CONTRIBUTION OF MECHANICAL ENGINEERING IN DISABILITY REHABILITATION

CONTENTINTRODUCTIONDISABILITY REHABILITATIONPROSTHETIC SYSTEMADVANTAGESREFERENCE

INTRODUCTIONThe rehabilitation community is at the threshold of a new age in which prosthetic devices will no longer be separate, lifeless mechanisms, but intimate extensions of the human body-structurally, neurologically, and dynamically.The force-controllable actuator comprises an electric motor and a mechanical transmission, resulting in a heavy, bulky, and noisy mechanism. As a resolution of this difficulty an electro active polymer-based artificial muscle technologies may offer considerable advantages to the physically challenged, allowing for joint impedance and motive force controllability, noise-free operationThe procedure for applying human elements to crash test dummy models is illustrated by substituting human lower limbs on a finite element model

DISABILITY REHABILITATIONDisability is a complex phenomenon, reflecting an interaction between features of a person's body.Disability is considered as a problem of the person, directly caused by disease, trauma, or other health condition which therefore requires sustained medical care provided in the form of individual treatment by professionals.Mechanical Engineering contributes to the service of Rehabilitation in the application of Bio-medical Engineering. Generally the Bio-mechanical engineering comprises of application of physics & material science in the aspect of Biological science.

Bio-mechanical engineering spread its wings in the field of prosthetic & orthotics, tissue engineering, bio-material science, gait analysis, surgery & implantation, artificial organs.Finite element analysis is a widely used theory in the mechanical solutions. Human anatomy constitutes of different mechanical joints.

PROSTHETIC SYSTEMProsthesis are basically the mechanical devices providing the external or internal support to the subjects with bio-mechanical disability.Prosthesis, prosthetic, or prosthetic limb is an artificial device extension that replaces a missing body part. It is part of the field of bio mechatronics, the science of using mechanical devices with human muscle, skeleton, and nervous systems to assist or enhance motor control lost by trauma, disease, or defect.

Upper Extremity Prosthetic Systems

The passive or cosmetic prosthesis is the oldest archetype. This device appeared as a gauntleted hand, or armored glove, and was made by skilled armorers. Although todays passive or cosmetic prostheses differ in that they appear as a static representation of the naked human hand, they are similarly made using craft techniques by highly skilled professionals (Figure 1a). However, although a remarkable static representation of the human hand is achieved, the absence of movement can promote feelings of unease in the observer. Current body-powered devices (Figure 1b) are operated using straps that commonly pass over the amputees shoulders and are operated by biscapula adduction (rounding of the back and shoulders). Fine control is possible as there is a pathway for feed-back to an intact joint enabling the amputee to know where the device is positional feedback and how much force is being exerted force feedback. However, the straps required for control are problematic.

They make donning and doffing the prosthesis difficult, and may interfere with other garments. Additionally, the movements that are needed for the control of the prosthesis are considered ungainly to some amputees. With this method of control, practically only a single degree of freedom can be controlled.

FUTURE WORK:

Although this research has concentrated on achieving analogies of the articulations of the skeletal limb, some further work has started towards analogies at the muscular level looking towards appropriate actuators and sensors. In these investigations an arm prosthesis has been developed, shown in Figure, complete with position sensors within the finger joint modules. From the largely successful results of the skeletal level research it is considered that such biomimetic methods may be of value in tackling the further challenges of actuation and control.

Lower Extremity Prosthetic Systems

The high quality of the C-leg is based on the highly sophisticated technologies that involves craftsmanship and many individual production n testing steps that are performed manually.The C-leg consist of mare than 500 individual componentsThe main electronics contain the central control of the C-leg, minute components are processed and assembled under the microscope.

To fill the hydraulic system of the knee joint with air free a special vaccum device is used, this technology guarantees the bound air is removed form the oil and it is visible in the form of bubbles.

The hydraulic system thus manufactured are absolutly unrivaled

To work under all the climatic condition each C-leg is simulated in a climate cabinet in which every C-leg is exposed to 15hr temperature-humidity cycle test. During this time the product is exposed to -15 to 65 degree and a humidity level of up to 85%.

Then the individual C-legs are tested in a gate simulator for final testing. In this final test every C-leg takes at least 1000 steps with a test load of 130 kg

WORKING OF C-LEGWalking is an automatic function process that we do not want to concentrate on it. Yet numerous complicated process take place every time we take a step. The request for movement is initiated by the brain and from there the impulses travel to spinal chord and from there to muscles through nerves. Then human body is equipped with numerous sensors. They provide feed back about the motion. This is a loop and occurs approximately 20 times a second.Many of these objectives are lost when some disabilities occur. The C-leg was designed with objective of approximating the human gauges, but how exactly walking with C-leg works?

2 sensors in the ankle and the knee supply information to the microprocessor, based on this information the microprocessor controls the hydraulics in real time the required operational energy is supplied by the integrated battery .In the C-leg the sensors effectively replace some of the bodies natural sensors and the hydraulics replace some of the stabilizing muscle functions.

Walking is divided into the stand phase and swing phase , in stand phase the main task is stabilizing the leg so that it can support the body weight , dynamic control is required in the swing phase which means the legs have to be controlled as it swings through with the lower leg it slows down n prepare for the next step The C-leg has high level of hydraulic damping in the stand phase offering security right where it is needed. It early leads the secured state when 2 criteria are met simultaneously, the knee must be fully extended and approximately 70% of the body weight must be supported by the fore foot only then the procedure switches to the swing phase. This is how the intelligent sate of the art controlled unit of the C-leg provides high safety and works.

ADVANTAGESEnergy: Recently, a study was conducted, comparing walking with prosthetic legs as opposed to walking with crutches. It was scientifically proven that people wearing prosthetic legs were using much less energy to walk compared to people using crutches.Mobility: Even if they are not exactly like the limbs that they are replacing, prosthetic limbs do offer a patient considerably more mobility compared to alternative options. As opposed to wheelchairs, prosthetic legs allow their users to climb stairs.Psychological advantages: More and more, prosthetic limbs are being made to look like the limbs they are actually replacing. Synthetic skin is being used to give the prosthetic limb an appearance as close as possible to the leg. The shape of the artificial limb also reflects the limb that is being replaced. This gives the amputee a better way to fit in with the crowd, which in turn is being translated into psychological comfort for him/her. A feeling of frustration can also overcome amputees who are not using prosthetic limbs

They can be easy to carry n even easily ditachable as compared to wheel chairs and crutches

REFERENCEPapers on New Horizons for O&P Technology: Merging Body and Machine.Papers on The National Crash Analysis CenterInformation from Internet

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