Coupled Dynamics and Integrated Control for Position and Attitude Motions of Spacecraft:A Survey

Inspired by the integrated guidance and control design for endo-atmospheric aircraft,the integrated position and attitude control of spacecraft has attracted increasing attention and gradually induced a wide variety of study results in last over two decades,fully incorporating control requirements and actuator characteristics of space missions.This paper presents a novel and comprehensive survey to the coupled position and attitude motions of spacecraft from the perspective of dynamics and control.To this end,a systematic analysis is firstly conducted in details to show the position and attitude mutual couplings of spacecraft.Particularly,in terms of the time discrepancy between spacecraft position and attitude motions,space missions can be categorized into two types:space proximity operation and space orbital maneuver.Based on this classification,the studies on the coupled dynamic modeling and the integrated control design for position and attitude motions of spacecraft are sequentially summarized and analyzed.On the one hand,various coupled position and dynamic formulations of spacecraft based on various mathematical tools are reviewed and compared from five aspects,including mission applicability,modeling simplicity,physical clearance,information matching and expansibility.On the other hand,the development of the integrated position and attitude control of spacecraft is analyzed for two space missions,and especially,five distinctive development trends are captured for space operation missions.Finally,insightful prospects on future development of the integrated position and attitude control technology of spacecraft are proposed,pointing out current primary technical issues and possible feasible solutions.

Real-Time Position and Attitude Estimation for Homing and Docking of an Autonomous Underwater Vehicle Based on Bionic Polarized Optical Guidance

As an important tool for marine exploration, the autonomous underwater vehicle(AUV) must home in and dock at a docking station(DS) to be recharged, repaired, or to exchange information at set intervals. However, the complex and hostile underwater environment makes this process challenging. This study proposes a real-time method based on polarized optical guidance for determining the position and attitude of the AUV relative to its DS. Four polarized artificial underwater landmarks are positioned at the DS, which are recognized by the AUV vision system. Compared with light intensity, the polarization of a light beam is known to be better maintained at greater propagation distances, especially in underwater environments. The proposed method, which is inspired by the ability of marine animals to communicate, calculates the pose parameters in less than 10 ms without any other navigational information. The simulation results reveal that the angle errors are small and the position errors are no more than 0.116 m within 100 m in the coastal ocean. The results of underwater experiments further demonstrate the feasibility of the proposed method, which extends the operating distance of the AUV beyond what is currently possible while maintaining the precision of traditional optical guidance.

Determining Attitude and Position in Deep Space Missions Using X Ray Pulsars

This paper initially reviews types of deep space navigation methods. Then, it studies the use of pulsars as one of sources emitting electromagnetic waves in navigation;hence more details regarding the pulsar physics and the history of navigation using pulsars are presented. The various methods of navigation (including radio method), their advantages and disadvantages—in comparison with navigation using pulsars in spacecraft—are discussed. Then, the equations necessary for calculating position and velocity of a spacecraft (such as the arrival time of pulse from pulsar to the receiver) are introduced, and the methods of calculating position and velocity are dealt with. Finally, two algorithms are presented for positioning, and one for velocity. Attitude determination follows the same simple methods presented in various articles.

Relative Position and Attitude Control for Drag-Free Satellite with Prescribed Performance and Actuator Saturation

An adaptive prescribed performance control scheme is proposed for the drag free satellite in the presence of actuator saturation and external disturbances.The relative translation and rotation dynamics between the test mass and outer satellite are firstly derived.To guarantee prescribed performance bounds on the transient and steady control errors of relative states,a performance constrained control law is formulated with an error transformed function.In addition,the requirements to know the system parameters and the upper bound of the external disturbance in advance have been eliminated by adaptive updating technique.A command filter is concurrently used to overcome the problem of explosion of complexity inherent in the backstepping control design.Subsequently,a novel auxiliary system is constructed to compensate the adverse effects of the actuator saturation constrains.It is proved that all signals in the closed?loop system are ultimately bounded and prescribed performance of relative position and attitude control errors are guaranteed.Finally,numerical simulation results are given to demonstrate the effectiveness of the proposed approach.

Data-driven real-time prediction for attitude and position of super-large diameter shield using a hybrid deep learning approach

The presented research introduces a novel hybrid deep learning approach for the dynamic prediction of the attitude and position of super-large diameter shields-a critical consideration for construction safety and tunnel lining quality.This study proposes a hybrid deep learning approach for predicting dynamic attitude and position prediction of super-large diameter shield.The approach consists of principal component analysis(PCA)and temporal convolutional network(TCN).The former is used for employing feature level fusion based on features of the shield data to reduce uncertainty,improve accuracy and the data effect,and 9 sets of required principal component characteristic data are obtained.The latter is adopted to process sequence data in predicting the dynamic attitude and position for the advantages and potential of convolution network.The approach’s effectiveness is exemplified using data from a tunnel construction project in China.The obtained results show remarkable accuracy in predicting the global attitude and position,with an average error ratio of less than 2 mm on four shield outputs in 97.30%of cases.Moreover,the approach displays strong performance in accurately predicting sudden fluctuations in shield attitude and position,with an average prediction accuracy of 89.68%.The proposed hybrid model demonstrates superiority over TCN,long short-term memory(LSTM),and recurrent neural network(RNN)in multiple indexes.Shapley additive exPlanations(SHAP)analysis is also performed to investigate the significance of different data features in the prediction process.This study provides a real-time warning for the shield driver to adjust the attitude and position of super-large diameter shields.

Design of trotting controller for the position-controlled quadruped robot

This work presents a controller designed for position-controlled quadrupedal dynamic locomotion,aiming at simple and robust trotting control. The controller takes the torso attitude angles and velocities into planning foot trajectories. Firstly design of the servo motor actuated quadruped robot is introduced and the kinematic equations are deduced. Then a scheme is presented for controlling the robot torso attitude based on the virtual leg model. Furthermore,it demonstrates the design of the controller which enables the robot to have a wide range of trotting gaits and omni-directional motions. Finally,results of robust trotting in various speeds,path tracking and push recovery in simulation are reported,and results of trotting on real quadruped robots will be studied.

Estimation of Quaternion Motion for GPS-Based Attitude Determination Using the Extended Kalman Filter

In this paper,the Global Positioning System(GPS)interferometer provides the preliminarily computed quaternions,which are then employed as the measurement of the extended Kalman filter(EKF)for the attitude determination system.The estimated quaternion elements from the EKF output with noticeably improved precision can be converted to the Euler angles for navigation applications.The aim of the study is twofold.Firstly,the GPS-based computed quaternion vector is utilized to avoid the singularity problem.Secondly,the quaternion estimator based on the EKF is adopted to improve the estimation accuracy.Determination of the unknown baseline vector between the antennas sits at the heart of GPS-based attitude determination.Although utilization of the carrier phase observables enables the relative positioning to achieve centimeter level accuracy,however,the quaternion elements derived from the GPS interferometer are inherently noisy.This is due to the fact that the baseline vectors estimated by the least-squares method are based on the raw double-differenced measurements.Construction of the transformation matrix is accessible according to the estimate of baseline vectors and thereafter the computed quaternion elements can be derived.Using the Euler angle method,the process becomes meaningless when the angles are at 90where the singularity problem occurs.A good alternative is the quaternion approach,which possesses advantages over the equivalent Euler angle based transformation since they apply to all attitudes.Simulation results on the attitude estimation performance based on the proposed method will be presented and compared to the conventional method.The results presented in this paper elucidate the superiority of proposed algorithm.

Complementary Kalman Filter as a Baseline Vector Estimator for GPS-Based Attitude Determination

The Global Positioning System(GPS)offers the interferometer for attitude determination by processing the carrier phase observables.By using carrier phase observables,the relative positioning is obtained in centimeter level.GPS interferometry has been firstly used in precise static relative positioning,and thereafter in kinematic positioning.The carrier phase differential GPS based on interferometer principles can solve for the antenna baseline vector,defined as the vector between the antenna designated master and one of the slave antennas,connected to a rigid body.Determining the unknown baseline vectors between the antennas sits at the heart of GPS-based attitude determination.The conventional solution of the baseline vectors based on least-squares approach is inherently noisy,which results in the noisy attitude solutions.In this article,the complementary Kalman filter(CKF)is employed for solving the baseline vector in the attitude determination mechanism to improve the performance,where the receiver-satellite double differenced observable was utilized as the measurement.By using the carrier phase observables,the relative positioning is obtained in centimeter level.Employing the CKF provides several advantages,such as accuracy improvement,reliability enhancement,and real-time assurance.Simulation results based on the conventional method where the least-squares approach is involved,and the proposed method where the CKF is involved are compared and discussed.

ATTITUDE RATE ESTIMATION BY GPS DOPPLER SIGNAL PROCESSING

A method is presented for near-Earth spacecraft or aviation vehicle's attitude rate estimation by using relative Doppler frequency shift; of the Global Positioning System (GPS) carrier. It comprises two GPS receiving antennas, a signal processing circuit and an algorithm. The whole system is relatively simple, the cost and weight, as well as power consumption, are very low.

Attention-based LSTM predictive model for the attitude and position of shield machine in tunneling

Shield machine may deviate from its design axis during excavation due to the uncertainty of geological environment and the complexity of operation.This study therefore introduced a framework to predict the attitude and position of shield machine by combining long short-term memory(LSTM)model with attention mechanism.The data obtained from the Wuhan Rail Transit Line 6 project were utilized to verify the feasibility of the proposed method.By adding the attention mechanism into the LSTM model,the proposed model can focus more on parameters with higher weights.Sensitivity analysis based on Pearson correlation coefficient was conducted to improve the prediction efficiency and reduce the irrelevant input parameters.Compared with LSTM model,LSTM-attention model has higher accuracy.The mean value of coefficient of determination(R^(2))increases from 0.625 to 0.736,and the mean value of root mean square error(RMSE)decreases from 3.31 to 2.24.The proposed LSTM-attention model can provide an effective prediction for attitude and position of shield machine in practical tunneling engineering.

Design on a Multi-Sensor Integrated Attitude Determination System for Small UAVs

This paper discusses the design and implementation of a low cost multi-sensor integrated attitude determination system for small unmanned aerial vehicles( UAVs),which uses strapdown inertial navigation system( SINS) based on micro electromechanical system( MEMS) inertial sensors,commercial GPS receiver,and 3-axis magnetometer.MEMS-SINS initial attitude determination cannot be well performed for the reason that the MEMS inertial sensors biases are time-varying and poor repeatability,therefore in this paper the magnetometer and inclinometer are used to assist the MEMS-SINS initial attitude determination and MEMS inertial sensors field calibration.Furthermore,the attitude determination algorithms are presented to estimate the full attitude during GPS signal outage and non-accelerating situation.Additionally,the attitude information estimation results are compared with the reference of the non-magnetic marble platform and 3-axis turntable.Then the attitude estimation precision satisfies the requirement of attitude measurement for small UAVs during GPS signal outage and availability.Finally,the small UAV autonomous flight test results show that the low cost and real-time attitude determination system can yield continuous,reliable and effective attitude information for small UAVs.

A Cross-Sectional Survey of Knowledge Attitude and Prevention Practice towards Malaria among Basic Schools Pupils Prior to Health Education Campaign

Background: Malaria has historically been a major public health concern in Yemen, noted to be the country with the highest prevalence in the Eastern Mediterranean Region. As more and more children attend school, governments are increasingly recognizing the importance of child health for educational achievement. Aim: The aim is to assess the baseline knowledge, attitude and practice of pupil towards malaria before the health education activities. Methods: We conducted a cross-sectional study, in four randomly selected districts (rural and urban) of Taiz governorate. The study population was 1598 pupils in primary schools. Data was collected using questioner. Results: The pupils who recognized mosquito bite as a route of malaria transmission was 769 (48.1%), while the pupils who recognized fever as the main symptom were 786 (49.2%), 281 (17.58%) of pupils recognized convulsion as a complication of malaria. Regarding protective method 881 (55.31%) were mentioned the cover of the tanks as a protective method, about the BN 293 (18.3%) of pupils known about the BN and 280 (17.5%) mentioned children & pregnancy were the vulnerable groups to malaria. Conclusions and Recommendation: the percentage of knowledge of malaria knowledge and methods of prevention was low (24.5%). Also, the positive attitude and practice toward malaria was 45%. The rate of having bed-nets was very low (10.1%). There were misconceptions of malaria cause and transmission (48.1%). We recommend conducting health education activities that will focus on increasing the knowledge, attitude and practice levels of malaria among school pupils.

Estimator-Based GPS Attitude and Angular Velocity Determination

In this paper,the estimator-based Global Positioning System(GPS)attitude and angular velocity determination is presented.Outputs of the attitude estimator include the attitude angles and attitude rates or body angular velocities,depending on the design of estimator.Traditionally as a position,velocity and time sensor,the GPS also offers a free attitude-determination interferometer.GPS research and applications to the field of attitude determination using carrier phase or Doppler measurement has been extensively conducted.The rawattitude solution using the interferometry technique based on the least-squares approach is inherently noisy.The estimator such as the Kalman filter(KF)or extended Kalman filter(EKF)can be incorporated into the GPS interferometer,potentially providing several advantages,such as accuracy improvement,reliability enhancement,and real-time characteristics.Three estimator-based approaches are investigated for performance comparison,including(1)KF with measurement involving attitude angles only;(2)EKF with measurements based on attitude angles only;(3)EKF with measurements involving both attitude angles and body angular rates.The assistance from body mounted gyroscopes,if available,can be utilized as the measurements for further performance improvement,especially useful for the case of signal-challenged environment,such as the GPS outages.Modeling of the dynamic process involving the body angular rates and derivation of the related algorithm will be presented.Simulation results for various estimator-based approaches are conducted;performance comparison is presented for the case of GPS outages.

面向变构型飞行器的强化学习位置姿态一体化控制方法

针对变构型飞行器在飞行过程中由于构型发生改变导致其质心、气动力、转动惯量和气动力矩以及飞行器的抗扰能力等参数或特性发生变化,对飞行器飞行控制品质产生较大影响的问题,提出一种基于强化学习的变构型飞行器一体化位置姿态控制方法,通过孪生延迟深度确定性策略梯度(TD3)强化学习算法训练神经网络控制律,实现变构型飞行器的一体化位置姿态控制。算法通过数学仿真与飞行试验进行了验证,仿真结果与飞行试验结果表明,该算法所设计的神经网络控制律能够实现变构型飞行器的一体化位置姿态控制,并对于外界干扰具有较强的适应能力。

飞机复合材料机身壁板装配技术分析与展望

复合材料以其优异的综合性能在航空航天领域得到了大量应用,其应用范围逐渐从次承力结构向主承力结构扩展,包括在机身结构的组成方面,传统的金属组装壁板逐渐被复合材料整体壁板所取代。由于复合材料壁板具有不同于传统金属材料壁板的装配工艺特点,因此对其装配方法和装配工艺提出了新的要求。针对圆筒状机身复合材料机身壁板的装配过程,分别介绍了复合材料机身壁板大尺寸测量技术、复合材料机身壁板装配定位调姿技术和复合材料机身壁板的先进制孔连接技术,系统总结了近年来国内外相关研究进展和应用情况,指出了飞机大尺寸复合材料结构装配技术未来的研究与应用方向。

面向机器人加工复杂轮廓误差控制的策略研究

针对机器人加工复杂曲面零件,提出一种面向加工轮廓误差的控制策略。通过向量的形式定义了机器人加工任务的轮廓误差,结合双向搜索、斐波那契搜索和球面线性插补算法,对机器人轮廓误差进行了估计;在此基础上通过将加权轮廓误差分量补偿到机器人任务空间的速度指令中,设计了机器人加工任务的轮廓控制策略。实验结果表明:对于位置和姿态轮廓误差,估计值与真实值的差异非常小,且与单纯的跟踪控制相比,位置和方向轮廓平均误差大约降低了30%,验证了所提加工轮廓误差控制策略的有效性。

基于RGB-D的像素级抓取检测算法研究

针对物体姿态随机、外形不规则、抓取环境复杂等机械臂抓取问题,提出一种基于RGB-D的像素级抓取检测方法。首先,对Cornell数据集基于像素级重标注,并生成抓取标签;然后,提出一种多残差提取卷积神经网络(CRE-Net),增强网络特征提取效果;最后,搭建仿真抓取系统,进行算法验证。实验结果表明:位姿检测精度达到93.99%,在对抗性抓取中,单物体抓取成功率为94.0%,多物体抓取成功率为73.3%。

呼吸科护士无创正压通气护理知信行现状调查及分析

目的:调查呼吸科护士无创正压通气(NIPPV)护理的知信行现状并分析呼吸科护士NIPPV护理行为的影响因素,为临床开展无创通气护理培训及管理提供依据。方法:采用自行设计的NIPPV护理知信行问卷对华南地区22所医院呼吸科的护士进行问卷调查,并分析NIPPV护理行为的影响因素。结果:共回收有效问卷215份,呼吸科护士NIPPV护理知信行总量表、知识维度、态度维度、行为维度得分分别为(98.29±12.51)分、(18.94±4.35)分、(28.44±4.75)分和(50.90±8.73)分。多元线性回归分析结果显示,NIPPV护理行为的主要影响因素为工作年限、是否接受过NIPPV护理知识或技能培训、所在科室是否有NIPPV护理流程规范、知识得分、态度得分。结论:呼吸科护士对无创通气护理的态度较为积极,无创通气护理的行为总体较好,但无创通气护理知识掌握程度有待提高。无创通气护理行为的主要影响因素为知识和态度、工作年限、是否接受过NIPPV护理知识或技能培训、所在科室是否有NIPPV护理流程规范。护理管理者应加强呼吸科护士的NIPPV护理知识和技能的培训,医疗机构应制订NIPPV护理操作流程规范,以规范护士的临床工作,提高NIPPV病人的护理质量。

国家形象与中德关系:中德主流媒体对“德国总理朔尔茨首次访华”的新闻建构比较研究

在国家形象建设中,国际传播至关重要。有效的国际传播策略有助于讲好中国故事,传播好中国声音,展现可信、可爱、可敬的中国形象。党的二十大闭幕后,德国总理朔尔茨(Olaf Scholz)作为首位访华的西方大国领导人备受外界关注,表明了德国作为中国重要外交伙伴的地位。本研究选取中国和德国各5家主流媒体对“德国总理朔尔茨首次访华”的新闻报道为分析样本,利用KH Coder软件进行文本挖掘并梳理报道热点,从框架理论的视角,分析对比中德主流媒体对“德国总理朔尔茨首次访华”报道的新闻框架,透视传播倾向,解析态度立场。研究发现,中德主流媒体的新闻建构存在差异。中国主流媒体主要从经济角度出发,德国主流媒体则倾向于从政治角度进行报道分析。对此,本文探究中德主流媒体报道差异的原因,并探讨向德国讲好中国故事的启示。

双臂工业机器人协作定位精度姿态误差校正

为提高机械臂在货物交接时对多种控制状态的适应能力,设计了一种双臂工业机器人协作定位精度姿态误差校正方法,以达到械臂运动参数校准的目的。建立了机械臂残余姿态误差数学模型,精确地对机械臂残余定位误差进行计算。研究结果表明:运动特性曲线呈现平滑分布的特点,加速度突变程度很小,表明该系统能够满足工况作业要求。姿态误差有效补偿能够更精确完成两臂协同定位,从而准确识别手臂基座标变换参数。本研究有助于提高双臂工业机器人协作动作效率,为后续的参数优化奠定一定的理论基础。