The development, implementation, and testing of a leader-follower based robust nonlinear formation controller is discussed in this thesis. This controller uses sliding mode control on the length and angle between the leader and follower vessels to produce the desired formation. A boat model, assuming planar motion (three degrees of freedom), is used as the bases for the controller. Open loop testing is performed to determine parameter values to match the simulation model to the physical one and, upon tuning of the controller to match, closed loop testing of the controller with a virtual leader is also performed. From these tests it is found that the controller is unstable, thus improvements to the controller, through changes made to the model and to the parameter identification process, are undertaken. Simulations comparing the initial and updated models of the vehicle to open loop data show an improvement in the new model.

Thesis (Ph. D.)--Ohio State University, 2006. / Title from first page of PDF file. Includes bibliographical references (p. 172-178).

Based on the Lyapunov stability theorem, a methodology of designing an adaptive sliding mode control (ASMC) scheme is proposed in this thesis for a class of linear dynamic systems with matched and mismatched perturbations. Firstly, by utilizing a pseudo control input in the design of a novel sliding surface function, one can not only suppress the mismatched perturbations in the sliding mode, but also achieve the objective of output tracking. In addition, the accuracy of output tracking can be adjusted through the designed parameter embedded in this pseudo controller. Then, a sliding mode controller is derived to guarantee the existence of the sliding mode in a finite time by using adaptive mechanism, which is used to overcome the lumped perturbations so that the upper bound of perturbations is not required. Finally, two illustrative examples are given to demonstrate the validity of the results.

No description available.

No description available.

Thesis (Ph. D.)--Ohio State University, 2007. / Title from first page of PDF file. Includes bibliographical references (p. 131-136).

No description available.

No description available.

Servo control of pneumatic actuators is difficult due to the high compressibility and non-linear flow of air. Friction as well as uncertainties in the parameters and model character-izing dynamics of the pneumatic systems further contribute to control challenges. These drawbacks cause stick-slip motion, larger tracking error and limit cycles, which degrades the control performances. Selection of a controller that satisfies requirements of the per-forming tasks is thus crucial in servo-pneumatic applications. This thesis focuses on the design and experimental evaluation of a model-based, nonlinear controller known as Dy-namical Adaptive Backstepping-Sliding Mode Control (DAB-SMC). Originally designed for chemical process control and applied only in simulations, the DAB-SMC is adopted in this thesis and applied to the new area of servo-pneumatic control of a single-rod, double acting pneumatic cylinder and antagonistic pneumatic artificial muscles (PAMs). The con-troller is further enhanced by augmenting it with LuGre-based friction observers to com-pensate the adverse frictional effect presents in both actuators. Unlike other research works, the actuators are subject to a varying load that influences control operations in two different modes: motion assisting or resisting. The implementation of DAB-SMC for such servo-pneumatic control application is novel. The mass flow rates of compressed air into and out of the actuators are regulated using one of the following valve configurations: a 5/3-way proportional directional valve, two 3/2-way or four 2/2-way Pulse Width Modu-lation (PWM)-controlled valves. Over the entire range of experiments which involve vari-ous operating conditions, the DAB-SMC is observed to track and regulate the reference input trajectories successfully and in a stable manner. Average root mean square error (RMSE) values of tracking for cylinder and PAMs when the compressed air is regulated using the 5/3-way proportional valve are 1.73mm and 0.10°, respectively. In case of regu-lation, the average steady-state error (SSE) values are 0.71mm and 0.04°, respectively. The DAB-SMC exhibits better control performance than the standard PID and classical SMC by at least 33%. The DAB-SMC also demonstrates robustness for up to 78% in un-certainty of load parameter. When the control valve is replaced by the PWM-controlled valves of 3/2-way and 2/2-way configurations, performance is slightly compromised. / May 2016

Orientador: José Paulo Fernandes Garcia / Banca: Laurence Duarte Colvara / Banca: Ivan Nunes da Silva / Resumo: O enfoque principal do trabalho foi dado ao Controle Discreto com Modos Deslizantes(CDMD) aplicado em sistemas que possuem atraso no processamento do sinal de controle e acesso somente à saída do sistema. A estratégia de controle tem por objetivo a utilização de técnicas de controle com modos deslizantes para a elaboração de uma lei de controle simples e robusta às incertezas da planta e ao atraso. O observador de estados apresentado possui características de modo deslizante, o qual realiza a estimação robusta do vetor de estados que na maioria dos casos práticos não é totalmente acessível. Os métodos de projetos propostos podem ser aplicados no controle de plantas estáveis ou instáveis com atraso no sinal de controle e acesso somente à saída da planta. Para comprovar a eficiência dos projetos apresentados neste trabalho, analisou-se o controlador atuando com acesso a todos estados e o controlador atuando juntamente com o observador robusto para a estimação dos estados. Os resultados foram obtidos através de simulações no Sistema Bola e Viga, Sistema Pêndulo Invertido Linear e Sistema Pêndulo Invertido Rotacional que são exemplos de plantas de natureza instável. / Abstract: The main focus was placed on the Discrete Sliding Mode Control (DSMC) applied to systems that have a delay in the processing of the control signal and access to the system output only. The control strategy is intended to use control techniques of sliding modes to elaborate a simple and robust control law against the uncertainties of the plant and the delay. The states observer presented has the characteristics of a sliding mode, which performs the robust estimation of the states vector that, in most practical cases, is not fully accessible. The design methods proposed may be applied to the control of stable or unstable plants with delay on the control signal and access to the plant output only. In order to attest the efficiency of the design presented in this work, the controller was analyzed at work with access to all states and jointly with the robust observer to estimate the states. The results were obtained by means of simulations in the Ball and Beam System, Linear Inverted Pendulum System, and Rotational Inverted Pendulum System, which are examples of plants of unstable nature. / Mestre