Nonlinear control of an autonomous vehicle

**Authors:**Mavungu, Masiala**Date:**2014-02-13**Subjects:**Nonlinear control theory , Automated guided vehicle systems**Type:**Thesis**Identifier:**uj:3999 , http://hdl.handle.net/10210/9355**Description:**M.Sc. (Mathematical Statistics) , This dissertation deals with the computation of nonlinear control strategies for an autonomous vehicle. The vehicle consists of two wheels attached to an axle. It is assumed that both wheels roll without slipping leading to nonholonomic constraints. A third order nonlinear kinematic model of the vehicle is derived from these constraints. It is further assumed that the vehicle has builtin feedback controllers independently regulating the rotational velocities of the wheels (using electric motors as actuators). Thus, the vehicle is maneuvered by applying a separate rotational velocity reference command to the feedback controller of each wheel. The closed loop system dynamics from the reference command to the wheel rotational velocity is approximately modelled by a first order system. This leads to a fifth order nonlinear state-space model for the vehicle. The above-mentioned reference commands constitute the control input variables of the vehicle model and are subject to amplitude constraints. Firstly, a methodology is developed for computing reference command strategies to drive the autonomous vehicle from a specified initial state to a desired final state in a given time and such that a circular obstacle is avoided. The vehicle performs the required maneuver whilst satisfying all the specifications and constraints. Secondly, feedback reference command laws are developed such that a specified point just ahead of the vehicle asymptotically tracks a given reference trajectory in the horizontal plane. The feedback control law steers the vehicle onto the reference path from any initial position and keeps it moving on the path. Thirdly, the stochastic system performance is evaluated when the above-mentioned tracking control strategy is applied and the initial state of the vehicle is a random vector.**Full Text:**

**Authors:**Mavungu, Masiala**Date:**2014-02-13**Subjects:**Nonlinear control theory , Automated guided vehicle systems**Type:**Thesis**Identifier:**uj:3999 , http://hdl.handle.net/10210/9355**Description:**M.Sc. (Mathematical Statistics) , This dissertation deals with the computation of nonlinear control strategies for an autonomous vehicle. The vehicle consists of two wheels attached to an axle. It is assumed that both wheels roll without slipping leading to nonholonomic constraints. A third order nonlinear kinematic model of the vehicle is derived from these constraints. It is further assumed that the vehicle has builtin feedback controllers independently regulating the rotational velocities of the wheels (using electric motors as actuators). Thus, the vehicle is maneuvered by applying a separate rotational velocity reference command to the feedback controller of each wheel. The closed loop system dynamics from the reference command to the wheel rotational velocity is approximately modelled by a first order system. This leads to a fifth order nonlinear state-space model for the vehicle. The above-mentioned reference commands constitute the control input variables of the vehicle model and are subject to amplitude constraints. Firstly, a methodology is developed for computing reference command strategies to drive the autonomous vehicle from a specified initial state to a desired final state in a given time and such that a circular obstacle is avoided. The vehicle performs the required maneuver whilst satisfying all the specifications and constraints. Secondly, feedback reference command laws are developed such that a specified point just ahead of the vehicle asymptotically tracks a given reference trajectory in the horizontal plane. The feedback control law steers the vehicle onto the reference path from any initial position and keeps it moving on the path. Thirdly, the stochastic system performance is evaluated when the above-mentioned tracking control strategy is applied and the initial state of the vehicle is a random vector.**Full Text:**

Nonlinear finite element program for reinforced concrete structural control

- Mushiri, Tawanda, Nyemba, Wilson R., Mbohwa, Charles

**Authors:**Mushiri, Tawanda , Nyemba, Wilson R. , Mbohwa, Charles**Date:**2016**Subjects:**Nonlinear control theory , Finite element method , Reinforced concrete - Quality control**Language:**English**Type:**Conference proceedings**Identifier:**http://hdl.handle.net/10210/217238 , uj:21615 , Citation: Mushiri, T., Nyemba, W.R & Mbohwa, C. 2016. Nonlinear finite element program for reinforced concrete structural control.**Description:**Abstract: Proprietary softwares are often used for structural control in engineering. Nonlinear structural control researches often uses nonlinear finite element toolbox (NLFET) code which was specifically developed for coding and simulations of structures. This paper provides an overview of the use of NLFET including the data structures and algorithms used to develop a nonlinear finite element program for reinforced concrete structural control. In order to make use of the nonlinear routines, powerful control and NLFET toolboxes, NFLET are implemented in MATLAB. The data of the structure is stored in MATLAB structures for maximum flexibility and to improve the readability of the code. Object oriented design is used to define element types so that new elements (both linear and nonlinear) can be added easily and without necessitating changes in the core analysis code. Solidworks was the software in this paper.**Full Text:**

**Authors:**Mushiri, Tawanda , Nyemba, Wilson R. , Mbohwa, Charles**Date:**2016**Subjects:**Nonlinear control theory , Finite element method , Reinforced concrete - Quality control**Language:**English**Type:**Conference proceedings**Identifier:**http://hdl.handle.net/10210/217238 , uj:21615 , Citation: Mushiri, T., Nyemba, W.R & Mbohwa, C. 2016. Nonlinear finite element program for reinforced concrete structural control.**Description:**Abstract: Proprietary softwares are often used for structural control in engineering. Nonlinear structural control researches often uses nonlinear finite element toolbox (NLFET) code which was specifically developed for coding and simulations of structures. This paper provides an overview of the use of NLFET including the data structures and algorithms used to develop a nonlinear finite element program for reinforced concrete structural control. In order to make use of the nonlinear routines, powerful control and NLFET toolboxes, NFLET are implemented in MATLAB. The data of the structure is stored in MATLAB structures for maximum flexibility and to improve the readability of the code. Object oriented design is used to define element types so that new elements (both linear and nonlinear) can be added easily and without necessitating changes in the core analysis code. Solidworks was the software in this paper.**Full Text:**

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