Abstract:[Objective]High-altitude wall operations carry inherent risks,and accidents can lead to economic loss and casualties.Wall-climbing robots were utilized as a substitute for human labour presents an effective solution.The stability of the adhesion mechanism in wall-climbing robots significantly impacts their reliability and efficiency,making the study of adhesion technology a crucial aspect of their design.Research on the adhesion mechanisms of wall-climbing robots and their applications lacks a systematic comparative analysis.[Analysis]The adhesion mechanisms and research progress of several standard adhesion methods—magnetic adhesion,negative pressure adhesion,electrostatic adhesion,and biomimetic adhesion were introduced,and their application scenarios were compared.Each adhesion method's advantages,disadvantages,and future prospects were analyzed.The adhesion methods of commonly used wall-climbing robots were analyzed,summarized,compared,and forecasted,aiming to provide valuable guidance for future research on wall-climbing robots.

Abstract:A method based on the polynomial interpolation combined with the segmental planning was pro-posed for the trajectory planning of redundant mobile manipulators.The kinematic analysis was carried out by considering the manipulator and the mobile platform as an integrated system,a generalized form of the geometric Jacobi matrix and its pseudo-inverse were derived.In the trajectory planning process,the trajectory running time and the spatial distance travelled by the end of the mobile manipulator were taken as the optimization objec-tives,the velocity and acceleration constraints of each joint were also taken into account,and a genetic algorithm was used to optimize the trajectory of the redundant mobile manipulator.The simulation results demonstrate that the trajectory of the optimized motion is smooth,and the displacement and velocity curves of the joints of the mo-bile platform and the manipulator are continuous and stable,which verifies the feasibility and effectiveness of the method.

Abstract:Aiming at the problem of high fault similarity in the transmission chain of wind turbines,this study proposes a single-sample wind turbine bearing fault diagnosis method based on empirical mode decompo-sition and signal equalization processing.In this method,the signal components of different modes are obtained by empirical mode decomposition of the actual monitoring fault signal.The energy value and peak value of each modal component are calculated,and some modal components with large energy and high peak value are select-ed for signal reconstruction to obtain a new fault signal.The new fault signal decomposed by wavelet packet,and the wavelet packet is decomposed into the third layer component for signal reconstruction.The variance of the re-constructed signal is used as the eigenvalue of the fault diagnosis.Non-linear equalization is performed on the eigenvalues,which solves the problem of signal mutual submergence.The concept of discrimination is intro-duced to quantify the difference between different fault signals.The experimental results show that the fault diag-nosis method proposed is effective,and the discrimination between the four faults on the transmission chain of the wind turbine before and after the treatment is significantly increased,which shows that the experimental method has a strong robustness.Compared with the improved fuzzy clustering method and the deep learning method based on the improved AlxeNet network,the method performs better.The fault diagnosis method only us-es a single sample to realize the fault diagnosis of the transmission chain of wind turbines,which is in line with the characteristic of the low failure rate of wind turbines,and is of great significance for improving the trouble-shooting efficiency of wind turbines in actual projects.

Abstract:For crossed roller bearings,manual assembly has problems such as low efficiency,high cost and large error,a four-degree-of-freedom robotic arm was designed to automatically assemble cross roller bear-ings.In order to improve the efficiency of the robotic arm,an improved gray wolf optimizer(IGWO)based on 3-7-3 polynomial segmented interpolation was proposed to plan the time-optimal trajectory of the robotic arm.The linear control factor of the algorithm was replaced with a nonlinear control factor,and the algorithm was com-bined with the beetle antennae search(BAS)algorithm.It can avoid falling into the local optimization and im-prove the solution efficiency and accuracy of the algorithm.The simulation results show that,compared with the gray wolf optimizer(GWO),the movement time of the improved gray wolf optimizer is shortened by 17%,the effi-ciency is significantly improved,and the trajectory curves of each joint are smooth and continuous.The research results provide a basis for the subsequent motion control of the robotic arm.

Abstract:Aiming at the low efficiency and poor accuracy of manual inspection in pipeline cleaning opera-tion,and the problems of pipeline maintenance,a spiral drive pipeline inspection and cleaning robot was pro-posed,which is driven by the spiral drive to ensure stable operation in the pipeline,adapts to the change of pipe-line diameter through the adaptable way of spring reducers,and cleans the dirt in the pipeline by the combina-tion of mechanical cleaning and high pressure water jet cleaning.Through the force analysis of the driving wheel body of the robot,the tractive force analysis model and the straight tube motion model of the robot driving unit were established.At the same time,the motion process of the robot in the tube was analyzed by using the coordi-nate transformation method,and the motion characteristics of the robot were studied.Finally,the traction force and velocity of the robot in the straight pipe were simulated and verified by experiments.The results show that the actual speed of the robot is 0.075 m/s,and the minimum tractive force in compliance with the design index is 39 N.It is concluded that the speed of the robot in the process of passing the straight pipe is positively correlated with the tangent value of the deflection angle of the driving wheel,and the simulation analysis results are basical-ly consistent with the actual situation.The research of the inspection and cleaning robot has certain reference value for the cleaning and maintenance of pipelines.

Abstract:In response to the optimization problem of meshing regions caused by the S-shaped tooth pro-file in the harmonic gear drive,a method for effective edge-conjugate tooth profile design was proposed.This method effectively avoids the difficulties of solving the complex S-shaped tooth profile equation.The convex tooth profile of the S-shaped tooth profile was taken as the base tooth profile.Tooth profiles of the flexspline and circular spline were designed using both the traditional backlash adjustment method and the effective edge-con-jugate method.The meshing characteristics and contact stress of the tooth profiles designed by the two design methods were compared and analyzed through the plane numerical analysis and the finite element modeling.The research results show that the effective edge-conjugate tooth profile design method can achieve both quadratic and two-point meshing,increasing the gear's meshing angle and meshing arc length.The total number of mesh-ing teeth per revolution is increased by 15.78％,with 55％of the flexspline teeth participating in the meshing,thereby enhancing the load capacity of the harmonic gear drive.Moreover,the effective edge-conjugate method leads to an enlargement of the contact area,reducing the maximum contact stress between the tooth profiles by 24.36％,which effectively decreases wear between the flexspline and circular spline tooth surfaces.

Abstract:[Objective]Compared with conventional parallel mechanisms,kinematic redundant parallel mechanisms offer advantages such as a larger orientation workspace and the ability to avoid singular configurations.However,their degree of mo-bility(L)is greater than the number of degrees of freedom(n)of the end effector,which results in an excessive number of rigid bodies and makes dynamic modeling more difficult.Therefore,a dynamic modeling method based on the principle of virtual work was proposed for the 3-[P(RR-RRR)SR]kinematic redundant parallel mechanism,further simplifying the modeling pro-cess.[Methods]Firstly,generalized variables were selected in the high-dimensional generalized space corresponding to the de-gree of mobility(L)of the mechanism.The kinematic transfer relations between the velocity and acceleration of each component within the mechanism and the system output velocity and acceleration were derived,and the Jacobian matrices of each compo-nent and the generalized variable were solved.Then,the dynamic model of the parallel mechanism was established using the principle of virtual work.Finally,the model was simulated by tracking the quintic polynomial trajectory of the end effector and compared with the calculation results of Adams software.[Results]The analysis results indicate that the maximum relative error between the theoretical and simulated values of the driving force/torque at each joint is only 1.58%.This demonstrates the accu-racy and reliability of the model,and also suggests that this method can provide reference for in-depth analysis of the dynamic characteristics of the mechanism and research on control strategies.

Abstract:[Significance]It is crucial to develop active assistant lower limb rehabilitation exoskeleton robots in light of the current situation of population aging and the sharp rise in the number of people with lower limb disorders.[Analysis]The current state of research on active assistant lower limb rehabilitation exoskeleton robots was reviewed both domestically and internationally;single-joint and multi-joint robots were the basis for classification;the structures,applicable populations,application scenarios,and other pertinent details of these two types of robots were particularly summarized.The main technologies were explained and analyzed(actuator type,human-machine doubling,energy and power,etc.).Finally,the analysis and prospect was conducted about the essential technologies and future development trends of active assistant lower limb rehabilitation exoskeleton robots.

Abstract:In order to improve the range of the electric forklift and climbing performance,a transmission scheme with a two speed gearbox was proposed in this study.First of all,based on the external characteristics and efficiency characteristics of the drive motor,a two-speed transmission system parameter matching method was proposed.Secondly,taking an electric forklift as the research object,its drive system was changed:on the basis of not changing the various parameters of the driving motor,change the transmission system from one gear to two gears,and match the main reduction ratio and the two gear reduction ratios of the transmission.Finally,using ADVISOR software to counterbalance electric forklift driving cycles simulation analysis.Results show that installing a two speed gearbox without changing the parameters of the driving motor can improve the power per-formance and fuel economy of the whole electric forklift;the acceleration time from zero to the maximum speed increases by 0.4 seconds,the full load climbing slope increases by 2.5%,and the battery energy consumption of the 2-hour equivalent working cycle of the forklift decreases by 3.5%.

Abstract:[Objective]Operational efficiency,smoothness and energy consumption have been bottlenecks in the trajectory optimization for industrial robots in the non-contact processing such as welding and painting.To this end,a trajectory planning method based on the improved particle swarm algorithm was proposed.[Methods]Firstly,an acceleration continuity constraint method based on smooth paths was proposed so that the velocity,acceleration and jerk of each joint of the robot were bounded and continuous.Secondly,a variable angle interpolation method was proposed to select the optimal torch end trajectory discrete points.Finally,a particle swarm with an elite mutation strategy was used to solve the time series corresponding to the optimal energy consumption.A method was proposed to apply an average fuzzy affiliation function to screen out the best solution of the Pareto front,and then the optimal continuous motion trajectory of energy consumption was planned.[Results]The test results show that the method improves the optimal time,the balance of shocks and the continuity of acceleration,and improves the optimization ability by 22.83%and 25.63%compared to the standard particle swarm and the genetic algorithm,respectively.Planning trajectories to meet industrial welding requirements are shown by Adams software dynamic simulation and practical welding test results.

Abstract:[Significance]The jumping function of quadruped robots is an important ability to achieve high maneuverability and adaptability in complex environments.[Analysis]The current research status of the jumping function of quadruped robots was reviewed,including the latest progress in the structural design,the control model design,and the control algorithm design.In terms of the structural design based on the jumping function,the skeleton structure,joint design,and material selection of quadruped robots were optimized to improve the jumping ability and the stability.In the design of control models based on the jumping function,various dynamic models were proposed to describe the jumping behavior of quadruped robots.These models can be used to predict and optimize the jumping performance,and provide a foundation for the subsequent control algorithm design.An accurate control model can ensure the stable and precise control,thereby improving the jumping performance and adaptability of robots.In the design of control algorithms based on the jumping function,traditional control methods such as PID control,fuzzy control,and adaptive control were widely used in the control of jumping function.In addition,advanced control methods such as reinforcement learning,neural networks,and genetic algorithms also were explored and applied.These methods can improve the jumping performance,the stability,and the adaptability,enabling robots to achieve efficient jumping in dynamic and complex environments.

Abstract:Aiming at the problems of the standard rapidly exploring random tree(RRT)algorithm in a com-plex environment,such as blind expansion,falling into local search,easy planning failure,low sampling success rate,and long paths,an adaptive goal-oriented strategy combined with an alternative strategy for regional sam-pling and an improved RRT algorithm of the greedy pruning strategy was proposed.Based on the kinematics of the manipulator,the envelope was used to simplify the manipulator model to improve the efficiency of collision detection.The adaptive goal-oriented strategy solved the problems of blind search,low search success rate,and difficult convergence of the RRT algorithm in complex environments;the regional sampling alternative strategy solved the problems of the RRT algorithm easily falling into local search,low sampling success rate,and long sampling time;the greedy pruning strategy eliminated redundant nodes and shortened the path,improved the path quality,and enhanced the robustness of the algorithm.In the Matlab and robot operating system(ROS),the obstacle avoidance simulation planning was carried out for different scenarios.The results show that the average search success rate of the improved RRT algorithm has increased by 82.4％,the average sampling success rate has increased by 67.5％,and the average path planning success rate has increased by 70％.The average time ef-ficiency is increased by 81.9％,and the average path length is shortened by 63.05％.Finally,the practicability and effectiveness of the algorithm were further verified by the trajectory planning of the physical manipulator.

Abstract:How to effectively calculate the contact stiffness of the joint surface and analyze the influence of the joint surface stiffness on the dynamic characteristics of the overall structure is one of the important subjects in the study of mechanical structures.However,at present,the fractal theory is simply applied to the calculation and analysis of the joint surface stiffness,and it is difficult to comprehensively analyze the microscopic contact characteristics.Therefore,it is urgent to propose a new method to calculate the contact stiffness of the tooth surface and to analyze the microscopic contact characteristics.Based on the W-M(Weierstrass-Mandelbrot)function,a three-dimensional solid model of the microcosmic joint surface of the tooth surface was constructed,and a new method for fractal representation of the rough surface profile based on the fractal dimension D and the tooth surface roughness was proposed,considering the influence of roughness on the stiffness.The contact deformation mechanism of asperities was discussed,and the law of contact stiffness changing with the deformation of asperities was revealed.The research shows that in the same roughness of the micro-joint surface,when the asperity deforms to the same level,the larger the fractal dimension D is,the greater the contact stiffness will be.In the joint surface with the same fractal dimension and different roughness,the smaller the roughness of the joint surface is,the greater the contact stiffness will be.

Abstract:The higher the linear speed of the gear is,the more significant the friction heat generation phe-nomenon will be,which is not conducive to the improvement of gear life and efficiency.Thus,it is necessary to conduct an analysis of the oil injection cooling characteristics of the gear pair under the high pitch line velocity and explore optimal cooling parameters.Based on the Hertz contact theory and gear meshing characteristics,the average contact stress,relative sliding velocity,and friction coefficient of the tooth surface were solved.Based on the heat generation theory,the average heat flux density of the tooth surface at the high pitch line velocity was obtained.Furthermore,the heat flux density of the tooth surface was used as a boundary condition,and a simula-tion model for the oil injection cooling characteristics of high speed gears with a pitch line velocity of 120 m/s was established.The effects of the injection speed,injection angle,and gear baffle configuration on the cooling characteristics were explored.The results show that increasing the injection speed can improve the cooling effect of the tooth surface to a certain extent.When the injection angle is 60° and the axial injection angle is 20° higher,a lower tooth surface temperature can be obtained.The axial baffle configuration has a better cooling effect on the tooth surface compared to other baffle configurations.

Abstract:A magnetic equivalent circuit method that can consider differences and interactions of each branch magnetic circuit was proposed for the solution of the output torque of slotted-type equivalent couplers.Due to the slotted form of the conductor rotor,the branches composed of the air gap,conductor,and tooth slot corresponding to the permanent magnet in the magnetic circuit are not the same.The specific form of each branch is related to the relative position of the inner and outer rotors.Since the conductor rotor adopts the slot-ted-type form,the branch magnetic circuits consist of air gap,conductor and cogging under the permanent mag-net are different.The specific form of the magnetic circuit is related to the relative position of the inner and outer rotors.The magnetic equivalent circuit method was used to consider the influence of different branch magnetic circuits on the electromagnetic torque and it was solved as a whole taking into account the interaction between the branches,so as to improve the calculation accuracy of the output torque of slotted-type equivalent couplers.Finally,the proposed method was used to predict the output torque of the magnetic couplers under different slip rates,pole-arc/pole-pitch ratios and slotting ratios,and the theoretical verification was carried out by 3D finite element analysis and experiments.It is verified that the proposed method can meet the accuracy requirements of engineering applications.

Abstract:Aiming at the current stage of inverse kinematics solving methods for multi-degree-of-freedom manipulators,most of which have the problems of low solving accuracy and poor generalization,an artificial evolved hummingbird algorithm(AEHA)was proposed for inverse kinematics solving of manipulators.Taking the six-degree-of-freedom manipulator as the research object,a nonlinear equation system of its inverse kine-matics was established;taking the position error of the end of the manipulator as the optimization objective,the fitness function was constructed by combining with the energy loss,so as to transform the inverse kinematics problem into the optimization problem of the objective function,and the proposed algorithm was used to solve the problem.The artificial hummingbird evolutionary algorithm improved the ability of the algorithm to get rid of the local optimum by introducing the Sobol sequence and the Levy flight strategy;the differential evolution strat-egy was introduced to realize the cross-evolution between individuals to avoid the premature convergence.Then,the proposed algorithm was verified that it had the good convergence accuracy by benchmark function test exper-iments.Finally,the inverse kinematics solving simulation was carried out on a six-axis manipulator.The results show that the artificial evolution hummingbird algorithm is better than the comparison algorithm in terms of solv-ing accuracy and stability,and the solving accuracy can reach 10-9 mm,which can be applied to the inverse kine-matics solving of multi-degree-of-freedom manipulators.

Abstract:Minimum entropy deconvolution(MED)is a popular algorithm in recent years,extensively ap-plied in feature extraction and fault diagnosis of components such as gearboxes and bearings.However,in the ac-tual computational process,the parameter settings of the MED inverse filter are highly sensitive to the extraction results.To address this issue,an optimized method was firstly proposed for extracting the fault characteristics of rolling bearings using MED.This method takes into account the energy proportion of feature frequencies under different lengths of inverse filters during the MED computation process,thereby determining the optimal parame-ters for the inverse filter.Additionally,the self-correlation of envelope signals is utilized to further enhance the weak fault characteristic signals of rolling bearings.By integrating self-correlated envelopes with the optimized MED method,a novel method for feature extraction and fault diagnosis of gearbox rolling bearings has been de-veloped.Simulations and tests have verified that this method can effectively enhance the characteristic signals related to bearing faults,and the optimized MED method is significantly superior to the traditional MED and oth-er related bearing signal processing methods.Notably,the self-correlated envelope,due to its ability to signifi-cantly enhance impulse components and its excellent denoising characteristics,shows more prominent results in the actual diagnosis of gearbox bearing faults.

Abstract:[Objective]The excessive wear of the scraper conveyor sprocket and the over-life working condition will lead to the occurrence of the stuck chain,broken chain and other faults,which will adversely affect the normal operation of the convey-or equipment.In order to guide users to replace the sprocket that is not suitable for further use and reduce the incidence of equip-ment failure,a mining scraper conveyor sprocket replacement and repair evaluation method was proposed.[Methods]Based on the Archard wear theory,firstly,the hardness characteristics of the quench hardness layer of the sprocket were studied,and then the dynamic simulation analysis on the meshing transmission process of the ring chain drive system under different wear degree of the sprocket was carried out.The dynamic characteristics of the scraper conveyor were tested to verify the accuracy of the simulation analysis.[Results]The test results show that when the wear depth of the sprocket chain socket reaches the maximum quenching hardness layer depth,the performance of the sprocket has decreased significantly,and the sprocket should be re-placed.When the speed fluctuation,the contact force and the tension increase abnormally in the ring chain drive system,the sprocket should also be replaced in time to ensure the stable operation of the equipment.The proposed method provides a basis for the maintenance and replacement of the scraper conveyor sprocket.

Abstract:[Objective]To explore the meshing and dynamic evolution of spur gear pairs under the combined influence of as-sembly errors and tooth surface friction,a method integrating geometric analysis of spur gear pairs with energy method was em-ployed.The impact of assembly errors and tooth surface friction on spur gear pair meshing was investigated.[Methods]A 6-de-gree-of-freedom bending-torsional coupling vibration model of spur gears was established based on the lumped mass method.Numerical solutions characterizing the meshing behavior and dynamic response of the system were obtained using the Runge-Kutta method.[Results]The analysis reveals that,the mesh stiffness amplitude of the spur gear pair decreases with the increase of the tooth surface friction coefficient.Additionally,simulation results demonstrate that appropriately adjusting the installation conditions and using reasonable tooth surface friction coefficients of spur gear pairs can improve its transmission accuracy and vibration characteristics.The research findings can provide references for the dynamic analysis of spur gear transmission sys-tems under the influence of systematic errors.

Abstract:[Objective]To address the difficulty of traveling for patients with lower limb motor dysfunction and promote the recovery of lower limb function,a multi-posture,multi-functional lower limb assistive device was designed,offering functions for mobility,assisted standing and lower limb rehabilitation training.[Methods]The static simulation was conducted using Ansys software to assess the safety of the device during use;the kinematics and dynamics models of lower limb exoskeleton were established to obtain the spatial posture and theoretical torque of each joint,providing theoretical support for the subsequent prototype fabrication;the"Zero-Moment Point"(ZMP)position model of the human body-assist device system was established,the theoretical ZMP was calculated,and the virtual prototype was imported into Adams software for simulation to obtain the variation in the supporting foot position,the stability of the device was validated by comparing the positions of ZMP and the supporting foot;the physical prototype was constructed.[Results]The rationality of the prototype design was validated by comparing simulation and experimental data,providing a basis for subsequent research.