Ergonomics in machine design - an overview | The Mechanical post

Welcome back! to The Mechanical post. Today let's learn about ergonomics, it's importance and it's applications starting with the definition of the ergonomics.

Ergonomics is defined as the enhancement or improvement of the overall as well as detailed designs of controls and operation interfaces between machines and man in all working conditions.


Ergonomics can be defined as the systematic study of the relationship between machines and its operators along with work environment, equipments used and various other factors, for increasing human as well as mechanical efficiency and removing those feature of design which cause inefficiency.

(I know that the 2nd definition is little big but by reading one or two times more it would be clear.)

All over the globe, you can't deny the fact that machines are present and work with men to produce various outputs. Almost everyone uses machines be it in the form of a cycle or an automobile or CNC or a lathe, all of these are machines but in various shapes and sizes with different applications. 

All these machines have a common goal i.e. to simplify or ease human efforts. In almost every aspect of life machines are needed. Therefore, it must be the responsibility of a design engineer to make the machine more efficient and safe to use.

Man machine relation in ergonomics :

The man - machine relation is what the ergonomics of machine design is all about. It is a type of closed loop system, in which the machine and its operator interact with each other. Let's understand it with an example.

 Say you are driving a car. It is a type of closed system in which you are the operator who commands the machine to do a particular task. So while driving the car you see that the fuel level indicator shows that you are out of gas. This shows that the machine is conveying the information. 

Now when you refill the tank, its your response to the machine. Similarly when you are driving and suddenly you need to take a turn, so you turn the steering wheel to convey information to car to take a turn. 

Thus in this way the machine and human interact. This interaction mainly takes place at 2 places.

  • At the display of the machine (in the above case is the fuel gauge indicator)
  • At the control device of the machine (in the above case is the steering wheel.)

It is necessary to study the interactions between man and machine to make the design product as efficient as possible.

The word ergonomics is derived from two greek words i.e. Ergon = work & nomos = natural laws. Therefore, ergonomics means " Natural law of work ". Ergonomics deals with knowledge of human characteristics such as :

1. Anatomy and physiology :

It is the knowledge of structure and function of human body, its senses and mental processes.

2. Psychology :

It is the knowledge of brain, nervous system and human behaviour.

3. Anthropometry :

It is the knowledge of human body size, its field of movement, field of view, speed of response to a situation and forces that can be exerted by a human.

Ergonomics also deals with the following topics:

1. Design of displays :

 Different dial displays of a car. 
Displays are the devices through which man ( machine operator ) receives information from the machine. 

Displays play a very crucial role in communication between man and machine. For e.g. a fuel level indicator, fire alarm indicators, warning alarms etc. There are two types of displays namely :

A) Qualitative displays - 
They are the ones which indicates the state or condition or direction without giving any values for e.g. the red yellow and green lights in the traffic signal, on off indicators in various machines etc.

B) Qualitative displays - 
They are the ones which give a numerical value about the machine which is needed by the operator for e.g. speedometer in automobiles, dial gauge indicator etc. 

2. Design of control :

Controls devices are the devices through which the machine receives information from the operator. 

Control devices may have the input motion like clockwise rotation, horizontal sliding and vertical sliding. 

For special purposes different movements or combinations may be used. Various types of controls used in machine are : push button, knob, hand-wheel, lever etc.

Rotating dials and push buttons of a radio system

3. Design of working environment :

Working environment play an important role in man and machine relation. Working conditions are directly proportional to the health, safety and thus efficiency of both.

The working environment must have optimum amount of light, air ventilation, humidity, heat, noise and vibration.

4. Design of safety :

You can't miss on this ! Safety is of utmost importance in machine design. No one wants to work with a dangerous machine.

 A safe machine ensures efficient functioning and allows the operator to work with peace of mind. Take for eg a paper shredding machine with exposed blades. This would be more unsafe as compared to a shredding machine with covered blades, isn't it ?

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Importance of ergonomics in design :

  • Ergonomics reduces physical and mental stresses
  • It helps in the study of Man - Machine relationship
  • With the help of ergonomics the overall interaction between man and machine can be improved
  • The machine can be made more comfortable, easy to use and more safer, thus making an overall good machine.
  • With the help of ergonomics wastage can be reduced and the output can be increased.                                                                                                                     

Applications of ergonomics in machine design :

  • Knowledge of ergonomics is applied to design the seats and various contact surfaces in automobiles to make the ride more comfortable.
  • The infotainment systems, speedometers, fuel gauge indicators of automobiles are ergonomically designed.
  • The knowledge of ergonomics is applied to make the operation of machines easy by providing control devices at reachable distance along with being properly positioned.
  • Ergonomics is also used to determine the height of the machine so that the operator can use it efficiently.
  • In placement of heavy machineries such as the lathe machine, ergonomics plays an important role in deciding where exactly the machine should be placed such that it would allow proper functioning of the machine without causing any problem to the worker. Like the place must be well ventilated, must have proper lighting etc.

We'll be back soon with another interesting article till then Keep learning and read The Mechanical post!

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