Energy-Based Inverted Equilibrium of the Axially Symmetric 3D Pendulum

Abstract

In this paper, we study the attitude control problems based on model of the 3D axially symmetric rigid pendulum. Three degrees of freedom pendulum (3D pendulum) is a rigid body supported by a frictionless pivot. According to relative position of the center of mass and the fixed pivot without friction, the 3D rigid pendulum can be divided into two balanced attitudes, Hanging equilibrium and inverted equilibrium. When the 3D rigid pendulum in axis symmetric case, the axis of symmetry is equivalent to axis of inertia of rigid body, and angular velocity around the axis of symmetry is constant that not equal to zero, as a result, the 3D rigid pendulum equal to the axisymmetric rigid pendulum. According to the motion attitude of the axially symmetric 3D pendulum, this article proposes a control method based on passivity, By analyzing the dynamic characteristics, and demonstrate the dynamic characteristics to meet the passive condition. Firstly, we use the passivity theory, from total energy of the system, to research the equilibrium stability of the axially symmetric 3D pendulum in the inverted position. Secondly, to utilize the passivity theory and the Lyapunov function that we proposed to deduce the control law based on the energy method, so that the axially symmetric 3D pendulum to reach asymptotically stable in equilibrium position, and the simulation results verify the availability of the method.