Browsing by Author "Dr. Nelson Couch, Committee Member"

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The Effect of Driver Cognitive Abilities and Distraction on Situation Awareness and Performance under Hazard Conditions
(2008-06-27) Jin, Sangeun; Dr. David Kaber, Committee Chair; Dr. Gary Mirka, Committee Member; Dr. David Dickey, Committee Member; Dr. Nelson Couch, Committee Member
Effect of personality type on performance of an overhead task
(2003-05-21) Sudhakaran, Sunil; Dr. Gary Mirka, Committee Chair; Dr. Nelson Couch, Committee Member; Dr. Hester Lipscomb, Committee Member
Individual factors are becoming increasingly more prevalent in studies that explore occupational musculoskeletal injury/illness. Empirical and theoretical evidence supports further research into the role of individual differences in psychosocial attributes in the occupational exposure, especially the injury outcome process and potential mechanisms that may be at work. The goal of the current work was to understand whether certain individuals may place themselves at risk by taking infrequent breaks (i.e. working through pain or fatigue) if they are given the freedom to decide the work pace and work-rest schedule. The hypothesis is that individuals with certain personality characteristics like type A maybe at higher risk due to their choice of less frequent breaks and a fast paced approach to work just to get the job done as compared to type B personality. This hypothesis is based on the inherent time-urgency characteristic of type A individuals. Sixteen subjects (8 of each personality type) were asked to perform a 40 cycle overhead assembly work involving running nuts onto bolts located on an overhead board. The whole 40 cycle session was self paced and subjects had the freedom to take as many breaks as they wanted and these breaks could be as long as they wanted. The results showed that there was no significant effect of personality type on the task performance variables- total cycle time, total break time, average break time, average cycle time, # of breaks, average pain scale and average pain scale at breaks. These results were not consistent with the theory which supported the fast working of type As based on their time-urgency characteristic. Although no previous studies have looked at an overhead assembly task, the results of this study were consistent with other recent studies in our laboratory showing no performance effects of personality type on simple, unchallenging tasks.
Effects of Time of Day and Warm-Up on Lifting Kinematics
(2007-06-13) McClure, Leigh R; Dr. Gary Mirka, Committee Chair; Dr. Sharon Joines, Committee Member; Dr. Nelson Couch, Committee Member
There is a real need to be able to understand the etiology of back injury. One area that has had only limited research is that of time of day effects. Previous studies have measured both the static (Adams et al., 1987) and dynamic (Fathallah et al., 1995) effects time of day has on the low back. These studies, however, measured maximum capabilities and did not relate their results to real world applications. The objective of the current study is to explore the effects that time of day and warm-up have on trunk kinematics during an industry inspired lifting task. Nine male and three female subjects participated in the study. A series of four separate experimental sessions, two AM sessions held one hour after rising and two PM sessions held nine hours after rising, were performed. During one AM and one PM session the subject was led through a series of physical warm-up exercises prior to performing the lifting exertions. Upon conclusion of the warm-up, subjects completed a lifting task with two separate weight conditions, 3.6 kg and 10.9 kg. The lifting task consisted of lifting a box from the floor, rotating approximately 130°, and placing the load on an adjacent conveyer. Twenty consecutive lifts were completed for each load condition. The independent variables were SESSION (AM and PM), WARM-UP, and LOAD (low-3.6 kg and high-10.9 kg). The dependent variables considered in this study were peak trunk range of motion and peak trunk velocity in the sagittal and rotational planes, and the (x,y) coordinate positions of each knee in the anterior/posterior and lateral directions at the peak trunk position. The experiment was of a split plot design and used MANOVA and subsequent univariate ANOVA to test for statistical significance. LOAD was the only independent variable that proved statistically significant, and was significant for trunk sagittal position, trunk sagittal velocity, and lateral knee position. Trunk sagittal position increased from 75 (±0.48)° to 78 (±0.50)° for the low and high conditions, respectively. Trunk sagittal velocity on the other hand decreased from the low (140 (±0.87)°/s) to the high (130 (±0.92)°/s) condition. Neither SESSION nor WARM-UP were found to affect these kinematics variables. The lack of statistical significance could have occurred for several reasons. The current study chose to measure range of motion (ROM) while doing an industry inspired lifting task. In order to complete the task subjects were not necessarily required to use a full range of motion. Instead, they used only the range of motion needed to accomplish the task. Results showed that SESSION had little effect on this ROM. Subjects were also allowed to complete the lifting task in any way they chose, which introduced inter-subject variability to the experiment because no two subjects used the same lifting technique. Overall intra-subject lifting strategies did not change with regard to SESSION or level of muscle WARM-UP.
Learning Curve Analysis of a Patient Lift Assist Device
(2006-02-07) Reid, Stephanie; Dr. Nelson Couch, Committee Member; Dr. Hester Lipscomb, Committee Member; Dr Gary A Mirka, Committee Chair
The prevalence of musculoskeletal disorders (MSDs) among health care workers is extremely high. In response to high injury rates associated with the patient transfer tasks, one of the most physically demanding tasks in the health care industry, ergonomic interventions have been developed. These ergonomic interventions were created to lessen the risk of MSDs development by reducing the load required of the worker, however workers often complain of the added task time that using the interventions introduce. It has been shown that an increased number of replications of a task will yield an increased proficiency in the task, and that this increased productivity follows a response called a learning curve. The use of learning curve theory has not been applied to the introduction of ergonomic interventions in the workplace. The objectives of the current study were to explore the possible application of learning curve theory in the process of introducing ergonomic interventions, and to evaluate the impact of training technique (passive training vs. active training) on variables describing the learning process. Eighteen subjects completed multiple replications of a patient transfer task after being trained in either an active or passive training method. The patient transfer task was completed with an ergonomic intervention, a mechanical patient lift assist device ('Opera' model manufactured by Arjo). The active training method took a hands-on approach to the training, while the passive method was similar to the see-one-do-one method currently prevalent in the health care industry. The task time-to-complete values were recorded for each repetition, and the dependent variable values were calculated for each subject. The dependent variable Learning Rate, a standard measure of the decrease in task performance as a function of task repetition, was 85.2% for the hands-on training and was 81.1% for the see-one-do-one training (this difference was not found to be statistically significant). However, the dependent variable Trial 0, the time-to-complete values for the first time the subject completed the patient handling task, was found to be significant (p<0.05). The average time-to-complete value for the hands-on method was 370 seconds while the average for the see-one-do-one method was 475 seconds. The dependent variable 'Delta 3' was also found to be significant. This measure quantifies the decrease in time-to-complete values for the across the first four trials. The Delta 3 values for the hands-on method was 82 seconds while the see-one-do-one method was 170 seconds, indicating a rapid 'merging' of performance in the two training methods. The study successfully applied learning curve theory to the introduction of an ergonomic intervention, and illustrated the dominance of an active training method when training workers to use the intervention (particularly in the early stages of learning to use the device). The results emphasize the importance in considering learning curves when workers are learning to use new equipment, especially ergonomic interventions that can prevent MSDs from occurring. The results also show that the method of training given to workers can impact the initial performance of a task.
System Level Airworthiness Tool: A Comprehensive Approach to Small Unmanned Aircraft System Airworthiness.
(2010-04-30) Burke, David Alexander; Dr. Nelson Couch, Committee Member; Dr. Stephen Cook, Committee Member; Dr. Paul Ro, Committee Member; Dr. Ashok Gopalarathnam, Committee Member; Dr. Charles E. Hall Jr., Committee Chair
One of the pillars of aviation safety is assuring sound engineering practices through airworthiness certification. As Unmanned Aircraft Systems (UAS) grow in popularity, the need for airworthiness standards and verification methods tailored for UAS becomes critical. While airworthiness practices for large UAS may be similar to manned aircraft, it is clear that small UAS require a paradigm shift from the airworthiness practices of manned aircraft. Although small in comparison to manned aircraft these aircraft are not merely remote controlled toys. Small UAS may be complex aircraft flying in the National Airspace System (NAS) over populated areas for extended durations and beyond line of sight of the operators. A comprehensive systems engineering framework for certifying small UAS at the system level is needed. This work presents a point based tool that evaluates small UAS by rewarding good engineering practices in design, analysis, and testing. The airworthiness requirements scale with vehicle size and operational area, while allowing flexibility for new technologies and unique configurations.
Visual Posture Observation Error and Training
(2003-06-04) Covalla, Elizabeth Danielle; Dr. Gary A. Mirka, Committee Chair; Dr. Nelson Couch, Committee Member; Dr. Carolyn M. Sommerich, Committee Member
The purpose of this study was to determine people's ability to visually estimate postural angles of the shoulder, trunk, and wrist. One application of these findings is to determine the effect of estimation error on common risk analysis tools that incorporate posture. Considerations are given to the effect of training, video mode, gender, body region, and subject characteristics on estimation error. Absolute error, algebraic error, and subject confidence are used to characterize visual estimation abilities. Results indicate that visual estimation error ranges between 7 and 10 degrees. Error further increased with wrist postures and female observers. Due to estimation errors, analysis tools that include posture are less accurate in predicting risk of injury. Eight, 12, and 14 percent of shoulder, trunk, and wrist postures, respectively, were misclassified causing Rapid Upper Limb Assessment (RULA) scores to shift by at least one point. For the Strain Index, forty percent of wrist postures were misclassified by participants causing as much as a two-thirds change in the final score.