Design and development of trunk stability mechanism for sitting position

This project is aim to design a passive device that can support weak muscles of the trunk, provides postural stability and maintain the human trunk in balanced position. It is designed for the patients who are suffering from trunk disorders, a human trunk is a central part that connect the head with

Project Title

Design and development of trunk stability mechanism for sitting position

Project Area of Specialization

Wearables and Implantable

Project Summary

This project is aim to design a passive device that can support weak muscles of the trunk, provides postural stability and maintain the human trunk in balanced position. It is designed for the patients who are suffering from trunk disorders, a human trunk is a central part that connect the head with the lower limb.It is a simple elastic belt mechanism along with the springs attached at the back of the chair and is covered by four elastic belts from the front view which are connected at one point that is center of mass of upper limb. This design aims to avoid the patient from trunk falls in two anatomical planes that is saggital and coronal planes.The design will be tested by the individuals along with the software analysis which includes force sensitive resistor that is used to measure the force, EMG data analysis of the individual, measurement of elasticity through UTM machine and designing on software.

Project Objectives

• Stabilization of trunk muscles.
• Balance movements.
• Supporting of week muscles.
• Posture control while sitting.
• Avoiding of trunk falls in two anatomical planes(saggital and coronal)

Project Implementation Method

Anthropometry is the measurement of human individual. It has been used for the identification, for the purposes of understanding human physical variation human to correlate physical with racial and physiological trait.
In designing of the biomechanical devices the anthropometry data is useful which gives us the standard length of the different body parts segments in terms of height which vary person to person.

These body segments length is standard which we use in designing the force equations. For the equation of the forces the mass of the person is very important because on every person the force will change. We use anthropometric table for determining the centre of mass of the trunk and the mass of the trunk which is used in designing of equations.
? TRUNK: Below Neck and above waist without hand is treated as trunk.
? Height of the Human Being From Age 18 to 24 = 173 cm or 1.73 m or 1730 mm ? Weight of the human being From Age 18 to 24 = 136.7 lb or 62 Kg
As we know that trunk is the segment below neck without hands and above the waist so the length of the trunk is calculated by following formula.
In the above figure:
• length of the human being from Shoulder to the Leg = 0.818H (where ‘H’ is height of the human being)
• Length of the human being from Waist to Leg = 0.530 H
Length of the Trunk = (Length from shoulder to Leg) – (Length from Waist to Leg) Length of the Trunk = 0.818H – 0.530H
Length of the Trunk = 0.288H

The material of the spring is important in any biomechanical devices because all the springs have different properties. We use Spring steel material spring which is best for our objectives.
We have two forces which apply on the person is force of spring which is acts on the waist of the person. The other force is the another spring force which apply on the shoulder. These forces depends upon the flexion angle between the patients and the object. The maximum angle which we take from the research is 80 degrees. Average height of the people is 173 cm.
According to the equilibrium: F=kx ( the spring force) Where x is:
???? ?????????????=???? ????????????
3.2.1 MAKING EQUATION OF THE FORCES:
???????????????????? ???????? ???????????????????????? = ???? ? ???? ? 2???????? where r= Initial length of the spring 360
FROM NECK TO CENTRE OF THE MASS: ????????????????????????????????????????????????????= ????? ???? ????????????? eq#01
????????????
Where ‘r’ is Initial length of the spring r= 0.15778H FROM CENTRE OF THE MASS TO WAIST:
????????????????????????????????????????????????????= ????? ???? ????????????? eq#02 ????????????
Where ‘r’ is Initial length of the spring r= 0.172789H
We take the value of theta from 0 to 80 degrees. On every angle the force of the
spring and the belt changes.

• Mass of the Trunk = 0.497 x Total body mass Mass of the Trunk = 0.497 x 62 Kg
Mass of the Trunk = 30.814 Kg
• Weight of the Trunk = Mass of the Trunk x 9.81 Weight of the Trunk = 30.814 x 9.81
Weight of the Trunk = 302.28534 N
• Centre of the Mass (TRUNK) = 0.5 Proximal x Trunk Length Centre of the Mass (TRUNK) = 0.5 x 0.288H
Centre of the Mass (TRUNK) = 0.144H

Benefits of the Project

• Can be very useful in rehabilitation centers.
• Source of confidence to handicaps.
• Help to cure torn muscles.
• Provides postural stability.
• Allows to perform work for the person who is continuously on chair.
• Allows movement in two anatomical planes.
• Avoiding of trunk falls.
• Can  replace wheel chairs for those who are in state of trunk disorders.

Technical Details of Final Deliverable

• Load cell
• Force sensitive resistor 
• Springs 
• Elastic belts
• Buckle
• Elasticity testing on UTM machine.
• Emg testing.

Final Deliverable of the Project

HW/SW integrated system

Type of Industry

Medical

Technologies

Wearables and Implantables

Sustainable Development Goals

Good Health and Well-Being for People, Industry, Innovation and Infrastructure

Required Resources

If you need this project, please contact me on contact@adikhanofficial.com