Ergonomic Evaluation of Commercially Available Operator Lifts for Farmers with Disabilities

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Ergonomic Evaluation of Commercially Available
Operator Lifts for Farmers with Disabilities
Aaron M. Yoder, Ph.D. Penn State
University, Purdue University Breaking New
Ground Resource Center
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Background

• 692-1,697 persons in agriculturally related
  occupations or industries with a spinal cord
  injury.
• An estimated 4,500 persons with spinal cord
  injuries presently in the agricultural
  population.
• Innumerable others (19) with mobility
  restrictions. (e.g. strokes, arthritis,
  amputations, back injuries, and others)

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Background (cont.)

• Assistive technology allows them to return to
  work
• motor vehicles
• agricultural equipment
• agricultural workplaces

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Background (cont.)

• Many will, however, return to work without the
  appropriate technology

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Background (cont.)
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Background (cont.)
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Background (cont.)
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Background (cont.)
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Background (cont.)
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Background (cont.)
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Background (cont.)
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Background (cont.)
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Background (cont.)

• Purdue Universitys Breaking New Ground Resource
  Center has taken a leadership role in assisting
  farmers and ranchers with disabilities continue
  farming safely.

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Background (cont.)
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Background (cont.)
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Background (cont.)
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Background (cont.)
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Purpose

• To develop and administer a systems approach for
  evaluating ergonomic and safety issues related to
  the application of commercially available
  operator lifts used on agricultural and other
  off-road machinery to provide a means for
  operators with restricted mobility to gain access
  to the operators station.

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Objective 1

• Develop and administer a standardized approach to
  conduct 11 on-site visits to collect
  observational and interview data from individuals
  who currently own and use both locally made and
  commercially available operator lifts to access
  and operate their agricultural equipment.

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Objective 2

• Conduct a formal ergonomic analysis, with an
  emphasis on safety and usability, of two
  configurations of commercially available
  LifeEssentials operator lifts designed for
  accessing agricultural equipment.

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Objective 3

• Develop a standardized user survey instrument for
  obtaining user demographics and feedback on
  operator lifts being used on self-propelled
  agricultural equipment and to test the following
  hypotheses
• Ho1 A majority of the lift users have spinal
  cord injuries.
• Ho2 A majority of the lift users have use of
  their upper body.
• Ho3 Owning a lift allows the lift users to
  continue to be productive in an agricultural
  operation.
• Ho4 Commercially manufactured lifts are safer
  than home built models.

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Objective 4

• Validate the analysis strategies and survey
  instrument by utilizing a panel of experts in the
  field of assistive technology to conduct an
  independent ergonomic evaluation of the operator
  lifts.

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Objective 5

• Collect ergonomic and demographic data from
  agricultural operator lift users using the survey
  instrument previously mentioned in Objective 3.

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Related Literature

• Secondary Injury
• Systems Approach
• Machinery Ergonomics in Agriculture
• Related Standards
• Expert Panels
• Lift Design Characteristics

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Secondary Injury

• 17 of farm operators had physical disabilities
  that prevented them from completing essential
  farm tasks.
• Increasing mean age of farm operators has led to
  a higher prevalence of disabling conditions.
• Secondary injury risk is more severe for
  individuals with SCI.

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The Systems Approach

• To ensure completeness in the ergonomic
  evaluation of operator lifts.
• Hagel The whole is more than the sum of its
  parts
• Gestalt psychologists recognized the importance
  of objectiveness or wholeness to human
  perception.

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The Systems Approach (cont.)

• Explosion in use during WW II in Human Factors
• In 1973, Meredith et al. emphasized that the
  systems approach warranted attention and respect
  as a stand alone philosophy, worthy of study,
  separate from the engineering discipline.
• Used by scientists, engineers and agricultural
  safety specialists.

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The Systems Approach (cont.)
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Machinery Ergonomics in Agriculture

• ASAE Publication- Human Factors (1991)
• An Ergonomic Checklist for Tractors and
  Agricultural Machinery. (Hansson, 1991)
• Cab Accessibility How important is it? (Latif
  and Christianson, 1988)
• Safe access to farm tractors and trailers.
  (Hammer, 1991)

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Machinery Ergonomics in Agriculture (cont.)

• Risks in using modified tractors by operators
  with SCI and their co-workers (Willkomm, 1997)
• Assessment of work-related injury risk for
  farmers and ranchers with physical disabilities
  (Allen et al., 1995)

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Related SAE Standards

• SAE J2092 Testing of Wheelchair Lifts for Entry
  to or Exit from a Personally Licensed Vehicle
• SAE J2093 Design Considerations for Wheelchair
  Lifts for Entry and Exit from a Personally
  Licensed Vehicle
• SAE J1725 Structural Modifications for
  Personally Licensed Vehicles to Meet the
  Transportation Needs of Persons with Disabilities
• SAE J185 Access Systems for Off-Road Machines

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Expert Panels
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Lift Design Characteristics
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Methodology

• Objective 1 Observational and Interview
  Analysis
• Objective 2 Initial Ergonomic Analysis by the
  Researcher
• Objective 3 Preliminary Questionnaire
  Development
• Objective 4 Panel of Experts
• Objective 5 Questionnaire Administration

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Observational and Interview Analysis

• Telephone Conversations
• Informal survey
• 11 Site Visits
• Photographs
• Informal survey

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Initial Ergonomic Analysis by the Researcher

• Heuristic Analysis and EMEA conducted on
  LifeEssentials operator lift system.
• Results used for the initial development of the
  lift users questionnaire.

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Heuristic Analysis
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Error Modes and Effects Analysis (EMEA)
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Preliminary Questionnaire Development

• Based on key areas identified from the
  preliminary observations, interviews and
  ergonomic analyses
• Demographics
• Ergonomic Information
• controller usability
• transfers
• Mail

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Panel of Experts

• Four Members
• Mailed Information
• Met for Two Days
• Heuristic Analysis and EMEA
• Validation of Questionnaire

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Findings

• Observational and Interview Analysis
• Ergonomic Analysis by the Researcher
• Questionnaire Development
• Panel of Experts
• Questionnaire Administration

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Panel of ExpertsHeuristic Analysis
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Panel of ExpertsHeuristic Analysis (cont.)
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Panel of ExpertsHeuristic Analysis (cont.)
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Panel of ExpertsHeuristic Analysis (cont.)
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Panel of ExpertsHeuristic Analysis (cont.)
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Panel of ExpertsHeuristic Analysis (cont.)
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Panel of ExpertsHeuristic Analysis (cont.)
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Panel of ExpertsHeuristic Analysis (cont.)
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Panel of ExpertsHeuristic Analysis (cont.)
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Panel of ExpertsHeuristic Analysis (cont.)
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Panel of ExpertsEMEA
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Panel of ExpertsEMEA (cont.)
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Panel of ExpertsEMEA (cont.)
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Panel of ExpertsEMEA (cont.)
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Questionnaire Administration

• Initial mailing sent to 127 potential lift users
• 40 returned due to incomplete or invalid
  addresses
• 60 (69) of the remaining 87 were completed and
  returned
• 4 did not qualify, leaving 56 to analyze

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Questionnaire Administration (cont.)

• Survey Comments

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Questionnaire Administration (cont.)

• Survey Comments (cont.)

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Questionnaire Administration (cont.)

• Survey Comments (cont.)

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Questionnaire Administration (cont.)

• Survey Comments (cont.)

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Questionnaire Administration (cont.)

• Survey Comments (cont.)

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Questionnaire Administration (cont.)

• Survey Comments (cont.)

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Questionnaire Administration (cont.)

• Survey Comments (cont.)

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Conclusions

• Observational and Interview Analysis
• Introduction to users and types of lifts
• Collected user data
• Initiated ideas of problems with lifts
• Aided in the development of the Questionnaire

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Conclusions

• Ergonomic Analysis by Researcher
• Heuristic and EMEA
• Identified additional areas of concern
• Aided in the development of the Questionnaire

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Conclusions

• Panel of Experts
• Heuristic and EMEA
• Identified areas of concern
• Validated analysis strategies
• Validated questionnaire

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Conclusions

• Questionnaire Administration
• H01 75 of the lift users had SCI
• H02 76 of the lift users had full use of arms
• H03 17 could use same machinery before
• H04 Low response by locally fabricated
• 8(16) of 49 commercially manufactured
• 1 (14) of 7 locally fabricated

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Recommendations

• An adaptation of the questionnaire and ergonomic
  analyses used in this study could be used to
  assess other assistive technology devices used in
  the agricultural population.
• A standard aimed at the testing and use of
  operator lifts to access agricultural and other
  off-road equipment by operators with physical
  disabilities should be submitted to the Adaptive
  Standards Committee of the Society of Automotive
  Engineers. An initial draft has been developed
  based on the review of ASAE and SAE standards and
  the findings of this study.

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Recommendations (cont.)

• The information gained from this study should be
  used to justify the safety and applicability of
  operator lifts in agriculture to organizations
  that supply funding for the use of and research
  pertaining to assistive technology.
• Additional studies in the area of secondary
  injuries involving assistive technology should be
  conducted to gain a clearer perspective on the
  issue.