With an increased push for commercial autonomous cars, the demand of high speed systems capable of performing in unstructured driving environments is growing. In this thesis, the behavior of a bio-inspired predator prey model is considered to stimulate a more organic response to obstacles and a moving target than existing algorithms. However, the current predator prey model has a disconnect between the desired velocities commanded and the torque signals provided to the motors due the dynamics of the vehicle not accounted for. This causes the vehicle to derail from its intended trajectory at sharp turns. In this study, we start by adding dynamic behavior to the unicycle model to account for the varying dynamics of the vehicle. A backstepping algorithm is developed to connect the predator-prey model commanding desired velocities to an appropriate torque controller for the motors of the vehicle. To account for the unknown dynamic model parameters an adaptive control approach is utilized. Three different controllers are developed and evaluated. Out of the three, the indirect MRAC backstepping controller is deemed unsuitable due to its limitations with handling unknown parameter structure. The direct MRAC backstepping is deemed suitable and therefore simulated and implemented on the vehicle. The newly derived controller is able to overcome the disconnect and allow the vehicle to optimally track its trajectory for a velocity range of 1 m/s to 9 m/s despite varying dynamics. Lastly, the L1 adaptive backstepping controller is introduced and simulated to provide an alternative, more robust solution to the direct MRAC backstepping controller. / Master of Science

In this work, a unicycle system with reaction wheel is presented, considering the construction, the modeling, the design and test of the controllers. Firstly, a mechanical model considering a tridimensional computer aided design (3D CAD) is built in order to assist the construction and, after that, the modeling using the Lagrange method. In this work, linear controllers are designed and, therefore, the linearization of the system is done by the Jacobian, that is, assuming small variations around the equilibrium point. In this situation, there is no coupling between the pitch and the roll angles, thus resembling two inverted pendulums. The prototype is constructed by attaching the electronic components, the battery, the wheels and the motors to a body, to make it fully autonomous. The positioning of the parts has to balanced in order to maintain the position of the center of mass along the vertical and horizontal axis of symmetry. Then, a linear control project is done to stabilize the plant using two techniques that are validated considering simulations of the nonlinear coupled system. Then, the techniques were tested in the built prototype. The first one consists of the optimal LQR control that, although it worked, presented some problems due to parametric uncertainties. Therefore, the H2 control is used via LMI in such a way that the project becomes similar to the LQR, but in this way it is possible to insert parametric uncertainties and find a controller with some degree of robustness to them. / Neste trabalho, é apresentado um sistema de um monociclo com roda de reação, mostrando desde a construção, passando pela modelagem até o projeto e teste dos controladores. Primeiramente, é feito o projeto mecânico por meio de um desenho assistido por computador tridimensional (3D CAD), para auxiliar a construção e, em seguida, a modelagem por meio do método de Lagrange. Naturalmente, o sistema é não linear e os ângulos de arfagem e rolamento são acoplados. Neste trabalho, controladores lineares são projetados e, portanto, a linearização do sistema é feita pelo Jacobiano, ou seja, assumindo pequenas variações em torno do ponto de equilíbrio. Nesta situação, o modelo desacopla os ângulos de arfagem e rolamento. O protótipo é construído fixando os componentes eletrônicos, a bateria, as rodas e os motores a um corpo, de forma a ser totalmente autônomo. O posicionamento das peças precisa ser equilibrado, de forma a manter a posição do centro de massa ao longo dos eixos de simetria vertical e horizontal. Em seguida, é feito um projeto de controle linear para estabilização da planta usando duas técnicas que são validadas via simulações do sistema não linear acoplado. Depois, as técnicas são testadas no protótipo construído. A primeira consiste do controle ótimo LQR que, apesar de ter funcionado, apresentou alguns problemas devidos a incertezas paramétricas. Logo, é usado o controle H2 via LMI, de tal forma que o projeto equivalha ao LQR, mas desta forma é possível inserir incertezas paramétricas e achar um controlador com algum grau de robustez a elas.

In this work, a unicycle system with reaction wheel is presented, considering the construction, the modeling, the design and test of the controllers. Firstly, a mechanical model considering a tridimensional computer aided design (3D CAD) is built in order to assist the construction and, after that, the modeling using the Lagrange method. In this work, linear controllers are designed and, therefore, the linearization of the system is done by the Jacobian, that is, assuming small variations around the equilibrium point. In this situation, there is no coupling between the pitch and the roll angles, thus resembling two inverted pendulums. The prototype is constructed by attaching the electronic components, the battery, the wheels and the motors to a body, to make it fully autonomous. The positioning of the parts has to balanced in order to maintain the position of the center of mass along the vertical and horizontal axis of symmetry. Then, a linear control project is done to stabilize the plant using two techniques that are validated considering simulations of the nonlinear coupled system. Then, the techniques were tested in the built prototype. The first one consists of the optimal LQR control that, although it worked, presented some problems due to parametric uncertainties. Therefore, the H2 control is used via LMI in such a way that the project becomes similar to the LQR, but in this way it is possible to insert parametric uncertainties and find a controller with some degree of robustness to them. / Neste trabalho, é apresentado um sistema de um monociclo com roda de reação, mostrando desde a construção, passando pela modelagem até o projeto e teste dos controladores. Primeiramente, é feito o projeto mecânico por meio de um desenho assistido por computador tridimensional (3D CAD), para auxiliar a construção e, em seguida, a modelagem por meio do método de Lagrange. Naturalmente, o sistema é não linear e os ângulos de arfagem e rolamento são acoplados. Neste trabalho, controladores lineares são projetados e, portanto, a linearização do sistema é feita pelo Jacobiano, ou seja, assumindo pequenas variações em torno do ponto de equilíbrio. Nesta situação, o modelo desacopla os ângulos de arfagem e rolamento. O protótipo é construído fixando os componentes eletrônicos, a bateria, as rodas e os motores a um corpo, de forma a ser totalmente autônomo. O posicionamento das peças precisa ser equilibrado, de forma a manter a posição do centro de massa ao longo dos eixos de simetria vertical e horizontal. Em seguida, é feito um projeto de controle linear para estabilização da planta usando duas técnicas que são validadas via simulações do sistema não linear acoplado. Depois, as técnicas são testadas no protótipo construído. A primeira consiste do controle ótimo LQR que, apesar de ter funcionado, apresentou alguns problemas devidos a incertezas paramétricas. Logo, é usado o controle H2 via LMI, de tal forma que o projeto equivalha ao LQR, mas desta forma é possível inserir incertezas paramétricas e achar um controlador com algum grau de robustez a elas.

In the field of mobile robotics, many applications require feedback control laws that provide perfect path following. Previous work has shown that transverse feedback linearization is an effective approach to designing path following controllers that achieve perfect path following and path invariance. This thesis uses transverse feedback linearization and augments it with dynamic extension to present a framework for designing path following controllers for certain kinematic models of mobile robots. This approach can be used to design path following controllers for a large class of paths. While transverse feedback linearization makes the desired path attractive and invariant, dynamic extension allows the closed-loop system to achieve the desired motion along the path. In particular, dynamic extension can be used to make the mobile robot track a desired velocity or acceleration profile while moving along a path.

In the field of mobile robotics, many applications require feedback control laws that provide perfect path following. Previous work has shown that transverse feedback linearization is an effective approach to designing path following controllers that achieve perfect path following and path invariance. This thesis uses transverse feedback linearization and augments it with dynamic extension to present a framework for designing path following controllers for certain kinematic models of mobile robots. This approach can be used to design path following controllers for a large class of paths. While transverse feedback linearization makes the desired path attractive and invariant, dynamic extension allows the closed-loop system to achieve the desired motion along the path. In particular, dynamic extension can be used to make the mobile robot track a desired velocity or acceleration profile while moving along a path.

The usage of autonomous ground vehicles is growingextensively. Therefore, it is important to gain a better understand-ing for the fundamentals of their communication network. Inthis paper, three important areas will be considered: Trajectorytracking, formation control and collision avoidance. Firstly,trajectory tracking is implemented for unicycles to direct them toa reference path. Secondly, formation control is examined for twoapproaches: A method based on virtual structure with a presettrajectory for unicycles and a method based on displacement forpoint agents. Finally, collision avoidance is incorporated withthe displacement-based controller. For this case, agents keepformation without colliding within formation and with staticobstacles in the workspace. The proposed controllers are verifiedthrough simulations in MATLAB. / Användningen av autonoma markfordon har ökat kraftigt de senaste åren. Således är det viktigt att få en bättre förståelse för grunderna i deras kommunikationsnätverk. I detta projekt studeras tre essentiella områden: projektilspårning, formationshållning och undvikning av kollisioner. Först och främst implementeras projektilspårning för en enhjuling där den styrs mot en önskad projektilbana. Därefter betraktas formationshållning genom två metoder: Den första metoden handlar om virtuella strukturer med en förutbestämd bana för enhjulingar. Den andra metoden baseras på en förskjutningsbaserad regulator. Slutligen införs undvikning av kollisioner tillsammans med den förskjutningsbaserade regulatorn för att uppnå ett kollisionsundvikande robotsystem. Samtliga objektiv inom de tre områdena nås med varierande precision. / Kandidatexjobb i elektroteknik 2020, KTH, Stockholm

The master thesis deals with the issue of a single-wheeled robot, especially its construction and movement in more difficult terrain with the possibility of collecting samples. A variant of the robot balanced by a pair of gyroscopes was chosen as the most suitable construction. The robot is able to move in a space with an inclination of up to 24° and is equipped with its own manipulator design.