A comprehensive study on Mecanum wheel-based mobility and suspension solutions for intelligent nursing wheelchairs.

Intelligent nursing wheelchairs significantly enhance mobility and independence for elderly individuals with disabilities. However, traditional designs often suffer from large turning radii that restrict their functionality in confined spaces. Addressing this critical challenge, this study introduces an innovative design utilizing a Mecanum wheel chassis that allows for omnidirectional movement, significantly improving maneuverability and stability. Our design incorporates independently controlled Mecanum wheels, overcoming traditional constraints and enhancing user autonomy. To address issues such as wheel spacing variations and hub center tilting, which can lead to slipping and inaccurate motion control, we developed a novel suspension system that stabilizes the chassis, minimizes slipping risks, and boosts motion control accuracy. Experimental validations, including shock absorption and positioning tests, demonstrate that our suspension system markedly enhances the wheelchair's control performance and stability, thereby providing users with enhanced precision and potentially improving their quality of life.

Mathematical modeling of the push-pull effect for various acceleration profiles and countermeasures.

BACKGROUND: The push-pull maneuver (PPM) can lead to loss of consciousness in pilots of high-performance aircraft. Modeling of the physical and physiological aspects of this phenomenon should allow improved countermeasures. METHODS: A structurally based mechanistic computer model was developed to incorporate dynamic carotid baroreflex responses and detailed modeling of vessel segments for different anatomic regions. The model was used to predict the effect of the PPM on cardiovascular responses and the protection afforded by extended coverage anti-G suits (ECGS) and neck pressure. RESULTS: The model was validated by comparing the simulation results with previously published experimental data obtained during centrifuge and tilt-table studies. Simulations of various PPM acceleration profiles indicated that +Gz tolerance was reduced in the presence of higher +Gz levels prior to the push phase, more -Gz levels during the push phase, and prolongation of the push phase. On the other hand, the onset rate for the two phases had only minor effects on +Gz tolerance. Model output suggested that improved protection could be provided by an ECGS with minimal inflation delay and a multilevel pressure schedule in which the leg bladders inflated to a higher pressure than the abdominal bladder. Modeling application of a 100-mmHg neck pressure during the push phase partly inactivated the carotid baroreflex, but induced only a small increase in tolerance. CONCLUSIONS: Mathematical modeling and simulation showed that +Gz tolerance for the PPM might be increased by improving the design and inflation schedule of the ECGS.