Dynamics and Control of Inertially Actuated Maneuvers and Locomotion of Robotic Systems.

摘要

Inertially actuated robots belong to a class of systems that use transfer of momentum to progress in space and time. This momentum is usually generated by spinning masses, disks, or wheels. Despite the simple actuation mechanism, these systems are usually difficult to analyze since their equations of motion involve many nonlinear terms. In addition, inertially actuated systems are under-actuated systems dealing with singularities in mapping between joint and Cartesian spaces. Therefore, nonlinear control design approaches fail in directly controlling the displacements of such systems. Hence, for generating locomotion and maneuvers indirect control alternatives should be considered.;Recent research studies in the System Laboratory at SMU established that a wide range of inertially actuated locomotion systems can be generated. This dissertation is devoted to studying the dynamics and control of inertially actuated robotic systems. Three different robots are presented; Pivot Walker Robot, Bouncing Robot, and Wheeled Baton Robot. The work done in this thesis is significant since, to the best of our knowledge, no previous work that addresses the use inertial actuation in generating maneuvers and locomotion of mobile robots has been conducted.;First, the Pivot Walker robot is studied. The Pivot Walker robot is a three-dimensional inertially actuated robot that is equipped with two independently spinning masses. The research objective is to develop an control scheme to steer the robot on a given desired path in the horizontal plane. This work presents a mathematical framework for accessibility and controllability assessment of the general nonlinear systems. The study establishes the critical role of the surface friction plays in generating locomotion. Also, a non-singular control alternative is proposed based on angular progression, which is called "pivot walking". The corresponding locomotion is composed on successive pivoted steps that enables the robot to follow a desired path in the horizontal plane. In this regard, a Trajectory Generation Algorithm is developed to convert the desired path to a set of locomotion parameters in order to steer the robot along the trajectory. Finally, a prototype is built to experimentally verify the theoretical concepts. The experimental prototype implements a gravitational pivot switching mechanism to switch the pivot joint position as required by the pivot walking locomotion.;Following the successful inertially actuated locomotion in the horizontal plane, an inertially actuated jumper robot is studied. The Bouncing Robot is an inertially actuated mass-spring system in the vertical plane. The robot is composed of a main mass, spring and two spinners connected to the main mass. The research objective is to find a control scheme leading to a periodic jump of the main mass. In this regard, a nonlinear adaptive controller is developed to drive the system toward a periodic orbit in the state space. Furthermore, it is shown that the control successfully steers the system's trajectory to an asymptotically stable limit cycle. Methods of Poincare Mapping and Floquet Basic Theory are used for verification of the existence and stability of the corresponding limit cycles. The work studies the effect of control and system parameters changes of limit cycle and its stability. Finally, an experimental prototype is built to verify the practical utility of the presented theoretical methods and concepts.;In the third work, the combination of wheeled transportation and inertial actuation is studied. The Wheeled Baton is an inertially actuated wheeled system in the vertical plane. The main advantage of this system is not that it can only function as a simple wheeled vehicle, but it can also operate in many other dynamic modes. The wheels of the vehicle can be used to produce inertial effects that enables the robot to perform high mobility maneuvers and aerial acrobatics. This system has also the unique ability to perform locomotive and non-locomotive tasks on very low friction surfaces. In this regard, different modes of motion of the system are identified. Also, the actuation torque schedules are defined analytically in order to provide different modes of transition. Several numerical simulation cases are conducted to verify the validity of the proposed ideas and concepts. They show that the robot can perform different locomotions and maneuvers, which are not impossible for wheeled transportation.;All in all, these works show that the inertially actuation is successful in generating the robotic locomotion and maneuvers. In addition, it is shown that the inertial actuation needs some sort of external forces, e.g. friction force, spring force, etc, to accomplish progression in space and time.