Aravindan t k Seminar

8/3/2019 Aravindan t k Seminar

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SEMINAR

By

ARAVINDAN T K011209025

7 th SEMESTER

MECHANICAL ENGINEERINGSASTRA UNIVERSITY


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1.BIO METRICS

It is the branch of science thatincludes measurements ofphysiological variables and

parameters.

BMI provides the tools by whichthese measurements can beachieved.


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1.1 - RANGE

The range of an instrument is generallyconsidered to include all the levels

of input amplitude & frequency overwhich the device is expected tooperate.

The objective is to provide aninstrument that will give a usablereading from the smallest expectedvalue of the variable or parameterbeing measured to the largest.


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1.2 SENSITIVITY

The sensitivity of an instrumentdetermines how small a variation of

a variable or parameter can bereally reliably measured.


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1.3 LINEARITY

The degree to which variations in theoutput of an instrument follow input

variations is referred to as thelinearity of the device.


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1.4 HYSTERESIS

It is a characteristic of someinstruments where by a given valueof the measured variable results in

a different reading when reached inan ascending direction from thatobtained when it is reached in a

descending direction .


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1.5 - FREQUENCY RESPONSE

The frequency response of aninstrument in its variation insensitivity over the frequency rangeof the measurement. It is importantto display a wave shape that is afaithful reproduction of the originalphysiological signal.


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1.6 ACCURACY

It is a measure of systemic error. Errors can occur in amultitude of ways. Although not always presentsimultaneously, the following errors should beconsidered.

1. Errors due to tolerances of electronic components.2. Mechanical errors in meter movements.3. Component errors due to drift or temperature

variations.4. Errors due to poor frequency response.5. Errors due to change in atmospheric pressure or

temperature.6. Reading errors due to parallel inadequate

illuminations or excessively wide ink traces on a penrecording.

Two additional sources of Errors are Correct instrument zeroing or making correct baseline. The effect of the instrument on the parameter to be

measured & vice versa. ( Specially in measurementsin living organism )


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1.7 - SIGNAL TO NOICE RATIO

It is important that the signal to noise ratio be high as possible.


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1.8 STABILITY

In control engineering, Stability isthe ability of a system to resume asteady state conditions following adisturbance at the input rather thanbe driven into uncontrollableoscillation.


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1.9 - ISOLATION

Electrical Isolation is to be made for

avoiding interference between differentinstruments used simultaneously. It canbe achieved by using magnetic or

optional coupling technique or usingradio tetemetry.

Telemetry is also used where movementof the person or animal to be measured.


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1.10 SIMPLICITY

All systems & instrumentsshould be as simple as possible

to eliminate the chance ofcomponent or human error.


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INSTRODUCTION TO THE MAN MACHINESYSTEM

A classical exercise in Biomedical engineeringanalysis involves the measurement ofOUTPUTS from an unknown system as they areaffected by various combinations of INPUTS.

The object is to learn the nature & characteristicsof the system. This unknown system, oftenreferred to as a BLACK BOX, may have avariety of configuration for a given combinationof INPUTS and OUTPUTS. The end product ofsuch an exercise is usually a set of Input Output equations intended to define theinternal functions of the Box. These functionsmay be relatively simple or extremely complex.


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BLACK BOX

One of the most complex black box isliving organism.

Especially the living human being . HUMAN BODY AS BLACK BOX

Human body is Bio chemico physico electro thermo hydraulico pneumatico magnaticomechanically engineered machine,which runs automatically through thevital force, now a days called Bioenergy.


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BIO POTENTIAL SIGNALS

It is a well known fact that human body is a sourceof various bio- potential signals, which are mostuseful during physiological ,clinical & therapeuticbiological activities of living body. These signalscan be picked up from the surface of the body orfrom within the body. These signals are used asparameters in various Bio- medical studies. Thisblack box ( Human body ) consists Biological ,chemicals , physical , electrical , thermal ,haudralic, pneumatic, acoustical, magnetically &

mechanical systems, all interacting with eachother.

It also contains a powerful computer, several types

of communicating systems, and a great varietyof control systems. To further complicate thesituation.


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1.Upon attempting to measure the INPUTS & OUTPUTS, It would besoon learnt that none of the INPUT & OUTPUTS relationship isdeterministic i.e. repeated applications of a given set of INPUTvalues will not always produce the same OUTPUT values.In fact , many of the outputs seems to show a wide range ofresponses to a given set of INPUTS, depending on someseemingly relevant conditions, where as others appear to becompletely random & totally unrelated to any of the inputs.

2. Many of the important variables to be measured are not readilyaccessible to measuring devices. The result is that some keyrelationships can not be determined or that less accuratesubstitute measures must be used.

3. Due to high degree of interaction among the variables, it is oftenimpossible to hold one variable constant while measuring therelationship between two others.

4. It is difficult sometime to determine which are the inputs & which arethe outputs, for they are never labeled & almost inevitably includeone or more feedback paths.

5. The application of measuring device. Which often affects themeasurements to the extent that they many not represent normalconditions reliably.

6. The process of measuring must not in any way endanger the life ofthe person on whom the measurements are being made, & heshould not get any undue pains, discomfort or any otherundesirable conditions. Additional factors that add to the difficultyof obtaining valid measurements are.

A. Safety considerationsB. The environment of the hospital where these measurements are

performed,

C. The medical person usually involved in measurements.D. Ethical & legal considerations.


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Because the large amount of interactionbetween the instrumentation system &

the subject being measured. It isessential that the person on whommeasurements are made beconsidered an integral part of theInstrumentation system. In other words

In order to make sense out of thedata to be obtained from the black box

( the human being ) , the internalcharacteristics of the black box must beconsidered in the design & applicationof any measuring instruments,consequently the overall system, whichincludes both the human organism &Instrumentation required for the

measurement of the human is calledthe MAN MACHINE SYSTEM.


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INSTRUMENTATION SYSTEM

It is defined a the set of instruments &equipments utilized in themeasurement of one or morecharacteristic or phenomena + thepresentation of information obtainedfrom those measurements in a formthat can be read , interpretedrecorded and preserved by man.


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BASIC OBJECTIVES OF THEINSTRUMENTATION

1. Information Gathering2. Diagnosis

3. Evaluation4. Monitoring5. Control


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1. INFORMATION GATHERING

In this system, machine is used to

measure natural phenomena &other variables to aid man in hissearch for the knowledge abouthimself and the universe in whichhe lives.

In this setting, the characteristic of themeasurements may not be knownin advance.


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EVALUATION

Measurements are used to determinethe ability of a system to meet itsfunctional requirements.

These could be classified as Proof of performance or Qualitycontrol tests.


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MONITORING

Instrumentation is used to monitorsome process or operation in orderto obtain continuous or periodic

information about the state of thesystem being measured.


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CONTROL

Instrumentation is sometimes used toautomatically control the operationof a system based on changes in

one or more of the internalparameters or in the output of thesystem.


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Bio Medical instrumentation cangenerally be classified into two

major types :

1. Clinical Instrumentation .

2.Research Instrumentation.


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Clinical Instrumentation

Basically devoted to the area of

Diagnosis

Patient care

Treatment of Patients ( Therapeuticuse )


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RESEARCH INSTRUMENTATION

It is used primarily in the search fornew knowledge related to varioussystems that compose the human

organism.

Some instruments can be used inboth areas.


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MAN MACHINE SYSTEM


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MAN MACHINE SYSTEM


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Components of Man Machine

system

SUBJECTSTIMULUSTRANSDUCERSIGNAL PROCESSING UNITDISPLAY MACHINE

RECORDINGCONTROL UNIT


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1. The subject

The subject is the human being onwhom the measurements are

made.

2 STIMULUS


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2. STIMULUSIn many measurements the response to some

form of external stimulus is required.The instrumentation used to generate &

present this stimulus to the subject is a vital

part of the Man Machine systemwhenever responses are measured.

The stimulus may be

Visual ( e.g. a flash of light )Auditory ( e.g. a tone)Tactile ( e.g. a blow to the Achilles tendon)

Direct electrical stimulation of some part ofthe nervous system.

3 THE TRANSDUCER


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3. THE TRANSDUCER

A transducer is a device, capable ofconverting one form of energy or signalto another.

In Man Machine system each transduceris used to produce an electrical signalthat is an analog of the phenomenonbeing measured. The transducer maymeasure temperature, Pressure , flow,or any of the other variables that can befound in the body, but its output isalways an electric signal.

Two or more transducers may be usedsimultaneously to obtain relativevariations between phenomena.

4 SIGNAL PROCESSING UNIT


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4. SIGNAL PROCESSING UNIT

It is the part of the instrumentationssystem that amplifies , modifies or inany other way changes the electricoutput of the transducer.

It is also used to combine or relate theoutputs of two or more transducers.

The purpose of SPU is to process thesignals from the transducers in orderto satisfy the functions of the system

& to prepare signals suitable foroperating the display or recordingequipment that follows.


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6. RECORDING


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Data processing and transmission equipment

It is often necessary, or at least desirable torecord measured information for possiblelater use or to transmit it from one locationto another.( Local to Local or local to global ).

Where automatic storage or processing of datais required or where computer control isemployed on online analog or digitalcomputer may be part of instrumentationsystem.

Recorders are of two typesGraphic pen recorder is a device used to

produce a paper record of analogwaveforms.

Magnetic tape recorder is a device used fordata recording for future playback.


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7. CONTROL DEVICES

Where ever it is desirable to have

automatic control of the stimulus,transducers or any other part ofMan Machine system, a control

system is incorporated.It usually consists of a feedback loop inwhich part of the output from the

signal processing unit ( SPU ) ordisplay machine is used to controlthe operation of the system in someway.

PHYSIOLOGICAL SYSTEMS OF THE BODY


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It is well known fact that human body is Bio chemico electro thermo hydraulico pneumatieo

physico magnato mechano dynamicallyengineered machine. To obtain valid measurements from a living human

being. It is necessary to have deep understanding of thesubject on which the measurements are being made.

Within the human body can be found Biological,chemical, electrical, thermal , hydrolical pneumatical,physical, magnetic mechanical & dynamical & manyother types of the systems each of them communicateswith an external environment & internally with the othersystems of the body.

By the help of a multilevel control system andcommunication network, these individual systems areorganized to perform many complex functions of thebody.

Through the integrated operations of all thesesystems, & their various subsystems, man is able tosustain life, learn to perform usual tasks, acquirepersonality and behavioral traits , and even reproducehimself.


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THANK YOU

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