Control-Oriented LFT Modelling and H_∞ Control of Differentially Driven Wheeled Mobile Robot

Abstract

Wheeled mobile robot (WMR) is a versatile robotic platform with huge potential for widespread application in various sectors like delivery and handling material, home and office service, edutainment, surveillance, rescue operations, etc. ( C. C. Ward and K. Iagnemma, “Model-Based Wheel Slip Detection for Outdoor Mobile Robots,” in Proc. of IEEE International Conference on Robotics and Automation, pp. 2724–2729, April 10–14, 2007.). In most of the applications, WMR is expected to have high-speed interaction for the high degree of autonomy in a structured and unstructured environment. The control law which is to be implemented in the WMR should be robust enough to handle the system uncertainties in the presence of disturbance and noise ( N. Nawash, “H-Infinity Control of an Autonomous Mobile Robot,” Master of Science Thesis, Cleveland State University, Electrical Engineering Dept. 2005.). Various sub-systems of the WMR like sensors, actuators, controller power supply unit, wire and wireless communication links are interconnected in a delicate manner to perform the specific task. The complete dynamic model of the system is very much complicated due to the presence of cross-coupled dynamics, gravitational forces, friction force, slippage, drag force and various nonlinearities. Moreover, the presence of internal and external disturbances, noise and uncertain dynamic forces makes the overall dynamic model quite complex ( N. Nawash, “H-Infinity Control of an Autonomous Mobile Robot,” Master of Science Thesis, Cleveland State University, Electrical Engineering Dept. 2005.; M. Nitulescu, “Theoretical Aspects in Wheeled Mobile Robot Control,” in Proc. IEEE International Conference on automation, Quality and testing, Robotics, vol. 2, pp. 331–336, May 22–25, 2008.; M. M. Yamamoto, D.P.F. Pedrosa, and A. A. D. Medeiros, “Um simuladordiâmico para-mini robôsmôveis com modelagemcolisões,” In SBAI - SimpósiosBrasileiro de AutomacãoInteligente, Bauru, SP, Brazil, 2003. ( Portuguese).;). As demand increases, the performance of the WMR is steadily improved by deriving the appropriate mathematical modelling by incorporating all possible uncertainties into the system model ( S. N. Sidek, Dynamic Modelling and Control of Nonholonomic Wheeled Mobile Robot Subjected to Wheel Slip’, PhD Thesis, Graduate School of Vanderbilt University, Electrical Engineering Dept., 2008.).