Theory and prediction of position error for automated guided vehicles with ultrasonic sensing based on time-of-flight theory

摘要

Automated Guided Vehicles (AGVs) are based on a physical track system that greatly limits the ability of the AGV to adapt to changing needs. If the physical track system could be replaced with a trackless AGV, its flexibility could be greatly enhanced. For an AGV to navigate to a known position by trackless means, it should have the capability to locate its own position relative to a global position;This research utilized an ultrasonic distance measurement system based on time-off-light theory to estimate AGV triangulation position. This study also focused on an adaptive navigation and control system that would situate the AGV at any arbitrary position and with an arbitrary two-dimensional attitude. Absolute navigation and control instructions were based on simple control command statements;The absolute navigational algorithm was designed to navigate the AGV with the least possible deviation from a specified path. With the adaptive approach, the AGV can correct its ground track before an unacceptable position error has occurred. A statistical study based on distance and position error, their correlation, and the predicted position error was necessary to test the performance of the new trackless system;To validate this approach, the trackless method was compared with the existing tracked navigation system from several aspects including the duration of ground track completion time. The results from the test runs gave a good insight into the trackless AGV navigation system and the corresponding position error.