Research On Indoor Location Method Of Robot Based On UWB Radar

In the era of great material abundance,the development of medicine has made great contributions to the improvement of medical level,and at the same time,it has also delayed the normal death time of human beings,so human beings are facing the problem of aging and the rapid increase of the aging population.In the future,the elderly care and nursing of aging and aged population will bring huge burden to the society.To solve this problem,we must rely on the development of indoor robots that can complete the task of elderly care.In addition,in many indoor mobile robot applications,in order to complete some typical tasks,the robot needs to know its exact position in the working environment,and even the precise position of some manipulator,which needs to rely on positioning technology to achieve.As the position of robot changes constantly in the working environment,wireless positioning technology is essential in most robot positioning systems.The commonly used wireless location technology is easy to be interfered by noise,and there are also problems such as multipath effect and non-line-of-sight propagation.For example,wi-fi,bluetooth,infrared,ultrasonic,radio frequency signal and other wireless positioning technologies all have the above problems.Due to the band and bandwidth limitations of these wireless positioning technologies,the indoor positioning and tracking system based on these technologies cannot achieve satisfactory positioning accuracy at present.UWB signal can obtain high precision ranging error due to its own characteristics,and has strong anti-interference ability,strong penetration,good anti-multipath effect and other unique advantages.Therefore,it is a very good choice to improve indoor positioning accuracy.In this paper,the indoor positioning method based on UWB radar robot is studied.The specific work of the paper is as follows:(1)Aiming at the indoor positioning problem of robots,several common indoor robot positioning technologies are introduced,and their advantages and disadvantages are analyzed.Aiming at UWB positioning technology,its characteristics and indoor multipath model are described.(2)The indoor positioning methods of robot are analyzed.Four methods of sensor ranging are discussed,and the positioning geometry models based on them are described.According to the theoretical analysis,the positioning system based on RSSI method has low positioning accuracy in indoor environment.The positioning system based on AOA method needs large array antenna,which has complex hardware requirements and is not suitable for indoor multi-path dense environment.It is difficult to implement the positioning system based on TDOA.The system based on TOA method can give full play to the advantages of uwb signal bandwidth and improve the positioning accuracy.TOA method based on distance measurement is selected as the positioning method in this paper.Then,the two-way time-of-flight(TW-TOF)ranging technology suitable for UWB is demonstrated on the theoretical basis.(3)The three-dimensional positioning method of robot based on UWB radar is studied.Firstly,according to the principle of ranging and the geometric relationship of positioning,the three-dimensional positioning mathematical model of the system is established.Secondly,the research of localization algorithm is carried out by using non-linear least squares(NLS),Levenberg-Marquart(L-M)algorithm and weighted non-linear least squares(WNLS)algorithm.Three algorithms are used to solve the mathematical model of the positioning system established in this paper.For the three algorithms,a set of simulation data and two sets of real ranging data are used for MATLAB simulation analysis.According to the experimental results,the following conclusions can be drawn: L-M algorithm can obtain positioning accuracy similar to NLS algorithm,while WNLS algorithm can obtain better positioning accuracy than the above two algorithms.The number of iterations of the three algorithms is basically the same,and the number of iterations of WNLS is even less,so WNLS is the preferred positioning algorithm in system integration.