Trajectory Tracking Control of Omnidirectional Automated Guided Vehicles Using Laser Sensor

Abstract

Today, Automated Guided Vehicles (AGVs) are used in many factories and modern hospital. Automated guided vehicle (AGV) applications in the automotive industry include automated raw material delivery, automated work in process move-ments between manufacturing cells, finished goods transport, etc. Omnidirectional AGV (OAGV) is one of principal requirement for AGVs designed for health gen-eral-hospital services. This dissertation is about control of OAGV for tracking a trajectory using laser sensor. The OAGV consists of three independent driving omnidirectional wheels which equally are spaced at 1200 from one another. In this dissertation, the following five problems are considered. First, a structure of the OAGV used for experiment is proposed. A real OAGV system is developed with several interconnected devices such industrial computer as main controller, monitor, keyboard, mouse, DC servo drivers, etc. A laser sensor device NAV-200 is used to detect the OAGV posture in indoor environment in real time. Second, mathematical modelings of the OAGV with three driving omnidirec-tional wheels in the presence of disturbance and friction with unknown parameter are presented. A kinematic modeling of OAGV under its center of gravity coincident with its geometric center is presented and called as kinematic modeling 1 of OAGV and a dynamic modeling of the OAGV under bounded uncertain friction and slip disturbance force vector is presented and called as dynamic modeling 1 of OAGV. A kinematic modeling and a dynamic modeling of the OAGV under its center of gravi-ty different from its geometric center and step change of mass due to load change without disturbance are presented and called as kinematic modeling 2 and dynamic modeling 2, respectively. Third, based on the kinematic modeling 1 of OAGV, a decentralized algorithm for motion control of OAGV is introduced. Using the proposed decentralized algo-rithm, a trajectory tracking controller based on PD fuzzy logic is proposed. Firstly, the posture of OAGV including position and orientation is measured using laser-based localization sensor. Secondly, from the measured posture and the desired pos-ture, a posture error is defined. Thirdly, based on the posture error, a decentralized control strategy based on PD fuzzy controller is developed for OAGV to track a de-sired curved path at a given bounded velocity. The effectiveness of the developed decentralized algorithm and the proposed trajectory tracking control strategy are demonstrated through simulations and experiments. Fourth, based on the dynamic modeling 1 of the OAGV system, an adaptive con-troller is designed for simultaneous stabilization and trajectory tracking such that OAGV follows a reference trajectory with sharp edges. The system stability is guar-anteed by the Lyapunov stability theory. The simulation and experimental result are presented to illustrate the effectiveness of the proposed tracking controller. Finally, based on the kinematic modeling 2 and dynamic modeling 2 of the OAGV, an adaptive sliding mode controller and an update law are designed for OAGV to track a reference trajectory with 2 curved lines and 3 straight lines. The system stability is guaranteed by the Lyapunov stability theory. Simulation and ex-perimental results are presented to demonstrate the effectiveness of the proposed controller and the update law. Keywords: Omnidirectional Automatic Guided Vehicle (OAGV), Omnidirec-tional Wheels, Three Wheels, Decentralized Algorithm, PD Fuzzy Controller, Center of Mass, Load Change, Adaptive Control Theory.