最新刊期
卷 49 ， 期 11 ， 2025
- 摘要：SignificanceWith the intensification of global aging, the number of patients suffering from lower limb motor dysfunction caused by conditions such as stroke and spinal cord injury is continuously increasing. Lower limb rehabilitation exoskeleton robots, as novel intelligent integrated rehabilitation devices, are primarily utilized to assist patients in achieving standing and walking, providing precise physical support and motion guidance. They represent a focal point of contemporary rehabilitation medicine research. A comprehensive review of the current research status and application progress of lower limb rehabilitation exoskeleton robots was conducted. [Analysis] Firstly, these robots were classified based on operational posture, driving mode, and mechanical structure. Five key technologies in their research and development were explored, including motion information sensing, motion intention recognition, human-computer interaction, virtual reality, and artificial intelligence, alongside a discussion of their clinical applications. Secondly, an in-depth analysis of current training efficacy evaluation methods for rehabilitation exoskeleton robots was performed from three perspectives: clinical scale assessment, sensor-based rehabilitation effect evaluation, and bio-detection technology-based rehabilitation effect evaluation, encompassing both domestic and international studies. Finally, future development directions in the field of lower limb rehabilitation exoskeleton robots were projected, with an exploration of potential technological breakthroughs and application prospects.关键词：Rehabilitation robot;Exoskeleton;Rehabilitation medical;Key technology;Human-computer interaction;Rehabilitation effect evaluation117|12|0更新时间：2025-11-17
Review
- 摘要：ObjectiveDue to its numerous advantages, the spiral bevel gear is widely used in the transmission fields of aerospace, automotive, marine, engineering, and port machinery. Given the limitations in load-bearing capacity of milled spiral bevel gears and the low forming precision of hot forging (≥1 000 ℃), the warm forging (≤750 ℃) forming technology was investigated.MethodsA mold tooth surface model was constructed based on the tooth surface of the gear, and the effects of forging speed, die preheating temperature, friction coefficient, and workpiece heating temperature on the stress and strain during the warm forging were analyzed. Process parameter optimization was completed through orthogonal tests. Using the optimal process parameter combination, a warm forging test was conducted.ResultsThe gear inspection results prove the accuracy of the warm forging process. The research outcomes provide support for the fatigue-resistant manufacturing of large spiral bevel gears （driven gears）.关键词：Spiral bevel gears;Warm forging;Numerical simulation;Process parameter optimization;Warm forging test89|112|0更新时间：2025-11-17
- 摘要：ObjectiveTo understand the unclear transmission mechanism between machine tool errors and gear helix deviations in the gear through rolling process, a mapping model for machine tool errors and helix deviations was proposed.MethodsFirstly, a machine tool topological structure diagram was established based on spatial configuration and axis distribution of rolling forming equipment, revealing transmission paths and categories of machine tool errors. Subsequently, the position-posture error transformation matrix between the rolling wheel and gear was derived through homogeneous coordinate transformation theory and multi-body system topological principles. Then, a mapping model connecting machine tool errors with gear helix deviations was developed by solving double-parameter envelope equations based on the rolling wheel’s involute tooth surface equation. Finally, Matlab simulations and rolling tests were conducted to validate the error model.ResultsThe results show that machine tool translation errors remain constant along tooth width, rotational errors increase linearly, and perpendicularity errors exhibit parabolic variation. Gear helix deviations demonstrate proportional relationships with translation errors, rotational errors, and perpendicularity errors respectively. Combined effects of translation/rotational errors with perpendicularity errors cause varying degrees of helix deviation amplification. This study provides foundation for subsequent error compensation strategies and machining accuracy improvement in gear rolling processes.关键词：Throughfeed rolling;Machine tool error;Homogeneous coordinate transformation;Envelope equation;Helix deviation24|2|0更新时间：2025-11-17
- 摘要：ObjectiveThe inverted planetary roller screw mechanism (IPRSM) is a new precision heavy-duty transmission device with high precision, large load, and long life. Due to the characteristics of multi-parts, multi-point contact, and multi-moving pairs, the dynamic behavior of the IPRSM are difficult to predict accurately.MethodsTo address this issue, a dynamic model of IPRSM was established by using the RecurDyn software, considering the complex contact and motion relation between the nut, the roller, the lead screw, and the cage. Based on verifying the validity of the dynamic model, the model was successfully used to analyze the influence of the nut speed and the screw load on the transmission characteristics of the IPRSM.ResultsThe results indicate that the average contact forces between the rollers and the screw, as well as between the rollers and the nut, exhibit a positive correlation with both the nut rotation speed and the screw load. Due to the contact deformation between various components, uneven load distribution occurs between the meshing teeth of the rollers and the screw, and also between the left and right journals of the rollers and the inner holes of the cage. This research can provide support for the structural design and optimization of the IPRSM.关键词：Inverted planetary roller screw mechanism;Dynamic analysis;Transmission characteristics;Simulation modeling390|447|0更新时间：2025-11-17
- 摘要：ObjectiveWhen calculating the time-varying meshing stiffness based on the potential energy method, the length and position of the traditional cantilever beam model are usually fixed, and the change of the position of the cantilever beam root caused by crack propagation is ignored, which brings a large error to the accurate obtaining of the meshing stiffness. To solve the above problems, considering the increase of the length of the cantilever beam model caused by crack propagation, a method for calculating the time-varying meshing stiffness of cracked gears based on the extended cantilever beam model was proposed.MethodsAccording to the proposed method, the effective section moment of inertia and the effective bearing area of the gear which decrease due to gear root crack propagation were calculated. On this basis, different crack stages were divided according to the crack length, and the time-varying meshing stiffness of the gear under different crack stages was calculated. The finite element model (FEM) of gear meshing was established to verify the proposed method.ResultsThe results show that, compared with the traditional cantilever beam model, the meshing stiffness calculated by the proposed method is closer to the finite element model because the propagation energy of the crack propagation part is taken into account, which verifies the effectiveness and accuracy of the proposed method.关键词：Potential energy method;Gear root crack;Time-varying meshing stiffness;FEM22|6|0更新时间：2025-11-17
- 摘要：ObjectiveThe main bearing of the shield machine bears complex concentrated loads (including huge axial force and overturning moment). To improve the finite element simulation efficiency of the slewing bearing and reduce its maximum contact load, a non-planar structure design method for the inner ring raceway of the bearing was proposed.MethodsTaking the three-row cylindrical roller bearing as the research object, the finite element analysis was carried out by adopting the modeling method of equivalent cylindrical rollers with nonlinear springs. The internal contact load distribution and overall deformation characteristics were obtained under the combined loads of typical working conditions.ResultsThe results show that the equivalent modeling method effectively can reduce the calculation scale and shorten the calculation time; the contact loads of the upper and lower rows of rollers present an approximately symmetrical distribution; compared with the maximum contact load of the circular raceway bearing, the maximum contact load of the non-planar raceway bearing is reduced by about 9%, and the roller load distribution is more uniform with all values decreased. Reference value is provided by this study for prolonging the service life of the bearing.关键词：Three-row cylindrical roller bearing;Nonlinear spring;Load distribution;Non-planar raceway;Finite element22|5|0更新时间：2025-11-17
- 摘要：ObjectiveAiming at the problems of traditional rapidly-exploring random tree (RRT) algorithm in multi-degree-of-freedom manipulator path planning, such as the unguided search and the poor path quality, a heuristic RRT algorithm based on collision-free channels was proposed.MethodsObtaining collision-free channels in the workspace through a sphere-based wavefront expansion algorithm (Wavefront algorithm), setting up path targeting points, and utilizing the environmental information to inspire the tree growth instead of the traditional blind searching; the random point sampling function was improved, and the multi-dimensional Gaussian distribution model and Gaussian mixture model (GMM) of the path targeting points in the joint space corresponding to the joint angles were used as the heuristic terms, respectively, to guide the end-effector of the manipulator to direct the fast and stable expansion in the collision-free channel.ResultsSimulation and analysis results show that the heuristic RRT algorithm reduces the path search time and the number of iterations, and the path length is shortened by 39.32% compared with the traditional RRT algorithm.关键词：Path planning;Manipulator;Rapidly-exploring random tree;Collision-free channel;Heuristic sampling;Gaussian distribution18|5|0更新时间：2025-11-17
Theory·Research
- 摘要：ObjectiveTraditional circular deployable and foldable mechanisms suffer from low deployment accuracy, poor stability, and limited expandability, while spatial deployable and foldable mechanisms possess advantages such as small stowed size, large deployed volume, and light weight.To meet the needs of future space technology development, feature synthesis was performed on the eight-bar loop using the germ diagram method, and different tower-shaped spatial deployable and foldable mechanisms were constructed.MethodsBased on the ideas of screw theory and the equivalent isolation method, the geometric coordination and motion synchronism of the tower-shaped circular deployable and foldable mechanism were analyzed. Computer-aided design was adopted, and the mapping relation between design parameters and performance was analyzed through numerical simulation.ResultsThe analysis results verify the stability and effectiveness of the deployment and folding processes of the tower-shaped circular deployable and foldable mechanism.关键词：Spatial deployable and foldable mechanism;Screw theory;Tower-shaped circular mechanism20|5|0更新时间：2025-11-17
- 摘要：ObjectiveTo improve the terrain adaptability of wheel-legged mobile robots and simplify the control of driving and wheel-leg mode switching, a parallel variable topology mechanical leg with zero coupling and partial motion decoupling was proposed.MethodsFirstly, a variable topology kinematic joint was designed based on the structure composition principles of variable topology mechanism. Secondly, a variable topology mechanical leg was designed and analyzed based on the position and orientation characteristics (POC) sets. Then, using the topological characteristic kinematics method, the symbolic position forward and inverse solutions of the mechanical leg were solved, and its workspace and singularity were analyzed. Finally, a quadruped robot was constructed using the variable topology mechanical legs, and the gait planning was carried out on the steep slope and gully terrain to test its obstacle-crossing capability.ResultsThe variable topology mechanical leg has two motion modes of wheel and leg. The POC set in the leg mode is 2R1T, and the POC set in the wheel mode is 3T1R. The switching of the two motion modes based on the variable topology kinematic joint reduces the time required for mode switching and is simple to control. Obstacle-crossing tests have shown that the variable topology mechanical leg has strong passing capability for the complex terrain such as steep slope and gully.关键词：Mechanical leg;POC set;Variable topology;Motion decoupling;Singular configuration27|4|0更新时间：2025-11-17
- 摘要：ObjectiveRobots are widely used in many fields such as the production and the life because of their excellent intelligence and stability. However, the singularity of their structural form limits their ability to be applied in the complex and changing environments. To solve this problem, a novel 2-UPU/(UPUU)PU parallel mechanism was proposed and applied to the leg structure of a mobile robot to enhance the robot’s adaptability in the complex terrain.MethodsFirstly, the constraint-motion relation in the screw theory was used to analyze the mechanism, determine the motion degrees of freedom of the mechanism, and specify the driving part; the vector method was used to construct the inverse solution equation of the parallel mechanism. After determining the structural dimensions of the mechanism, the inverse solution analysis was carried out using Adams software and verified by Matlab software to ensure the feasibility of the mechanism. In addition, based on the constraints of the physical rods, the workspace of the parallel mechanism was analyzed to clarify that its reachable workspace can meet the robot’s movement requirements. Finally, an application example of the novel 2-UPU/（UPUU）PU parallel mechanism was constructed, and its movement mode was planned.ResultsThe study shows that the parallel mechanism can be used as a foot-end structure of a mobile robot to realize the robot’s movement in complex environments.关键词：Parallel mechanism;2-UPU/（UPUU）PU;Screw theory;Positional inverse solution;Workspace19|5|0更新时间：2025-11-17
- 摘要：ObjectiveTo solve the problems of insufficient motion flexibility and limited operation space of existing minimally invasive surgical instruments, and to improve their clinical applicability, a 5-degree-of-freedom (5-DOF) composite cable-driven minimally invasive surgical instrument was designed.MethodsSpecifically, the 5 DOFs of the instrument were achieved for the opening/closing of the surgical forceps, pitching/yawing of the snake-like joint, rotation of the axial rotation joint, and surgical space expansion of the parallel joint. To address the vibration and reduced transmission efficiency caused by motion coupling of the cable-driven system, a high-efficiency decoupling device was designed. Precise calculations and parameter optimization were carried out based on the motion coupling principle to ensure the motion independence of each component and the overall stability of the system. Combined with the instrument structure design, kinematic analysis and workspace solution were conducted, and the rationality of the structure and the correctness of the kinematics were verified.ResultsThe functional integrity and motion space coverage of the designed instrument are both able to effectively meet the clinical operation requirements of common minimally invasive surgeries.关键词：Minimally invasive surgical instrument;Cable-driven;Kinematic decoupling;Kinematics;Workspace analysis18|6|0更新时间：2025-11-17
- 摘要：ObjectiveAimed at the functional limitations of traditional wheel-legged robots in complex terrain environments, a design method for a variable telescopic wheel-legged robot was proposed. By adjusting the motor speed, the mechanism could change the distance between the wheels and the ground, and realize multiple actions such as variable diameter of the telescopic wheels and direction change of the wheel-legged robot.MethodsA detailed design and model construction of the structure were conducted using SolidWorks software. Different motion modes were achieved by changing the motor speed. The operating mechanism of the variable telescopic wheel-legged structure was elaborated in detail. The wheeled mode was adopted for traveling on flat roads, while the legged mode could surmount obstacles under complex terrain conditions. Kinematic models for the straight-moving and turning modes of the wheel-legged robot were established using differential equations, and dynamic analysis was performed using the Lagrangian model. Finally, virtual prototype simulation of the robot’s walking on flat and complex roads as well as obstacle surmounting was carried out using Adams software.ResultsThe simulation results show that the proposed variable telescopic wheel-legged robot is highly feasible, can adapt to various complex terrains, possesses the stability of wheeled mechanisms, and meanwhile has the high obstacle-surmounting capability of legged mechanisms.关键词：Wheel-legged robot;Obstacle surmounting;Variable diameter structure;Lagrange equation;Adams simulation25|3|0更新时间：2025-11-17
- 摘要：ObjectiveTo address the challenges traditional robots face in overcoming obstacles on the truss walls of communication towers, a tandem-type wall-climbing inspection robot was proposed for communication towers, featuring two walking modes.MethodsThrough the structure design of the robot and analysis of its movement patterns, the standard D-H method was used to establish coordinate systems and construct forward and inverse kinematic equations. The differential transformation method was employed to derive the robot’s velocity Jacobian matrix. Subsequently, the Robotics toolbox in Matlab software was utilized to simulate the robot’s reachable workspace and the motion trajectories of single-step movements in both walking modes. Finally, a prototype was developed and tested.ResultsThe results demonstrate that both simulations and prototype test confirm the robot’s excellent mobility and obstacle-crossing capabilities on communication towers, effectively addressing the difficulties traditional wall-climbing inspection robots encounter in navigating and accessing areas during inspection tasks on communication towers.关键词：Wall-climbing robot;D-H method;Jacobian matrix;Kinematics simulation;Prototype test19|4|0更新时间：2025-11-17
- 摘要：ObjectiveBy using the stacked compound planetary gear train, a more compact gear reducer can be obtained, and the radial size and mass of the reducer can be reduced.MethodsA mathematical model for parameter optimization design of a stacked compound planetary gear train with 5 planetary gears per layer was established, and the parameter optimization analysis was carried out on the background of a certain type helicopter main gearbox NGW planetary gear train. The sequential quadratic programming method was used to optimize the parameters of the gear train.ResultsWhen the minimum radial size of the gear train is taken as the objective function, the radial size is reduced by 22.5％, and the corresponding volume by 11.7％. When the minimum volume of the gear train is taken as the objective function, the radial dimension is reduced by 11.5％, and the corresponding volume by 23.2％. When the minimum radial size and volume of the gear train are the double objective functions, the radial size and volume of the gear train are reduced by 16％ and 21.5％ respectively, by the linear weighting method, which is more significant than the single objective optimization.关键词：Planetary gear train;Stacked compound planetary gear;Sequential quadratic programming method17|5|0更新时间：2025-11-17
Design·Calculation
- 摘要：ObjectiveControlling the indentation rolling resistance is an important way to reduce energy loss during the operation of high-capacity and long-distance belt conveyors. Most scholars at home and abroad use the Winkler model to derive the mechanical model of indentation rolling resistance. However, there are relatively few models derived through Hertzian contact theory. It is necessary to conduct research on this situation in order to provide a scientific method for calculating indentation rolling resistance.MethodsAn indentation rolling resistance model based on Hertzian contact theory was derived, and the accuracy of the indentation rolling resistance model was verified by combining the test bench and simulation results.ResultsThe results show that the indentation rolling resistance increases with the increase of belt speed and loading pressure; under the same transportation volume, increasing the belt speed ratio and increasing the material mass can both effectively reduce the indentation resistance.关键词：Conveyor belt;Indentation rolling resistance;Hertzian contact theory;Finite element simulation14|2|0更新时间：2025-11-17
-
Comparison of contact strength calculation of spiral bevel gears based on HB, ISO and AGMA standards
摘要：ObjectiveAimed at the difference in the evaluation of tooth surface contact strength of spiral bevel gears by the strength check criterions in three standards, namely the Aviation Industry Standard of China (HB for short), the International Organization for Standardization (ISO) standard, and the American Gear Manufacturers Association (AGMA) standard, the optimal strategy for the design of spiral bevel gear pairs was explored through comparative analysis.MethodsFirstly, in-depth analysis was conducted on the influence of different strength check criterions on the tooth surface contact strength of spiral bevel gears from the aspects of calculation principle, calculation formula, and correction coefficient. Secondly, case analysis was carried out to explore the influence law of different gear blank parameters on the correction coefficient and contact stress.ResultsThe results show that, in terms of calculation principle, the AGMA standard is calculated based on the Hertz contact theory using the original parameters at the large end, while the HB and ISO standards are calculated based on the midpoint equivalent gear model combined with the Hertz contact theory. In terms of the correction coefficients introduced in the contact stress calculation formula and their corresponding calculation formulas, the ISO standard considers more comprehensive factors and is more complex in calculation than the HB and AGMA standards, among which the calculation of dynamic load factor and helix load distribution factor has the greatest impact on the stress results. In terms of the variation law of contact stress, among the three standards, gear blank parameters such as number of teeth, module, tooth width, helix angle, and pressure angle all have a great impact on contact stress, but the variation law of the influence of helix angle on contact stress is slightly different. In addition, there is no fixed relation where one is more conservative than the other two among the contact strength calculation results of the three standards.关键词：Strength check criterion;Spiral bevel gear;Contact strength;Contact pressure25|7|0更新时间：2025-11-17 - 摘要：ObjectiveAiming at the problems that high-speed train rolling bearing faults have strong randomness,severe noise interference and scarce fault data, which further lead to insufficient local feature extraction capability and low diagnosis accuracy of diagnostic models,a fault diagnosis method based on ResNet-18 network with dual time-frequency feature fusion was proposed.MethodsWith ResNet-18 network as the basic architecture,the original one-dimensional vibration signals were converted into two types of time-frequency diagrams by short time Fourier transform (STFT) and continuous wavelet transform (CWT) to achieve dual-channel feature extraction. Subsequently, the two extracted features were fused through a self-attention feature fusion layer. Tests were conducted using bearing data from Case Western Reserve University (CWRU, USA) and bench test data of high-speed train rolling bearings.ResultsThe results show that the classification accuracy of the proposed model reaches 99.66%, demonstrating excellent diagnostic performance,which can provide reference for the engineering application of high-speed train rolling bearing fault diagnosis.关键词：High-speed train rolling bearing;Fault diagnosis;Time-frequency diagram;ResNet-18 network;Self-attention21|2|0更新时间：2025-11-17
- 摘要：ObjectiveAimed at the frictional heat generation problem of cylindrical roller thrust bearings caused by severe rolling-sliding between rollers and raceways under low-speed and heavy-load conditions, a study on the fluid-solid coupling temperature rise characteristics of bearings based on rolling-sliding characteristics was conducted.MethodsA rigid-flexible coupled dynamic model of cylindrical roller thrust bearing was established via Adams software to analyze the rolling-sliding characteristics and cage slippage rate under different working conditions. A local method was adopted to construct a frictional power loss model, and the power loss was calculated by combining the post-processing parameters of Adams software. Based on the heat transfer theory, a fluid-solid coupling temperature rise model was established to study the temperature rise law of the raceway, and this model was verified through tests.ResultsThe results show that the increase in axial load makes the pure rolling point approach the theoretical position and reduces the slippage rate. The increase in rotational speed causes the pure rolling point to first approach and then deviate from the theoretical position, and the slippage rate to first decrease and then increase. Under low-speed and heavy-load conditions, the growth amplitude of frictional torque decreases with the increase in axial load, and the frictional torque decreases with the reduction in rotational speed. The maximum error between the temperature rise simulation and the test is 8.98%.关键词：Cylindrical roller thrust bearing;Rolling-sliding;Friction power loss;Temperature rise;Test24|1|0更新时间：2025-11-17
Test·Analysis
- 摘要：ObjectiveTo address the limitations of conventional magnetorheological (MR) dampers, such as poor controllability of torque output and low torque density, a high-torque-density spiral convective MR damper with dual operational modes for both forward and reverse rotation was proposed.MethodsFirstly, a mathematical model was established to characterize the damping torque output across multiple flow channels. Then, a physical prototype of the MR damper was developed. Lastly, a dynamic torque performance test platform was constructed to evaluate its torque output under forward and reverse modes at speeds of 40 r/min, 80 r/min, 120 r/min, 160 r/min, and 200 r/min, with excitation currents of 2 A, 4 A, and 6 A.ResultsTest results demonstrate that at 6 A excitation current and 200 r/min speed, the average steady-state torque of forward and reverse mode reaches 2.72 N·m and 2.56 N·m; the average starting torque of forward and reverse mode achieves 7.34 N·m and 7.81 N·m; the maximum torque density reaches 10 826.82 N/m2 in the forward rotation mode. These findings validate the effectiveness of the proposed design in overcoming the inherent limitations of traditional MR dampers.关键词：Magnetorheological fluid;Spiral convection;Rotary damper;Torque density;Dynamic characteristic11|6|0更新时间：2025-11-17
- 摘要：ObjectiveAiming at the problems of weak fault features and difficult fault feature extraction in vibration signals of low-speed and heavy-load rolling bearings, a fault diagnosis method based on ResNet18 residual network with squeeze-and-excitation (SE) attention mechanism was proposed.MethodsFirstly, the vibration signals collected by the sensor were converted into two-dimensional time-frequency diagrams via short-time Fourier transform (STFT). By virtue of its advantages in fault feature extraction, noise resistance and visualization,more fault feature information was captured. Then, the two-dimensional time-frequency diagrams were input into the improved STFT-SE-ResNet18 model. With the help of the SE attention mechanism, adaptive channel weights were learned, which enabled the model to pay more attention to useful channel information and improved the learning ability and recognition accuracy of the model.Finally, comparative experiments were conducted between this model and other network models.ResultsThe results show that the proposed model has high fault diagnosis accuracy and strong anti-interference ability under different working conditions,with remarkable fault diagnosis effect, demonstrating high superiority and great application potential.关键词：Low-speed heavy-load bearing;STFT;Attention mechanism;Residual network;Fault diagnosis34|4|0更新时间：2025-11-17
Development·Application
- Technical support is provided by Beijing Founder electronics co., LTD 豫ICP备05013835号-5
京公网安备11010802024621 - It is recommended to read the content of this site in Chrome&IE9+. Please switch to extreme mode in browser 360.
- Cookies We use cookies to help provide and enhance our service and tailor content. By continuing, you agree to the use of cookies.
0