Research On Linkage-based Octahedral Moving Mechanism Of Spatial Sarrus Mechanism

Generally,the basic movement modes of robots include the wheel,crawler,and leg types.Combining some of them can construct hybrid moving mechanisms,such as the wheel-legged,wheel-tracked,and wheel-track-legged mechanisms.Besides,some new movement modes,such as deformable wheel type and integral moving types,have also been attracted.The integral moving mechanisms have no fixed fuselage and moving system.Most of these mechanisms take polyhedrons as the overall shape structure,and can move in a variety of postures,which solve the problem that the moving mechanisms cannot move when the mechanisms are overturned.The integral closed chain moving mechanisms have good stiffness and bearing capacity.In recent years,the researches of the integral closed chain mobile mechanisms are under the spotlight.In this paper,a new type of octahedral rod type moving mechanisms is constructed by using integral closed chain mechanisms,and a new design method of mechanism combination is proposed.The spatial single closed chain Sarrus mechanism and octahedron are combined with each other with different ‘weight’ relationships,and a total of 73 new configuration schemes in three categories are synthesised.Three materialized mechanisms with different categories are selected for kinematic analysis,mobile gait planning,virtual prototype simulation,and prototype test.The Sarrus-large-weight single drive octahedral moving mechanism in the first category is analysised.A connecting rod in the spatial single closed chain Sarrus mechanism is designed as an octahedral structure,and the Sarrus mechanism occupies a large weight in the new mechanism.Two motors are required for most moving mechanisms to achieve these two gaits.However,this new mechanism is a single-powered moving mechanism with straight and steering gaits achieved by a single motor,which reduces the number of the motor.The centroid projection point(COG)method is used to theoretically analyze the feasibility of the steering gait,a virtual prototype is desinged for motion simulation,and a physical prototype is made to verify the feasibility of the mechanism movement.The Sarrus-medium-weight multi-mode octahedral moving mechanism in the second category is proposed.The spatial single closed chain Sarrus mechanism and octahedral weight are combined,the driving gear train and driven gear train are added to the branch chain,and the rolling moving mode,wheel moving mode and hybrid moving mode are planned and applied to different obstacle terrain.The zero moment point(ZMP)method is used to theoretically calculate the feasibility of rolling,analyze the trafficability of climbing,trenches and other common obstacle terrain,build a virtual prototype to simulate the motion gait,and make a physical prototype to verify the motion feasibility.The Sarrus-small-weight rolling octahedral mobile mechanism in the third category is proposed.The spatial single closed chain Sarrus mechanism is designed as a part of octahedral structure and occupies a lower weight in the new mechanism.A variety of steering modes of the new mechanism are planned: random probability steering and determined one-way steering,directional rolling gait,and collision gait and non collision gait are planned.Using the method of centroid ground projection point,the feasibility of steering gait and rolling gait is theoretically analyzed,the virtual prototype simulation is built,and the physical prototype is made to test the feasibility of mechanism movement.Summarizing the work of the full text,this paper puts forward a new mechanism design method,builds three prototypes,completes the analysis of the three mechanisms,and makes a contribution to the configuration of rolling mobile robot.