Research On Motion Analysis And Control Techonology Of A Spherical Mobile Robot

The advantage of the spherical mobile robot includes high maneuverability, and that the robot can resume stability even if a collision happened with the other obstacles. So it is very suitable to be used in those environments, such as industrial building, civil application, defense construction and space exploration domain. But, till now, because of the feature of the point contact between the spherical shell and the ground, there are no effective methods that can sovle the problems about the motion analysis and control techonology of a spherical mobile robot, which prevents further research and application of the robot. So, in order to sovle these problems, this thesis discusses deeply the motion analysis and control techonology of the robot. The following aspects are contained in this thesis.Firstly, based on the Euler-Lagrangian method, the dynamics model of the spherical mobile robot was developed, treated by reduced-order and transformed to normal nonlinear system using coordinate and input control transformation. Then, the double loop linear motion control strategy was designed. The problem of the dynamic equilibrium was proposed, and the dynamics models of the planar motion were developed in the case of uniform and uneven of the shell's mass distribution, respectively. Then, using the partial linearization method, both of the two models were transformed to cascade nonlinear systems with non-triangular and triangular normal form, respectively. Moreover, the dynamic balance controllers with exponential stability were developed. The stability analysis, simulation and test verification were finished for the motion control and balance control strategies.Secondly, the spherical mobile robot was simplified as the "spheroid-pendulum" and the "spheroid-frame" model, and their dynamics differential equations were developed, respectively. The motion characteristic of the drive mechanism along the two drive shafts was discussed by solving the approximate solutions of the differential equations. For the sake of robust control, the uncertainty dynamics model of spherical mobile robot was developed while the coupling effect of the drive mechanism was regarded as the interference items of the spheroid motion. Then, the robust motion controllers were designed, using the slide-mode variable structure method, and the stability analysis, simulation and test verification were finished for the control strategies.Thirdly, the kinemics model's controllability of the spherical mobile robot was analyzed using the theories of differential geometry, and the kinematics model was transformed to normal form. Then, the nonlinear controller was proposed for the attitude control. Based on the robust motion control and the kinemics model, the control strategy of line path following based on the curvature of the shell was proposed. Moreover, the stability analysis, simulation and test verification were finished for the attitude control and path following control strategies.Based on the results of the theoretical research above, the embedded control system for the spherical mobile robot was designed. The possible faults of the system were discussed in detailed, and the fault-tolerant strategies of the control system were proposed for faults. Moreover, the dual-redundant servo control system of the motors was developed, and test verification was finished.Finally, based on the sensor fusion technology including the gyroscope, optical encoders, laser rangefinders and vision sensor, the strategies of autonomous motion control was developed. The models of the odometer and the laser rangefinders were developed, respectively, and the errors of the models were analyzed from the view of the uncertainty information description. Moreover, the test verification of the presented motion control was finished.