Research On The Key Technology Of Multi-mode Wheel-tracked Bionic Wall-Climbing Robot

As an important equipment to replace human working on steep walls and obtain real-time environmental information in three-dimensional space,wall-climbing robots can improve working efficiency and ensure operation safety,which can be widely applied in the detection of chemical equipment and nuclear fuel tanks,cleaning of glass curtain walls,anti-terrorism investigation and other fields.The traditional attachment methods for wall-climbing robots such as vacuum,magnet,and static electricity are only suitable for specific application scenarios.Subsequently,a series of bionic wall-climbing robots have been developed by imitating the special attachment and movement capabilities of creatures including geckos,spiders,salamanders,and other insects.However,most of the existing biomimetic wall-climbing robots can only climb on a single type of wall surface,and cannot realize the synergistic combination of multiple attachment methods,which fail to solve the stability and adaptability problems on different wall surfaces.In the paper,the foot morphological characteristics of typical creatures such as flies and geckos,insects,abalones and clingfishes have been used as bionic objects,whose adhesion,grasping and adsorption movements on the wall surfaces have been observed respectively.Then,the corresponding adhesive belt,flexible spines and negative pressure adsorption system have been separately proposed.Integrating the characteristics of key mechanical structures and components and fitting different operational requirements,a single-mode bionic wall-climbing robot with adhesive belts and flexible spines has been developed respectively.After analyzing the shortcomings of the single-mode wall-climbing robots,a bionic wall-climbing robot with the composite structure of "adhesion-grasping-adsorption" has been described.On condition of the robot's static safe attachment conditions on smooth and rough wall surfaces and multi-mode kinematic and dynamic analysis,the principle prototype of the highly reliable bionic wall-climbing robot with multi-mode movement has been fabricated,whose climbing-wall ability has been tested through experiments on various walls.The main finding and innovations of the paper are as follows.1.The three innovative attachment mechanisms including adhesive belts,flexible spines and negative pressure adsorption system have been designed respectively.By separately observing the motion characteristics of adhesion,grasping,and adsorption for typical creatures such as flies and geckos,insects,abalones and clingfishes on complex walls,the corresponding biomimetic wall-climbing mechanisms have been designed respectively,which include adhesive belts,flexible spines and the negative pressure adsorption system.The contacting models between the above attachment mechanisms and walls have been independently established to analyze parameters affecting attachment forces,which provide a theoretical basis for the development of single-mode and multi-mode bionic wall-climbing robots.2.Based on a comprehensive integration method of key motion structures and components,two types of single-mode bionic wall-climbing robots with adhesive belts and flexible spines have been developed respectively.Aiming at the consistent features on smooth or rough walls,the configuration scheme for the single-mode wall-climbing robot with adhesive belts and tracked spines has been proposed respectively.Based on the Kendall's peeling theory,a mathematical contacting model between the adhesive belt and wall surfaces with preload has been established.Moreover,the robot prototypes have been manufactured by rapid prototyping and precision machining technology respectively,whose wall-climbing performances have been tested on glass wall and acrylic plates.According to the insect's"hanging" mode,a wall-climbing robot with parallel tracked spines has been presented.In addition,the grasping and detaching movements of spines in the limit rail have been analyzed.Faced with rough and vibrating wall environments and based on the insect's"grasping" mode,a wall-climbing robot with tracked cooperative grasping spines has been proposed.Using the closed vector equation and Euler formula,the movement rules of the spine tip during the grasping and detaching states have been revealed respectively The dynamic characteristics of the cooperative grasping mechanism have been analyzed and simulated to obtain the quantitative relationships among structural parameters,motion modes and force transmission.Finally,the above two robot prototypes with flexible spines have been manufactured respectively,and the climbing performances have been independently tested on rough walls including the static sandpaper,screen window,foam,and vibrating sandpaper.3.The configuration scheme with composite structures of "adhesion-grasping-adsorption" has been proposed.Combined with the kinematic and dynamic simulation analysis,a multi-mode bionic wall-climbing robot has been presented.In view of the shortcomings of the single-mode bionic wall-climbing robot in the movement process,and based on the three bionic mechanisms containing the adhesive belts,flexible spines and negative pressure adsorption system,a bionic wall-climbing robot combined with the mechanism of "adhesion-grasping-adsorption" has been designed using the comprehensive configuration method for tasks on complex wall surfaces.Furthermore,the safe attachment conditions on smooth and rough wall surfaces have been derived to obtain the relationship of the adsorption force with respect to the peeling force of adhesive belts,grasping force of spines and geometric dimension of the robot.Besides,the kinematic and dynamic models of the robot on smooth and rough walls have been established through nonholonomic constraints respectively.Finally,the principle prototype of highly reliable bionic wall-climbing robot with adaption to various walls has been fabricated and the wall-climbing performances have been verified.The experimental results show that the robot can not only climb stably on vertical rough and smooth walls,but also achieve rapid climbing on some ceiling walls.