Download Human-Machine Systems

Human-Machine Systems
1
We will cover:
- Introduction
- Classification of Human-Machine Systems
- Characteristics of Systems
2
Introduction
•A system could be defined with mathematical symbols and
set theory.
•A Human-Machine System could be defined verbally as an
arrangement of people and machines (or physical
components) interacting within an environment in order to
achieve a set of system goals.
•Examples of Human-Machine Systems include a person
with a hammer, an office machine with its operator, oil
refineries, hospitals, a rescue operation of a crashed
airplane.
•The task of a human factors specialist is to optimize the
interaction between people and machine elements of the
system while taking the environment into account
•An example of an interaction between a person and a
3machine is shown in figure 1.1(p15)
Classification of Human-Machine Systems
1. Manual Systems: Consisting of hand tools and other
aids coupled by a human operator who controls the
operation. The source of power is human physical energy.
2.Mechanical Systems (Semiautomatic): Consisting of
integrated physical parts (such as powered machine tools).
The function is performed with little variation and the power
is provided by the machine. The user usually manipulates
the control devices.
3.Automated Systems: Operational functions are
performed with little or no human intervention (such as
robots). But are they Human-Machine Systems?
Automated systems require humans to install, program,
reprogram, and maintain. Hence, they must be designed
with the same attention paid to manual or mechanical
4
systems.
Characteristics of Systems
1.
2.
3.
4.
5
Systems Are Purposive: A system has a purpose.
The purpose of the system is the system goal or
objective. A system could have more than one
objective.
Systems Can Be Hierarchical: A system may be
composed of a number of subsystems. System
boundary and resolution limit must be set.
Systems Operate in an Environment: The system
environment is every thing outside its boundaries. It
could range from immediate environment (such as a
chair) through intermediate (such as an office) to
general (such as a city).
Components Serve Functions: Each component
serves at least one function that is related to achieving
the system goal. There are four basic functions:
A.Sensing (information receiving).
B.Information Storage.
C.Information Processing and Decision.
D.Action Functions (Physical control action or
process and communication action).
Figure1.2 page17
5.Components Interact: Components work together to
achieve a system goal. Each component has an effect on
other components.
6.Systems, Subsystems, and Components Have Inputs
and Outputs: The outputs of one system or component
are the inputs to another. A system receives inputs from
the environment and makes outputs to the environment.
Inputs and outputs could be physical entities (such as
materials), electric impulses, mechanical forces, or
information.
6