Although the mechanisms of steady-state visual evoked potentials (SSVEPs) have been well studied, none of them have been implemented with strictly experimental conditions. Our objective was to create an ideal observer condition to exploit the features of SSVEPs. We present here an electroencephalographic (EEG) eye tracking experimental paradigm that provides biofeedback for gaze restriction during the visual stimulation. Specifically, we designed an EEG eye tracking synchronous data recording system for successful trial selection. Forty-six periodic flickers within a visual field of 11.5° were successively presented to evoke SSVEP responses, and online biofeedback based on an eye tracker was provided for gaze restriction. For eight participants, SSVEP responses in the visual field and topographic maps from full-brain EEG were plotted and analyzed. The experimental results indicated that the optimal visual flicking arrangement to boost SSVEPs should include the features of circular stimuli within a 4–6° spatial distance and increased stimulus area below the fixation point. These findings provide a basis for determining stimulus parameters for neural engineering studies, e.g. SSVEP-based brain-computer interface (BCI) designs. The proposed experimental paradigm could also provide a precise framework for future SSVEP-related studies.

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The trajectory planning and obstacle avoidance of serial robot is an important area of research and efficient optimization algorithms are needed. This article proposes an intermediate point obstacle avoidance algorithm to ensure smooth trajectory and efficient movement during the obstacle avoidance process. Using the intermediate point obstacle avoidance algorithm, the robotic arm can steer obstacle around with the minimum joint space variations and the shortest end motion trajectory. We also design a novel collision detection strategy and fitness evaluation function based on genetic algorithm to optimize the intermediate point parameters. In order to evaluate the performance of the intermediate point obstacle avoidance algorithm, we have conducted three typical experiments: single obstacle, multiple obstacles, and no obstacle. The experimental results demonstrate that the proposed method can not only effectively realize the obstacle avoidance, but also efficiently improve the movement performance of the robotic arm.

Vector represents a major category of data managed by GIS, which is traditionally used for representing geographic entities such as political borders, roads, rivers and cadastral information. In this paper we present a key data structure and associated render-time algorithm for the combined display of multi-resolution 3D terrain and traditional GIS vector data, which is designed to create fully 3D scenes that deliver the best possible quality and do not require dynamic texture generation and handling. The algorithm allows the system to adapt the visual mapping to the context and user needs, and enables users to interactively modify vector through the visual representation, which represents a basic mechanism for 3D GIS interface and facilitates the development of visual analysis and exploration tools.

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