Single wheel robot: gyroscopical stabilization on ground and on incline.

by Loi-Wah Sun.Thesis (M.Phil.)--Chinese University of Hong Kong, 2000.Includes bibliographical references (leaves 77-81).Abstracts in English and Chinese.Abstract --- p.iAcknowledgments --- p.iiiContents --- p.vList of Figures --- p.viiList of Tables --- p.viiiChapter 1 --- Introduction --- p.1Chapter 1.1 --- Motivation --- p.1Chapter 1.1.1 --- Literature review --- p.2Chapter 1.1.2 --- Gyroscopic precession --- p.5Chapter 1.2 --- Thesis overview --- p.7Chapter 2 --- Dynamics of the robot on ground --- p.9Chapter 2.1 --- System model re-derivation --- p.10Chapter 2.1.1 --- Linearized model --- p.15Chapter 2.2 --- A state feedback control --- p.16Chapter 2.3 --- Dynamic characteristics of the system --- p.18Chapter 2.4 --- Simulation study --- p.19Chapter 2.4.1 --- The self-stabilizing dynamics effect of the single wheel robot --- p.21Chapter 2.4.2 --- The Tilting effect of flywheel on the robot --- p.23Chapter 2.5 --- Dynamic parameters analysis --- p.25Chapter 2.5.1 --- Swinging pendulum --- p.25Chapter 2.5.2 --- Analysis of radius ratios --- p.27Chapter 2.5.3 --- Analysis of mass ratios --- p.30Chapter 3 --- Dynamics of the robot on incline --- p.33Chapter 3.1 --- Modeling of rolling disk on incline --- p.33Chapter 3.1.1 --- Disk rolls up on an inclined plane --- p.37Chapter 3.2 --- Modeling of single wheel robot on incline --- p.39Chapter 3.2.1 --- Kinematic constraints --- p.40Chapter 3.2.2 --- Equations of motion --- p.41Chapter 3.2.3 --- Model simplification --- p.43Chapter 3.2.4 --- Linearized model --- p.46Chapter 4 --- Control of the robot on incline --- p.47Chapter 4.1 --- A state feedback control --- p.47Chapter 4.1.1 --- Simulation study --- p.49Chapter 4.2 --- Backstepping-based control --- p.51Chapter 4.2.1 --- Simulation study --- p.53Chapter 4.2.2 --- The effect of the spinning rate of flywheel --- p.56Chapter 4.2.3 --- Simulation study --- p.58Chapter 4.2.4 --- Roll up case --- p.58Chapter 4.2.5 --- Roll down case --- p.58Chapter 5 --- Motion planning --- p.61Chapter 5.1 --- Performance index --- p.61Chapter 5.2 --- Condition of rolling up --- p.62Chapter 5.3 --- Motion planning of rolling Up --- p.65Chapter 5.3.1 --- Method I : Orientation change --- p.65Chapter 5.3.2 --- Method II : Change the initial velocities --- p.69Chapter 5.4 --- Wheel rolls Down --- p.70Chapter 5.4.1 --- Terminal velocity of rolling body down --- p.73Chapter 6 --- Summary --- p.75Chapter 6.1 --- Contributions --- p.75Chapter 6.2 --- Future Works --- p.76Bibliography --- p.7

Design, construction, and experiments with a compass gait walking robot

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2011.Cataloged from PDF version of thesis.Includes bibliographical references (p. 91-93).In recent years a number of new computational techniques for the control of nonlinear and underactuated systems have been developed and tested largely in theory and simulation. In order to better understand how these new tools are applied to real systems and to expose areas where the theory is lacking testing on a physical model system is necessary. In this thesis a human scale, free walking, planar bipedal walking robot is designed and several of these new control techniques are tested. These include system identification via simulation error optimization, simulation based LQR-Trees, and transverse stabilization of trajectories. Emphasis is put on the topics of designing highly dynamic robots, practical considerations in implementation of these advanced control strategies, and exploring where these techniques need additional development.by Zachary J Jackowski.S.M

Conception d’un quadrirotor à rotors inclinables pour le suivi de trajectoires agressives

RÉSUMÉ Les quadrirotors sont des plateformes robotiques aériennes peu coûteuses et agiles. Plusieurs applications sont envisageables avec ces robots tels que l’exploration des mines ou les opérations de reconnaissance et sauvetage. Ces missions nécessitent de naviguer dans des environnements encombrés et imprédictibles. Le véhicule utilisé doit pouvoir éviter rapidement des obstacles tout en circulant à haute vitesse. Le quadrirotor étant sous-actionné est limité dans son agressivité puisqu’il doit s’incliner avant d’accélérer. De plus, les contrôleurs conventionnels utilisés ne prédisent pas le comportement qu’aura le véhicule durant la trajectoire en utilisant sa dynamique ce qui l’empêche de planifier assidument les manœuvres complexes. Dans ce contexte, l’objectif principal de ce mémoire est de s’affranchir de ces deux limitations en développant un quadrirotor capable d’incliner ses moteurs pour accélérer plus rapidement et d’utiliser un contrôleur prédictif pour le suivi de trajectoire. Plus spécifiquement, une modification au design conventionnel du quadrirotor est proposée par l’ajout d’un seul actuateur pour permettre des manœuvres agressives dans un seul axe. Puis, un ILQR qui est un contrôleur prédictif sans optimisation numérique, est développé. Celui-ci tient compte de l’état à jour du quadrirotor pour la linéarisation et la résolution du problème de contrôle optimal. En premier lieu, le modèle dynamique du quadrirotor à moteurs inclinables est présenté. Puis, une loi de contrôle basé sur un schéma de contrôle en cascade avec une boucle régulant la dynamique en translation à l’aide d’un ILQR et une autre la dynamique en rotation avec un régulateur PD sont implémentées. Ensuite, la solution proposée est testée en simulation et comparée aux approches conventionnelles tant en termes de conception mécanique qu’en asservissement. L’erreur en suivi de trajectoire est diminuée de plus de 1483% avec un impact supérieur de l’ajout de l’inclinaison des moteurs. Enfin, un prototype expérimental est conçu avec des pièces électroniques et mécaniques standards et largement accessibles. La différence entre le design conventionnel et le quadrirotor à moteurs inclinables est étudiée sur des trajectoires agressives. L’erreur diminue de plus de 26% avec l’ajout d’un actionneur alors qu’en simulation pour la même trajectoire l’erreur diminue de 38% ce qui indique que la même tendance est conservée.----------ABSTRACT Quadrotors are cost-effective and agile aerial robotic platforms. Numerous applications are possible with these robots like mines exploration or search and rescue operations. Nevertheless, these missions require navigating through cluttered and unpredictable environments. The vehicle used for these operations must be able to avoid newly located obstacles fast while travelling at high speeds for time critical missions. Quadrotors are underactuated systems and therefore limited in their overall maneuvers because they need to tilt their whole body before accelerating in a direction. Also, conventional controllers used with these systems don’t predict the behavior of the vehicle during a trajectory by using the systems dynamics which prevents them from planning diligently complex maneuvers. In this context, the main objective of this master thesis is to mitigate these two limitations by developing a quadrotor able to tilt his motors thrust to accelerate faster and to use a predictive controller for the trajectory tracking problem. Specifically, a modification to the conventional quadrotor mechanical system is proposed by adding a single actuator to enable aggressive motions in a single axis. Then, an ILQR, which is a predictive controller and does not require parameter optimization, is developed. The latter is a state- dependent controller who behaves as a nonlinear controller by considering the known updated state of the vehicle to solve the optimal control problem. First, the dynamic model of the quadrotor with tilting motors is found. Then, a control law based on a cascade control scheme with a loop for the translational dynamics regulated by an ILQR controller and another loop for the rotational dynamics with a PD controller is implemented. Afterwards, the proposed solution is tested in simulations and compared with conventional approaches in terms of mechanical design and control. Trajectory tracking error is reduced by more than 1483% with the tilting motors modification having a superior impact on performance. Finally, an experimental prototype is designed with standard electronic and mechanical pieces available off-the-shelf. The difference between the conventional design and the quadrotor with tilting motors is studied on this custom-made quadrotor on aggressive trajectories. The error has decreased by more than 26% by adding an actuator while in simulation for the same trajectory this error decrease by 38% which indicates that the same trend is maintained

Preserving the Planar Dynamics of a CompliantBipedal Robot with a Yaw-Stabilizing Foot Design

The ATRIAS agile humanoid robot, along with a number of other spring-mass walking machines, currently have two instabilities: one resulting from inertial forces on the torso which cause the robot to spin like a top, and another resulting from stiff ground collisions which cause chattering of the point-contact toes. This thesis presents a solution to these two problems in a manner consistent with the exacting design philosophy of springmass walking machines. A passive, compliant, line-contact foot is proposed with only 120 grams of added mass and a fully-adjustable return mechanism

Large space structures and systems in the space station era: A bibliography with indexes (supplement 05)

Bibliographies and abstracts are listed for 1363 reports, articles, and other documents introduced into the NASA scientific and technical information system between January 1, 1991 and July 31, 1992. Topics covered include technology development and mission design according to system, interactive analysis and design, structural and thermal analysis and design, structural concepts and control systems, electronics, advanced materials, assembly concepts, propulsion and solar power satellite systems

Sensitivity Studies on Offshore Submarine Hoses on CALM Buoy with Comparisons for Chinese‑Lantern and Lazy‑S Configuration:OMAE2019‑96755

With more developments into cost-effective offshore designs, the application of offshore hoses has been adapted for water depths that are not too deep, and for short-service life platforms. This has led to the advances on offloading and loading operations in the offshore industry based on the utilization of Catenary Anchor Leg Moorings (CALM) buoys. However variations in the soil stiffness and environmental conditions necessitates the investigation on the behaviour of the submarine hoses based on the structural and hydrodynamic behaviour. The sensitivity study will help hose manufacturers in the problem of submarine hose failures due to high curvatures. In this study, dynamic analysis is carried out based on the design of the submarine hoses attached to a CALM buoy for both cases of the Chinese-lantern configuration and Lazy-S configurations. Six mooring lines are attached to the CALM buoy with a water depth of 26 m and 100 m, respectively. Hydrodynamic simulation using ANSYS AQWA is first conducted and later coupled into the dynamic models in Orcaflex. Sensitivity studies were conducted to study the effect of wave height, flow angles, soil stiffness and hose hydrodynamic loads on the structural behaviour of the submarine hoses