Magnetic Field-based Navigation of a Mobile Robot

Abstract

This thesis explores a unique system and method to control the position of a remote vehicle. A handheld cylindrical transmitter generates an alternating dipole field at a specific frequency. A self-contained robot utilizes three loop antennas mounted in each of the Cartesian axes to continually determine its position in the dipole field. The vehicle then maneuvers to maintain a specific positional relationship along the transmitter's axis. Since the robot's movement is determined by magnetic field sensing, there is no line-of-sight requirement. The robot's position can be maintained in the dark and behind walls as easily as in a bright open room. The system can be divided into four subsystems: the transmitter, the receiving electronics, the microcontroller and its decisions, and the mobile platform, with the latter three comprising the robot. The transmitter radiates the dipole field by passing an AC signal through a solenoid antenna. This field is detected, filtered, and amplified using a microprocessor-based automatic gain control. The microcontroller uses field information to control robot movement. Each subsystem is discussed in length, with detailed theory presented in the Appendices. The control methods presented in this thesis are proven not only by the underlying theory but also by operation of a successful embodiment. The embodiment employs simple electronics to perform all necessary processes while avoiding the use of expensive components. Example photos, schematics, software source code, and mechanical design are discussed in such detail that the reader may reproduce the working system. Suggested improvements and alternative embodiments are presented to encourage extension of this technology to more practical applications.