In this work, we propose an assistive navigation system for visually impaired people (ANSVIP) that takes advantage of ARCore to acquire robust computer vision-based localization. To complete the system, we propose adaptive artificial potential field (AAPF) path planning that considers both efficiency and safety. We also propose a dual-channel human–machine interaction mechanism, which delivers accurate and continuous directional micro-instruction via a haptic interface and macro-long-term planning and situational awareness via audio. Our system user-centrically incorporates haptic interfaces to provide fluent and continuous guidance superior to the conventional turn-by-turn audio-guiding method; moreover, the continuous guidance makes the path under complete control in avoiding obstacles and risky places. The system prototype is implemented with full functionality. Unit tests and simulations are conducted to evaluate the localization, path planning, and human–machine interactions, and the results show that the proposed solutions are superior to those of the present state-of-the-art solutions. Finally, integrated tests are carried out with low-vision and blind subjects to verify the proposed system.
The polymeric foamed composites were developed from the biodegradable poly(butylene succinate) (PBS) reinforced by the biomass-based cellulose nanocrystals (CNC) via the melt-compounding treatment. As the highly-crystalline and rigid nanoparticles, the presence of CNC in the polyester matrix can simultaneously enhance the flexural strength and flexural modulus of the foamed composites. With the addition of 5 wt% CNC, the flexural strength and modulus of the PBS foamed composite increased by 50 and 62.9 % in comparison with those of the neat foamed material. Furthermore, the introduction of the CNC significantly affected the cells morphology, structure and stability during the foaming process, which facilitated the increase of the cell density and the homogeneous cell size and distribution of the foamed composites. With the addition of 5 wt% azodicarbonamide as the chemical blowing agent and 5 wt% CNC as the bionanofillers, the foamed composite showed the increased cell density of 7.1 9 10 5 cell/ cm 3 , which was 69.1 % higher than that of the neat foamed material. The mechanical enhancement of the foamed composites was attributed to the nanoreinforcement of the CNC served as the stress transferring phase, and meanwhile the promising improvement on the cells structure and stability for the foamed composites was ascribed to the effect of the CNC acted as the nucleation component.
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