Based on multiple unmanned aerial vehicles（UAVs） flight at a constant altitude,a fault-tolerant cooperative localization algorithm against global positioning system（GPS） signal loss due to GPS receiver malfunction...Based on multiple unmanned aerial vehicles（UAVs） flight at a constant altitude,a fault-tolerant cooperative localization algorithm against global positioning system（GPS） signal loss due to GPS receiver malfunction is proposed.Contrast to the traditional means with single UAV,the proposed method is based on the use of inter-UAV relative range measurements against GPS signal loss and more suitable for the small-size and low-cost UAV applications.Firstly,for re-localizing an UAV with a malfunction in its GPS receiver,an algorithm which makes use of any other three healthy UAVs in the cooperative flight as the reference points for re-localization is proposed.Secondly,by using the relative ranges from the faulty UAV to the other three UAVs,its horizontal location can be determined after the GPS signal is lost.In order to improve an accuracy of the localization,a Kalman filter is further exploited to provide the estimated location of the UAV with the GPS signal loss.The Kalman filter calculates the variance of observations in terms of horizontal dilution of positioning（HDOP） automatically.Then,during each discrete computing time step,the best reference points are selected adaptively by minimizing the HDOP.Finally,two simulation examples in Matlab/Simulink environment with five UAVs in cooperative flight are shown to evaluate the effectiveness of the proposed method.展开更多
In cooperative localization with sparse communication networks, an agent maybe only receives part of locating messages from the others. It is difficult for the receiver to utilize the part instead of global knowledge....In cooperative localization with sparse communication networks, an agent maybe only receives part of locating messages from the others. It is difficult for the receiver to utilize the part instead of global knowledge. Under the extended Kalman filtering, the utilization of the locating message is maximized by two aspects： the locating message generating and multi-locating messages fusing. For the former, the covariance upper-bound technique, by introducing amplification coefficients, is employed to remove the dependency of locating messages on the global knowledge. For the latter, an optimization model is setup; the covariance matrix determinant of the receiver＇s state estimate, expressed as a function of the amplification coefficients, is selected as the optimization criterion, under linear constraints on the amplification coefficient characteristics and the communication connectivity. Using the optimization solution, the local optimal state of the receiver agent is obtained by the weighting fusion. Simulation with seven agents is shown to evaluate the effectiveness of the proposed algorithm.展开更多
Cooperative path planning is an important area in fixed-wing UAV swarm.However,avoiding multiple timevarying obstacles and avoiding local optimum are two challenges for existing approaches in a dynamic environment.Fir...Cooperative path planning is an important area in fixed-wing UAV swarm.However,avoiding multiple timevarying obstacles and avoiding local optimum are two challenges for existing approaches in a dynamic environment.Firstly,a normalized artificial potential field optimization is proposed by reconstructing a novel function with anisotropy in each dimension,which can make the flight speed of a fixed UAV swarm independent of the repulsive/attractive gain coefficient and avoid trapping into local optimization and local oscillation.Then,taking into account minimum velocity and turning angular velocity of fixed-wing UAV swarm,a strategy of decomposing target vector to avoid moving obstacles and pop-up threats is proposed.Finally,several simulations are carried out to illustrate superiority and effectiveness.展开更多
交替方向乘子法(Alternating Direction Method of Multipliers,ADMM)是将大规模优化问题进行分步求解,有效简化了计算过程,近来被应用到定位问题中。通过引入辅助变量,建立具有光滑目标函数的最小化问题,提出了基于ADMM的传感器网络协...交替方向乘子法(Alternating Direction Method of Multipliers,ADMM)是将大规模优化问题进行分步求解,有效简化了计算过程,近来被应用到定位问题中。通过引入辅助变量,建立具有光滑目标函数的最小化问题,提出了基于ADMM的传感器网络协同定位方法。借助于ADMM双变量交替迭代更新,推导了变量交替求解的代数解析表达式。通过引入近端缩放因子,对ADMM定位算法进行了优化,并从理论上说明了算法的全局收敛性。仿真分析结果表明,所设计的ADMM算法具有良好的全局收敛性能。在所测试的噪声水平内,ADMM算法的估计误差非常接近于克拉美罗下界(Cramer-Rao Lower Bound,CRLB)值。展开更多
稳定高精度的定位是实现地面无人车辆协同自主行驶的先决条件。激光同时定位与建图(Simultaneous Localization and Mapping,SLAM)技术在缺少几何特征的走廊、隧道、沙漠等场景中难以实现精准定位。为此提出一种无人车蛙跳协同的激光SLA...稳定高精度的定位是实现地面无人车辆协同自主行驶的先决条件。激光同时定位与建图(Simultaneous Localization and Mapping,SLAM)技术在缺少几何特征的走廊、隧道、沙漠等场景中难以实现精准定位。为此提出一种无人车蛙跳协同的激光SLAM退化校正方法。估计当前帧每个特征点的法向量,并提出一种激光SLAM退化检测算法,当检测到环境退化时,使用两个无人车之间的测距信息对激光SLAM进行退化校正,在位姿图中进一步优化定位结果,并在自主搭建的两个无人车平台上进行测试。研究结果表明,新方法与当前主流激光SLAM方法相比获得了更高的建图效果,证明了新方法能够显著提高激光SLAM在退化场景中的定位效果。展开更多
基金supported by the National Natural Science Foundation of China(60974146)the Natural Science and Engineering Research Council of Canada(NSERC)
文摘Based on multiple unmanned aerial vehicles（UAVs） flight at a constant altitude,a fault-tolerant cooperative localization algorithm against global positioning system（GPS） signal loss due to GPS receiver malfunction is proposed.Contrast to the traditional means with single UAV,the proposed method is based on the use of inter-UAV relative range measurements against GPS signal loss and more suitable for the small-size and low-cost UAV applications.Firstly,for re-localizing an UAV with a malfunction in its GPS receiver,an algorithm which makes use of any other three healthy UAVs in the cooperative flight as the reference points for re-localization is proposed.Secondly,by using the relative ranges from the faulty UAV to the other three UAVs,its horizontal location can be determined after the GPS signal is lost.In order to improve an accuracy of the localization,a Kalman filter is further exploited to provide the estimated location of the UAV with the GPS signal loss.The Kalman filter calculates the variance of observations in terms of horizontal dilution of positioning（HDOP） automatically.Then,during each discrete computing time step,the best reference points are selected adaptively by minimizing the HDOP.Finally,two simulation examples in Matlab/Simulink environment with five UAVs in cooperative flight are shown to evaluate the effectiveness of the proposed method.
基金supported by the National Natural Science Foundation of China(61273357)
文摘In cooperative localization with sparse communication networks, an agent maybe only receives part of locating messages from the others. It is difficult for the receiver to utilize the part instead of global knowledge. Under the extended Kalman filtering, the utilization of the locating message is maximized by two aspects： the locating message generating and multi-locating messages fusing. For the former, the covariance upper-bound technique, by introducing amplification coefficients, is employed to remove the dependency of locating messages on the global knowledge. For the latter, an optimization model is setup; the covariance matrix determinant of the receiver＇s state estimate, expressed as a function of the amplification coefficients, is selected as the optimization criterion, under linear constraints on the amplification coefficient characteristics and the communication connectivity. Using the optimization solution, the local optimal state of the receiver agent is obtained by the weighting fusion. Simulation with seven agents is shown to evaluate the effectiveness of the proposed algorithm.
基金Supported by National High Technology Research and Development Program of China （863 Program） （2007AA809502C） National Natural Science Foundation of China （50979093） Program for New Century Excellent Talents in University （NCET-06-0877）
文摘Cooperative path planning is an important area in fixed-wing UAV swarm.However,avoiding multiple timevarying obstacles and avoiding local optimum are two challenges for existing approaches in a dynamic environment.Firstly,a normalized artificial potential field optimization is proposed by reconstructing a novel function with anisotropy in each dimension,which can make the flight speed of a fixed UAV swarm independent of the repulsive/attractive gain coefficient and avoid trapping into local optimization and local oscillation.Then,taking into account minimum velocity and turning angular velocity of fixed-wing UAV swarm,a strategy of decomposing target vector to avoid moving obstacles and pop-up threats is proposed.Finally,several simulations are carried out to illustrate superiority and effectiveness.
文摘交替方向乘子法(Alternating Direction Method of Multipliers,ADMM)是将大规模优化问题进行分步求解,有效简化了计算过程,近来被应用到定位问题中。通过引入辅助变量,建立具有光滑目标函数的最小化问题,提出了基于ADMM的传感器网络协同定位方法。借助于ADMM双变量交替迭代更新,推导了变量交替求解的代数解析表达式。通过引入近端缩放因子,对ADMM定位算法进行了优化,并从理论上说明了算法的全局收敛性。仿真分析结果表明,所设计的ADMM算法具有良好的全局收敛性能。在所测试的噪声水平内,ADMM算法的估计误差非常接近于克拉美罗下界(Cramer-Rao Lower Bound,CRLB)值。
文摘稳定高精度的定位是实现地面无人车辆协同自主行驶的先决条件。激光同时定位与建图(Simultaneous Localization and Mapping,SLAM)技术在缺少几何特征的走廊、隧道、沙漠等场景中难以实现精准定位。为此提出一种无人车蛙跳协同的激光SLAM退化校正方法。估计当前帧每个特征点的法向量,并提出一种激光SLAM退化检测算法,当检测到环境退化时,使用两个无人车之间的测距信息对激光SLAM进行退化校正,在位姿图中进一步优化定位结果,并在自主搭建的两个无人车平台上进行测试。研究结果表明,新方法与当前主流激光SLAM方法相比获得了更高的建图效果,证明了新方法能够显著提高激光SLAM在退化场景中的定位效果。
