针对小型机载光电平台无法准确获取视轴指向问题, 设计了一种基于激光测距的目标定位算法。利用机载光电侦察平台锁定跟踪目标的特性, 对同一目标多次测量, 采用激光测距装置获取目标与载机间的距离信息。根据WGS-84定义的地球椭球模型建立系统的测量方程。考虑到测量方程的非线性, 利用扩展卡尔曼滤波对目标位置进行估计。该定位方法精度只受到GPS接收机定位精度和激光测距机测量精度的影响, 目标定位误差与机载光电侦察设备视轴指向测量无关。采用蒙特卡洛法仿真分析载机位置测量误差及激光测距系统位置误差对目标定位的影响, 结果显示该算法定位精度较高。采用飞行试验数据验证了该目标定位算法的有效性, 在飞行高度8 000 m时, 目标定位精度优于8 m。相比于传统定位算法, 该方法可将定位精度明显提高。同时此定位方法易于部署, 可操作性强, 具有较大的应用价值。

As the line of sight (LOS) measurement cannot be obtained accurately for a small-scale, airborne, electro-optical imaging system, a laser range finder (LRF) is proposed based on a target geolocation algorithm. According to target locking and tracking characteristics of an airborne photoelectric detection platform, the same target is measured repeatedly. The distance between the airborne electro-optical imaging system and target is measured by the LRF. Considering the ellipsoidal earth model and global digital elevation model, which is defined by the World Geodetic System 1984, a system measurement equation has been established. Owing to the nonlinearity of the measurement equation, an extended Kalman filter is applied to the target geographical position estimation. The geolocation calculation accuracy is primarily affected by the measurement errors of the GPS and LRF and is independent of the LOS measurement error. The influence of the aircraft position measurement and distance measurement errors on the target geolocation calculation accuracy is analyzed using Monte Carlo method. The simulation result demonstrates that the proposed algorithm has high target geolocation accuracy. The validity of the geolocation algorithm is verified by the flight test in which the plane flies at altitude of 8 000 m for photographing the target and the root mean square error of the target geolocation is less than 8 m. When compared with the traditional algorithm, the target geolocation accuracy is improved by four times using our proposed algorithm. Further, this algorithm is easy to deploy and has strong operability and great practical value.