Publication Date

2014

Document Type

Thesis

Committee Members

Carolin Cao (Committee Chair), Chandler Phillips (Committee Member), Joseph Slater (Committee Member)

Degree Name

Master of Science in Industrial and Human Factors Engineering (MSIHE)

Abstract

Vibrotactile feedback, used as sensory substitution for loss of haptic feedback, has been utilized to improve performance in manual control, teleoperation and during minimally invasive surgical tasks. Stochastic resonance (SR), introduced into the human control system as white noise at a sub-threshold level, has shown promise to improve the sensitivity of tactile receptors resulting in enhancement of performance for a variety of manual tracking and sensorimotor tasks. The purpose of this study was to determine if SR could improve performance (accuracy, speed) in a simulated laparoscopic palpation task and to compare it to vibrotactile feedback (VIB). It was hypothesized that both VIB and SR feedback would result in better performance over no feedback (Control). Furthermore, SR feedback was expected to lead to the greatest increase in performance by improving subjects' haptic sensitivity to tissue compliance and consistency. A total of 16 subjects (10 female, 6 male) performed a palpation task using laparoscopic tools to detect the presence of tumors (compacted felt) embedded in simulated tissue samples (silicone gel) in a laparoscopic trainer box. Subjects were randomly assigned to one of three different conditions: (1) Control and SR, (2) Control and VIB, (3) Control and VIB+SR and (4) Control and Control. The control condition was performed before the vibration condition to set a baseline for performance as well as to account for carry-over effects related to vibrotactilefeedback and human performance. The vibrotactile feedback and SR vibrations were administered via two different haptic actuators attached to subjects' dominant upper and lower arms, respectively. Each subject was presented 36 tissue samples (24 w/tumor, 12 non-tumor) in random order, under the control condition and then presented the same 36 samples in a different random order under the assigned vibration condition (SR, VIB, VIB+SR, Control), for a total of 72 tissue samples (48 w/tumor, 24 non-tumor). A maximum of 30 seconds was allowed for each trial. The dependent variables of accuracy and time to detection were measured. Results show significant improvement over the control condition in accuracy with the Control-SR group only. A one-way ANOVA was performed on the delta accuracy and delta time values for each subject group and results show that the SR group performed significantly better than the VIB and VIB+SR groups in terms of improved accuracy (See Figure 1). Results for the time variable did not produce any significant effects, suggesting that SR increases accuracy in compliance differentiation, but not in the time needed to make a decision during the process. The results have implications for the design of instruments and potential methods for increasing accuracy performance in minimally invasive surgical procedures such as in the case of tissue compliance differentiation. This technology could help surgeons better identify tumors located in healthy surrounding tissue.

Page Count

101

Department or Program

Department of Biomedical, Industrial & Human Factors Engineering

Year Degree Awarded

2015

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