Study On Control Methodology For The Slope Motion Of A Spherical Robot

Spherical robot has wide application prospect in national defense, industry and planetary exploration fields, due to its advantage of compact structure and dexterous motion with no tipping over during its rolling process. Spherical robot inevitably encounters such situations as climbing slopes in practical applications, and climbing ability has become one of the important indexes to measure the motion performance of a spherical robot. On the other hand, the contact between the shell of a spherical robot and its rolling surface can be approximately characterized as a point contact, which makes its motion control problem become one of the most difficult aspects to take theoretical and technical research on spherical robot. Therefore, the dynamics and control problems of the slope motion of a spherical robot are deeply studied in this thesis, and the following aspects are contained in this thesis.Firstly, the planar and spatial dynamics of the slope motion are derived for the two locomotion forms of the spherical robot. The dynamic model of the climbing motion is established by utilizing the Lagrangian formulation, based on which the equilibrium condition of the climbing motion is analyzed and the state space model of the robotic system is derived. The spatial dynamic model of the spherical shell and the multibody dynamic model of the spherical robot are established respectively by utilizing the constrained Lagrange formulation, based on which the state space representation of each system is given.Secondly, the position and velocity control problems of the climbing motion are studied based on the planar dynamic model, under the condition that the inclination of the slope is known. An adaptive decoupled sliding mode controller and an adaptive hierarchical sliding mode controller are proposed respectively for position control of the climbing motion. An adaptive hierarchical sliding mode controller is proposed for velocity control of the climbing motion. The stability analysis of the proposed controllers, along with simulation and experimental studies is carried out.Thirdly, the position control problem of the climbing motion is studied based on the planar dynamic model, under the condition that the inclination of the slope is unknown. An adaptive neural network sliding mode controller and an adaptive fuzzy sliding mode controller are proposed respectively for position control of the climbing motion. The stability analysis of the proposed controllers, along with simulation and experimental studies is carried out.Fourthly, the set-point control problem of the slope motion is studied based on the spatial dynamics of the rolling spherical shell, under the condition that the inclination of the slope is unknown. An adaptive backstepping sliding mode controller and a model reference adaptive sliding mode controller are proposed respectively for set-point control of the slope motion. The stability analysis of the proposed controllers, along with simulation and experimental studies is carried out.Fifthly, the trajectory tracking problem of the slope motion is studied based on the spatial dynamics of the rolling spherical shell. An input-output feedback linearization controller and an adaptive sliding mode controller are proposed respectively for trajectory tracking control of the slope motion. The stability analysis of the proposed controllers, along with simulation and experimental studies is carried out.Finally, the path tracking problem of the slope motion is studied based on the spatial dynamics of the rolling spherical shell. An input-output feedback linearization controller and an adaptive sliding mode controller are proposed respectively for path tracking control of the slope motion. The stability analysis of the proposed controllers, along with simulation and experimental studies is carried out.