Study On Several Problems Of A Spherical Rolling Robot

Spherical rolling robot is an important branch of mobile robot.As a kind of new mobile robot with spherical outline,spherical rolling robot has the characteristics of strong anti-external interference ability,flexible walking through rolling,ideal turning radius being zero,no instability,and driving components and control elements configured in the spherical shell.Recently,not only spherical rolling robots have changed from the original conception to reality,but also robot prototypes with multiple internal configurations have been developed.Spherical rolling robot has strong adaptability to complex physical environment,which obtains practical applications in many fields and has high application value.However,the existing pendulum-driven spherical rolling robot has limited driving torque,poor motion sealing,immature dynamic modeling and high difficulty of motion control.According to these problems,this thesis proposes a dual-drive,single-pendulum spherical rolling robot with good motion sealing,large driving moment and omnidirectional motion capability,which can be applied in environmental detection,indoor and outdoor patrol inspection,post-disaster search and rescue.The mechanical structure design,kinematics and dynamics modeling,and trajectory tracking controller design are studied respectively in this thesis.This thesis mainly focuses on the following main research contents:Firstly,the configuration of the existing spherical rolling robot is analyzed,and according to the eccentric moment driving principle,a dual-drive and single-pendulum spherical rolling robot is proposed.The spherical rolling robot is mainly composed of the spherical shell,the main beam,and the pendulum,which can realize omnidirectional rolling movement under the action of the lateral driving motor and the longitudinal driving motor.The key parts including the spherical shell,main beam,pendulum,driving device,and transmission mechanism are designed and selected respectively,and the climbing ability and obstacle surmounting ability of the spherical rolling robot are analyzed to verify the correctness of the theoretical design.Secondly,for the ground rolling motion of the spherical rolling robot,the nonholonomic motion constraint equation and the spatial multi rigid body dynamics model of the spherical rolling robot are established respectively.Reasonable assumptions are made for the actual robot system according to the mechanical structure characteristics of the robot,and a simplified model of the multi rigid body system is established when the spherical rolling robot rolling on the horizontal ground.The nonholonomic constraint equation of the plate-ball system is derived when the spherical rolling robot moving on the horizontal ground.The kinetic energy and potential energy of the homogeneous symmetric thin spherical shell,the symmetric main beam and the pendulum articulated on the main beam are calculated respectively,and the multi rigid body dynamics model of the spherical rolling robot system is derived using reasonable simplification and the Lagrangian equation with constraint multiplier.Finally,a trajectory tracking controller based on generalized super-twisting second-order sliding mode disturbance observer and double power reaching law is proposed for the trajectory tracking problem of the spherical rolling robot.The sliding variable of the controlled robot system is designed according to the control target of the robot system trajectory tracking.According to the designed sliding variable,the auxiliary sliding variable of the system is defined.According to the defined auxiliary sliding variable,a continuous generalized super-twisting second-order sliding mode disturbance observer is designed to accurately estimate the system uncertainty.According to the designed sliding mode disturbance observer,the trajectory tracking controller is designed using double power reaching law.The simulation experiments of linear and circular trajectory tracking control of the spherical rolling robot is taken using MATLAB,and the simulation results verify the effectiveness of the proposed trajectory tracking control algorithm.