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In this paper, a novel tree climbing robot mechanism was designed, based on the tree climbing movement and posture of the primates. The overall design and tree climbing gait of the tree climbing robot were analyzed in detail. According to the screw theory, the DOF of the leg of the tree climbing robot is calculated. The forward and inverse kinematics equations of the tree climbing robot were established and solved. The kinematics of the leg parallel mechanism was established, furthermore, the singularity of the leg mechanism was analyzed and three types of singularity were derived. The simplified diagrams and the corresponding model diagrams, at the singular points, were drawn. Finally, the movement is simulated and analyzed. And the changes of the leg joint angular and the foot-end displacement and the relationship between the driving displacement and angles of the tree climbing robot by numerical simulation is obtained at the same time. Prototype physical model of the tree climbing robot was made, which further verified the rationality and feasibility of the tree climbing robot mechanism studied in this paper.

Abstract：Metamorphic mechanism would result in impact when it is changing from one configuration to the next. What is more, it would make the mechanism be unstable. Therefore, dynamic stability of metamorphic mechanism is expected to be analyzed. It is important for metamorphic mechanism to apply and spread in practical engineering. The controllable metamorphic palletizing robot mechanism is investigated. The largest Lyapunov exponent is used as metrics of dynamic stability of the system. Based on the nonlinear dynamic model of the novel controllable metamorphic palletizing robot mechanism system of all configurations under the actual operating, mechanism material parameters, control parameters and internal impact excitation are taken into consideration. After time series of steady-state responses of the mechanical system are solved by Newmark method, time delay and embedding dimension are figured out by C_C method. And phase space of the time series of steady-state responses are reconstructed. Then Wolf method is applied to calculate the largest Lyapunov exponent of this time response series. And phase diagrams of the system output paths are used to analysis stability of the system. The research provides some references for stability study of metamorphic mechanism. Key words：metamorphic