SINS/GPS组合导航的半实物仿真实验系统设计

采用实时分布网络组建SINS／GPS组合导航的全弹道半实物仿真实验系统；研制了一种主从式紧耦合双处理器结构的导航计算机，以数字信号处理器作导航算法处理机，以单片微控制器作输入输出接口处理机，二者以互中断高速并行接口相联，软件采用主从流水线协议，双机协同流畅，处理速度快，满足了组合导航系统对导航计算机在数据吞吐和处理能力以及体积、重量、功耗诸方面的要求；由于三轴转台只能模拟三个角运动而不能模拟三个线运动，故通过外部的线运动补偿来完成完整的导航计算。     

高旋弹卫星导航接收机半实物仿真

半实物仿真是测试卫星导航接收机在高旋外弹道环境条件下工作性能的有效手段。为测试卫星导航接收机在高旋外弹道环境条件下的性能,阐述了二维弹道修正引信实现弹道修正的工作原理和北斗卫星导航接收机的基本工作原理;建立了高旋7自由度弹道模型;设计了半实物仿真系统,编写了仿真模型,并在RT-LAB实时仿真平台上运行;分别在非旋转条件和旋转条件下对卫星导航接收机进行了半实物仿真测试,仿真测试结果显示仿真机数据与弹上机转换后数据曲线重合。实验表明：半实物仿真系统可有效检验高旋炮弹卫星导航接收机功能和准确度。     

野外自主车陆地组合导航系统研究

在分析了各种导航系统特点的基础上，本文提出了一种新的组合导航系统－由陆地惯性系统和全球定位系统构成的陆地组合导航系统，在建立组合导航系统数学模型的基础上详细讨论了组合滤波器设计，系统校正方式等设计问题，分析了系统非线性和斜坡等对导航系统性能的影响。     

智能RLED动态目标中机器手的模糊鲁棒控制系统

给出了一种电机驱动机器手中非线性机电模型的模糊鲁棒闭环控制系统,此控制系统可处理非结构环境下的三个主要的智能机器人导航问题：自动化规划、快速连续导航中的避障、处理结构和（或）非结构不确定性。     

Autonomous Navigation of UAV in Foliage Environment

This paper presents a navigation system that enables small-scale unmanned aerial vehicles to navigate autonomously using a 2D laser range finder in foliage environment without GPS. The navigation framework consists of real-time dual layer control, navigation state estimation and online path planning. In particular, the inner loop of a quadrotor is stabilized using a commercial autopilot while the outer loop control is implemented using robust perfect tracking. The navigation state estimation consists of real-time onboard motion estimation and trajectory smoothing using the GraphSLAM technique. The onboard real-time motion estimation is achieved by a Kalman filter, fusing the planar velocity measurement from matching the consecutive scans of a laser range finder and the acceleration measurement of an inertial measurement unit. The trajectory histories from the real-time autonomous navigation together with the observed features are fed into a sliding-window based pose-graph optimization framework. The online path planning module finds an obstacle-free trajectory based the local measurement of the laser range finder. The performance of the proposed navigation system is demonstrated successfully on the autonomous navigation of a small-scale UAV in foliage environment.     

自适应模糊多环控制在惯导平台稳定回路中的应用

稳定回路控制是决定平台导航系统精度的关键因素之一.传统的校正控制动态性能和抗干扰性能较差,而模糊控制具有稳态误差,因此单一的控制往往很难实现更高精度的导航.为了得到较好的导航精度,以某惯导平台为研究对象,在传统单闭环回路的基础上,引入电流环和速率环,并加入模糊控制,形成复合三环控制,同时针对复合控制切换抖动的问题,设计了基于模糊控制的自适应调节机构.仿真结果表明,采用自适应模糊多环控制,不仅消除了系统控制切换产生的抖动以及模糊控制带来的稳态误差,而且有效改善了控制系统的动态性能.     

Realtime Edge Based Visual Inertial Odometry for MAV Teleoperation in Indoor Environments

A working solution for control and teleoperation of Micro Aerial Vehicles using a frontal camera and an inertial measurement unit as sole sensors is presented. The system is an extension of an edge based visual odometry algorithm to integrate inertial sensors. A mixed tightly-loosely coupled approach is used, taking advantage of each sensor in this minimalistic setup, while keeping the complexity low. The system runs completely on board a MAV providing a semidense output that is more useful for navigation than the sparse maps generated by most feature based systems. To the best of the author’s knowledge, the system is the first semidense VO method running fully on board a MAV for vision in the loop control. An extensive evaluation of the method is presented using the EuRoC MAV dataset, that is specially targeted for MAV navigation in realistic situations. Some of the practical issues of teleoperation are also addressed, in particular how data is transmitted and presented to the user. Finally, real life experiments are included to illustrate the performance of the complete system and the teleoperation interface.     

多传感器组合导航系统性能评估

在民航基于性能的导航(PBN)运行中,组合导航系统的导航性能决定飞机是否可以在相应导航规范要求下的航路上飞行,是实施PBN的关键。以DME/DME/IRS组合导航系统为例,提出机载组合导航系统导航性能的评估思路与方法,利用卡尔曼滤波及二元高斯分布概率计算的手段确定导航系统的定位性能,并对该方法进行仿真验证。结果证明,该方法实时性好,可以评估不同完好性要求条件下的导航定位精度,方法切实可行,便于计算。     

Evaluation of diagnostician user interface aspects in a virtual reality-based tele-ultrasonography simulation

ABSTRACT

Ultrasonography (USG) is a common medical examination that can be performed remotely and that highly benefits from robotics. In this paper, we evaluate a novel interface for a telediagnosis system that features haptic feedback and a 2D/3D visualization of the remote site. A Virtual Environment (VE) representing the patient site was used for the validation to stress the interaction capabilities of the interface and to decouple expert's interface performance from the effects of the whole teleoperation loop of a telediagnosis system. The interface evaluation measures include the accuracy that doctors achieve when positioning the interface's end-effector in the VE and the success of experts to perform tasks related to cardiac USG that require force feedback. Twelve experienced sonographers performed four experiments in which visualization modality and VE navigation technique varied. Given the limitations of an evaluation in simulated settings, both quantitative results and experts' opinions suggest that the interface is suitable for integration in tele-USG systems. After a positive evaluation of latencies and rendered forces, we show how navigation condition influences the accuracy of the end-effector positioning as well as the covered distance and the elapsed time to accomplish the tasks. Similarly, we highlight the effect of visualization on accuracy.     

A new autonomous celestial navigation method for the lunar rover

A secure and autonomous navigation system is needed for the lunar rover in future lunar missions in case of emergencies. Celestial navigation is a very attractive solution for long distance navigation on the Moon without the need of ground navigation aids. It only uses star altitudes, which are measured by a high accuracy star sensor and inertial measurement unit (IMU) to estimate the position of the rover. The navigational accuracy of this method depends largely on the accuracy of measurements, so the measurement errors have a great impact on the navigational performance. A new autonomous celestial navigation method for the lunar rover is presented in this paper, which uses the augmented state unscented particle filter (ASUPF) to deal with the systematic error and random error in the measurements. The validity and feasibility of this new method is tested and examined by the hardware-in-loop test. A position estimation error within 60 m is obtained. Compared to the conventional method, this method shows better navigation performance and higher adaptability to these measurement errors.     

Adaptive vector-tracking loop for low-quality GPS signals

Recently, several researchers have studied a vector-tracking loop to improve tracking performance for Global Positioning System receivers. The advantage of the vector-tracking loop is that noise is reduced in all of the tracking channels. In addition, the vector-tracking loop can operate successfully when the independent scalar tracking loop approach fails. However, the vector-tracking loop is vulnerable to low-quality signals because all tracking channels are dependent on each other. To solve this problem, this paper proposes an adaptive vector-tracking loop based on a linear local filter and an adaptive navigation filter. The covariance rescaling method is used to lessen the effect of low-quality signals. The proposed adaptive vector-tracking loop shows a better tracking performance compared to the conventional vector-tracking loop that is used when satellite signals are low quality.     

基于GPS的仿生六足机器人实时导航定位

根据微小型仿生六足机器人的作业任务和工作环境要求,搭建一套基于嵌入式数字信号处理器TMS320VC 5509A DSP和Superstar II GPS接收板卡的机器人导航系统。采用Marconi Binary串行数据传输标准协议采集全球定位系统(GPS)的定位数据,提出用切面投影定位法对GPS提供的定位数据进行坐标转换,并根据转换后的结果对仿生六足机器人的航迹进行修正。实验结果表明该导航定位系统具有良好的实时性和定位精度。     

多导航传感器系统实时在线性能评估算法研究

从实际工程应用的角度出发,提出了多套导航系统存在情况下的导航系统性能实时在线评估算法。对同类测量导航系统采用加权最小二乘算法以得到一套更高精度的测量信息,在此基础上,利用开环卡尔曼滤波分别对惯导系统实现实时信息融合,再对单独融合后的导航结果进行加权处理得到最终的融合导航结果,并以此作为导航系统性能评价的基准和实现对导航系统的在线故障检测。通过实时仿真结果表明:应用该算法对导航系统进行评估,能够在不增加系统本身负担的情况下,具有较高的性能评价精度,是一种切实可行的方法。     

鼠类脑细胞导航机理的移动机器人仿生SLAM综述

针对同步定位与地图构建（SLAM）问题中传统概率算法存在计算量大、复杂度高、易陷于局部最优解等问题,本文提出一种未来深入研究的方法建议,将鼠类脑细胞中边界细胞（border cells）、局部场景细胞（view cells）、网格细胞（grid cells）、速度细胞（speed cells）、位姿细胞（pose cells）等具有定位导航功能的细胞应用于SLAM研究中,构建一种基于多细胞导航机制的BVGSP-SLAM模型。结合具有实时关键帧匹配的闭环检测算法以避免光线变化对SLAM的影响,融入速度细胞和边界细胞以避免移动障碍物对SLAM的影响,利用鼠类混合细胞衍生出的数学模型分析该系统的鲁棒性和实时性。将生物细胞模型引入SLAM,并形成了建模、仿真与实验验证一体化的研究体系,为移动机器人SLAM研究领域多样化提供重要的理论参考。     

基于改进锁频锁相的高动态同步算法

针对卫星定位导航系统多谱勒频移大的特点,根据设计的实际系统推导出锁频锁相算法的理论表达式。对叉积算法得到的结果利用改进的平滑算法进行处理,降低了噪声方差。与此同时使锁频环和锁相环同时工作,加快了更新时间。对上述改进算法进行单片FPGA实现,采用NiosII代替传统的DSP对算法的锁频锁相部分进行实现,增加了系统的稳定性和可靠性。通过实验验证,提出的改进算法解决了环路跟踪精度和动态性能不能兼顾的矛盾,各项技术指标达到或超过系统设计的要求。     

Robust omnidirectional mobile robot topological navigation system using omnidirectional vision

Robust topological navigation strategy for omnidirectional mobile robot using an omnidirectional camera is described. The navigation system is composed of on-line and off-line stages. During the off-line learning stage, the robot performs paths based on motion model about omnidirectional motion structure and records a set of ordered key images from omnidirectional camera. From this sequence a topological map is built based on the probabilistic technique and the loop closure detection algorithm, which can deal with the perceptual aliasing problem in mapping process. Each topological node provides a set of omnidirectional images characterized by geometrical affine and scale invariant keypoints combined with GPU implementation. Given a topological node as a target, the robot navigation mission is a concatenation of topological node subsets. In the on-line navigation stage, the robot hierarchical localizes itself to the most likely node through the robust probability distribution global localization algorithm, and estimates the relative robot pose in topological node with an effective solution to the classical five-point relative pose estimation algorithm. Then the robot is controlled by a vision based control law adapted to omnidirectional cameras to follow the visual path. Experiment results carried out with a real robot in an indoor environment show the performance of the proposed method.     

基于相关滤波技术实现激光陀螺抖动信号的剥除

为了满足惯导系统对机械抖动激光陀螺快速跟踪方面的应用需求,基于相关滤波技术实现了激光陀螺抖动误差信号的剥除.首先从理论上对基于相关滤波去除抖动的思想进行了详细的分析,提出了基于相关滤波进行抖动剥除的开环模型,为了提高系统的稳定性,在开环模型的基础上提出了闭环模型.其次介绍了基于相关滤波闭环模型实现抖动剥除的软硬件设计,最后用所研制的系统对某一型号的激光陀螺进行了测试,通过对采样信号和误差信号的观测,系统工作稳定,在5 kHz的采样条件下,陀螺剥除后的剩余脉冲控制在±1内.     

基于SAR辅助的惯导/星光组合导航系统研究

针对高空、长航时无人飞行器在对地观测成像期间对导航自主性和高精度的需求,研究了基于SAR辅助的惯导/星光姿态组合导航系统.针对SAR图像导航输出的间断性和多传感器组合导航系统中量测输出的不同步特性,设计了解决非连续性量测修正的多传感器组合导航滤波器模型.提出了解决多传感器量测不同步问题的异步集中滤波算法.仿真结果表明:...     

Validation of nonlinear integrated navigation solutions

There exist numerous navigation solutions already implemented into various navigation systems. Depending on the vehicle in which the navigation system is used, it can be distinguished in most cases among; navigation, tactical, and commercial grade categories of such systems. The core of these systems is formed by inertial sensors, i.e. accelerometers and angular rate sensors/gyros. Navigation and tactical grade systems commonly rely on fiber optic/ring laser gyros and servo/quartz accelerometers with high resolution, sensitivity, and stability. In the case of cost-effective navigation systems, for example piloted light and ultralight aircraft, usually use commercial grade sensors, where the situation differs. The sensor outputs are less stable and sensitive, and suffer from manufacturing limits leading to temperature dependency, bias instability, and misalignment which introduces non-negligible disturbances. These conditions commonly limit the applicability of the navigation solution since its stand-alone operation using free integration of accelerations and angular rates is not stable. This paper addresses a cost-effective solution with commercial grade inertial sensors, and studies the performance of different approaches to obtain navigation solution with robustness to GNSS outages. A main goal of this paper is thus comparison of a nonlinear observer and two extended Kalman filter solutions with respect to the accuracy of estimated quantities and their sensitivity to GNSS outages. The performance analyses are carried out on real flight data and evaluated during phases of the flight when the solutions are challenged by different environmental disturbances.