Research Of UWB Indoor Positioning Technology Based On TOA Scheme

As the requirement of indoor positioning continuing to increase, the research on UWB (Ultra-Wide Bandwidth, UWB) indoor location has become more and more important. UWB indoor positioning system usually has good communication and positioning performance. The time of arrival (TOA) scheme is one of the classic UWB positioning methods, and it can deal with ranging based on time. The indoor location schemes based on time need to realize time synchronization among positioning devices to achieve accurate positioning in the distance, which means this kind of schemes needs extra synchronization module in the system. Besides, the realization of precise synchronization can be very difficult, and the time synchronization module will consume more power.This paper proposes a TOA scheme without the time synchronization module. The location devices exchange time information by two-way ranging algorithm, and the sending and receiving timestamps are parts of the data frame. Through this way of communication, we can implement ranging and then positioning period. This paper completes the ranging process between a tag and an anchor based on decaWave1000 development board, and we realize positioning with improved location algorithm named iterating WLS estimating algorithm by using the results of ranging period. The experiments show that TOA scheme can achieve precise UWB positioning without time synchronizing. We can achieve positioning results by the accuracy of 10-30cm. Compared with the existing positioning scheme, this scheme reduces time synchronization module and then makes power consumption of the whole system lower. Besides, the improved localization algorithm makes the positioning system has better location and robustness performance. The main work of this paper includes the following aspects:(1) Analyze the current typical UWB positioning scheme including ranging algorithm and positioning algorithm, introduce major research aspects of UWB indoor location, and point out the positioning scheme based on time can achieve a good precision positioning performance without using time synchronizing.(2) Research the two-way ranging algorithm of TOA positioning scheme, describe the two stages of this algorithm and detailed communication process, show the the principle of ranging without time synchronizinion module by analyzing the frame structure.(3) Design the state machine of two-way ranging algorithm as an example, describe the working process of each device as well as the work done by each state, and realize the instance of state machine on decaWave1000.(4) Based on ranging results on the hardware platform, realize localization by Chan algorithm and Taylor algorithm, and compare the advantages and disadvantages of the two algorithms on accuracy and computation performance.(5) Propose an improved positioning algorithm called iterating WLS estimating algorithm based on WLS algorithm, and prove that the algorithm has higher positioning accuracy and robustness performance compared with classical algorithms.(6) Describe the hardware environment of TOA positioning system, and prove that the scheme can realize transmission ranging up to 150 m, stable positioning error between 10 cm ?30 cm and this scheme is a kind of positioning scheme of low power consumption and high precision with no need of time synchronization.