Mobile Robot Ultrasonic Indoor Positioning System Research

With technical development of information industry, Positioning System like GPS is widely used, but GPS is difficult to be utilized in an indoor environment. Meanwhile, personal service robot in indoor environment is in a great need. Localization is the basis for autonomous navigation, where a simple and affordable locatization system is neede. This thesis presented an Ultrasonic Indoor Positioning System to meet this demand.Firstly, this paper introduces a Time-of-Arrival based Ultrasonic Indoor Positioning System, where the Cayley-Menger bideterminant algorithm is adopted to solve the trilateration problem. An error analysis proved the effect of this method., a new structure for Time-Differences-of-Arrival based system is then presented to imitate the configuration of passive acoustic sensing. Parameters of a four-element cross array are determined through simulation results. Another positioning error analysis with the Extended Kalman Filter algorithm is undertaken to evaluate the error more precisely.To construct the Ultrasonic Indoor Positioning System, a robot mobile platform with three wheels, a Data acquisition card NI PCI-6115 and a control system were integrated together. According to the features of the ultrasonic transducers, signal sending and receiving circuits were designed and debugged. Finally, a beacon encoding method was desgned and analysed.To verify the feasibility of the system, some fundamental experiments were carried out in this work. The positioning error of the Time-of-Arrival based system and the Time-Differences-of-Arrival based system were both achieved. With the application of Extended Kalman Filter, the accuracy of Time-Differences-of Arrival based system was enhanced.