Design And Analysis Of A Novel Controllable Metamorphic Tree-climbing Robot Mechanism

As a special robot working in high altitude environment,tree-climbing robot is widely used in forest engineering,pipeline damage detection,military monitoring,environmental detection and other engineering fields.Existing design schemes of tree climbing robot mechanism drive complex,can not flexibly adapt to different shapes and diameters of trees,and can not carry a variety of operating equipment.In this paper,a new type of controllable metamorphic tree-climbing robot mechanism is designed,which combines the climbing characteristics of primates and the characteristics of metamorphic mechanism and controllable mechanism.The mechanism has not only the controllable,adjustable and flexible output properties,but also the multi-functional stage change of metamorphic mechanism.Tree-climbing robots can adapt to different tasks and flexibly apply to different occasions because of the characteristics of chemical,multi-topological and multi-degree-of-freedom.They have the characteristics of simple driving and strong load capacity.They can also simulate the body structure of primates,realize multi-directional steering and obstacle avoidance,and adapt to trees of different diameters and shapes.The theoretical analysis of tree climbing robot mechanism design is also carried out.Firstly,after analyzing the characteristics of primate tree-climbing animals,the design requirements of primate-like tree-climbing robot mechanism are summarized,and the body.Based on this,the hip joint mechanism and the foot self-locking and mechanisms are designed,then,the overall model of the tree-climbing robot mechanism is obtained.the dimension synthesis of the tree-climbing robot mechanism is carried out considering that the hip and foot self-locking mechanism of the tree-climbing robot is far from the singular position,satisfying the the design space of the hip joint and avoiding interference in the process of tree-climbing.Reliability on kinematic accuracy of hip joint motion accuracy is analyzed,considering the error factors such as the length error of the rod,the error factor of the hinge gap and the input error of the hip joint mechanism,and numerical simulation is carried out,Secondly,the position analysis is carried out on the support leg and the swing leg respectively,including the positive solution of the position analysis and the inverse of the position analysis.On this basis,the motion of the tree-climbing robot mechanism is equivalent to a redundant parallel mechanism,and the position is solved by analytical method.The analytical expression of the speed and acceleration of the robot is derived,and the kinematics of the leg structure is simulated numerically.Then the kinematics reliability of the hip joint in the leg mechanism is analyzed considering the factors such as the length error,input parameter error and clearance error,and the kinematics reliability of the leg mechanism is simulated numerically.Then,based on the analysis of the principle of the foot clasping mechanism,the two anti-falling methods of the robot are given,active fall arrest and passive fall arrest.The numerical value of the minimum friction coefficient of the surface of the tree that meets the anti-falling requirements is used as an indicator for evaluating the anti-falling performance of the robot.The two working conditions of the robot in the process of climbing trees are given:straight trees with equal diameter,inclined trees with equal diameter,and the analytical expressions of the minimum friction coefficient corresponding to active and passive anti-falling modes under the above three working conditions are derived,and through numerical simulation,the relationship between the minimum friction coefficient and the mechanism size parameters,input parameters and tree parameters under three working conditions is obtained,and provide theoretical basis for further optimization of mechanism parameters,control of input parameters and selection of appropriate tree climbing methods to improve fall arrest performance.Finally,the coordinate system of the robot leg structure is established,and the position of the center of mass and the velocity of the center of mass are obtained,and then the total kinetic energy and the total potential energy of the robot leg structure are calculated.The joint space Lagrange dynamic equation of the tree-climbing robot leg structure is obtained.Finally,the model is imported into the virtual simulation software to simulate the kinematics and dynamics of the leg structure of the tree-climbing robot mechanism.