| Author: | Chow, Sin Wei Cathy |
| Title: | Design and development of a non-powered exoskeleton device to cater to the physical needs of puppeteers |
| Advisors: | Shin, Kristina (SFT) So, Chun Lung Billy (RS) |
| Degree: | Ph.D. |
| Year: | 2022 |
| Subject: | Puppeteers Costume Costume design Robotic exoskeletons Hong Kong Polytechnic University -- Dissertations |
| Department: | School of Fashion and Textiles |
| Pages: | xiv, 181 pages : color illustrations |
| Language: | English |
| Abstract: | Puppeteers require an ergonomically designed load carrier system to carry heavy loads with minimal muscular stress during dynamic performances that involve giant puppets. They would benefit from an exoskeleton with appropriate ergonomics and power augmentation that would more easily facilitate mobility and balancing of the body with less muscle activity output. This is the primary goal of this study through which a prototype is designed with reference to experimental and numerical analyses. To achieve this goal, a load carrier named the Passive Wheeled Puppet-operating Exoskeleton (PuppetX) is designed. The system includes two small wheels attached to the footwear and a hybrid spring device on the knees to facilitate sliding and knee-bending movements, respectively. To evaluate the effectiveness of the load carrier, two other commercially available load mounting systems—Tepex and SuitX—are selected as the benchmarks for system evaluation. Ten professional male puppeteers are recruited to participate in a wear trial, in which bouncing and overground walking, and common puppeteering tasks, are evaluated. The surface electromyography (sEMG) signals of five bilateral muscles—the lumbar erector spinae (LES), rectus femoris (RF), biceps femoris (BF), tibialis anterior (TA), and medial gastrocnemius (MG)—are collected and used to analyse the muscle utilisation patterns, while the kinematics of the trunk angles, hips, and knee joints are measured by using inertial measurement units (IMUs) for body motion analyses. Different loading conditions (with and without external loads of 11.1 kg) are tested for all three exoskeleton systems. Subjective measurements of the experiences of the users with the three systems are also assessed by using the NASA Task Load Index (TLX) questionnaire and user estimations of affordable performance time. The evaluation results show that during bouncing, the mean peak sEMG values of PuppetX are significantly lower in the left BF (L_BF; p = .005), right TA (R_TA; p = .044), and right MG (R_MG; p = .013) than those of SuitX, with reductions of 46.0%, 69.7% and 53.5%, respectively, thus suggesting that PuppetX can efficiently transfer the overhead external load to the ground through the leg structure. The feet and ankles of PuppetX users no longer bear all the weight. Less muscle activity of the shank muscles is hence required to maintain body balance and perform dorsiflexion movement during bouncing. However, more muscle activity is required in the gait trials with PuppetX. Significantly higher sEMG values are observed in both sides of the RF (93 - 160% higher), R_TA (60 - 64% higher), and left MG (L_MG; 36.3% higher) when compared to Tepex and SuitX. Due to the wheels attached to the footwear, PuppetX users adopt a sliding strategy during gait. Greater balancing skills might be required to maintain body balance during locomotion, especially under more unstable conditions with heavy overhead loads. Despite the increased muscle activation in the gait trials, the subjective ratings of PuppetX are satisfactory. The estimated affordable performance time of PuppetX (mean = 29.4 mins) is significantly higher than that of SuitX (mean = 18.1 mins, p =.001) and Tepex (mean = 20.8 mins, p = .019). The total weighted workload (WWL) scores of PuppetX (mean = 42.07, SD = 15.81) from the NASA-TLX questionnaire do not differ significantly from those of Tepex (mean = 35.30, SD = 13.67), and are significantly lower (p = .049) than those of SuitX (mean = 53.63, SD = 17.53), thus indicating less workload demand. The NASA-TLX findings also show that physical demand is the primary concern of the participants when using the exoskeletons to perform puppeteering tasks, followed by effort and mental demands. Moreover, the estimated affordable performance time of PuppetX is found to be negatively correlated to the physical demand WWL (r = -.777, p =.008), which suggests that lowering the physical demand would result in a longer affordable performance time. Improving the mechanism of this design feature might help to reduce the WWL demand. To the best of my knowledge, this newly developed prototype is the first to incorporate skating wheels and a spring and flexible beam hybrid system for enhanced exoskeletal mobility and knee power augmentation, respectively. PuppetX contributes to the extant operation on exoskeletons by serving as a model sample to assist puppet operators, specifically those who carry oversized puppets, in overcoming load carriage difficulties. The findings of this study will enable the use of PuppetX as a feasible and effective device for puppeteers in operating large puppets. This approach can benefit operators by minimising their physical output and thus helping them to enhance the quality of their performance both physically and psychologically. These improvements may also facilitate the development of large-scale creations of greater and more spectacular visual proportions. Fewer injury-related issues might be realized for puppeteers, thus reducing compensation budgets and facilitating a caring culture. An appropriate prototype could be further customised and built as a valid reference model for designers in future applications. |
| Rights: | All rights reserved |
| Access: | open access |
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