最新刊期
卷 48 ， 期 6 ， 2024
- 摘要：To grasp the force status of the main bearing preload of precision planetary cycloidal reducers for robots, combined with structural characteristics of the reducer, the static model that considers the external load and the meshing force of cycloidal gears is established to analyze the force and internal contact state of 110E reducer main bearings under the rated working condition, and actual force results are obtained. Under this condition, aiming at the high tipping stiffness requirement of precision reducers, based on the Romax Designer simulation analysis software, the equivalent model of the reducer is established. The influence of the main bearing preload on the tipping stiffness is analyzed. The results show that the tipping stiffness increases with the increase of the preload, and the optimal preload range that satisfies the tipping stiffness and fatigue life is 5 μm to 20 μm. It has certain reference significance for the selection of the main bearing installation preload.关键词：Precision planetary cycloidal reducer for robots;Main bearing;Tipping stiffness;Preload386|128|0发布时间：2024-06-19
- 摘要：Based on the mathematical model of gear turning cutters and face gears, a tooth surface deviation model for gear turning is established using gear shaping as the theoretical tooth surface. Using the incremental method, the influence of machining parameters such as offset distance, cutting depth, shaft intersection angle, and rolling ratio on tooth surface accuracy is analyzed, and a method for correcting the tooth surface deviation ratio of face gears is presented. The tooth surface deviation in gear turning is mainly concentrated at four vertex positions, and the tooth surface deviation is most sensitive to the correction of the roll ratio, but not to the offset amount. Using a three-parameter deviation sensitivity matrix, the proportional relation between the tooth surface deviation and machining parameters is determined. Through two trial cuts, the tooth surface deviation is corrected, and the feasibility of the proportional correction method is verified.关键词：Skiving;Face gear;Machining parameter;Proportional correction59|151|0发布时间：2024-06-19
- 摘要：The tail gear reducer is an important component of the helicopter transmission system, and bearing preloading is a key link in the assembly of the tail gear reducer, which directly affects the stability, service life, and noise of the helicopter tail rotor. According to the bearing support configuration, a force model of the preloaded bolt is established to obtain the tightening torque of the bolt and the axial force applied to the support surface; based on the stress relationship, a finite element analysis model for the preloading of the tail reducer bearing is established, and the installation error of the bevel gear pair is extracted according to the analysis results. The processing results show that the tooth surface clearance of the spiral bevel gear pair decreases with the increase of the torque, and the imprint position gradually moves towards the large end with the increase of the torque; the experimental results are in good agreement with the finite element calculation results, and the method can be further extended to other types of reducers.关键词：Reducer;Bearing preload;Spiral bevel gear;Contact patch;Backlash56|77|0发布时间：2024-06-19
- 摘要：A new configuration of multi-dimensional platform is proposed to meet the dual requirements of orientation adjustment and vibration isolation. In the branch, the active orientation adjustment and passive vibration isolation units are fused in the form of closed-loop subchain. In the case of passive vibration isolation, suppose that the electric cylinder is locked instantaneously. The equivalent motion screw is used to describe the motion characteristics of the closed-loop subchain, and the branch containing the closed-loop subchain is equivalent to the series branch. Based on this, the first and second order influence coefficients of the mechanism are derived, which are concise and compact, and lay a foundation for the establishment of the motion differential equation and the analysis of the vibration characteristics of the mechanism. Based on the virtual work principle, the complete flexibility matrix and the directional stiffness model, which considers the gravity, external force and the changing trend of poses, are derived. The expression of the directional stiffness in different coordinate systems is analyzed by numerical examples, which provides reference for the performance analysis of the mechanism.关键词：Orientation adjustment and vibration isolation;Parallel mechanism;Screw;Kinematics;Stiffness48|54|0发布时间：2024-06-19
- 摘要：The planetary gear train has compact structure, high transmission efficiency, and is widely used in industrial manufacturing. There is a wide application space for the planetary gear train of the self-locking mechanism. In this study, the power flow direction and efficiency formula of the 3K(Ⅲ) type planetary gear train are analyzed, and the operation performance is improved by optimizing the efficiency of this kind of planetary gear train when it is self-locking. Thus, the setting of the transmission ratio and the corresponding efficiency of the reverse self-locking planetary gear set with higher transmission efficiency can be obtained. Firstly, the transmission ratio of the epicyclic gear train is solved by using the basic formula. Secondly, the power flow direction of epicyclic gear trains is analyzed according to different conditions. Thirdly, the efficiency curve is drawn based on the above conditions and the transmission ratio of the self-locking gear train is analyzed with an example. Finally, through detailed case studies, the accuracy and efficacy of this approach are verified, providing the transmission ratio setting for maximizing the efficiency of the planetary gear train during reverse self-locking scenarios.关键词：Epicyclic gear train;Self-locking;Meshing efficiency;Power flow127|147|0发布时间：2024-06-19
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Research on Stability of the High-order System Based on the Routh Criterion and Dominant Pole Method
摘要：The force model of the omnidirectional robot moving on the slope is constructed, the system function of the model is calculated, and the influence on the system due to load, slope θ, inertia and other disturbances is analyzed. The Routh criterion is proposed as the stability condition of the high-order system, and the root-locus dominant pole method is used to obtain a similar second-order system. The system performance index is observed and the optimal solution is obtained. The simulation results show that when the load K is 3.25 kg, the self-correction effect of the omni-directional robot on the slope motion system is better, which shows that using the Routh criterion and dominant pole method to study the stability of the high-order system is feasible and effective, and it provides a certain reference for future research on high-order system correction under the disturbance of the variable θ.关键词：Omnidirectional robot;Routh criterion;Dominant pole method;System stability29|75|0发布时间：2024-06-19
Theory·Research
- 摘要：Aiming at the people with hip joint dysfunction, a novel weak-coupling parallel hip-joint rehabilitation mechanism is proposed. The mechanism and human lower limbs form a closed motion chain, so that it has three rotational degrees of freedom, and its rotation center coincides with the human hip joint center, which can meet the need of hip-joint rehabilitation. The human-machine inverse kinematics model is established using the closed loop vector method. The human-machine forward kinematics model is established using the numerical method. The fuzzy adaptive proportional-derivative (PD) controller is designed based on the fuzzy control theory. The control law is constructed using the tracking error and its derivative. The parameters of controllers are adaptively adjusted online using the fuzzy algorithm. The simulation and experiment results show that the fuzzy adaptive PD controller has fast response speed and good tracking effect.关键词：Parallel mechanism;Weak-coupling;Hip-joint rehabilitation;Trajectory tracking;Fuzzy adaptive46|77|0发布时间：2024-06-19
- 摘要：Aiming at the problems of large inertia, low flexibility and difficulty in working in narrow space of traditional manipulators, a new type of wire-driven manipulator with 6-DOF is designed, and its forward and inverse kinematics are studied. The kinematics characteristics of the rotation joint, parallelogram joint and snake joint in the new manipulator are analyzed, and the forward and inverse kinematics models of the manipulator are established. The simulation experiment is carried out in Matlab environment, and the position and posture of the proposed forward and inverse kinematics model are verified. The results show that the proposed kinematics model can be well used for the end position control of the manipulator. Finally, the workspace of the manipulator is calculated by the Monte Carlo method.关键词：Wire-driven manipulator;Kinematic;Simulation analysis;Workspace875|269|0发布时间：2024-06-19
- 摘要：In order to solve the problem of sample damage caused by excessive pressure exerted by the manipulator during underwater operation and the problem that sample cannot be saved after grasping, this study designs an underwater sampling manipulator driven by two coupling cylinder drivers that imitates the eating mode of acuttlefish. There is a bias impeller pump inside the manipulator, which forms a low pressure area to drive the water flow to draw the samples that are difficult to collect without contact. The three-dimensional model of the manipulator is established and the kinematics equation of the manipulator is calculated. The functional relation between the driver and the end effector is solved by the closed-loop vector method. The workspace and trajectory planning are obtained, and the rationality and feasibility of the manipulator structure are verified. Finally, the manipulator is assembled on the underwater robot, and the underwater navigation sampling at different angles is simulated, which lays a certain foundation for the future research of the manipulator in visual control and grasping.关键词：Underwater manipulator;Bionics;Sampling mechanism;Kinematic analysis;Workspace49|41|0发布时间：2024-06-19
- 摘要：Based on special requirements of modern advanced automobile electric power steering （EPS） for steering transmission, the nylon helical gear steel worm transmission with stable transmission, low noise and low cost has been widely used. However, due to its special material, the traditional design method of worm gears is not applicable. In this study, by analyzing the special situation of the nylon helical gear steel worm transmission, considering some factors such as performance, structure and cost, structural parameters and safety factors of the helical gear worm transmission mechanism under given conditions are designed and analyzed by Kisssoft software. According to the principle of easy processing, no failure and equal strength, the value of reasonable modification coefficient and the design method of each parameter of helical gear are put forward, and the model is simulated and verified by Workbench software. The results show that the optimized nylon helical gear steel worm transmission meets the design requirements and has better comprehensive performance.关键词：Helical worm transmission;Optimization design;Modification factor;Simulation analysis54|93|0发布时间：2024-06-19
- 摘要：With the increasing demand of noise-vibration-harshness(NVH) performance of the electric vehicle drive system, higher requirements are put forward for gear design in the electric drive system. Based on numerical simulation, in this study, the gear web design of the wheel of an offset gearbox for the electric drive system is optimized. From mode of vibration, tooth root stress, transmission error to manufacturing error sensitivity, five kinds of gear web designs are analyzed, including simple plate, simple plate with weight reduction bore, simple plate with curved oval bore, simple plate with ribs and complex plate. The results show that with the complex plate design, the mode of vibration, tooth root stress, transmission error and manufacturing error sensitivity of the wheel can all be improved, especially for the natural frequency, which is significantly improved compared with the other four designs. The staggered plate spoke structure optimized using the method described in this study, under the same quality conditions, compared to the common circular weight reduction hole plate structure, increases the first modal frequency of the gear by 72% and reduces the transmission error by 18%. This can effectively avoid the high-speed gear whistling problem caused by large gear resonance.关键词：Gear web;Numerical simulation;Mode of vibration;Tooth root stress;Transmission error;Manufacturing error sensitivity61|101|0发布时间：2024-06-19
- 摘要：With the frequent occurrence of natural disasters and field wars nowadays, it is of great significance to search for targets and transport supplies in the complex terrain in the field. However, the environment is harsh for natural disasters and field warfare, the process of searching targets and transport supplies is often faced with a series of problems, such as complex terrain, difficulty and high cost, which restrict the smooth progress of search operations. In order to solve these problems, a multifunctional lightweight robot with capabilities of crawling, wheeled movement, and overcoming obstacles in complex terrain has been proposed, and the mechanical structure design is conducted. Combined with its design model, the maximum stride length of its movement, the maximum tilt angle, lifting range and other performance parameters are calculated and analyzed, and the stress and strain simulation is carried out. Finally, the engineering prototype is made to verify its performance. The research results show that the lightweight robot can realize three functions: crawling, wheeled movement and overcoming obstacles. The maximum inclination angle of the robot over obstacles can reach 53°, and its maximum height through obstacles can reach 4.1 cm.关键词：Crawling;Wheeled movement;Overcome obstacles;Multifunctional83|91|0发布时间：2024-06-19
- 摘要：In order to effectively relieve the trapped-oil phenomenon of external gear-pumps and gear-motors, based on its constant output capacity, by analyzing the influence of large modulus under equal displacement on the load flow, leakage flow and unloading flow in trapped-oil chamber, a design method of large modulus with equal displacement is proposed. Based on the instantaneous balance of these three flows, and the deductive calculation of the unloading area under different modules with the same tooth profile parameters, the trapped-oil pressure is calculated and the relief degree of the trapped-oil phenomenon is judged. The results show that the tooth width coefficient under equal displacement is inversely proportional to the third power of the modulus for a given gear-pairs and working conditions, the larger the modulus is, the more the trapped-oil phenomenon tends to be relieved, and the smaller the radial force is, the smaller the tooth width coefficient will be. The unloading area under different modules and the same tooth shape parameter is equal to the module square multiplied by the unloading area under the reference module of 1, which provides great convenience for calculating the unloading area under different modules with the same tooth profile parameters.The inlet and outlet pressures outside the unloading groove are reversed, leading to a more serious trapped-oil phenomenon in the gear-pump than in the gear-motor, but the small modulus motor also shows more serious trapped-oil phenomenon. It is concluded that the maximized or larger modules is included in the gear-pump and gear-motor design criteria.关键词：Gear-pump and gear-motor;Relief of trapped-oil phenomenon;Large modulus with equal displacement;Tooth width coefficient;Trapped-oil pressure32|101|0发布时间：2024-06-19
Design· Calculation
- 摘要：The dynamic characteristics of high speed gear transmission under high speed conditions have an important influence on the reliable operation of equipment. The gear pair model is established, the dynamic characteristics of high-speed gear drive are analyzed, and the dynamic simulation is carried out under the condition of dynamic excitation of gears. The results show that the fluctuation amplitude of angular velocity increases respectively by 6.12% and 3.46%, after the driving gear is moved by 0.2 mm in the axial direction and 0.15° in the vertical direction. The fluctuation amplitude of the contact force increases respectively by 0.58% and 4.56%. The axial displacement error has a greater influence on the angular velocity, and the angle error has a greater influence on the contact force. When the acceleration time increases from 5 seconds to 10 seconds, the fluctuation amplitude of angular velocity decreases by 10.7% and the standard deviation of angular velocity decreases from 6.974 8 to 6.406. The fluctuation amplitude of contact force increases by 0.58%. After the load increases from 1 000 N·m to 1 626.75 N·m and 2 000 N·m, the standard deviation of angular velocity decreases from 6.974 8 to 4.774 75 and 4.749 45, the fluctuation amplitude of contact force increases respectively by 4.3% and 4.25%, and the rated load is more stable than the gear transmission under light load. The difference of angular velocity and contact force fluctuation is not obvious in the case of heavy load.关键词：High speed gear;Load excitation;Dynamic simulation;Error excitation59|70|0发布时间：2024-06-19
- 摘要：In order to improve the accuracy of natural frequency analysis and calculation for the coupling rotor system, a transfer matrix method is proposed to construct a dynamic analysis model of the rotor when conducting modal characteristics research on permanent magnet eddy current couplings. By unifying the magnetic force of the permanent magnet into a zero mass hinge connection, the magnetoelectric force of the eddy current coupling is simplified, and the complex research model is transformed into a mechanical strength problem. The Riccati transfer matrix method is used to perform modal analysis on the rotor that has been equivalently processed, and the natural frequency of the coupling is obtained. On this basis, compare the analysis results with the accurate 3D finite element simulation results. The results show that this method can accurately analyze the natural frequency of permanent magnet eddy current couplings, and the error generated by high-precision simulation model analysis is not more than 8%. This study provides a theoretical basis for the study of the dynamic characteristics of permanent magnet eddy current couplings by comparing the improved calculation data with the finite element analysis results.关键词：Permanent magnet eddy current coupling;Modal analysis;Transfer matrix method;Finite element analysis32|64|0发布时间：2024-06-19
- 摘要：Gears with a thin web are often used in aerospace occasions because it has many advantages, such as low-weight and structure-load matching. However, due to the small rigidity and the complex process with the multiple physics, such as stress field and temperature field, it is difficult to accurately control and predict the deformation and machining accuracy. In this study, taking the heat treatment and turning process of the gear with thin web as the research object, the mapping model between the process parameters and its stress field is established, and the correctness of the model is verified by experiments. Based on this model, the effects of different process parameters, routing and clamping methods on the deformation in the heat treatment and turning process of the aviation gear with thin webs are analyzed, and the main factors leading to the deformation of parts are defined and optimized.关键词：Multi-physics field coupling;Aviation gear;Thin web;Turning simulation;Deformation control32|84|0发布时间：2024-06-19
- 摘要：In order to construct an accurate model of asymmetric involute modified helical gears and analyze the influence of pressure angles on its contact stress, based on the gear meshing principle and the secondary development of SolidWorks in C#, a mathematical model and an accurate physical model for developing an asymmetric involute modified helical gear from a rack tool are established. At the same time, the finite element method is used to analyze the tooth surface contact stress, and it is compared with the tooth surface contact stress of the symmetrical modified helical gear calculated by the traditional formula method. The study shows that when the pressure angle on one side of the tooth surface is the same, the tooth surface contact stress of the asymmetric involute modified helical gear is very close to that of the symmetric modified helical gear, and the increase and decrease trends of contact stress with changes in the pressure angle are basically the same. It shows that the change of the non-working side tooth surface pressure angle has no obvious influence on the working side tooth surface contact stress. Therefore, the traditional formula method used to calculate the tooth surface contact stress of symmetrical modified helical gears can be used to approximate the tooth surface contact stress of asymmetric involute modified helical gears. This method provides reference for the design of asymmetric involute modified helical gears.关键词：Asymmetrical gear;Modified gear;Mathematical model;Secondary development of;SolidWorks29|178|0发布时间：2024-06-19
- 摘要：In order to investigate the influence of the error of center distance between the driving pinion and rack track meshing and the error of axis non-parallelism on the contact stress distribution during the curved driving of rack-rail trains, an analytical model of rack and pinion contact stresses is established based on the finite-length line contact theory by considering the two kinds of errors comprehensively. Comparison with the finite element simulation of rack and pinion contact under error conditions shows that the established model has good computational accuracy. Based on the model, the contact stress response under different error levels and the combined two types of errors are investigated, the effects of the two types of errors on the contact stress distribution are revealed, and countermeasures are proposed accordingly. The results show that the proposed contact stress analysis model can accurately respond to the contact condition of the rack and pinion under the combined effect of the meshing center distance error and the axial non-parallelism error. The contact stress level increases with the increase of the meshing center distance error. The degree of axial non-uniformity of contact stresses increases with the increase of axis non-parallelism error. The meshing center distance error enhances the axial contact stress inhomogeneity caused by the axial non-parallelism error, and the axial non-parallelism error has a slight inhibitory effect on the effect of the meshing center distance error. The intrinsic mechanism of the meshing center distance error is the reduction of the load carrying area at the same load level, and the intrinsic mechanism of the axial non-parallelism error is the greater deformation produced by the rack and pinion taking the lead in contact on the inside of the curve. Root gouging of the pinion eliminates the effect of axial non-parallelism error, and helix modification of the pinion reduces the effect of axial non-parallelism error.关键词：Rack-rail train;The finite-length line contact theory;Rack and pinion;Meshing center distance error;Axis non-parallelism error;Tooth profile optimization41|102|0发布时间：2024-06-19
- 摘要：Aiming at the design challenges of multi-branch orthogonal compliant vector force measuring system, a finite element method with beam connection units is proposed, and finite element models of dynamometry branches and vector force measuring system are established using this method. Structural characteristics analysis is carried out for six branch forms and lateral layout forms. Based on this, combined with a case study of vector force measuring system, detailed parameter design is conducted using the finite element model, resulting in a compact and minimally coupled structure. Calibration tests for the three load components of the vector force measuring system (axial force, normal force, and pitching moment) are performed, with uncertainties of calibration around 0.5% of the full scale (FS). To address the significant impact of the loading accuracy of high-load vector force measuring systems on calibration measurements, a performance evaluation method based on the ratio of load to measurement is proposed. Through this method, the repeatability of the three-component measurement of the designed vector force measuring system is around 0.4%FS, and the hysteresis of large-range measurement is within 0.7%FS. The research findings have quite reference significance for the structural design and performance analysis of orthogonal vector force measuring systems.关键词：Vector force measuring system;Flexure mechanism;Flexure hinge;Flexure element;Vector thrust57|96|0发布时间：2024-06-19
Test·Analysis
- 摘要：The planetary bearing is one of the most important components for wind turbine gearboxes, due to the complication of the load and the special position. How to analyze the load center becomes the critical job for design engineers. Based on current design specifications, two 3 MW gearboxes with back to back arrangement are tested on the 10 MW testing benches, and strain testing is conducted on planetary gears during the experiment. For further utilization of these testing results about the strain of the gear, the least square method is taken to precisely estimate the load position of the applied center for the planetary bearings during the development for the new wind turbine gearbox.关键词：Strain testing;Planetary gear;Bearing;Load distribution on the tooth surface34|31|0发布时间：2024-06-19
- 摘要：The phase transformation temperature of C55E material can be obtained by simulating TTA curve, CCT curve and TTT curve with material simulation software JMatPro. The isothermal quenching process of C55E steel chain plates is formulated by the obtained transformation temperature. The results show that the isothermal quenching process parameters formulated by the material simulation software JMatPro are the quenching temperature of 850 ℃, the isothermal temperature of 310 ℃, and the isothermal time of 25 min. The hardness of the chain plate after isothermal quenching meets the technical requirements, and the strength, fatigue and other properties of the chain are close to the 50CrV material treated by the same process.关键词：C55E steel;JMatPro software;Isothermal quenching;Fatigue30|46|0发布时间：2024-06-19
- 摘要：In order to improve the accuracy and efficiency of bench fatigue tests of main reducers, an equivalent method of bench fatigue tests based on actual driving load spectrum is proposed in this study. By collecting the actual driving load spectrum of users and the test site, the road condition and road load spectrum of the test site are reconstructed by using rain-flow counting and elite strategy non-dominated sorting genetic algorithm. In order to verify the effectiveness of the equivalent method, the finite element model of the main reducer is established and the static strength analysis is carried out to verify the mesh independence and model validity. Based on the transient dynamic model, the relation between different torques, rotational speeds and gear stresses is studied, and the frequency equivalent relation corresponding to the program load spectrum amplitude is obtained. Based on the relation between rotational speeds and gear stresses and the probability density analysis of rotational speeds in each torque interval, the corresponding speed of each class of load spectrum is determined, the load spectrum of rotating bending fatigue test program is compiled, and the equivalent relation between the compiled load spectrum and the original load spectrum is verified by the finite element model. The results show that the damage position of the gear is consistent with that of the original load spectrum under the action of the equivalent load spectrum, the maximum error of the damage value is 0.15%, and the acceleration is 4.7 times.关键词：Main reducer;Fatigue test;Load spectrum;Equivalent method44|113|0发布时间：2024-06-19
- 摘要：It is difficult and costly to carry out fatigue life test for high-torque laminated couplings due to its large load. Therefore, the equivalent test piece is designed for high-torque laminated couplings to meet the requirements of universal coupling test equipment and reduce the test cost. The equivalent design principle of a laminated coupling is established, and a design method for equivalent test pieces of a high-torque laminated coupling is proposed based on equivalent symmetric cyclic stress. The accuracy and feasibility of the design method are verified by theoretical calculation and finite element simulation analysis.关键词：Laminated coupling;Equivalent test piece;Equivalent symmetric cyclic stress;Fatigue life55|70|0发布时间：2024-06-19
- 摘要：Aiming at the problems of structure, volume, function and wearability of various cervical spine rehabilitation institutions at home and abroad, a spherical coupled cervical spine rehabilitation robot scheme is proposed. Firstly, starting from the common rehabilitation actions of patients with cervical spondylosis, a new type of spherical coupled mechanism is designed according to the physiological structure and kinematic mechanism of the human neck, aiming at better realizing the rehabilitation training of the head and neck of patients. The screw theory is used to analyze the degree of freedom of the mechanism, the kinematics and dynamics model of the robot is established, the solution formula and dynamic equation of the mechanism kinematics is obtained, and the movement space of the mechanism is obtained through Matlab simulation to verify that it meets the space requirements for rehabilitation training. The step function is written through the model action in Adams, and the curve obtained from the kinematics simulation is compared and analyzed with the theoretical calculation results. Finally, the transient dynamics analysis is performed on the key parts of the robot through Ansys Workbench, and the stress nephogram of the mechanism is obtained to verify the rationality of its structural design, which lays the foundation for prototype construction and control strategy research.关键词：Cervical spine rehabilitation;Spherical coupled robot;Kinematics simulation;Transient dynamics165|69|0发布时间：2024-06-19
Development·Application
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