Published papers

© 2018, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved. Camera-mounted quadrotor is currently being utilized as teleoperation robot for search and rescue purposes. However, controlling a quadrotor with proportional R/Cs in remote is not intuitive. Thus, combination with Head Mount Display (HMD) is proposed to increase the ease of maneuverability and sense of immersion. However, it has been reported that the video that contains vibration may induce virtual reality (VR) sickness. Particularly, a quadrotor can largely be disturbed by the wind causing the video to oscillate. Our experiment implies that the large amplitude of vibration and low frequency may have effect on inducing VR sickness. This study investigates the effect of a certain frequency of vibration to VR sickness, and proposes the attitude control of a quadrotor to avoid such movement which may induce sickness.

© 2019 JSME. A vibration-isolating bed for ambulances using an inerter is proposed. The structure of the bed is assumed to consist of a bottom frame fixed to the ambulance floor and an upper frame on which the stretcher is placed. Both are connected only by the suspension, including the inerter, in the vertical and horizontal directions. Because the inerter can reduce the gain of the high frequency band and delay the response, the time when maximum acceleration is applied to bed can be shortened by passively in a limited space in ambulance. We consider the bed as a plant and the suspension as a controller, and then formulate the state equation. To reduce the acceleration within the movable range of the bed, the controller that minimizes the H∞ norm of the transfer function from the external force acting on the bed to acceleration is calculated by bilinear matrix inequality. The transfer function determines the structure and coefficient of the suspension. The usefulness of the bed is verified by numerical simulations.

© 2020 Zeidan et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Background Hallux valgus is the most common forefoot deformity and affects the transverse arch structure and its force loading patterns. This study aims to clarify the differences in the transverse arch structure and the force under the metatarsal heads individually, between normal feet and hallux valgus feet, and between hallux valgus feet with pain and without pain. We further test the association between the parameters of the transverse arch and hallux valgus angle and between the parameters and pain in hallux valgus. Methods Women's feet (105 feet) were divided into normal group (NORM) and hallux valgus group (HVG); and further into subgroups: hallux valgus without pain (HV Pain (-)) and hallux valgus with pain (HV Pain (+)). Transverse arch height and metatarsal heads height were measured using weight-bearing ultrasound imaging. Force under the metatarsal heads was measured using force sensors attached directly on the skin surface of the metatarsal heads. The measurements were taken in three loading positions: sitting, quiet standing and 90% weight shift on the tested foot. Differences between the groups were compared using Student t-test and Wilcoxon Exact test. Multivariate logistic analysis with adjustment for physical characteristics was also conducted. Results Transverse arch height was significantly higher in HVG than in NORM in all positions; there were no significant differences between HV Pain (+) and HV pain (-). Lateral sesamoid wassignificantly higher in HVG and HV Pain (+) than in NORM and HV Pain (-) respectively when bearing 90% of the body weight unilaterally. There was a trend of higher forces under the medial forefoot without significant difference. Transverse arch height and lateral sesamoid height were associated with the hallux valgus angle, while lateral sesamoid height was associated with forefoot pain in hallux valgus deformity. Conclusions This study shows the differences in the transverse arch structure between normal feet and feet with hallux valgus, and between hallux valgus feet with and without pain. This finding is noteworthy when considering future treatments of painful feet, notably the height of the lateral sesamoid which seems to play a role in forefoot pain.

CASE: A 77-year-old woman with knee osteoarthritis (OA) complained of right (ipsilateral) knee pain for more than 5 years with gait asymmetry. The OA and quadriceps muscle weakness were more severe in the left (contralateral) knee, but she had no pain. Bracing of the left knee led to decreased gait asymmetry, as determined with an inertial measurement unit, and reduced pain in the right knee. CONCLUSION: This case highlights the contralateral knee effect on ipsilateral chronic knee pain, possibly through gait asymmetry. These findings provide a mechanistic insight into knee OA-related pain in patients with gait asymmetry and suggest a new rehabilitative approach.