Human-machine system

The human machine systems consists of three main systems

• The first component : is the human component which includes all human characteristics , like anatomical, physiological and psychological elements.

• The second component : is the machine component like chairs, tools and equipment with which the human-being interacts

• The third component: is the environment , it is the place and the circumstances in which the work is carried out and it includes physical and social aspects

• The physical aspects includes noise, vibration, light, climate and chemical substance

• The social aspects includes the family and the surrounding people as colleges

environments

Machine

Human

N.BThe work space is the three dimension space in which the work is carried out . This required the study of the dimension of machine and the dimension of the human (anthropometry). It also needs knowledge about the activities during work and work rate

Simple and complex ergosystem

• Simple ergosystem means one human and one machine in the work environment

• Complex ergosystem means one human interact with different machines or several humans use one machine

The output of the ergosystem

• This output may arise directly from the machine under human control or from the human component when the decision is taken

• The out put of ergosystem may itself be human as in hospital whose output is cured patients

• All ergosystems are communicated with each other by their respective inputs and outputs

• The output of a particular ergosystem may be the input to other connected work systems or vice versa

senseCNS

MS

displayCentral processing

controls

INPUT

OUTPUT

HUMAN

MACHINE

In the human component of ergosystem

• The senses are the means of the input by which the human is aware of the surrounding. We have 5 sense sight, smell, taste, hearing and touch and other sense like balance, body position in space, and sense of speed

• The brain is the main information processing centre in the human which contain low level programs to control the basic sensorimotor work activities and higher level cognitive processes

• Which responsible about planning , decision making and problem solving activities of work

• Physical and mental work need education, training, energy and motivation.

• The psychological aspects and motivation support and sustain the working behavior

• the effectors : are the systems by which information is entered into a machine or passed from one human to the other . They include hands , feet , voice……..

The machine component of the ergosystem

• Controls : the human interaction with the machine depends on the presence of suitable controls which are used by the effectors of the human as the keyboard of the computer, handle of the tool.

• The controlled process information system: is the basic operation of the machine as central processing unit of the computer and its controlled by human .

• Display : the output of the information system . Like screen of the computer

Strategies in the design of an ideal HMS

• The purpose of the ergonomics is to enable the ergosystem to function better by improving the interactions between the human component and other components .

• Most strategies concerned with human component but the other component play a role .

• Human error are often attributed to the design of the work space which do not take the characteristics and limitation of the human into account

There are four main strategies

• Which are considered important in the design of an ideal HMS.

• These are classified into reducing stress , designing the machines, matching the job – demands with the people abilities and improving the people’s knowledge about their environment .

• The first strategy : concerned with stress which either physical or mental

• Poor designed equipment may make subject to assumed bad posture that will make abnormal stress on the subject

• when this stress exceed the subject tolerance and limits, the performance and the productivity will decline and the safety and health of subject will deteriorate

• The second strategy : is concerned with the design .

• Machines and equipments should be design with the human characteristics in the mind

• Good matching between the machine dimensions and the human characteristics will help the subjects to do their job easily safely and efficiently

• The third strategy : aims to match the job demands with the people abilities both physical and behavioral to ensure a safe and productive life style.

So• If the demands of specific task can be matched

with human abilities optimal work environment

• If the human’s abilities exceed the task demand safer human-machine system

• If the demands exceed the human abilities case injuries and health problems

will takes place

Task Demands Human Abilities

unsafe safe

balance

• The fourth strategy is to educate and physically train people to improve their knowledge and awareness of their environment by proper motor learning which is a set of learning associated with practice and experiences .

• That leads to relatively permanent changes in the capabilities or skilled performance

• Two concepts are used 1- fit man to job like pilot who drive fight airplane . this need highly qualified person

• 2- fit job to man like carrying objects , it does not much training