message immediately to the doctor or the nearest nursing home through the GSM.

BACKGROUND:

Quadriplegia is paralysis caused by illness or injury to a human that results in the partial or total loss of use of all their limbs and torso. It is caused by damage to the brain or the spinal cord at a high level C1 – C7 – in particular, spinal cord injuries secondary to an injury to the cervical spine. The injury, which is known as a lesion, causes victims to lose partial or total function of all four limbs.[1]

The wheelchair is driven by the tilt control and the accelerometer. Patient heartbeat and temperature monitoring are additional features to the tilt driven wheelchair. The main objective of our project is to help make the patient more independent.

PROBLEM STATEMENT:

Since quadriplegia limits the mobility of patients,they are forced to depend extensively on others.This may even cause emotional stress to the patient.The patient will not be able to do his day to day activity also.Our project addresses the problems caused due to mobility impairments.We intend to make the patient independent at least at their home.

 MOTIVATION AND PRIOR WORK:

Some of the recent and interesting developments in the area motivated us to formulate a viable solution for the issue we chose. Prior work in this area includes:

A remote controlled wheelchair, which takes the accelerometer readings as its input and sends it to a receiving laptop via blue-tooth,which in turn activates micro controllers, directing servo motors to pull the strings, and acrylic gates push the joystick accordingly to steer the vehicle.[2]

A wheelchair equipped with four computers, sensors and computer-driven arms and hands created by doctoral students at the University of Pittsburgh.[3]

A motor powered wheelchair driven by the tongue movement.[4]

 OUR CONTRIBUTION:

In our project, the accelerometer reading obtained from the tilt of the patients head controls the motor driven wheelchair through relays. In addition, the wheelchair is equipped with temperature and heartbeat monitoring system that sends an alert message to concerned authorities in case these values cross the preset upper and lower thresholds.

The accelerometer sensor is placed on a hat which is to be worn by the patient. It is connected to the micro-controller. Whenever the patient wants to move, he has to tilt his head in the appropriate direction. Based on the patient’s head movement,the micro-controller sends signal to the two motors that are attached to the two wheels of the wheelchair. To turn at any point,the person has to move his head in specific direction. In this case,the controller provides zero voltage to one motor and full voltage to another motor. Due to this,only one wheel moves while the other does not;thereby enabling the person to turn either left or right according to his/her need.

The patient monitoring circuit which consists of the heartbeat and temperature sensors,is very useful in case of emergencies. The controller is programmed such that ,during the continuous monitoring of the patient parameters,if at any time these values cross the preset threshold values ,a message is sent to the doctor,the nearest nursing home,to the relatives or care takers of the patient so that immediate help can be bought when required.

This simple circuit can be mounted on any motor powered wheelchair of the patient.

The prototype of our proposed project has been tested on different students in the Assistive Technology lab of our college and was found to be working effectively.We have got a positive response from all the people to whom the prototype was demonstrated including the caretakers of some rehabilitation schools.

HEAD  CONTROLLED WHEELCHAIR

 BLOCK DIAGRAM

Figure 1

Accelerometer: An accelerometer sensor measures acceleration. In our prototype we used MMA7660 accelerometer for this purpose. The output from this is made available to TI- MSP430 family low power micro controller. Depending on the movement of the head the micro controller will calculate the intended directions and controls the motion of the wheel chair

Temperature sensor: A temperature sensor is used to measure the body temperature. We used is TMP100 as our temperature sensor.

Heartbeat sensor:It is used as a tool to measure heart rate through fingertip, in this case. The blood volume inside a fingertip slightly changes with heart beat as the blood is being pumped. This change in blood volume inside the finger artery is detected with a simple optical sensor system and then further amplified using appropriate signal conditioning circuit to generate a pulse of magnitude +5V. These pulses are later counted and the measured heart rate displayed.

Micro controller unit: This forms the core .MSP-430 micro controller is used to control and interface all the different input and output modules to get the desired result.

GSM Module: This part of the output section is used to send messages when there is a change beyond the thresholds of either the temperature sensor or the heartbeat sensor.We have used GSM modem of wavecom make.

 HPMD (High Power Motor Driver) circuit:This circuit is used to drive the wheelchair based on the input obtained from the micro controller section which processes the accelerometer output.

TOTAL COST OF TILT CONTROLLED WHEELCHAIR

 

S.No Component TI/Non TI Cost per component Quantity
1 MSP-EXP430F548 TI 149USD 1
2 TL2575-05 TI 1.1USD 2
3 TMP100NA/250 TI 0.75USD 1
4 Heart beat sensor Non TI 1
5 JTAG Non TI 1600INR 1
6 GSM RS232 Non TI(wavecom) 2800INR 1
7 Motor driven section and wheelchair circuitry. Non TI 16800INR
8

miscellaneous (resistors, capacitors, pcb etc.)

 

Non TI 1000INR

Total cost of the project = Rs 29,213.83

 

CONCLUSION:

The wheelchair moves in accordance with the movement of the patient’s head.This simple circuit can be mounted on any motor powered wheelchair of the patient.The prototype of our proposed project has been tested on different students in the Assistive technology lab of our college and was found to be working.The demo of the prototype has been given to caretakers from different rehabilitation centers during National conference on Assistive technology held at our college and the feedback obtained was positive.

FUTURE WORK:

Further testing of the prototype is in process. We plan to incorporate a PWM circuit so that the movement of the wheelchair would be easy. In addition,we plan to incorporate a switch to power ON/OFF the circuit so that it could be used only when needed .This way the person would be free to move his head when the power to the circuit is OFF and the power could be efficiently utilized.

 ACKNOWLEDGEMENT:

We would like to thank Prof.I.A.Pasha and Prof.Ashok Shigli for guiding us throughout our project. Special thanks to Mr.Junaid for helping us to give shape to our ideas.

REFERENCES:

  1. Quadriplegia”.Internet:http://en.wikipedia.org/wiki/Quadriplegia,Jan.31,2011[Feb.5,2011]
  2. Sean Hollister”.Student moves quadriplegics with Wiimote wheelchair control”.Internet: http://www.engadget.com/2010/05/14/student-moves-quadriplegics-with-wiimote-wheelchair-control-vid/,May.14,2010[Feb.1,2011]
  3. Researchers hope to build a better wheelchair”.Internet:http://www.post-gazette.com/pg/09190/982704-114.stm, Jul.9,2009 [Feb.1,2011]
  4. Quadriplegics Can Operate Powered Wheelchair With Tongue Drive System”.Internet:http://www.sciencedaily.com/releases/2009/07/090706112906.htm, Jul.8,2009[Feb.2,2011]

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