Ergonomics integrates knowledge
derived from the human sciences to match jobs, systems, products, and the
environments to the physical and mental abilities and limitations of people.
Ergonomics emerged as a discipline during World War II when the human operator
became increasingly the weakest link in modern sophisticated military systems.
After the war, the discipline continued to grow to meet the challenge of
civilian applications. The emphasis in the early days was on a human
productivity and work physiology. As the disciplined matured, other fundamental
objectives were recognized, such as provisions for safer and healthier working
environments and the improvements to be recognized by the quality of working
life. The potential of ergonomics is becoming widely recognized by industry,
governments, labor and the general public. Ergonomics has contributed to the
development of industrial workplaces, transportation, aerospace systems, office
design, computer hardware and software, and consumer products.
In the work environment, the
selection and creation of tools, machines, and work process have been pertinent
since the evolution of our species. With the Industrial Revolution, machines
such as the spinning jenny and rolling mills were developed to improve work
process. This is the same motivation behind much of ergonomics today. In the
early 1900's, the production of industry was still largely dependent on human
power/motion and ergonomic concepts were developing to improve worker
productivity. Scientific management, a method that improved worker efficiency by
improving the job process became popular during that period.
World War II prompted greater
interest in human-machine interaction as the efficiency of sophisticated
military equipment (i.e. airplanes) could be compromised by bad or confused
design. Design concepts of fitting the machine to the size of the soldier and
logical/understandable control buttons evolved. After World War II, the focus of
concern expanded to include worker safety as well as productivity. Research
began in a variety of areas such as: (1) muscle force required to perform manual
tasks, (2) compressive low back disk force when lifting, (3) cardiovascular
response when performing heavy labor, and (4) perceived maximum load that can be
carried, pushed or pulled.
Areas of knowledge the involved
human behavior and attributes became known as cognitive or human factors. Areas
of knowledge that involved physical aspects of the workplace and human abilities
became known as industrial ergonomics or simply ergonomics. Contributors to
ergonomics/human factors concepts include industrial engineers, industrial
psychologists, occupational medicine physicians, industrial hygienists, and
safety engineers. Professions that utilized ergonomics/human factors information
include architects, occupational therapists, physical therapists, occupational
medicine nurses, design, manufacturing and industrial engineers, and insurance
loss control specialist. For this particular project the ergonomic concentration
was centered on improving a particular lifting system. Identifying ergonomic
risk factors are vital in preventing workplace related industries. It is
recognized that the fastest growing job related industries in the United States
are Repetitive Strain Injuries. The objective of the lifting system is to
improve conditions for workers. In order to alleviate some of the repetitive
strain for workers there were several design specifications that had to be
implemented.
First it was necessary to use a psychophysical analysis of the designated task.. It is very important to establish what an operator perception of the task they can perform safely. For the initial design of the lift, the particular dimensions must accommodate both genders. The National Institute of Safety and Health provides a risk assessment model that can be used as a tool for assessing the physical stress of two handed, manual lifting task. For optimal performance involving minimal risk there were several design characteristics implemented. For any manual material handling system the optimal load should be less than 51 lbs. The load should be handled within the maximum comfort zone. For this particular lift, the lift height was 40 ", which is between the recommended 33-43" maximum comfort zone. Also the horizontal distance of the load should be less than 12". Another design characteristics that were implemented included a high friction surface and stability, to reduce balance shifting or twisting when transferring the load. Also the operator is able to remove the load without the lift jerking. By implementing the following specification in the design of the lifting system certain risk are reduced for operators. The maximum height of the lift accommodates both the 95th percent male as well as the 5th percent female.