AHRS航姿解算中的两种滤波方法的比较研究

关于飞行姿态角优化问题,由于加速度计的测量值中同时包含了重力加速度和运动加速度信息,并且磁传感器易受铁磁性物质干扰,直接利用加速度计的测量值计算横滚角和俯仰角易产生较大误差,进而在利用磁传感器的测量值计算航向角时也将会引入了误差.为了减小加速度计和磁传感器的姿态解算算法所解算的姿态角误差,提出利用陀螺仪的输出,分别设计了互补滤波器和卡尔曼滤波器(Kalman Filter)对加速度计和磁传感器的输出进行处理,采用VN-100的微惯性测量单元(Micro Inertial Measurement Unit,MIMU)的数据进行MATLAB仿真,并对两种滤波器的滤波效果进行了比较.实验结果表明,互补滤波和Kalman滤波均能提高该算法的姿态角精度,并且互补滤波器比Kalman滤波器效率更高,性能更好.     

Learning LOGO: effects on learning BASIC and statistics

Abstract Two experiments were conducted to examine the effects of a period of training in the use of the turtle graphics aspects of LOGO on both attitudes towards computers and the learning of BASIC and statistics. A group of 15 subjects spent 10 hours learning LOGO . Their performance on subsequent learning of BASIC was significantly better than that of a control group, but no differences were found in attitudes towards computers or in the learning of statistics.     

Attitudes toward intimate partner violence in dating relationships.

Prevention of intimate partner violence on college campuses includes programs designed to change attitudes, and hence, a scale that assesses such attitudes is needed. Study 1 (N = 859) cross validates the factor structure of the Intimate Partner Violence Attitude Scale-Revised using exploratory factor analysis and presents initial validity data on the scale. In Study 2 (N = 687), the obtained three-factor structure (Abuse, Control, Violence) is tested using confirmatory factor analysis, and it is shown to be concurrently related to assault in romantic relationships and to predict psychological aggression 14 weeks later. The findings are discussed in the context of how understanding and modifying attitudes assessed by the Intimate Partner Violence Attitude Scale-Revised may improve interventions aimed at reducing intimate partner violence. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Computer attitude scales: How relevant today?

Since the increase in the use of computers as learning tools, there have been many scales developed that can measure various aspects of ‘computer attitude’. The aim of this study is to examine the relevance of a number of these scales and determine whether they are still appropriate for use today. Four computer attitude scales, which are used widely, are assessed. It was found that the scales are reliable. However, the degree of predictive validity for each scale varied and the various underlying constructs appear to reflect different aspects of attitude. In addition, these constructs had changed since the original creation of the scales. This suggests that the traditional style of computer attitude scale is no longer as relevant as when first developed, and judicious selection and care need to be exercised over their use and the interpretation of findings.     

高职院校学生艾滋病认知状况调查

目的了解高职院校大学生对艾滋病(AIDS)的认识、态度及个人信念,为学校开展艾滋病健康教育提供依据。方法随机抽取243名大学生进行问卷调查。结果高职院校大学生对艾滋病的知识性问题知晓率不高,有93.4%的学生知道艾滋病可以通过血液传播;对性传播、母婴传播也有正确认识。大部分学生对艾滋病有恐慌情绪,正确安全性观念的持有率较低。结论应结合大学生对艾滋病的认识情况及行为特点,有针对性地开展艾滋病健康教育。     

Finite-time fault tolerant attitude stabilization control for rigid spacecraft

A sliding mode based finite-time control scheme is presented to address the problem of attitude stabilization for rigid spacecraft in the presence of actuator fault and external disturbances. More specifically, a nonlinear observer is first proposed to reconstruct the amplitude of actuator faults and external disturbances. It is proved that precise reconstruction with zero observer error is achieved in finite time. Then, together with the system states, the reconstructed information is used to synthesize a nonsingular terminal sliding mode attitude controller. The attitude and the angular velocity are asymptotically governed to zero with finite-time convergence. A numerical example is presented to demonstrate the effectiveness of the proposed scheme.     

Cascaded Kalman and particle filters for photogrammetry based gyroscope drift and robot attitude estimation

Based on a cascaded Kalman–Particle Filtering, gyroscope drift and robot attitude estimation method is proposed in this paper. Due to noisy and erroneous measurements of MEMS gyroscope, it is combined with Photogrammetry based vision navigation scenario. Quaternions kinematics and robot angular velocity dynamics with augmented drift dynamics of gyroscope are employed as system state space model. Nonlinear attitude kinematics, drift and robot angular movement dynamics each in 3 dimensions result in a nonlinear high dimensional system. To reduce the complexity, we propose a decomposition of system to cascaded subsystems and then design separate cascaded observers. This design leads to an easier tuning and more precise debugging from the perspective of programming and such a setting is well suited for a cooperative modular system with noticeably reduced computation time. Kalman Filtering (KF) is employed for the linear and Gaussian subsystem consisting of angular velocity and drift dynamics together with gyroscope measurement. The estimated angular velocity is utilized as input of the second Particle Filtering (PF) based observer in two scenarios of stochastic and deterministic inputs. Simulation results are provided to show the efficiency of the proposed method. Moreover, the experimental results based on data from a 3D MEMS IMU and a 3D camera system are used to demonstrate the efficiency of the method.     

Strength and conflicting valence in the measurement of food attitudes and preferences

There is a trend in current attitude research to move away from a simple uni-dimensional view of attitude, towards examining a more multivariate concept of attitude. An extensive array of attitudinal properties or dimensions has been provided, defined and categorised as ‘attitude strength’. Attitude strength has only recently been adapted as a conceptual framework for research in marketing and consumer studies. Our objective in this paper is to introduce some of the attitude strength concepts and literature in order to improve the measure and understanding of research dealing with measurement of food preferences, perceived food quality and satisfaction with food products, food suppliers, etc. The paper takes a particular focus upon problems in comprehending the middlemost choice or neutrality when measuring attitude items along a traditional bipolar semantic differential or a bipolar hedonic preference scale. Through several propositions, we have outlined how future research should note that both attitude ambivalence (mixed feelings) and non-attitude (lack of confidence in evaluation) could be threats to comprehending the middlemost response alternative on a questionnaire as neutral when measuring food attitudes or preferences in the traditional way. Our approach should also deal with some of the shortcomings of analysing attitude–behaviour consistency when modelling food consumption behaviour.     

ATTITUDE RATE ESTIMATION BY GPS DOPPLER SIGNAL PROCESSING

A method is presented for near-Earth spacecraft or aviation vehicle‘s attiude rate cstimation 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 relatvely simple,the cost and weight,as well power consumption,are very low.     

Consumers’ familiarity with and attitudes towards food quality certifications for rice and vegetables in Vietnam

This study investigates consumers’ attitudes towards, and familiarity with, food quality certification in selected urban areas in the South of Vietnam. Cross-sectional data were collected by means of a consumer survey (n = 500). Consumers’ awareness of food quality-related terms was relatively low. Less than half the participants claimed to understand the meaning of good agricultural practices (GAP), organic food and sustainability. Consumers’ familiarity with food quality certification (Vietnamese Good Agricultural Practices (VietGAP), Global Good Agricultural Practices (GLOBALG.A.P.), organic, and Hazard Analysis and Critical Control Points (HACCP)) was also low. Familiarity with food quality certification was positively associated with general attitude and food choice motives, namely food safety concern, perceived importance of healthy eating, and perceived importance of environmental consequences relating to food purchase. Food safety concern and perceived importance of environmental consequences were positively associated with consumers’ attitudes towards safe vegetables, as well as high quality rice. Perceived importance of healthy eating was positively related to attitude towards high quality rice. Findings suggest that food safety aspects of safe vegetables and high quality rice should be emphasized during policy and marketing activities for food quality certification. Additionally, an increase in the perceived importance of environmental consequences relating to quality food purchase should be encouraged to enhance positive consumer attitudes towards quality food. Efforts to improve public awareness and knowledge of food quality certification and sustainable agricultural practices in developing countries such as Vietnam are highly recommended.