自适应红外隐身系统的背景投影建模

实现目标自适应红外隐身的第一步是获取遮挡背景图像,这部分图像是观察者处于某一视点观察目标时,被目标所遮挡住的背景。而当观察者在不同的视点观察目标时,被目标所遮挡住的背景是不同的,目标与遮挡背景满足透视投影的关系。为求得目标与遮挡背景的关系,首先建立了三套坐标系,即目标本体坐标系、视点坐标系以及热像仪坐标系,然后通过推导三套坐标系之间的转换关系,建立了目标表面各点与热像仪获取背景图像点之间的对应模型,从而实现了遮挡背景的获取。最后通过实验对该模型进行了验证,结果表明:该模型能够正确获取不同视点下的遮挡背景,为工程应用奠定了基础。

一种改进的基于直方图反向投影的目标跟踪方法

用直方图反向投影法跟踪目标,其可靠性的一个必要条件是:目标的色度带宽较窄而背景区域的带宽较宽,这降低了其实际应用价值。因此本文中做出了以下改进:首先,对图像做预处理,增强颜色对比度,并且用局部背景代替全部背景做目标跟踪;其次,用三维联合直方图和核密度联合直方图作为目标特征,对颜色特征加以空间位置权重,以突出目标颜色而抑制背景颜色;再次,跟踪过程中对概率密度图加以合理更新,以适应环境光线、旋转、缩放时的鲁棒性。

Nonlinear Modeling of a High Precision Servo Injection Molding Machine Including Novel Molding Approach

A nonlinear mathematical model of the injection molding process for electrohydraulic servo injection molding machine (IMM) is developed.It was found necessary to consider the characteristics of asymmetric cylinder for electrohydraulic servo IMM.The model is based on the dynamics of the machine including servo valve,asymmetric cylinder and screw,and the non-Newtonian flow behavior of polymer melt in injection molding is also considered.The performance of the model was evaluated based on novel approach of molding - injection and compress molding,and the results of simulation and experimental data demonstrate the effectiveness of the model.