Study Of Quadruped Wall-Climbing Robots With Bioinspired Flexible Spiny Feet Featuring Radial Configuration

A wall-climbing robot(WCR)is a kind of mobile robots capable of scaling steep slopes,cliffs and even inverted surfaces.WCRs can be used for many applications such as building maintenance,healthmonitoring for petro/oil tank surface,and search and rescue inhazardous environment,space exploration,etc.,and has become a hot topic in the robotics research.The key technology in developing WCRs is the adhesion system that allows WCRs to overcome gravity and adhere to walls.Conventional WCRs use electro-magnetic forces,sucking forces,electrostatic adhesion,track fixing,etc.,to climb on the walls.However,these techniques have their inherent disadvantages that limit applications in practice.For examples,the electro-magnetic adhesion fails on non-ferromagnetic materials;Sucking forces produced by negative pressure are not sustainable on rough surfaces and completely lose function in vacuum conditions;Electrostatic adsorption has high energy consumption and it is still in its early stages.Track-fixed WCRs require pre-laying of tracks and cannot work in unstructured environment.All of these methods are very inefficient,need more power for operation and are noisy.The nature and manmade surfacesaround usare mostly rough and dusty.It is a challenge for the research of wall-climbing robot to complete the task on these surfaces.In nature,many animals can utilize their claws/spines to climb freely on various surfaces.From the perspective of bionics,this research studies the system of spine-inspired wall-climbing robots.Firstly,through the morphologic study of the trasal system of the Serica orientalis Motschsky,a flexible contact model of the spine and the rough surface was established.On the basis of theoretical analysis,the double anchor points flexible spine and thecorresponding spine array were developed.Then,based on the attachment and detachment mechanism of the spine array and the actual grasping effect,a three-row opposedgripper with spines was designed as the foot and tested.Finally,quadruped WCRs were designed based using the designed foot with body and legs configuration inspired by the gecko.Two generations of WCR prototypeswere fabricated,and their performancesweretested.The main findings and innovations of the research are summarized as follows:(1)An elastic contact model was established based on the spherical contact model between the insect spine and the surface,which more clearly dissected the contact and adhesion characteristics of the spine,and laid a theoretical foundation for the design of the compliant spiny system.(2)A single anchor point unit was designed by tuning elements in the stiffness matrix,and aflexiblespine with double anchor points was proposed based on the understanding of the contact mechanisms of the spiny system with the surface asperities.This design successfully increased the density of interlocking point in unit space.According to the structural characteristics of the flexible spine,the manufacturing process was designed with patch production was realized.(3)A three-row opposed gripping mechanism with radial configuration for theWCRwas designed and fabricated according to the mechanical behaviors of the spiny toe pad.The gripping mechanism employed an opposed spoke configuration with 3 rows of 31 toes on each linkage array.The Chebyshev four-bar linkage mechanism was used to apply attachment and detachment of the array.A single servo was utilized as the actuator,which drove the three arrays via a bevel system.(4)Using the gripping mechanism as the foot,and mimicking the body and legs'configuration of the gecko,two generations of quadruped WCRs were designed,fabricated and tested.The second version of the WCR was able to hang on the inverted rough ceiling,and climb on vertical rough wall,which verified the reliability of the key components.