Because the signals of global positioning system （GPS） satellites are susceptible to obstructions in urban environment with many high buildings around, the number of GPS useful satellites is usually less than six. I...Because the signals of global positioning system （GPS） satellites are susceptible to obstructions in urban environment with many high buildings around, the number of GPS useful satellites is usually less than six. In this case, the receiver autonomous integrity monitoring （RAIM） method earmot exclude faulty satellite. In order to improve the performance of RAIM method and obtain the reliable positioning results with five satellites, the series of receiver clock bias （RCB） is regarded as one useful satellite and used to aid RAIM method. From the point of nonlinear series, a grey-Markov model for predicting the RCB series based on grey theory and Markov chain is presented. And then the model is used for aiding RAIM method in order to exclude faulty satellite. Experimental results demonstrate that the prediction model is fit for predicting the RCB series, and with the clock-based RAIM method the faulty satellite can be correctly excluded and the positioning precision of GPS receiver can be improved for the case where there are only five useful satellites.展开更多
A three-dimensional positioning method for global positioning system(GPS)receivers based on three satellites was proposed.In the method,the measurement equation used for positioning calculation was expanded by means o...A three-dimensional positioning method for global positioning system(GPS)receivers based on three satellites was proposed.In the method,the measurement equation used for positioning calculation was expanded by means of two measures.In this case,the measurement equation could be solved,and the function of positioning calculation could be performed.The detailed steps of the method and how to evaluate the positioning precision of the method were given,respectively.The positioning performance of the method was demonstrated through some experiments.It is shown that the method can provide the three-dimensional positioning information under the condition that there are only three useful satellites.展开更多
The linear ultrasonic motor(LUSM)has many merits such as high precision,quick response,self-locking when power off and so on.However,it also has some drawbacks such as strong non-linear and time-varying characteristic...The linear ultrasonic motor(LUSM)has many merits such as high precision,quick response,self-locking when power off and so on.However,it also has some drawbacks such as strong non-linear and time-varying characteristics,which are harmful to high precision positioning.Fig.1 shows a positioning stage driven by LUSMs.In this paper,the macro-micro control mode is adopted to realize the requirements of the large-workspace and high precision positioning.The switching macro-micro control depends on switching threshold,and it can be described as follows(E denotes the position error,D denotes switching threshold):When E>D,the PID based macro control method is adopted to realize large stroke and quick response;When E≤D,the normal distribution theory combined with the technology of fuzzy logic approach is employed to realize high precision positioning.展开更多
基金Project(20090580013) supported by the Aeronautic Science Foundation of ChinaProject(ZYGX2010J119) supported by the Fundamental Research Funds for the Central Universities,China
文摘Because the signals of global positioning system （GPS） satellites are susceptible to obstructions in urban environment with many high buildings around, the number of GPS useful satellites is usually less than six. In this case, the receiver autonomous integrity monitoring （RAIM） method earmot exclude faulty satellite. In order to improve the performance of RAIM method and obtain the reliable positioning results with five satellites, the series of receiver clock bias （RCB） is regarded as one useful satellite and used to aid RAIM method. From the point of nonlinear series, a grey-Markov model for predicting the RCB series based on grey theory and Markov chain is presented. And then the model is used for aiding RAIM method in order to exclude faulty satellite. Experimental results demonstrate that the prediction model is fit for predicting the RCB series, and with the clock-based RAIM method the faulty satellite can be correctly excluded and the positioning precision of GPS receiver can be improved for the case where there are only five useful satellites.
基金Project (ZYGX2010J119)supported by the Fundamental Research Funds for the Central Universities of China
文摘A three-dimensional positioning method for global positioning system(GPS)receivers based on three satellites was proposed.In the method,the measurement equation used for positioning calculation was expanded by means of two measures.In this case,the measurement equation could be solved,and the function of positioning calculation could be performed.The detailed steps of the method and how to evaluate the positioning precision of the method were given,respectively.The positioning performance of the method was demonstrated through some experiments.It is shown that the method can provide the three-dimensional positioning information under the condition that there are only three useful satellites.
文摘The linear ultrasonic motor(LUSM)has many merits such as high precision,quick response,self-locking when power off and so on.However,it also has some drawbacks such as strong non-linear and time-varying characteristics,which are harmful to high precision positioning.Fig.1 shows a positioning stage driven by LUSMs.In this paper,the macro-micro control mode is adopted to realize the requirements of the large-workspace and high precision positioning.The switching macro-micro control depends on switching threshold,and it can be described as follows(E denotes the position error,D denotes switching threshold):When E>D,the PID based macro control method is adopted to realize large stroke and quick response;When E≤D,the normal distribution theory combined with the technology of fuzzy logic approach is employed to realize high precision positioning.
