Abstract:[Objective]Aiming at the problems such as the differences in the massage effects of different practitioners and the large physical consumption of traditional Chinese medicine,based on the engineering analysis of typical massage techniques,a kind of massage robot with a 3-UPS/PPR parallel mechanism as the core was proposed,so that it can complete the massage techniques instead of the practitioner.[Methods]Firstly,the degree of freedom analysis of the mechanism was carried out by us-ing the spiral theory and verified by using the K-G formula.Then,the closed vector method was applied to solve its position in-verse solution,the Jacobian matrix model was established,and the singularity analysis was conducted.The workspace of the mechanism was solved using the limit boundary search method,along with the analysis of its motion/force transfer performance.Finally,tapping,rubbing,rolling and other maneuvers were simulated by using the Adams software.[Results]The results show that the mechanism can realize 2T1R three degrees of freedom without accompanying motions,and the workspace is internally continuous without fault cavities,with no singular positions and excellent transfer performance.Through the introduction of cha-constrained branched chain to improve the smoothness of massage manipulation,the structure is relatively simple,which is an ef-fective attempt for the engineering of traditional Chinese medicine massage manipulation.

Abstract:A modeling method of finite element model for precise assembly of face gear transmission with installation error coupling was studied,and the bearing contact characteristics of face gear transmission were ana-lyzed.The discrete points of the tooth surface of the face gear and the cylindrical gear and the assembly angle of the gear pair with installation error were obtained by the numerical calculation method,and the high-precision modeling and assembly of the finite element model of the face gear transmission were realized.Through the sec-ondary development of Abaqus,the finite element bearing contact analysis results and bearing contact character-istic parameters of face gear with installation error coupling were obtained.The results show that when the shaft angle error is too large,the stress concentration will occur,and the contact stress of the tooth surface increases by 41.33％compared with that without error.When the axial installation error exceeds 0.4 mm,the tooth surface meshing will produce interference.In the case of the coupling of offset and axial installation error,the influence of axial installation error on the bearing contact characteristics is the same as that of the axial installation error when the offset installation error is kept constant.

Abstract:A norm adaptive step size rapidly-exploring random tree(RRT)algorithm suitable for manipu-lators was proposed to address the issues of fixed step size debugging time,poor collision detection performance,and low search efficiency of the traditional RRT algorithm in multidimensional environments.Firstly,a kinemat-ic model with a 6-degree-of-freedom UR5 manipulator was established,and the forward kinematic analysis was performed.Secondly,by combining the norm inequality and the Jacobian matrix,a step mapping relation be-tween the workspace of the manipulator and the joint space was constructed,dynamically changing the search step size of the joint space while ensuring the effectiveness of collision detection.Finally,the simulation analysis results show that the norm adaptive step size RRT algorithm has higher search efficiency than the traditional fixed step size RRT algorithm and does not require the manual step size adjustment,and the path search time has been reduced by 29.32％,thus improving the efficiency of manipulator path planning.

Abstract:[Significance]Pipeline robots are efficient and intelligent devices specifically designed for mobility within pipelines to perform tasks such as inspection and cleaning.The application of this technology can significantly reduce the risks and costs associated with manual pipeline operations while improving operational efficiency and safety.[Analysis]The application prospects of pipeline robots in the fields of pipeline inspection and cleaning,as well as the development trends of their technologies,were analyzed in depth.An overview of the current research status of pipeline robots was provided,with classifications from multiple perspectives including their movement modes,functions,and application fields.Through the review of the development history of pipeline robots,the key technical points in this field have been further refined.Insights into technical challenges and future development trends have been put forward,aiming to provide references and guidance for the further research and application of pipeline robot technology.

Abstract:In the design of the micro-positioning platform,a three-dimensional bridge-type amplification mechanism capable of generating high displacement amplification ratio was introduced.On this basis,a four-bar symmetric guiding mechanism was incorporated to effectively reduce the parasitic displacement at the output end.This design allows the micro-positioning platform to fully leverage the advantages of both mechanisms.By applying the strain energy theory,the second theorem of Castigliano,and Lagrange's theorem,the static and dy-namic mathematical models of the micro-positioning platform were established.The theoretical analysis re-vealed the influence of key dimensions on the displacement amplification ratio of the platform.Through calcula-tion,the amplification ratio and natural frequency were determined to be 19.90 and 193.26 Hz respectively,un-der the optimal parameters.Finite element analysis was used to verify the amplification ratio and natural fre-quency,resulting in relative errors of 4.3％and 5.9％respectively.This confirms the superior performance of the improved micro-positioning platform proposed in this study,as well as the accuracy of the theoretical analysis method.It provides theoretical guidance for the mathematical modeling of flexible micro-positioning platforms with amplification mechanisms.

Abstract:A human lower limb rehabilitation device based on a planar five-bar mechanism was intro-duced,aiming at meeting the early,mid and late rehabilitation training needs of stroke patients who are bedrid-den after surgery.This device has the characteristics of simplicity and reliability,and can be placed at the end of the bed or moved with the patient's walking.The device mainly consists of a lower mobile platform,a manual lift-ing component,an upper power transmission mechanism,and left and right training mechanisms.Sensors were attached to the universal joint brackets of the ankle and knee joints,allowing real-time collection and feedback of the patient motion information.Through kinematics analysis and Adams software simulation,the results show that adjusting the initial phase of the double crank of the device can change the motion track of the joint points,thus obtaining the range of motion of human lower limb joints under different motion modes,achieving the pur-pose of horizontal training and walking training,and meeting the training needs of patients in different rehabilita-tion stages.

Abstract:This study takes the shift process of a commercial vehicle equipped with an automated mechan-ical transmission(AMT)as the research object,with the aim of reducing shift shock and shortening shift time.Simulink was used to construct a shift control strategy without the participation of synchronizers,which includes dynamic coordination of power sources and active synchronization control of motors based on optimal control principles.Then,AMESim was used to establish a complete vehicle shift simulation model.Taking the shift from fifth gear to sixth gear as an example,a comparative analysis of the shift performance between AMESim and Simulink joint simulation and traditional shift strategies was conducted.The simulation results show that the syn-chronization time is reduced by 21.42％during the shift process,the maximum impact is reduced by 24.88％,and the entire shift time is reduced by 18％.Finally,the control strategy proposed in this research was validated in real-time using the dSPACE semi physical simulation platform.

Abstract:[Objective]Aiming at the problem that the bearing fault feature extraction is difficult and the recognition accura-cy is not high due to the characteristics of local strong non-stationarity and nonlinearity of the vibration signal of reciprocating compressor bearing clearance,a new method based on GMDE and MFO-MKELM algorithm was proposed.[Methods]First,spread on multiscale entropy in the process of coarse graining,the average coarse graining way to a certain extent,"neutralize"the dynamics of the original signal mutation behavior,and reduce the accuracy of the entropy analysis.A generalized multiscale entropy algorithm spread,application of the reciprocating compressor vibration signals of bearing clearance for fault feature ex-traction was proposed;then,the polynomial kernel function and the improved Gaussian kernel function were linearly combined to construct the multiple kernel extreme learning machine intelligent recognition algorithm,and the fault diagnosis research was carried out on the extracted feature vector set.[Results]Simulation results show that the recognition accuracy of the fault diagno-sis method is as high as 98.6%,which effectively realizes the intelligent diagnosis of different types of bearing faults.

Abstract:To change the physical harm caused by the constant posture of disabled people for a long time,a three-posture adjustable multi-functional integrated wheelchair bed was proposed,which realized the timely transformation of sitting,standing and lying.The device includes a bed chair conversion mechanism,an auxilia-ry standing mechanism and a bed body lifting mechanism.The kinematic mathematical model of each mecha-nism was established,and the kinematic simulation was carried out based on the Matlab software.The virtual prototype model of the wheelchair bed was constructed,and the Admas simulation was carried out.The physical prototype of the multi-functional wheelchair bed was built,and its motion stability was verified experimentally.The rationality of the prototype was verified by comparing the test curve with the simulation curve,providing a basis for further research on the wheelchair bed.

Abstract:[Objective]The transmission error is a critical performance indicator in the design of cycloidal pin wheel reduc-ers.The influence of design parameters for crank bearings and output shaft pins on this error is frequently neglected in existing research.To address the issue,a method for calculating transmission error based on the kinematic and mechanical analysis was introduced,thereby offering theoretical foundation for the optimization of design and the enhancement of performance in cycloi-dal pinwheel reducers.[Methods]Firstly,the motion locus of the meshing point between cycloidal gear teeth and pin teeth was obtained based on the instantaneous motion locus of the cycloidal pin gear mechanism and the meshing interval between them.Subsequently,the design range for the distribution circle radius of crank bearing and output shaft pin was defined.A contact force analysis model for the crank bearing and the output pin was established,and their respective force influences were calculat-ed.Finally,by Masta software,the influence of distribution circle radius on transmission error of cycloidal pinion reducers was analyzed.[Results]The results show that within the design range for distribution circle radius of the crank bearing and the output shaft pin,the larger values result in smaller transmission errors but greater forces exerted on these components.This study pro-vides valuable insights for designing and optimizing domestic cycloidal reducers.

Abstract:[Objective]Aiming at the problems of large size,heavy weight and safety of human-machine interaction of traditional rigid wheelchair manipulators,a 6-degree-of-freedom rope driven flexible wheelchair manipulator was designed.[Methods]The manipulator adopted a flexible translation structure,which can keep the end posture unchanged while changing the end position,realized the decoupling of position and posture,and effectively improved the rigidity of the flexible manipulator.The kinematic model of the flexible manipulator was established based on the constant curvature modeling method,and the kinematic analysis between the drive space,joint space,and operation space as well as the decoupling analysis between each flexible joint were carried out.A simulation model based on Adams virtual prototype was established.[Results]By comparing with the numerical simulation results of Matlab software,the accuracy of the kinematic algorithm is verified,which provides a basis for the subsequent motion control of the manipulator.

Abstract:[Objective]In order to solve the problems of random sampling,inefficient search,and difficulty in providing op-timal paths in complex environments faced by traditional Informed-RRT* algorithms,an improved Informed-RRT* path plan-ning algorithm based on the sea-horse optimizer(SHO)was proposed.[Methods]This algorithm combined the strengths of In-formed-RRT* and SHO.An adaptability function was introduced to evaluate the suitability of sampled nodes,thereby enhanc-ing guidance towards sampling objectives.Additionally,adaptive step sizes and random perturbations were employed to adapt to obstacles in the environment,and the best individuals were chosen to guide the expansion direction of the random tree.[Results]Through multiple sets of simulation and prototype tests,it is demonstrated that the improved Informed-RRT* algorithm exhibits faster convergence speed,higher search efficiency,and superior path planning performance,providing an efficient solution for path planning in complex environments.

Abstract:[Objective]The fatigue load of the yaw system is the main cause of wind turbine failures,and the phenomenon of gear and shaft breakage in yaw drive and other gearboxes is still a high-frequency fault.The failure analysis results indicate that the production process of raw materials,organizational control results,macroscopic mechanical performance adjustment,component assembly clearance,meshing relationship,and vibration influence are the main causes of failure.By studying and an-alyzing these patterns,the cause of tooth breakage in the output teeth of the sun gear in the yaw drive gearbox of onshore wind turbines can be identified,providing technical support for the subsequent research and design of wind turbine yaw systems.[Methods]Through physical and chemical performance testing of failed output teeth and SEM fracture analysis,the gear struc-ture design and unit operating status were investigated to determine the cause of tooth breakage.[Results]The results show that the abnormal decomposition of the martensitic structure on the surface layer of the output tooth resulted in a surface hardness be-low 58 HRC and a shallower hardening layer depth by 10%,which reduced the surface contact strength of the tooth.Multiple non-metallic inclusions about 5 micrometers were found on the fracture surface,and rough machining marks on the tooth root surface further reduced the bending strength of the tooth root.During operation,the effective meshing area between the gear racks was only 50%,indicating severe uneven loading.This resulted in the working stress of the teeth exceeding the allowable stress,triggering fatigue wear and early cracking on the tooth surface,and causing tooth fracture when the load exceeds the bear-ing limit.The phenomenon of partial load broken tooth is improved after machining technique and tooth shape optimization.

Abstract:In order to improve the NVH performance of a three-in-one electric drive system,the structural transmission path is designed and optimized.Firstly,the weak components with the highest NVH contribution to the electric drive assembly were identified by analytical method,frequency positioning method and plate contri-bution analysis method.Then,the material distribution of the controller cover plate(the weak component with the highest NVH contribution)was optimized with the modal frequency as the optimization goal and the volume fraction as the constraint.The simulation results show that the frequency of each mode of the optimized cover plate is increased,the first mode is increased by 34％,and the sound power level under unit excitation is reduced by 2-7 dB.Finally,NVH bench performance test was carried out on the electric drive assembly with optimized cover plate.The test results show that compared with the original electric drive assembly,the total sound pressure level of the electric drive assembly optimized cover plate has a certain reduction in different frequency ranges,es-pecially in the middle and high frequency band,and the reduction effect is more significant,reducing 2-4 dB.

Abstract:[Objective]When the gear with constant relative curvature(CRC)transmission is in a mixed elastohydrodynam-ic lubrication state,the wear coefficient is not constant,and the traditional Achard adhesive wear model is no longer applicable.It is necessary to conduct adhesive wear analysis on CRC gears under mixed elastohydrodynamic lubrication.[Methods]Under mixed elastohydrodynamic lubrication,a dynamics model considering time-varying friction and a modified Achard adhesive wear model were established to calculate the adhesive wear depth of gears with constant relative curvature.The time-varying friction coefficient model was verified by comparing results with the experimental data.Through numerical examples,the effects of parameters such as modulus,input torque,and rotational speed on wear were discussed.[Results]The results show that the wear depth at the root of the driving and driven gears should be greater than that at the top of the teeth,and the wear depth at the pitch point was the smallest.The maximum wear depth occurs at the root of the tooth or at the boundary point of the meshing ar-ea of a single pair of teeth.Increasing the modulus,tooth width,input speed,and reducing input torque can effectively reduce wear depth.Increasing the transmission ratio or decreasing the relative curvature value under specific conditions can reduce wear depth.

Abstract:[Objective]In order to enable the inspection robot to pass through the large gradient line smoothly and to improve the climbing ability along the line of the dual-armed wheeled inspection robot,an analysis and optimization was carried out for a dual-armed wheeled inspection robot.[Methods]Firstly,the force characteristics of the robot during uniform slope climbing were analyzed using a static mechanics model,and a virtual prototype of the robot was established using Adams simulation software to determine its maximum slope-climbing angle.Then,both single-factor and response surface methods were used to analyze the influence of parameters such as the wrapping angle of the walking wheels,the clamping force of the front gripping wheels,and the clamping force of the rear gripping wheels on the robot's maximum slope-climbing angle.Finally,the maximum slope-climbing angle was derived using a linear regression equation,and the optimization results were validated through tests with a robot prototype.[Results]The results show that after optimization,the robot's maximum slope-climbing angle reaches 32°,an increase of 92%compared to that before optimization.The results indicate that modifying the walking wheel structure and increasing the clamping force can effectively improve the slope-climbing capability of the inspection robot along steep lines.

Abstract:[Objective]Addressing the issue of vibration and noise suppression in electric drive axles for new energy vehicles and the limitations of gear modification based on engineering experience,a method for predicting vibration response in electric drive axles using support vector regression(SVR)was proposed.[Methods]Initially,a gear transmission system model for the electric drive axle was constructed,and its validity was confirmed through simulated contact spot analysis compared with test data.Subsequently,a prediction model of gear micro-modification parameters and vibration response was established based on SVR,targeting transmission error,maximum contact stress,and tooth load distribution coefficient of the electric drive axle gears.Finally,a non-dominated sorting genetic algorithm(NSGA-Ⅱ)with an elitist strategy was introduced to optimize the micro-modification parameters of the gears.[Results]Simulation results demonstrate that post-optimization modification leads to a 49%reduction in transmission error,a 4%decrease in maximum contact stress,improved uniform load distribution,and a 93%reduction in peak vibration acceleration.Test validation reveals a reduction in noise levels across various operating conditions,with the maximum noise drop being approximately 4 dB(A).This research provides insights and a basis for vibration and noise reduction in gear transmission systems of electric drive axles for new energy vehicles.

Abstract:A splash lubrication simulation model of a planetary gear train was established based on the moving particle semi-implicit(MPS)method,and it was verified by experiments to explore the splash lubrication behavior of the planetary transmission.Through the simulation,the oil distribution characteristics,the number of lubricating oil particles in the engagement zones,and the churning loss of the rotating components were studied.The results show that in the rotation of the planetary gear train,the interior space of the gearbox can be divided into three regions:the oil-pool region,the oil-dragging region,and the oil-poor region.The number of oil particles in different engagement zones and the churning torque of each component show periodic variations during the planet gear passes through the three regions.The numbers of oil particles in the inner and outer engagement zones reach the peak when the planet gear runs into the oil-pool region,and both drop rapidly to a minimum value after entering the oil-poor region.The churning torque of the planet gear rises sharply to the peak after entering the oil-pool region and keeps the peak value until the planet gear enters the oil-dragging region,then the churning torque turns to fall until stabilizing at a very low level when the planet gear enters the oil-poor region.Different from the planet gear,the churning torque of the planetary frame drops sharply when one of the planet gears enters the oil-pool region and rises rapidly when that planet gear enters the oil-dragging region and the next one has not entered the oil-pool region.The churning torque of the sun gear is small and insensitive to the planet gear positions.Among the total churning power of the planetary gear train,the sum of the three planet gears accounts for about 60％,followed by the planetary frame,and the sun gear accounts for the least.

Abstract:The operating speed of the radial double-end mechanical seal of the lubricating oil in the ultra-high-speed gear transmission bearing chamber of the torpedo turbine engine is as high as 50 000 r/min.Facing extreme conditions such as friction heat generation,high temperature and high pressure of the sealing medium,the sealing performance is difficult to guarantee,thus affecting the lubrication characteristics of gears and bearings.To solve this problem,the thermal-fluid-solid coupling simulation model of the mechanical seal of the ultra-high speed gearbox was established,and the cooling water flow field of the mechanical seal and the temperature rise and deformation of its end face were analyzed.The effects of spring pressure,cooling water flow and static ring interference on the temperature rise and deformation of the seal end face under hot conditions were studied.The results show that the pressure difference between the two sides of the inner seal in the hot state is 1.1 MPa,which is 11 times that of the cold state.The maximum temperature of the inner and outer seal faces reaches 400℃and 370℃,which is about three times that in the cold state.The deformation of the seal end face in the hot state is greater than that in the cold state,and the deformation of the inner seal end face is greater than that of the outer layer.The temperature rise of the seal end face increases with the increase of the spring pressure and decreases with the increase of the cooling water flow rate.The optimal cooling water flow rate is 0.2 kg/s.With the increase of spring pressure,the deformation of the end face of the moving ring gradually increases,while the deformation of the end face of the static ring is almost unchanged,and the cooling water flow rate has little effect on the deformation of the sealing end face.The deformation of the end face in the static ring increases with the increase of the interference,and the deformation of the end face of the inner static ring is larger than that of the outer layer.

Abstract:To reveal the dynamic sliding characteristics of synchronous meshing of thread pairs and gear pairs of the planetary roller screw mechanism,a calculation method for the sliding angle of the planetary roller screw mechanism was proposed,and a numerical model of the planetary roller screw mechanism was established to verify the correctness of the sliding angle calculation method.Firstly,based on the mechanism of the pitch cir-cle offset,the kinematics analysis model of the slip angle was established,and its correctness was verified by comparing with the numerical solution.On this basis,the influences of the screw speed,nut load on the sliding angle and the sliding distance of thread gear and gear pairs were analyzed.The research results indicate that the sliding angle increases with the increase of the screw speed and the nut load.The sliding distance on the roller screw side is much greater than that on the roller nut side,and both increase with the increase of the screw speed and the nut load.The sliding distance of the gear pair decreases with the increase of the screw speed and increas-es with the increase of the nut load.