ABSTRACT
Origami can enable structures that are compact and lightweight. The facets of an origami structure in traditional designs, however, are essentially nondeformable rigid plates. Therefore, implementing energy storage and robust self-locking in these structures can be challenging. We note that the intricately folded wings of a ladybird beetle can be deployed rapidly and effectively sustain aerodynamic forces during flight; these abilities originate from the geometry and deformation of a specialized vein in the wing of this insect. We report compliant origami inspired by the wing vein in ladybird beetles. The deformation and geometry of the compliant facet enables both large energy storage and self-locking in a single origami joint. On the basis of our compliant origami, we developed a deployable glider module for a multimodal robot. The glider module is compactly foldable, is rapidly deployable, and can effectively sustain aerodynamic forces. We also apply our compliant origami to enhance the energy storage capacity of the jumping mechanism in a jumping robot.
ABSTRACT
OBJECTIVE: This study aimed to determine the effect of walking speed on the electromyographic (EMG) activity of the rectus abdominis (RA) and erector spinae (ES) muscles during treadmill high-heeled walking at different shoe heel heights. METHODS: Twenty-five young healthy women volunteered to participate in this study. The subjects performed treadmill walking at speeds of 3 km/h and 6 km/h for 30 seconds under 3 high-heeled conditions: barefoot, 3-cm heels, and 7-cm heels. Surface electromyography (EMG) data were collected from standard sites on the RA and ES muscles during treadmill walking. RESULTS: For all heel heights, the EMG activity of the RA and ES muscles was significantly higher at the 6 km/h speed than at the 3 km/h speed (p < 0.05). Furthermore, EMG activity increased significantly with increasing shoe heel height, regardless of the walking speed (p < 0.05). CONCLUSION: These findings indicate that walking speed and shoe heel height may contribute to the increased activity of the trunk muscle during high-heeled walking. This study provides information for future studies performed with the aim of predicting possible changes in trunk muscle activity during high-heeled walking.