Ergonomics : Definition, Design Consideration, Examples

Ergonomics: Definition

It is defined as the relationship between man & Machine and the application of anatomical, physiological & Psychological principles to solve the problems arising from man-machine relationships.

Ergonomics is defined as the scientific study of the man-machine-working environment relationship and the application of anatomical, physiological, and psychological principles to solve the problems arising from the relationship.
• Ergonomics is related to the comfort between the man and machine while operating the machine.
• The objective of ergonomics is to make the machine fit for the user rather than to make the user adapt himself or herself to the machine.

Communication between man and machine

  • The machine has a display unit and a control unit.
  • A man (user) receives the information from the machine display through the sense organs.
  • He (or she) then takes the corrective action on the machine controls using the hands or feet.
  • This man-machine closed-loop system is influenced by the working environment factors such as lighting, noise, temperature, humidity, air circulation, etc.
Concept Of Ergonomics
Concept Of Ergonomics

Ergonomics Design Consideration : 

1. Anatomical factors in the design of the driver’s seat:

The design of the driver’s seat of an automobile is such that it is adjustable and comfortable to the end-user.

2. Layout of instrument dials and display panels for accurate perception by the operators:

The basic objective behind the design of displays is to minimize the fatigue to the operator, who has to observe them continuously.

The ergonomic considerations in the design of displays are as follows:

i) The scale on the dial indicator should be divided into suitable numerical divisions like 0-5-10-15 OR 0-10-20-30 and not 0-5-25-35
ii) The number of subdivisions between numbered divisions should be minimum.
iii) The size of letter or number on indicator is given as Height of letter or number ≥ /200
iv) Vertical figures should be used for stationery dials, while radially oriented figures are used for rotating dials.
v) The pointer should have a knife-edge with a mirror in the dial to minimize Parallex Error.

ergonomics examples - workspace and chair design
ergonomics examples – workspace and chair design

3. Design of hand levers and handwheels:

The controls used to operate the machines consist of levers, handwheels, knobs, switches, pushbuttons, and pedals. Most of them are hand-operated. When a large force is required to operate the controls, levers and handwheels are used. When the operating forces are light, push buttons or knob are used.

The ergonomic considerations in the design are as follows:

i) The controls should be easily accessible and logically positioned.
ii) The shape of the control component, which comes in contact with the hands, should conform with the anatomy of human hands.
iii) Proper color produces beneficial psychological effects. The controls should be painted with a grey background of machine tools to call for attention.

4. Lighting, noise, and climatic conditions in the machine environment:

The working environment affects significantly the man-machine relationship. It affects the efficiency and possibly the health of the operator.

The major working environmental factors are:

I. Lighting:

• The amount of light that is required to enable a task to be performed effectively depends upon the nature of the task, the cycle time, the reflective characteristics of the equipment involved, and the vision of the operator.
• The intensity of light in the surrounding area should be less than that at the task area. This makes the task area the focus of attention.
• Operators will become less tired if the lighting and color schemes are arranged so that there is a gradual change in brightness and color from the task area to the surroundings. The task area should be located such that the operator can occasionally relax by looking away from the task area towards a distinct object or surface. The distinct object or surface should not be so bright that the operator’s eyes take time to adjust to the change when he or she again looks at the task.

II. Noise:

• The noise at the workplace causes annoyance, damage to hearing, and reduction of work efficiency. Noise caused by equipment that a person is using is less annoying than that caused by the equipment being used by another person because the person has the option of stopping the noise caused by his equipment. If the noise level is too high, it should be reduced at the source by maintenance, by the use of silencers and by placing vibrating equipment on isolating mounts. If required, earplugs should be provided to the operators to reduce the effect of noise.

III. Temperature:

• For an operator to perform the task efficiently, he should neither feel hot nor cold. When heavy work is done, the temperature should be relatively lower and when the light work is done, the temperature should be relatively higher.

IV. Humidity and Air circulation:

• At high temperatures, the low humidity may cause discomfort due to drying of throat and nose and high humidity may cause discomfort due to sensation of stuffiness and over sweating in an ill-ventilated or crowded room
• The proper air circulation is necessary to minimize the effect of high temperature and humidity.

Ergonomics considerations Examples : 

I) For assembly jobs, material should be placed in a position such that the worker’s strongest muscles do most of the work.
ii) For detailed work which involves close inspection of the materials, the workbench should be lower than for heavy work.
iii) Hand tools that cause discomfort or injury should be modified or replaced. Workers are often the best source of ideas on ways to improve a tool to make using it more comfortable. For example, pliers can be either straight or bent, depending on the need.
iv) A task should not require workers to stay in awkward positions, such as reaching, bending, or hunching over for long periods.
v) Workers need to be trained in proper lifting techniques. A well-designed job should minimize how far and how often workers have to lift.
vi) Standing work should be minimized since it is often less tiring to do a job sitting than standing.
vii) Job assignments should be rotated to minimize the amount of time a worker spends doing a highly repetitive task since repetitive work requires using the same muscles again and again and is usually very boring.
viii) Workers and equipment should be positioned so that workers can perform their jobs with their upper arms at their sides and with their wrists straight.

Ergonomics consideration in the design of the Lathe machine.

1) The controls on lathe should be easily accessible and properly positioned.
2) the control operation should involve minimum motions.
3) Height of lathe should be matched with the worker for operation
4) Lathe machine should make less noise during operation.
5) force & power capacity required in turning the wheel as per operation or human being can apply normally.
6) should get the required accuracy in operation.

Aesthetics in automobile Design –

The appearance should contribute to the performance of the product, thought the extent of contribution varies from product to product for example chromium plating of automobiles components improves the corrosion resistance along with the appearance.
Similarly the aerodynamic shape of the car improves the performance of the performance as well as gives the pleasing appearance lesser air resistance resulting in the lesser fuel consumption. The appearance should reflect the function of the product for example. The aerodynamic shape of the car creases the speed.

Importance of Aesthetic considerations in design –

Each product is to be designed to perform a specific function or a set of functions to the satisfaction of customers. In the present days of the buyer’s market, with several products available in the market are having most of the parameters identical, the appearance of the product is often a major factor in attracting the customer.
For any product, there exists a relationship between the functional requirement and the appearance of a product. The aesthetic quality contributes to the performance of the product, through the extent of contribution varies from product to product. The job of an industrial designer is to create new shapes and forms for the product which are aesthetically appealing.

For example. (1) The chromium plating of automobile components improves the corrosion resistance along with the appearance. (2) the aerodynamic shape of the car improves the performance as well as gives the pleasing appearance

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Sachin Thorat

Sachin is a B-TECH graduate in Mechanical Engineering from a reputed Engineering college. Currently, he is working in the sheet metal industry as a designer. Additionally, he has interested in Product Design, Animation, and Project design. He also likes to write articles related to the mechanical engineering field and tries to motivate other mechanical engineering students by his innovative project ideas, design, models and videos.

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