Nonlinear control of a ball and plate system with visual feedback

Abstract

The aim of this project was to investigate sliding mode control schemes on a ball and plate balancing system. The control challenge of the ball and plate problem is to balance a ball-or even make it track a desired trajectory-on a fiat plate, solely by tilting the plate relative to the horizontal plane. The problem is of particular interest to the control community because it is open-loop unstable and exhibits nonlinear and multivariable dynamics. Consequently, it is considered to be a standard control setup that is commonly used to demonstrate, test and validate various control methods. In this thesis, a detailed description is given on the design and implementation used to construct a novel ball and plate balancing system that is equipped with visual feedback. This is not a trivial task due to the challenges involved in constructing the actuation mechanisms required to rate the plate relative to the horizontal plane, and the difficulty in controlling the setup once it is built. Following a thorough literature review on the problem the research was then focused on the implementation and evaluation of two different control schemes: the linear full-state feedback controller and the sliding node controller. The sliding control strategy was selected due to its: • robust nature that can compensate for the nonlinear terms and parametric uncertainties present in the system. • order reduction property which reduces the complex system dynamics into simpler first-order stabilization problems. Then comparing the simulation and experimental results obtained by the two controllers, it was concluded that the sliding controller managed to obtain a faster and more accurate operation for continuously changing reference inputs. The robustness of the designed control scheme was also verified, since the system's performance was insensitive to model changes.