No abstract

The application and development of new technology make it possible to acquire real-time data of vehicles. Based on these real-time data, the behavior of vehicles can be analyzed. The prediction of vehicle behavior provides data support for the fine management of traffic. This paper proposes speed and acceleration have fractal features by R/S analysis of the time series data of speed and acceleration. Based on the characteristic analysis of microscopic parameters, the characteristic indexes of parameters are quantified, the fractal multistep prediction model of microparameters is established, and the BP (back propagation neural networks) model is established to estimate predictable step of fractal prediction model. The fractal multistep prediction model is used to predict speed acceleration in the predictable step. NGSIM trajectory data are used to test the multistep prediction model. The results show that the proposed fractal multistep prediction model can effectively realize the multistep prediction of vehicle speed.

Laser scanning technology can quickly capture a large area of high-precise 3D spatial data, and get the information of buildings, roads, vegetation and other urban objects from raw data. Based on this information general frame of these objects can be modelling. In this paper, an object-based classification method is proposed for urban objects based on LIDAR points: determine the contents of the objects contained in the scene; extract inherent features of different objects; establish objects feature knowledge database; combine and compare objects’ features and distribution of LIDAR points; derive a set of rule to express the point cloud classification which can be received by computer through fuzzy judgement. The method has been applied to LIDAR points by LYNX. The experiment results show that the proposed classification method is promising and usable.

With the development of Mars exploration, NASA has been preparing plans for a crewed mission to Mars in the next few decades. One challenge associated with crewed missions to the Mars is the high ballistic-coefficient and human-class payloads. Because of the high ballistic-coefficient, the maximum limit value of the reference flight path angle is always the reference flight path angle meeting the downrange and altitude for the constant flight path angle algorithm. So this paper presents an improved algorithm which the terminal velocity is controlled by dynamic pressure controller, and the controller is used to modulate the velocity and altitude to meet final constraints. Simulations results of a Mars entry scenario illustrate that the improved algorithm achieves the final constraints within allowable tolerances.