Review of key technologies of climbing robots

In recent years,the robot industry has developed rapidly,and researchers and enterprises have begun to pay more attention to this industry.People are barely familiar with climbing robots,a kind of special robot.However,from their practical value and scientific research value,climbing robots should studied further.This paper analyzes and summarizes the key technologies of climbing robots,introduces various kinds of climbing robots,and examines their advantages and disadvantages to provide a reference for future researchers.Many countries have studied climbing robots and made some achievements.However,due to the complexity of climbing robots,their climbing efficiency and accuracy need to be further improved.The new structure can improve the climbing efficiency.This paper analyzes climbing robots such as mechanical arms,magnetic attraction,and claws.Optimization methods and path planning can improve the accuracy of work.This paper involves some control methods,including complex intelligent control methods such as behavior-based robot control.This paper also investigates various kinematic planning methods and expounds and summarizes various path planning algorithms,including machine learning and reinforcement learning of artificial intelligence,ant colony algorithm,and other algorithms.Therefore,by analyzing the research status of climbing robots at home and abroad,this paper summarizes three important aspects of climbing robots,namely,structural design,control methods,and climbing strategies,elaborates on the achievements and existing problems of these key technologies,and looks forward to the future development trend and research direction of climbing robots.

A New Self-Loading Locomotion Mechanism for Wall Climbing Robots Employing Biomimetic Adhesives

A versatile locomotion mechanism is introduced and experimentally verified. This mechanism comprises four rectangular wheels （legs） with rotational phase difference which enables the application of pressure to each contacting surface for securing it to the surface using bio-inspired or pressure-sensitive adhesives. In this mechanism, the adhesives are applied to two rigid plates attached to each wheel via hinges incorporating torsional springs. The springs force the plates back to their original position after the contact with the surface is lost in the course of locomotion. The wheels are made of low-modulus elastomers, and the pressure applied during contact is controlled by the elastic modulus, geometry and phase difference of wheels. This reliable adhesion system does not rely upon gravity for adhering to surfaces, and provides the locomotion mechanism with the ability to climb walls and transition from horizontal to vertical surfaces.

Optimal Gait for Bioinspired Climbing Robots Using Dry Adhesion： A Quasi-Static Investigation

Legged robots relying on dry adhesives for vertical climbing are required to preload their feet against the wall to increase contact surface area and consequently maximize adhesion force. Preloading a foot causes a redistribution of forces in the entire robot, including contact forces between the other feet and the wall. An inappropriate redistribution of these forces can cause irreparable detachment of the robot from the vertical surface. This paper investigates an optimal preloading and detaching strategy that minimizes energy consumption, while retaining safety, during locomotion on vertical surfaces. The gait of a six-legged robot is planned using a quasi-static model that takes into account both the structure of the robot and the character- istics of the adhesive material. The latter was modelled from experimental data collected for this paper. A constrained optimi- zation routine is used, and its output is a sequence of optimal posture and motor torque set-points.

Investigation on the Effect of the Tension Degree of Tracks on the Adsorption Performance of Tracked Wall Climbing Robot

In this paper,a new tracked wall climbing robot with permanent magnetic units is designed,and the tension degree of robot’s tracks is found to have a significant impact on the robot’s adsorption performance.This tracked wall climbing robot is a remotely controlled robot.All the control devices can be installed on the robot body.All the permanent magnetic units are arranged on the light track.In order to illustrate the relationship between the tension degree and the adsorption performance,when absorbed on the vertical surface and 180⁃degree inverted surface,the static force analysis of the robot is presented.Finally,experiments were demonstrated to prove that higher tension degree of tracks can make adsorption performance better.

Multi-Scale Compliant Foot Designs and Fabrication for Use with a Spider-Inspired Climbing Robot

Climbing robots are of potential use for surveillance, inspection and exploration in different environments. In particular, the use of climbing robots for space exploration can allow scientists to explore environments too challenging for traditional wheeled designs. To adhere to surfaces, biomimetic dry adhesives based on gecko feet have been proposed. These biomimetic dry adhesives work by using multi-scale compliant mechanisms to make intimate contact with different surfaces and adhere by using Van der Waals forces. Fabrication of these adhesives has frequently been challenging however, due to the difficulty in combining macro, micro and nanoscale compliance. We present an all polymer foot design for use with a hexapod climbing robot and a fabrication method to improve reliability and yield. A high strength, low-modulus silicone, TC-5005, is used to form the foot base and microscale fibres in one piece by using a two part mold. A macroscale foot design is produced using a 3D printer to produce a base mold, while lithographic definition of microscale fibres in a thick photoresist forms the ＇hairs＇ of the polymer foot. The adhesion of the silicone fibres by themselves or attached to the macro foot is examined to determine best strategies for placement and removal of feet to maximize adhesion. Results demonstrate the successful integration of micro and macro compliant feet for use in climbing on a variety of surfaces.

Critical Suction Characteristic Analyses of a Wall Climbing Robot

A new method called critical suction is used based on the wall climbing robot demands of miniature structure, moving smartly and low noise. It makes the robot achieve the homeostasis state in the suction cup, and in this condition the robot can stay on the wall reliably and move smartly. The fluid mechanics model and fluid network model are set up to analyze the robot suction system when the airflow is steady or changes suddenly. Furthermore, simulation results indicate the close relation between the key parameters of robot structure and the suction system. Finally the method of critical suction proves correct in theory.

Synergy Between Soft Feet and an Active Tail to Enhance the Climbing Ability of a Bio-inspired Climbing Robot

Lizards use the synergy between their feet and tail to climb on slopes and vertical terrains.They use their soft adhesive feet with millions of small hairs to increase their contact area with the terrain surface and press their tails against the terrain to actively maintain stability during climbing.Inspired by this,we propose a bio-inspired climbing robot based on a new approach wherein the synergy between soft feet and an active tail with a soft adhesive tip allows the robot to climb stably on even and uneven terrains at different slope angles.We evaluate and compare the climbing performance of the robot on three different terrains(hard,soft,and fluffy)at different slope angles.Various robot configurations are employed,including those with standard hard feet and soft feet in combination with an active tail-with and without a soft tip.The experimental results show that the robot having soft feet and a tail with the soft tip achieves the best climbing performance on all terrains,with maximum climbing slopes of 40°,45°,and 50°on fluffy,soft,and hard terrains,respectively.Its payload capacity depends on the type of terrain and the inclination angle.Moreover,our robot performs multi-terrain transitions(climbing from horizontal to sloped terrains)on three different terrains of a slope.This approach can allow a climbing robot to walk and climb on different terrains,extending the operational range of the robot to areas with complex terrains and slopes,e.g.,in inspection,exploration,and construction.

The Kinematics and Force Analysis of a New Leg Mechanism for Multi-legged Wall-Climbing Robot

This paper presents a new kind of leg mechanism with which the wall climbing robot can easily perform the ground to wall transition by itself.To get its walking envelope and limit position,the forward/inverse kinematics and the statics of the mechanism are solved.All of these lay the foundation for ground to wall transition gait programing,mechanism parameter selection and optimization.

An Autonomous Wall-Climbing Robot for Inspection of Reinforced Concrete Structures: SIRCAUR

A wall-climbing inspection robot has been designed to climb on safety-critical concrete structures by adhering to reinforcement steel bars(rebars)using permanent magnets to generate the adhesion forces.Simulation and experimental validation have been performed to determine the optimum flux focusing magnet configurations with the robot operating on 30–35 mm of concrete cover over rebars arranged in different patterns.The goal of adhesion force optimization is to be able to carry a ground-penetrating radar(GPR)sensor which detects rebar corrosion,concrete delamination,and concrete cover deterioration.The autonomous robot uses an ultra-wide band localization system and GPR data to control its motion trajectories to avoid regions where there is an insufficient density of rebars.Nondestructive testing(NDT)inspection data acquired by GPR are transmitted wirelessly to a ground station for processing and monitoring by NDT technicians.

Design and motion control analysis of double helix wall climbing robot

For the detection environment of complex walls such as high-rise buildings,a double helix wall climbing robot(DHWCR)with strong adsorption force and good stability is designed and developed,which uses symmetrical propellers to provide adsorption force.The symmetrical driving structure can provide smooth thrust for the DHWCR,so that the robot can be absorbed to the wall surface with different roughness.A left and right control frame with multiple degrees of freedom is designed,which can adjust the fixed position of the brushless propeller motor in the front and back directions,realize the continuous adjustable thrust direction of the robot,and improve the flexibility of the robot movement.Using the front wheel steering mechanism with universal joint,the steering control of the DHWCR is realized by differential control.In the vertical to ground transition,the front and rear brushless motors can provide the pull up and oblique thrust,so that the DHWCR can smoothly transition to the vertical wall.The motion performance and adaptability of the DHWCR in the horizontal ground and vertical wall environment are tested.The results show that the DHWCR can switch motion between the horizontal ground and vertical wall,and can stably adsorb on the vertical wall with flexible attitude control.The DHWCR can move at a fast speed.The speed on the horizontal ground is higher than that on the vertical wall,which verifies the feasibility and reliability of the DHWCR moving stably on the vertical wall.

Analysis of Mechanical Adhesion Climbing Robot Design for Wind Tower Inspection

Maintenance of wind turbine farms is a huge task,with associated significant risks and potential hazard to the safety and well-being of people who are responsible for carrying the tower inspection tasks.Periodic inspections are required for wind turbine tower to ensure that the wind turbines are in full working order,with no signs of potential failure.Therefore,the development of an automated wind tower inspection system has been very cnucial for the overall performance of the renewable wind power generation industry.In order to determine the life span of the tower,an investigation of robot design is discussed in this paper.It presents how a mechanical spring-loaded climbing robot can be designed and constructed to climb and rotate 360°around the tower.An adjustable circular shape robot is designed that allows the device to fit in different diameters of the wind generator tower.The rotational module is designed to allow the wheels to rotate and be able to go in a circular motion.The design further incorporates a suspension that allows the robot to go through any obstacle.This paper also presents a finite element spring stress analy sis and Simulink control system model to find the optimal parameters that are required for the wind tower climbing robot.

Fast Control of Negative Pressure Response of a Bio-inspired Suction Cup Actuated by Shape Memory Alloy

A bio-inspired suction cup actuated by shape memory alloy(SMA)for miniature wall climbing robots is developed based on studying characteristics of biological suction apparatus.Some fast control strategies are introduced to improve negative pressure response.Theoretic model of the suction cup is built,and simulation and experiments results indicate the effectiveness of the fast control strategies.The largest negative pressure of the suction cup can reach 14 000 Pa,and its generating and cancelling just need 5 s.Research results indicate the suction cup can be used as an adhesion mechanism for miniature wall climbing robots.

A Wheeled Wall-Climbing Robot with Bio-Inspired Spine Mechanisms

This paper presents a wheeled wall-climbing robot with the ability to climb concrete, brick walls using circular arrays of miniature spines located around the wheel. The robot consists of two driving wheels and a flexible tail, just like letter “T”, so it is called Tbot. The simple and effective structure of Tbot enables it to be steerable and to transition from horizontal to vertical surfaces rapidly and stably. Inspired by the structure and mechanics of the tarsal chain in the Serica orientalis Motschulsky, a compliant spine mechanism was developed. With the bio-inspired compliant spine mechanism, the climbing performance of Tbot was improved. It could climb on 100° （10° past vertical） brick walls at a speed of 10 cm·s^-1. A mechanical model is also presented to analyze the forces acting on spine during a climbing cycle as well as load share between multi-spines. The simu- lation and experiment results show that the mechanical model is suitable and useful in the optimum design of Tbot.

A Bionic Starfish Adsorption Crawling Soft Robot

A variety of soft wall-climbing robots have been developed that can move in certain patterns.Most of these soft robots can only move on conventional surfaces and lack adaptability to complex surfaces.Improving the adaptability of soft robots on complex surfaces is still a challenging problem.To this end,we study the layered structure of the starfish tube foot and the valve flap structure in the water vascular system,and use an ultrasonic stress detector to study the stiffness distribution of the arm structure.Inspired by the motion of the starfish,we present a bionic soft wall-climbing robot,which is driven by two groups of pneumatic feet and achieves body bending through active adaptation layers.We design the structure of the foot to flex to provide driving force,and there are suction cups at the end of the foot to provide suction.The soft foot has a simple structure design,adapts to a variety of surfaces,and does not damage the surface of the substrate.Variable stiffness layers achieve stiffness changes by the principle of line blocking.The Central Pattern Generator theory is introduced to coordinately control the multiple feet of the robot.After experiments,we verify the adaptability of the soft robot to curved surfaces.The research may provide a reference for the design and development of crawling soft robots on complex surfaces.

A Bio-inspired Climbing Robot with Flexible Pads and Claws

Many animals exhibit strong mechanical interlocking in order to achieve efficient climbing against rough surfaces by using their claws in the pads. To maximally use the mechanical interlocking, an innovative robot which utilizes flexible pad with claws is designed. The mechanism for attachments of the claws against rough surfaces is further revealed according to the theoretical analysis. Moreover, the effects of the key parameters on the performances of the climbing robots are obtained. It indicates that decreasing the size of the tip of the claws while maintaining its stiffness unchanged can effectively improve the attachment ability. Furthermore, the structure of robot body and two foot trajectories are proposed and the new robot is presented. Using experimental tests, it demonstrates that this robot has high stability and adaptability while climbing on vertical rough surfaces up to a speed of 4.6 cm.s^-1.

Optimization approach for a climbing robot with target tracking in WSNs

Climbing robots are being developed for various applications.The confined space requires a compact locomotion system with vertical and overhead climbing ability.To achieve surface transition,Steering geometry Interaction system and static force are used.WSNs ubiquitous infrastructure and excellent coverage,they can be used for providing location information for various location-based services,especially in indoor environments.This structure is designed for a magnetic wall-climbing robot to gradually decrease the magnetic force when it is transiting between perpendicular magnetic surfaces.This paper describes the design process of a magnetic wall climbing robot,which adopts SgI and has the potential to carry materials in a confined space with an energy efficient system model.To resolve the problem of target tracking,it is essential to deploy a system model.Over the last two decades,several researchers have recommended many remote user authentication schemes.Researchers are continuously trying to enhance the security in material handling automation system by introducing several features into their work.A working prototype has been built based on the optimized dimension.

Design,Mobility Analysis and Gait Planning of a Leech-like Soft Crawling Robot with Stretching and Bending Deformation

Soft climbing/crawling robots have been attracting increasing attention in the soft robotics community,and many prototypes with basic locomotion have been implemented.Most existing soft robots achieve locomotion by planar bending deformation and lack sufficient mobility.Enhancing the mobility of soft climbing/crawling robots is still an open and challenging issue.To this end,we present a novel pneumatic leech-like soft robot,Leechbot,with both bending and stretching deformation for locomotion.With a morphological structure,the robot consists of a three-chambered actuator in the middle for the main motion,two chamber-net actuators that act as ankles,and two suckers at the ends for anchoring on surfaces.The peristaltic motion for locomotion is implemented by body stretching,and direction changing is achieved by body bending.Due to the novel design and two deformation modes,the robot can make turns and transit between different surfaces;the robot,hence,has excellent mobility.The development of the robot prototype is presented in detail in this paper.To control its motion,tests were carried out to determine the relationship between step length and air pressure as well as the relationship between motion speed and periodic delay time.A kinematic model was established,and the kinematic mobility and surface transitionability were analyzed.Gait planning based on the inflating sequence of the actuating chambers is presented for straight crawling,turn making,and transiting between surfaces and was verified by a series of experiments with the prototype.The results show that a high mobility in soft climbing/crawling robots can be achieved by a novel design and by proper gait planning.

Abigaille-Ⅲ： A Versatile, Bioinspired Hexapod for Scaling Smooth Vertical Surfaces

This paper presents a novel, legged robot, Abigaille-Ⅲ, which is a hexapod actuated by 24 miniature gear motors. This robot uses dual-layer dry adhesives to climb smooth, vertical surfaces. Because dry adhesives are passive and stick to various surfaces, they have advantages over mechanisms such as suction, claws and magnets. The mechanical design and posture of Abigaille-Ⅲ were optimized to reduce pitchback forces during vertical climbing. The robot＇s electronics were designed around a Field Programmable Gate Array, producing a versatile computing architecture. The robot was reconfigured for vertical climbing with both 5 and 6 legs, and with 3 or 4 motors per leg, without changes to the electronic hardware. Abigaille-Ⅲ demonstrated dexterity through vertical climbing on uneven surfaces, and by transferring between horizontal and vertical sur- faces. In endurance tests, Abigaille-Ⅲ completed nearly 4 hours of continuous climbing and over 7 hours of loitering, showing that dry adhesive climbing systems can be used for extended missions.

Bioinspired Dry Adhesive Materials and Their Application in Robotics： A Review

Dry adhesives inspired from climbing animals, such as geckos and spiders, rely on van der Waals forces to attach to the opposing surface. Biological fibrillar dry adhesives have a hierarchical structure closely resembling a tree： the surface of the skin on the animal＇s feet is covered in arrays of slender micro-fibrils, each of which supports arrays of fibrils in submicron dimensions. These nano-meter size fibrils can conform closely to the opposing surfaces to induce van der Waals interaction. Bioinspired dry adhesives have been developed in research laboratories for more than a decade. To mimic the biological fibrillar adhesives, fibrillar structures have been prepared using a variety of materials and geometrical arrangements. In this review article, the mechanism and selected fabrication methods of fibrillar adhesives are summarized for future reference in adhesive development. Robotic applications of these bioinspired adhesives are also introduced in this article. Various successful appli- cations of bioinspired fibrillar adhesives can shed light on developing smart adhesives for use in automation.

Simulation of High Altitude Power-on-live Robot Based on Pro/E and ADAMS

In order to solve the existing problems that the manual operation with high risk of the electric power industry, large labor intensity and low degree of automation, combining with the existing various climbing robot at domestic and foreign, on this basis, a kind of high-altitude power-on-live robot suitable for the field is designed The model with the 3D modeling software Pro/E is established, with the help of the working principle of the robot. Adopting the mechanical dynamics simulation software ADAMS, a virtual prototype model for the whole machine and the dynamics simulation is carried out. Finally, the result demonstrates the feasibility of the design