The document discusses the topic of ergonomics and applied ergonomics. It defines ergonomics as the science of fitting tasks to humans. It describes ergonomics as covering a wide field including the human operator and their working environment. The key areas of study in ergonomics are outlined as anatomy, physiology, psychology, engineering sciences, and the integration of people's knowledge about machines and human capabilities. The objectives and applications of ergonomics in product design are also summarized.
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Ergonomics or Human Factors Engineering
1. Topic: Ergonomics
Subject: Applied Ergonomics
Submitted by Vinay Tiwari
Topic: Ergonomics
Subject: Applied Ergonomics
Submitted by Vinay Tiwari
1
Topic: Ergonomics
Subject: Applied Ergonomics
Submitted by Vinay Tiwari
2. Ergonomics
DefinitionDefinition
Ergonomics or human factors engineering is the science of fitting tasks
to man. The word “Ergonomics” is derived from the Greek words ergon
and nomos, meaning “work” and “natural laws”, respectively.
Ergonomics and human factors engineering are synonymous and cover a
very wide field, including the human operator and his working
environment.
The areas of study covered under human factors engineering are one
group comprising Anatomy, Physiology and Psychology & the other
group consisting of engineering sciences such as Physics, Mathematics,
Materials Science and Design.
Human factors engineering brings together two groups of specialists:
those who know about machines and processes, and those who know
about human capabilities.
Ergonomics or human factors engineering is the science of fitting tasks
to man. The word “Ergonomics” is derived from the Greek words ergon
and nomos, meaning “work” and “natural laws”, respectively.
Ergonomics and human factors engineering are synonymous and cover a
very wide field, including the human operator and his working
environment.
The areas of study covered under human factors engineering are one
group comprising Anatomy, Physiology and Psychology & the other
group consisting of engineering sciences such as Physics, Mathematics,
Materials Science and Design.
Human factors engineering brings together two groups of specialists:
those who know about machines and processes, and those who know
about human capabilities.
Ergonomics or human factors engineering is the science of fitting tasks
to man. The word “Ergonomics” is derived from the Greek words ergon
and nomos, meaning “work” and “natural laws”, respectively.
Ergonomics and human factors engineering are synonymous and cover a
very wide field, including the human operator and his working
environment.
The areas of study covered under human factors engineering are one
group comprising Anatomy, Physiology and Psychology & the other
group consisting of engineering sciences such as Physics, Mathematics,
Materials Science and Design.
Human factors engineering brings together two groups of specialists:
those who know about machines and processes, and those who know
about human capabilities.
Ergonomics or human factors engineering is the science of fitting tasks
to man. The word “Ergonomics” is derived from the Greek words ergon
and nomos, meaning “work” and “natural laws”, respectively.
Ergonomics and human factors engineering are synonymous and cover a
very wide field, including the human operator and his working
environment.
The areas of study covered under human factors engineering are one
group comprising Anatomy, Physiology and Psychology & the other
group consisting of engineering sciences such as Physics, Mathematics,
Materials Science and Design.
Human factors engineering brings together two groups of specialists:
those who know about machines and processes, and those who know
about human capabilities.
2Vinay Tiwari-2018
Ergonomics or human factors engineering is the science of fitting tasks
to man. The word “Ergonomics” is derived from the Greek words ergon
and nomos, meaning “work” and “natural laws”, respectively.
Ergonomics and human factors engineering are synonymous and cover a
very wide field, including the human operator and his working
environment.
The areas of study covered under human factors engineering are one
group comprising Anatomy, Physiology and Psychology & the other
group consisting of engineering sciences such as Physics, Mathematics,
Materials Science and Design.
Human factors engineering brings together two groups of specialists:
those who know about machines and processes, and those who know
about human capabilities.
Ergonomics or human factors engineering is the science of fitting tasks
to man. The word “Ergonomics” is derived from the Greek words ergon
and nomos, meaning “work” and “natural laws”, respectively.
Ergonomics and human factors engineering are synonymous and cover a
very wide field, including the human operator and his working
environment.
The areas of study covered under human factors engineering are one
group comprising Anatomy, Physiology and Psychology & the other
group consisting of engineering sciences such as Physics, Mathematics,
Materials Science and Design.
Human factors engineering brings together two groups of specialists:
those who know about machines and processes, and those who know
about human capabilities.
3. Ergonomics
Main Constituents areas of study in ErgonomicsMain Constituents areas of study in Ergonomics
Constituents
of Ergonomics
Constituents
of Ergonomics
PhysiologyPhysiologyAnthropologyAnthropology
Constituents
of Ergonomics
Constituents
of Ergonomics
Mechanical aids & MachinesMechanical aids & MachinesPsychologyPsychology
1. Anthropology: It is the study of the variation of human characteristics
such as height, reach, ratio of leg length to shoulder etc. Such variations
between the individuals & the sexes are noted and mean value and
spread is determined. The data is useful for determining the boundaries
of work-place, heights and shapes of seats and work tables. The is also
useful for designing the handles, levers etc. so they are easy to reach &
operate.
1. Anthropology: It is the study of the variation of human characteristics
such as height, reach, ratio of leg length to shoulder etc. Such variations
between the individuals & the sexes are noted and mean value and
spread is determined. The data is useful for determining the boundaries
of work-place, heights and shapes of seats and work tables. The is also
useful for designing the handles, levers etc. so they are easy to reach &
operate.
3Vinay Tiwari-2018
1. Anthropology: It is the study of the variation of human characteristics
such as height, reach, ratio of leg length to shoulder etc. Such variations
between the individuals & the sexes are noted and mean value and
spread is determined. The data is useful for determining the boundaries
of work-place, heights and shapes of seats and work tables. The is also
useful for designing the handles, levers etc. so they are easy to reach &
operate.
1. Anthropology: It is the study of the variation of human characteristics
such as height, reach, ratio of leg length to shoulder etc. Such variations
between the individuals & the sexes are noted and mean value and
spread is determined. The data is useful for determining the boundaries
of work-place, heights and shapes of seats and work tables. The is also
useful for designing the handles, levers etc. so they are easy to reach &
operate.
4. Ergonomics
Main Constituents areas of study in ErgonomicsMain Constituents areas of study in Ergonomics
2. Physiology: This is related with the study of
a) Speed, accuracy & force with which body movement can be carried
out
b) The human stamina
c) The influence of working conditions on man.
3. Psychology: This is the study concerned with the human behaviour,
human potential under various working conditions and under the
influence of mental strain, fatigue etc. The main contribution of
psychology to ergonomics lies in the field of information. The role of the
man in the working process can be represented as
2. Physiology: This is related with the study of
a) Speed, accuracy & force with which body movement can be carried
out
b) The human stamina
c) The influence of working conditions on man.
3. Psychology: This is the study concerned with the human behaviour,
human potential under various working conditions and under the
influence of mental strain, fatigue etc. The main contribution of
psychology to ergonomics lies in the field of information. The role of the
man in the working process can be represented as
2. Physiology: This is related with the study of
a) Speed, accuracy & force with which body movement can be carried
out
b) The human stamina
c) The influence of working conditions on man.
3. Psychology: This is the study concerned with the human behaviour,
human potential under various working conditions and under the
influence of mental strain, fatigue etc. The main contribution of
psychology to ergonomics lies in the field of information. The role of the
man in the working process can be represented as
2. Physiology: This is related with the study of
a) Speed, accuracy & force with which body movement can be carried
out
b) The human stamina
c) The influence of working conditions on man.
3. Psychology: This is the study concerned with the human behaviour,
human potential under various working conditions and under the
influence of mental strain, fatigue etc. The main contribution of
psychology to ergonomics lies in the field of information. The role of the
man in the working process can be represented as
4Vinay Tiwari-2018
2. Physiology: This is related with the study of
a) Speed, accuracy & force with which body movement can be carried
out
b) The human stamina
c) The influence of working conditions on man.
3. Psychology: This is the study concerned with the human behaviour,
human potential under various working conditions and under the
influence of mental strain, fatigue etc. The main contribution of
psychology to ergonomics lies in the field of information. The role of the
man in the working process can be represented as
2. Physiology: This is related with the study of
a) Speed, accuracy & force with which body movement can be carried
out
b) The human stamina
c) The influence of working conditions on man.
3. Psychology: This is the study concerned with the human behaviour,
human potential under various working conditions and under the
influence of mental strain, fatigue etc. The main contribution of
psychology to ergonomics lies in the field of information. The role of the
man in the working process can be represented as
Signal Reception Channel Decision Action Result
5. Ergonomics
Main Constituents areas of study in ErgonomicsMain Constituents areas of study in Ergonomics
4. Mechanical Aids & Machines: Under this part of study, considerations
are given to the design of machines or mechanical aids so as to make
operator’s task possible and reasonable reduction of the physical &
mental strain and leave him free to devote his attention to those factors
in his work where the judgment and flexibility which he/she alone can
be apply his/her advantage
Engineering: Design of work system suitable to worker
Anatomy: Study of body dimensions & relations for work design
Industrial Hygiene: Occupational hazards & workers health.
4. Mechanical Aids & Machines: Under this part of study, considerations
are given to the design of machines or mechanical aids so as to make
operator’s task possible and reasonable reduction of the physical &
mental strain and leave him free to devote his attention to those factors
in his work where the judgment and flexibility which he/she alone can
be apply his/her advantage
Engineering: Design of work system suitable to worker
Anatomy: Study of body dimensions & relations for work design
Industrial Hygiene: Occupational hazards & workers health.
4. Mechanical Aids & Machines: Under this part of study, considerations
are given to the design of machines or mechanical aids so as to make
operator’s task possible and reasonable reduction of the physical &
mental strain and leave him free to devote his attention to those factors
in his work where the judgment and flexibility which he/she alone can
be apply his/her advantage
Engineering: Design of work system suitable to worker
Anatomy: Study of body dimensions & relations for work design
Industrial Hygiene: Occupational hazards & workers health.
4. Mechanical Aids & Machines: Under this part of study, considerations
are given to the design of machines or mechanical aids so as to make
operator’s task possible and reasonable reduction of the physical &
mental strain and leave him free to devote his attention to those factors
in his work where the judgment and flexibility which he/she alone can
be apply his/her advantage
Engineering: Design of work system suitable to worker
Anatomy: Study of body dimensions & relations for work design
Industrial Hygiene: Occupational hazards & workers health.
5Vinay Tiwari-2018
4. Mechanical Aids & Machines: Under this part of study, considerations
are given to the design of machines or mechanical aids so as to make
operator’s task possible and reasonable reduction of the physical &
mental strain and leave him free to devote his attention to those factors
in his work where the judgment and flexibility which he/she alone can
be apply his/her advantage
Engineering: Design of work system suitable to worker
Anatomy: Study of body dimensions & relations for work design
Industrial Hygiene: Occupational hazards & workers health.
4. Mechanical Aids & Machines: Under this part of study, considerations
are given to the design of machines or mechanical aids so as to make
operator’s task possible and reasonable reduction of the physical &
mental strain and leave him free to devote his attention to those factors
in his work where the judgment and flexibility which he/she alone can
be apply his/her advantage
Engineering: Design of work system suitable to worker
Anatomy: Study of body dimensions & relations for work design
Industrial Hygiene: Occupational hazards & workers health.
6. Ergonomics
International Labour Organisation Defined Ergonomics as “The
application of human biological sciences in conjunction with the
engineering sciences to the worker and his work environment so as to
obtain maximum satisfaction for the worker which at the same time
enhance the productivity.”
International Labour Organisation Defined Ergonomics as “The
application of human biological sciences in conjunction with the
engineering sciences to the worker and his work environment so as to
obtain maximum satisfaction for the worker which at the same time
enhance the productivity.”
Objectives of ErgonomicsObjectives of Ergonomics
Two main objectives are:
1. To enhance the efficiency and effectiveness with which the activities
(Work) is carried out so as to increase the convenience of use, reduce
errors and increase in productivities.
2. To enhance the certain desirable human values including safety,
reduced stress & fatigue and improved quality of life.
“Designing for human use & optimizing working and living conditions”
Two main objectives are:
1. To enhance the efficiency and effectiveness with which the activities
(Work) is carried out so as to increase the convenience of use, reduce
errors and increase in productivities.
2. To enhance the certain desirable human values including safety,
reduced stress & fatigue and improved quality of life.
“Designing for human use & optimizing working and living conditions”
International Labour Organisation Defined Ergonomics as “The
application of human biological sciences in conjunction with the
engineering sciences to the worker and his work environment so as to
obtain maximum satisfaction for the worker which at the same time
enhance the productivity.”
International Labour Organisation Defined Ergonomics as “The
application of human biological sciences in conjunction with the
engineering sciences to the worker and his work environment so as to
obtain maximum satisfaction for the worker which at the same time
enhance the productivity.”
6Vinay Tiwari-2018
Two main objectives are:
1. To enhance the efficiency and effectiveness with which the activities
(Work) is carried out so as to increase the convenience of use, reduce
errors and increase in productivities.
2. To enhance the certain desirable human values including safety,
reduced stress & fatigue and improved quality of life.
“Designing for human use & optimizing working and living conditions”
Two main objectives are:
1. To enhance the efficiency and effectiveness with which the activities
(Work) is carried out so as to increase the convenience of use, reduce
errors and increase in productivities.
2. To enhance the certain desirable human values including safety,
reduced stress & fatigue and improved quality of life.
“Designing for human use & optimizing working and living conditions”
7. Ergonomics
Application of ErgonomicsApplication of Ergonomics
The area of applications of ergonomics has been classified as follow:
a)Design of man-machine system.
b)Design of controls & displays.
c)Anthropometry & Bio-mechanics
d)Accident, Fatigue & Safety
e)Control of physical work environment
f)Anthropometry & Bio-mechanics
The area of applications of ergonomics has been classified as follow:
a)Design of man-machine system.
b)Design of controls & displays.
c)Anthropometry & Bio-mechanics
d)Accident, Fatigue & Safety
e)Control of physical work environment
f)Anthropometry & Bio-mechanics
The area of applications of ergonomics has been classified as follow:
a)Design of man-machine system.
b)Design of controls & displays.
c)Anthropometry & Bio-mechanics
d)Accident, Fatigue & Safety
e)Control of physical work environment
f)Anthropometry & Bio-mechanics
The area of applications of ergonomics has been classified as follow:
a)Design of man-machine system.
b)Design of controls & displays.
c)Anthropometry & Bio-mechanics
d)Accident, Fatigue & Safety
e)Control of physical work environment
f)Anthropometry & Bio-mechanics
Ergonomics-Application
7Vinay Tiwari-2018
Safety, Health
comfort, Satisfaction
Utility
Effectiveness, Performance
Quality, Quantity
Benefits to
Employee
Benefits to
Employer
8. Ergonomics
Importance of Human Factors in Product & Equipments Design
The Human Factors Engineering (Ergonomics) is the link between
Engineering Science & Social Science.
1. Man, as occupant of space, i.e. to operate a machine, the human
operator should have adequate space, as dictated by human body
dimensions or anthropometry.
2. Man, as reader of display from the machine. That is, based on the
display data, man processes the data and takes action.
3. Man, as one who takes action through operating controls which
form a part of the machine.
Thus, man acts as applicator of force and controls the machine.
It will be obvious that human engineering in design should consider
application of forces and study of displays and controls.
Importance of Human Factors in Product & Equipments Design
The Human Factors Engineering (Ergonomics) is the link between
Engineering Science & Social Science.
1. Man, as occupant of space, i.e. to operate a machine, the human
operator should have adequate space, as dictated by human body
dimensions or anthropometry.
2. Man, as reader of display from the machine. That is, based on the
display data, man processes the data and takes action.
3. Man, as one who takes action through operating controls which
form a part of the machine.
Thus, man acts as applicator of force and controls the machine.
It will be obvious that human engineering in design should consider
application of forces and study of displays and controls.
Importance of Human Factors in Product & Equipments Design
The Human Factors Engineering (Ergonomics) is the link between
Engineering Science & Social Science.
1. Man, as occupant of space, i.e. to operate a machine, the human
operator should have adequate space, as dictated by human body
dimensions or anthropometry.
2. Man, as reader of display from the machine. That is, based on the
display data, man processes the data and takes action.
3. Man, as one who takes action through operating controls which
form a part of the machine.
Thus, man acts as applicator of force and controls the machine.
It will be obvious that human engineering in design should consider
application of forces and study of displays and controls.
Importance of Human Factors in Product & Equipments Design
The Human Factors Engineering (Ergonomics) is the link between
Engineering Science & Social Science.
1. Man, as occupant of space, i.e. to operate a machine, the human
operator should have adequate space, as dictated by human body
dimensions or anthropometry.
2. Man, as reader of display from the machine. That is, based on the
display data, man processes the data and takes action.
3. Man, as one who takes action through operating controls which
form a part of the machine.
Thus, man acts as applicator of force and controls the machine.
It will be obvious that human engineering in design should consider
application of forces and study of displays and controls.
8Vinay Tiwari-2018
Importance of Human Factors in Product & Equipments Design
The Human Factors Engineering (Ergonomics) is the link between
Engineering Science & Social Science.
1. Man, as occupant of space, i.e. to operate a machine, the human
operator should have adequate space, as dictated by human body
dimensions or anthropometry.
2. Man, as reader of display from the machine. That is, based on the
display data, man processes the data and takes action.
3. Man, as one who takes action through operating controls which
form a part of the machine.
Thus, man acts as applicator of force and controls the machine.
It will be obvious that human engineering in design should consider
application of forces and study of displays and controls.
Importance of Human Factors in Product & Equipments Design
The Human Factors Engineering (Ergonomics) is the link between
Engineering Science & Social Science.
1. Man, as occupant of space, i.e. to operate a machine, the human
operator should have adequate space, as dictated by human body
dimensions or anthropometry.
2. Man, as reader of display from the machine. That is, based on the
display data, man processes the data and takes action.
3. Man, as one who takes action through operating controls which
form a part of the machine.
Thus, man acts as applicator of force and controls the machine.
It will be obvious that human engineering in design should consider
application of forces and study of displays and controls.
9. Ergonomics
Human Being as applicator of Forces
Energy is converted into useful work by the human motor system. The
body can be regarded as a set of rigid members: the part of the limbs
between joints, the main parts of the trunk and head. All these parts are
quite heavy in relation to the available forces.
Two consequences follow from this. First, action will not be efficient if
the direction of force is such that the limb or any other part of the body
is moving against the force of gravity.
Second, the most effective way of generating forces is to use the
muscles and joints to get the body in a position such that use of body
weight is made to overcome forces.
Human Being as applicator of Forces
Energy is converted into useful work by the human motor system. The
body can be regarded as a set of rigid members: the part of the limbs
between joints, the main parts of the trunk and head. All these parts are
quite heavy in relation to the available forces.
Two consequences follow from this. First, action will not be efficient if
the direction of force is such that the limb or any other part of the body
is moving against the force of gravity.
Second, the most effective way of generating forces is to use the
muscles and joints to get the body in a position such that use of body
weight is made to overcome forces.
Human Being as applicator of Forces
Energy is converted into useful work by the human motor system. The
body can be regarded as a set of rigid members: the part of the limbs
between joints, the main parts of the trunk and head. All these parts are
quite heavy in relation to the available forces.
Two consequences follow from this. First, action will not be efficient if
the direction of force is such that the limb or any other part of the body
is moving against the force of gravity.
Second, the most effective way of generating forces is to use the
muscles and joints to get the body in a position such that use of body
weight is made to overcome forces.
Human Being as applicator of Forces
Energy is converted into useful work by the human motor system. The
body can be regarded as a set of rigid members: the part of the limbs
between joints, the main parts of the trunk and head. All these parts are
quite heavy in relation to the available forces.
Two consequences follow from this. First, action will not be efficient if
the direction of force is such that the limb or any other part of the body
is moving against the force of gravity.
Second, the most effective way of generating forces is to use the
muscles and joints to get the body in a position such that use of body
weight is made to overcome forces.
9Vinay Tiwari-2018
Human Being as applicator of Forces
Energy is converted into useful work by the human motor system. The
body can be regarded as a set of rigid members: the part of the limbs
between joints, the main parts of the trunk and head. All these parts are
quite heavy in relation to the available forces.
Two consequences follow from this. First, action will not be efficient if
the direction of force is such that the limb or any other part of the body
is moving against the force of gravity.
Second, the most effective way of generating forces is to use the
muscles and joints to get the body in a position such that use of body
weight is made to overcome forces.
Human Being as applicator of Forces
Energy is converted into useful work by the human motor system. The
body can be regarded as a set of rigid members: the part of the limbs
between joints, the main parts of the trunk and head. All these parts are
quite heavy in relation to the available forces.
Two consequences follow from this. First, action will not be efficient if
the direction of force is such that the limb or any other part of the body
is moving against the force of gravity.
Second, the most effective way of generating forces is to use the
muscles and joints to get the body in a position such that use of body
weight is made to overcome forces.
10. Ergonomics
For example, in lifting a weight off the ground, if the body and head are
moving upwards against gravity as the weight is lifted, then most of the
available force will be wasted within the body. Correspondingly, if a
worker is required to exert a downward force, for instance, to fit an
object into its surrounding part, then this task might well be
accomplished more easily, from a standing rather than a sitting position
For example, in lifting a weight off the ground, if the body and head are
moving upwards against gravity as the weight is lifted, then most of the
available force will be wasted within the body. Correspondingly, if a
worker is required to exert a downward force, for instance, to fit an
object into its surrounding part, then this task might well be
accomplished more easily, from a standing rather than a sitting position
For example, in lifting a weight off the ground, if the body and head are
moving upwards against gravity as the weight is lifted, then most of the
available force will be wasted within the body. Correspondingly, if a
worker is required to exert a downward force, for instance, to fit an
object into its surrounding part, then this task might well be
accomplished more easily, from a standing rather than a sitting position
For example, in lifting a weight off the ground, if the body and head are
moving upwards against gravity as the weight is lifted, then most of the
available force will be wasted within the body. Correspondingly, if a
worker is required to exert a downward force, for instance, to fit an
object into its surrounding part, then this task might well be
accomplished more easily, from a standing rather than a sitting position
To apply a downward force
Incorrect
Correct
Incorrect Correct
Incorrect Correct Correct
Incorrect Correct
Correct
Incorrect
10Vinay Tiwari-2018
Incorrect Correct
To look a work
Incorrect
Incorrect
Correct
To stand up
Incorrect
Correct
Incorrect
Aspects of weight distributionsAspects of weight distributions
Lifting & CarryingLifting & Carrying
11. Ergonomics
For maximum force
Controls allowing double arm
action with use of shoulder
and upper arm muscles
For maximum precision
With negligible precision
With some precision
Controls allowing use of back
shoulder and upper arm muscles
For maximum precision
With some force
With negligible force
Controls allowing double
arm action with use of
upper arm muscles
Lower arm fixed
support with wrist
and finger action
Use of hand controlsUse of hand controls
For maximum force
Hand-grip
Well designed
back rest Use of pedals (Stable
foot rest required)
Use of pedals (Stable
foot rest required)
11Vinay Tiwari-2018
160º
Well designed
back rest
For maximum precision In stable condition
In unstable condition
Rubber bar operated
by ankle movement
Treadle operated by
ankle movement
or by double
foot action
Use of pedals (Stable
foot rest required)
Use of pedals (Stable
foot rest required)
12. Ergonomics
Anthropometry: The starting point of the design of work spaces must be
the dimensions of the people who are going to operate within given
spaces. Thus, one of the primary responsibilities of ergonomics is to
provide data about body size. Such a study, which is part of the domain of
the anatomist, is called anthropometry.
Anthropometric data are often expressed in the form of 5th, 50th and
95th percentiles. A dimension quoted at 5th-percentile level means that
5% of the population considered are estimated to be smaller than this.
Correspondingly, only 5% of the population is larger than the 95th
percentile. The range from 5th to 95th percentile covers 90% of the
population.
The anthropometric data are make relevance with proper human body
diagram or dummy human operator scale model made of plastics/wood
called manikins with two dimensions only, with swivel points, correspon-
Anthropometry: The starting point of the design of work spaces must be
the dimensions of the people who are going to operate within given
spaces. Thus, one of the primary responsibilities of ergonomics is to
provide data about body size. Such a study, which is part of the domain of
the anatomist, is called anthropometry.
Anthropometric data are often expressed in the form of 5th, 50th and
95th percentiles. A dimension quoted at 5th-percentile level means that
5% of the population considered are estimated to be smaller than this.
Correspondingly, only 5% of the population is larger than the 95th
percentile. The range from 5th to 95th percentile covers 90% of the
population.
The anthropometric data are make relevance with proper human body
diagram or dummy human operator scale model made of plastics/wood
called manikins with two dimensions only, with swivel points, correspon-
Anthropometry: Man as Occupant of SpaceAnthropometry: Man as Occupant of Space
Anthropometry: The starting point of the design of work spaces must be
the dimensions of the people who are going to operate within given
spaces. Thus, one of the primary responsibilities of ergonomics is to
provide data about body size. Such a study, which is part of the domain of
the anatomist, is called anthropometry.
Anthropometric data are often expressed in the form of 5th, 50th and
95th percentiles. A dimension quoted at 5th-percentile level means that
5% of the population considered are estimated to be smaller than this.
Correspondingly, only 5% of the population is larger than the 95th
percentile. The range from 5th to 95th percentile covers 90% of the
population.
The anthropometric data are make relevance with proper human body
diagram or dummy human operator scale model made of plastics/wood
called manikins with two dimensions only, with swivel points, correspon-
Anthropometry: The starting point of the design of work spaces must be
the dimensions of the people who are going to operate within given
spaces. Thus, one of the primary responsibilities of ergonomics is to
provide data about body size. Such a study, which is part of the domain of
the anatomist, is called anthropometry.
Anthropometric data are often expressed in the form of 5th, 50th and
95th percentiles. A dimension quoted at 5th-percentile level means that
5% of the population considered are estimated to be smaller than this.
Correspondingly, only 5% of the population is larger than the 95th
percentile. The range from 5th to 95th percentile covers 90% of the
population.
The anthropometric data are make relevance with proper human body
diagram or dummy human operator scale model made of plastics/wood
called manikins with two dimensions only, with swivel points, correspon-
12Vinay Tiwari-2018
Anthropometry: The starting point of the design of work spaces must be
the dimensions of the people who are going to operate within given
spaces. Thus, one of the primary responsibilities of ergonomics is to
provide data about body size. Such a study, which is part of the domain of
the anatomist, is called anthropometry.
Anthropometric data are often expressed in the form of 5th, 50th and
95th percentiles. A dimension quoted at 5th-percentile level means that
5% of the population considered are estimated to be smaller than this.
Correspondingly, only 5% of the population is larger than the 95th
percentile. The range from 5th to 95th percentile covers 90% of the
population.
The anthropometric data are make relevance with proper human body
diagram or dummy human operator scale model made of plastics/wood
called manikins with two dimensions only, with swivel points, correspon-
Anthropometry: The starting point of the design of work spaces must be
the dimensions of the people who are going to operate within given
spaces. Thus, one of the primary responsibilities of ergonomics is to
provide data about body size. Such a study, which is part of the domain of
the anatomist, is called anthropometry.
Anthropometric data are often expressed in the form of 5th, 50th and
95th percentiles. A dimension quoted at 5th-percentile level means that
5% of the population considered are estimated to be smaller than this.
Correspondingly, only 5% of the population is larger than the 95th
percentile. The range from 5th to 95th percentile covers 90% of the
population.
The anthropometric data are make relevance with proper human body
diagram or dummy human operator scale model made of plastics/wood
called manikins with two dimensions only, with swivel points, correspon-
13. Ergonomics
-nding to the sites, at which joints permit movement. These can be made
for different percentile levels, so that the question of ranges is properly
dealt with.
-nding to the sites, at which joints permit movement. These can be made
for different percentile levels, so that the question of ranges is properly
dealt with.
Anthropometry: Man as Occupant of SpaceAnthropometry: Man as Occupant of Space
-nding to the sites, at which joints permit movement. These can be made
for different percentile levels, so that the question of ranges is properly
dealt with.
-nding to the sites, at which joints permit movement. These can be made
for different percentile levels, so that the question of ranges is properly
dealt with.
Sideways reach
Status
Upward
reach
Forward reach
Shoulder
elbow
height
Hand
breadth
Elbow- middle
finger length
Shoulder width
Sitting
height
Eye
height
above
seat
Thigh
clearance
height
Body size & PostureBody size & Posture
13Vinay Tiwari-2018
Eye
height
Status
Elbow
height
Shoulder
height Hand
height
Knuckle
height
Hand
breadth
Breadth across buttocks
Eye
height
above
seat
Elbow height
above seat
Buttock-knee length
Popliteal
height above
ground
Knee
height
above
ground
Thigh
clearance
height
Buttock-
Popliteal
length
14. Ergonomics
Body Part Desirable Posture Design Implications
Small variations of all postures
should be possible including
movement of inactive parts
All aspects of work space should
allow for these changesAll
Maximum height:
upward reach of
short man
Maximum height:
Knuckle height of
tall man
Clear visibility:
eye height of
short-bodied man
Roof height
above seat of tall
man
Anthropometry: Man as Occupant of SpaceAnthropometry: Man as Occupant of Space
Head
&
Neck
Head should be more balanced on
shoulder with horizontal line of
sight. Extensive frequent or rapid
head movement should be
avoided
Main display elements should be
at eye height or below. Angular
separation or display elements
should be limited.
Trunk
More or less vertical with normal
spinal curvature to minimize effort
of stabilizing musculature.
Facilitates breathing &
maintaining maximum stability.
Provision for back rest &
appropriate location of display &
controls.
Upper
limb
Upper arm roughly vertical;
forearm roughly horizontal; wrist
such that the palm faces
downwards & inwards.
Provision for arm rest &
placement of hand controls.
Seat height under
knees of short-
legged man
Seat width/
Buttocks width of
stout man
Door height
suitable for tall
man
Maximum reach
suitable for small
man
Postural aspects of seatingPostural aspects of seating
14Vinay Tiwari-2018
Upper
limb
Upper arm roughly vertical;
forearm roughly horizontal; wrist
such that the palm faces
downwards & inwards.
Lower
limb
Thighs roughly horizontal; lower
leg at obtuse angle to thigh; foot
at right angle to lower leg
Size, height & slope of seat;
provision for adjustments of foot
controls.
Importance of range of body size in designImportance of range of body size in design
Postural aspects of seatingPostural aspects of seating
15. Ergonomics
Seating at work spaceSeating at work space
Beck rest in the lumber
region in order to
provide variety of
postures
Top normally not
normal than reachBeck rest in the lumber
region in order to
provide variety of
postures
Arm rest required only
for ease of standing up
or sitting down &
postural change
Seat height
determined
by under
knee height
Height
determined
by elbow
height
Top thin
enough to
allow space
for things
15Vinay Tiwari-2018
Seat height
determined
by under
knee height
Seat length not longer
than buttock-knee length
Clearance to allow for
feet under seat while
standing up
Adequate space
under work top
for knees & feet
Height
determined
by elbow
height
Seat surface slightly tilted
backwards & not smooth
to maintain equilibrium.
Seat width determined by
sitting buttocks width
16. Ergonomics
The fundamental concept of human engineering is the system. A system
is composed of human, machines & other things that work together ( or
interact) to accomplish some goal which these same components could
not produce independently.
The man-machine system is combination of one or more human beings
& one or more physical components interacting to bring about, from
given inputs, some desire output.
Man-Machine system consists of any type of physical object, device,
equipment, facility & activities performed by man.
The fundamental concept of human engineering is the system. A system
is composed of human, machines & other things that work together ( or
interact) to accomplish some goal which these same components could
not produce independently.
The man-machine system is combination of one or more human beings
& one or more physical components interacting to bring about, from
given inputs, some desire output.
Man-Machine system consists of any type of physical object, device,
equipment, facility & activities performed by man.
Man-Machine SystemMan-Machine System
The fundamental concept of human engineering is the system. A system
is composed of human, machines & other things that work together ( or
interact) to accomplish some goal which these same components could
not produce independently.
The man-machine system is combination of one or more human beings
& one or more physical components interacting to bring about, from
given inputs, some desire output.
Man-Machine system consists of any type of physical object, device,
equipment, facility & activities performed by man.
The fundamental concept of human engineering is the system. A system
is composed of human, machines & other things that work together ( or
interact) to accomplish some goal which these same components could
not produce independently.
The man-machine system is combination of one or more human beings
& one or more physical components interacting to bring about, from
given inputs, some desire output.
Man-Machine system consists of any type of physical object, device,
equipment, facility & activities performed by man.
16Vinay Tiwari-2018
The fundamental concept of human engineering is the system. A system
is composed of human, machines & other things that work together ( or
interact) to accomplish some goal which these same components could
not produce independently.
The man-machine system is combination of one or more human beings
& one or more physical components interacting to bring about, from
given inputs, some desire output.
Man-Machine system consists of any type of physical object, device,
equipment, facility & activities performed by man.
The fundamental concept of human engineering is the system. A system
is composed of human, machines & other things that work together ( or
interact) to accomplish some goal which these same components could
not produce independently.
The man-machine system is combination of one or more human beings
& one or more physical components interacting to bring about, from
given inputs, some desire output.
Man-Machine system consists of any type of physical object, device,
equipment, facility & activities performed by man.
Man-Machine System
Manual System Mechanical System Automated System
17. Ergonomics
Man-Machine system is a closed loop system
The man will receive certain information from the machine either from
dials, displays, etc. designed for the purpose or by observation of
machine itself. He will process this information& make decisions on
what action to take & manipulate controls or attend machine in some
other ways as to affect its behavior in the required manner.
Environmental factor will have an influence on the working of the
system.
The efficiency with which the man functions depends on environmental
factors, on his own characteristics such as age, motivation, training &
experiences as well as the efficiency with which the machine provides
the information feedback control measures.
Man-Machine system is a closed loop system
The man will receive certain information from the machine either from
dials, displays, etc. designed for the purpose or by observation of
machine itself. He will process this information& make decisions on
what action to take & manipulate controls or attend machine in some
other ways as to affect its behavior in the required manner.
Environmental factor will have an influence on the working of the
system.
The efficiency with which the man functions depends on environmental
factors, on his own characteristics such as age, motivation, training &
experiences as well as the efficiency with which the machine provides
the information feedback control measures.
Man-Machine SystemMan-Machine System
Man-Machine system is a closed loop system
The man will receive certain information from the machine either from
dials, displays, etc. designed for the purpose or by observation of
machine itself. He will process this information& make decisions on
what action to take & manipulate controls or attend machine in some
other ways as to affect its behavior in the required manner.
Environmental factor will have an influence on the working of the
system.
The efficiency with which the man functions depends on environmental
factors, on his own characteristics such as age, motivation, training &
experiences as well as the efficiency with which the machine provides
the information feedback control measures.
Man-Machine system is a closed loop system
The man will receive certain information from the machine either from
dials, displays, etc. designed for the purpose or by observation of
machine itself. He will process this information& make decisions on
what action to take & manipulate controls or attend machine in some
other ways as to affect its behavior in the required manner.
Environmental factor will have an influence on the working of the
system.
The efficiency with which the man functions depends on environmental
factors, on his own characteristics such as age, motivation, training &
experiences as well as the efficiency with which the machine provides
the information feedback control measures.
17Vinay Tiwari-2018
Man-Machine system is a closed loop system
The man will receive certain information from the machine either from
dials, displays, etc. designed for the purpose or by observation of
machine itself. He will process this information& make decisions on
what action to take & manipulate controls or attend machine in some
other ways as to affect its behavior in the required manner.
Environmental factor will have an influence on the working of the
system.
The efficiency with which the man functions depends on environmental
factors, on his own characteristics such as age, motivation, training &
experiences as well as the efficiency with which the machine provides
the information feedback control measures.
Man-Machine system is a closed loop system
The man will receive certain information from the machine either from
dials, displays, etc. designed for the purpose or by observation of
machine itself. He will process this information& make decisions on
what action to take & manipulate controls or attend machine in some
other ways as to affect its behavior in the required manner.
Environmental factor will have an influence on the working of the
system.
The efficiency with which the man functions depends on environmental
factors, on his own characteristics such as age, motivation, training &
experiences as well as the efficiency with which the machine provides
the information feedback control measures.
18. Ergonomics
Man-Machine SystemMan-Machine System
Training & Experience
Secondary
Functions
Data Processing
Decision-Making
Manipulative
Functions
Display
Control
M
A
N
OUTPUT
INPUT
18Vinay Tiwari-2018
Manipulative
Functions
Control
INPUT
Environment i.e. light, noise, humidity, vibration etc.
19. Ergonomics
Display are necessary extensions to men’s senses & provide both prime
and supplemental information needed by operators in making decision
and effecting control responses.
Information presented by can be considered Dynamic or Static. Dynamic
information continuously changes or is subjected to change through
time e.g. traffic signals, charts or graphs.
Display are necessary extensions to men’s senses & provide both prime
and supplemental information needed by operators in making decision
and effecting control responses.
Information presented by can be considered Dynamic or Static. Dynamic
information continuously changes or is subjected to change through
time e.g. traffic signals, charts or graphs.
Display DesignDisplay Design
Display are necessary extensions to men’s senses & provide both prime
and supplemental information needed by operators in making decision
and effecting control responses.
Information presented by can be considered Dynamic or Static. Dynamic
information continuously changes or is subjected to change through
time e.g. traffic signals, charts or graphs.
Display are necessary extensions to men’s senses & provide both prime
and supplemental information needed by operators in making decision
and effecting control responses.
Information presented by can be considered Dynamic or Static. Dynamic
information continuously changes or is subjected to change through
time e.g. traffic signals, charts or graphs.
Quantitative
information
Representational
information
19Vinay Tiwari-2018
Classification of Display
Qualitative
information
Status
information
Warning &
signal indicators
Identification
information
Time phased
information
20. Ergonomics
1.Quantitative information: Display presentation that reflect the
approximate value of same variable such as temperature, speed, etc.
2. Qualitative information: Display presentation that reflect the
approximate value of same trend, rate of change, direction of change etc.
3. Status information: Display presentation indicate the condition or
status of the system such as ON-OFF conditions etc.
4. Warning & Signal indicators: Display the emergency. Unsafe condition.
5. Representational information: Pictorial & graphic presentation.
6. Identification information
7. Time phased information
1.Quantitative information: Display presentation that reflect the
approximate value of same variable such as temperature, speed, etc.
2. Qualitative information: Display presentation that reflect the
approximate value of same trend, rate of change, direction of change etc.
3. Status information: Display presentation indicate the condition or
status of the system such as ON-OFF conditions etc.
4. Warning & Signal indicators: Display the emergency. Unsafe condition.
5. Representational information: Pictorial & graphic presentation.
6. Identification information
7. Time phased information
Display DesignDisplay Design
1.Quantitative information: Display presentation that reflect the
approximate value of same variable such as temperature, speed, etc.
2. Qualitative information: Display presentation that reflect the
approximate value of same trend, rate of change, direction of change etc.
3. Status information: Display presentation indicate the condition or
status of the system such as ON-OFF conditions etc.
4. Warning & Signal indicators: Display the emergency. Unsafe condition.
5. Representational information: Pictorial & graphic presentation.
6. Identification information
7. Time phased information
1.Quantitative information: Display presentation that reflect the
approximate value of same variable such as temperature, speed, etc.
2. Qualitative information: Display presentation that reflect the
approximate value of same trend, rate of change, direction of change etc.
3. Status information: Display presentation indicate the condition or
status of the system such as ON-OFF conditions etc.
4. Warning & Signal indicators: Display the emergency. Unsafe condition.
5. Representational information: Pictorial & graphic presentation.
6. Identification information
7. Time phased information
20Vinay Tiwari-2018
1.Quantitative information: Display presentation that reflect the
approximate value of same variable such as temperature, speed, etc.
2. Qualitative information: Display presentation that reflect the
approximate value of same trend, rate of change, direction of change etc.
3. Status information: Display presentation indicate the condition or
status of the system such as ON-OFF conditions etc.
4. Warning & Signal indicators: Display the emergency. Unsafe condition.
5. Representational information: Pictorial & graphic presentation.
6. Identification information
7. Time phased information
1.Quantitative information: Display presentation that reflect the
approximate value of same variable such as temperature, speed, etc.
2. Qualitative information: Display presentation that reflect the
approximate value of same trend, rate of change, direction of change etc.
3. Status information: Display presentation indicate the condition or
status of the system such as ON-OFF conditions etc.
4. Warning & Signal indicators: Display the emergency. Unsafe condition.
5. Representational information: Pictorial & graphic presentation.
6. Identification information
7. Time phased information
21. Ergonomics
Types of Display
Visual display Auditory display
1 Quantitative display : (To
read precise numeric value
e.g. display for pressure
measurement, display for
speed measurement, angle
measurement). Conventional
quantitative displays are
mechanical devices as shown
in front rows
Fixed scale with moving point :
Pressure gauge, Automobile
speedometer.
It give superior
monitoring performance
than visual display, so
suitable for warning
devices .
Moving scale with fixed pointer:
Weighing machine to measure
human weight
Quantitative display : (To
read precise numeric value
e.g. display for pressure
measurement, display for
speed measurement, angle
measurement). Conventional
quantitative displays are
mechanical devices as shown
in front rows
Fixed scale with moving point :
Pressure gauge, Automobile
speedometer.
It give superior
monitoring performance
than visual display, so
suitable for warning
devices .
Moving scale with fixed pointer:
Weighing machine to measure
human weight
Digital Display: digital counter of
tape recorder
When message is simple
& short
Electronic Digital display When message is called
for immediate action
2 Qualitative display The display is used to read an
approximate value or indicate rate of
change, change in direction etc. e.g.
the increase or decrease in pressure
When the receiver
moves from one place to
another.
21Vinay Tiwari-2018
2 Qualitative display The display is used to read an
approximate value or indicate rate of
change, change in direction etc. e.g.
the increase or decrease in pressure
When the receiver
moves from one place to
another.
3 Check display This display gives information about
the parameters whether they are
normal
When continuously
changing in information
of some type is
presented
23. Ergonomics
The selection of controls should be considered with regard to the
functional requirements of the system. Controls are the means by which
information is transmitted to the machine from man.
1. Hand control: The anthropometric data for the human hand can be
used as an aid to design dimensions of hand controls.
2. Hand levers: Levers give a quick control action can accommodate large
forces. They are not suitable for fine adjustments . Levers can provide
ON/OFF or step by step control.
3. Hand wheels: Hand wheel provide a controlling torque via both hand &
they are used for heavy loads. They can provide good accuracy of
adjustments .
4. Cranks: Cranks are intended to provide torque via one hand. Smaller
cranks are use for fast control.
The selection of controls should be considered with regard to the
functional requirements of the system. Controls are the means by which
information is transmitted to the machine from man.
1. Hand control: The anthropometric data for the human hand can be
used as an aid to design dimensions of hand controls.
2. Hand levers: Levers give a quick control action can accommodate large
forces. They are not suitable for fine adjustments . Levers can provide
ON/OFF or step by step control.
3. Hand wheels: Hand wheel provide a controlling torque via both hand &
they are used for heavy loads. They can provide good accuracy of
adjustments .
4. Cranks: Cranks are intended to provide torque via one hand. Smaller
cranks are use for fast control.
Design of ControlsDesign of Controls
The selection of controls should be considered with regard to the
functional requirements of the system. Controls are the means by which
information is transmitted to the machine from man.
1. Hand control: The anthropometric data for the human hand can be
used as an aid to design dimensions of hand controls.
2. Hand levers: Levers give a quick control action can accommodate large
forces. They are not suitable for fine adjustments . Levers can provide
ON/OFF or step by step control.
3. Hand wheels: Hand wheel provide a controlling torque via both hand &
they are used for heavy loads. They can provide good accuracy of
adjustments .
4. Cranks: Cranks are intended to provide torque via one hand. Smaller
cranks are use for fast control.
The selection of controls should be considered with regard to the
functional requirements of the system. Controls are the means by which
information is transmitted to the machine from man.
1. Hand control: The anthropometric data for the human hand can be
used as an aid to design dimensions of hand controls.
2. Hand levers: Levers give a quick control action can accommodate large
forces. They are not suitable for fine adjustments . Levers can provide
ON/OFF or step by step control.
3. Hand wheels: Hand wheel provide a controlling torque via both hand &
they are used for heavy loads. They can provide good accuracy of
adjustments .
4. Cranks: Cranks are intended to provide torque via one hand. Smaller
cranks are use for fast control.
23Vinay Tiwari-2018
The selection of controls should be considered with regard to the
functional requirements of the system. Controls are the means by which
information is transmitted to the machine from man.
1. Hand control: The anthropometric data for the human hand can be
used as an aid to design dimensions of hand controls.
2. Hand levers: Levers give a quick control action can accommodate large
forces. They are not suitable for fine adjustments . Levers can provide
ON/OFF or step by step control.
3. Hand wheels: Hand wheel provide a controlling torque via both hand &
they are used for heavy loads. They can provide good accuracy of
adjustments .
4. Cranks: Cranks are intended to provide torque via one hand. Smaller
cranks are use for fast control.
The selection of controls should be considered with regard to the
functional requirements of the system. Controls are the means by which
information is transmitted to the machine from man.
1. Hand control: The anthropometric data for the human hand can be
used as an aid to design dimensions of hand controls.
2. Hand levers: Levers give a quick control action can accommodate large
forces. They are not suitable for fine adjustments . Levers can provide
ON/OFF or step by step control.
3. Hand wheels: Hand wheel provide a controlling torque via both hand &
they are used for heavy loads. They can provide good accuracy of
adjustments .
4. Cranks: Cranks are intended to provide torque via one hand. Smaller
cranks are use for fast control.
24. Ergonomics
5. Knobs: Rotating knobs are recommended for light loading control with
either fingers or with whole hand. Knobs are typically use in applications
such as instrument control panels
6. Push buttons & toggle switches: They are essentially used as light load
ON/OFF controls & normally designed for operation by one finger.
7. Joysticks: This is a type of hand control now extensively use in
computer applications including CNC machines /modern Off-Highway
Vehicles.
8. Foot pedals: These are used for fast action control with medium or
heavy loading capacity. They lack in accuracy & range which may be
obtained with hand controls. They are used in sitting position.
5. Knobs: Rotating knobs are recommended for light loading control with
either fingers or with whole hand. Knobs are typically use in applications
such as instrument control panels
6. Push buttons & toggle switches: They are essentially used as light load
ON/OFF controls & normally designed for operation by one finger.
7. Joysticks: This is a type of hand control now extensively use in
computer applications including CNC machines /modern Off-Highway
Vehicles.
8. Foot pedals: These are used for fast action control with medium or
heavy loading capacity. They lack in accuracy & range which may be
obtained with hand controls. They are used in sitting position.
Design of ControlsDesign of Controls
5. Knobs: Rotating knobs are recommended for light loading control with
either fingers or with whole hand. Knobs are typically use in applications
such as instrument control panels
6. Push buttons & toggle switches: They are essentially used as light load
ON/OFF controls & normally designed for operation by one finger.
7. Joysticks: This is a type of hand control now extensively use in
computer applications including CNC machines /modern Off-Highway
Vehicles.
8. Foot pedals: These are used for fast action control with medium or
heavy loading capacity. They lack in accuracy & range which may be
obtained with hand controls. They are used in sitting position.
5. Knobs: Rotating knobs are recommended for light loading control with
either fingers or with whole hand. Knobs are typically use in applications
such as instrument control panels
6. Push buttons & toggle switches: They are essentially used as light load
ON/OFF controls & normally designed for operation by one finger.
7. Joysticks: This is a type of hand control now extensively use in
computer applications including CNC machines /modern Off-Highway
Vehicles.
8. Foot pedals: These are used for fast action control with medium or
heavy loading capacity. They lack in accuracy & range which may be
obtained with hand controls. They are used in sitting position.
24Vinay Tiwari-2018
5. Knobs: Rotating knobs are recommended for light loading control with
either fingers or with whole hand. Knobs are typically use in applications
such as instrument control panels
6. Push buttons & toggle switches: They are essentially used as light load
ON/OFF controls & normally designed for operation by one finger.
7. Joysticks: This is a type of hand control now extensively use in
computer applications including CNC machines /modern Off-Highway
Vehicles.
8. Foot pedals: These are used for fast action control with medium or
heavy loading capacity. They lack in accuracy & range which may be
obtained with hand controls. They are used in sitting position.
5. Knobs: Rotating knobs are recommended for light loading control with
either fingers or with whole hand. Knobs are typically use in applications
such as instrument control panels
6. Push buttons & toggle switches: They are essentially used as light load
ON/OFF controls & normally designed for operation by one finger.
7. Joysticks: This is a type of hand control now extensively use in
computer applications including CNC machines /modern Off-Highway
Vehicles.
8. Foot pedals: These are used for fast action control with medium or
heavy loading capacity. They lack in accuracy & range which may be
obtained with hand controls. They are used in sitting position.
26. Ergonomics
Use Special Design Requirement
1 In array for rapid selection between
alternatives
To avoid slipping finger &
accidental activation
2 For definite, rarely used action involving
only choice of two ( normally On/Off)
To avoid excessive finger pressure
or nail damage
Types of ControlsTypes of Controls
2 For definite, rarely used action involving
only choice of two ( normally On/Off)
To avoid excessive finger pressure
or nail damage
3 For more than two & less than ten
choices
To avoid wrist action make total
movement less than 180º. Do not
use simple circular shape
4 For continuous variable Size depends mainly on resistance
to motion. Use circular shape with
serrated edge
When rotated through more than 360º is
needed
Grip handle should turn freely on
shaft
26Vinay Tiwari-2018
Size depends mainly on resistance
to motion. Use circular shape with
serrated edge
5 When rotated through more than 360º is
needed
Grip handle should turn freely on
shaft
6 For higher forces or very definite activity Identification of natural or zero
7 For precise activity involving large angles
or rotation
Identification of particular
position avoid slipping