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ABSTRACT This paper proposes a signal generation fault diagnosis method for the challenge of insufficient training samples in the planetary reducer of high‐pressure grinding roll (HPGR). The expression of the vibration response signal is derived, and a fault vibration signal model is established for the planetary reducer of HPGR. To generate the expanded samples, an adaptive fox optimization (AFO) algorithm is employed for optimizing the parameters of the fault vibration signal model, so that the simulated signal matches the measured signal. Before that, the measured vibration signal of the planetary reducer of HPGR is preprocessed by a tunable Q‐factor wavelet transform (TQWT). Finally, the residual convolution neural and long short‐term memory network with attention mechanism (ResCNN‐LSTM‐ATT) is utilized for feature extraction from collected signals, and the hierarchical fault classifier is developed for the fault classification. The experimental results show that the AFO algorithm has better performance, and the signals generated by the optimized fault vibration signal model are in good agreement with the measured signals. The classification accuracy of normal signals reaches 99.70%, which shows good diagnosis accuracy in both known fault classification and unknown fault identification. Compared to other methods, the proposed method has better diagnostic accuracy. [ABSTRACT FROM AUTHOR]

Objective Aiming at the problem that the assembly quality of interference fit components is difficult to control, a method for monitoring the assembly quality of such components based on digital twin technology is proposed.Methods Combined with digital twin technology, the framework of an assembly quality monitoring system for interference fit components is constructed; the actual assembly process is comprehensively analyzed and a real-time monitoring process of the assembly process based on the press-fitting force is designed; and a state prediction model of the press-fitting force based on the Markov model is established, and a comprehensive judgment of the assembly quality of the interference fit components is realized by the comprehensive comparison of theoretical press-fitting force, actual press-fitting force and press-fitting force prediction state.Results The interference fit between the output shaft and sun gear of a typical marine planetary reducer is used as an example for verification. The results show that this method can realize the real-time collection and monitoring of the press-fitting force at key points in the assembly process and predict the future quality characteristics of the point. At the same time, the experimental results of the physical assembly platform are compared with the model prediction results, and it is found that the two are consistent, which proves that the proposed method of monitoring the assembly quality of interference fit components based on digital twin technology is effective and feasible.ConclusionThe results of this study have important reference significance for the realization of quality monitoring in the process of the intelligent assembly of mechanical products.

Combining the linear conjugate tooth profile with the planetary gear transmission with small tooth difference, taking the linear conjugate small tooth difference planetary gear reducer as the research object, the structure natural frequency and vibration mode of the reducer are obtained through finite element modal analysis, which shows the reducer has good structural dynamic characteristics; through the simulation analysis of vibration characteristics, the vibration law of the reducer under typical working conditions is obtained, and the vibration test experiment is carried out. The vibration experiment results are consistent with the simulation results. The vibration characteristics research results show that the input speed has a significant impact on the vibration amplitude and frequency of the linear conjugate small tooth difference planetary gear reducer.

The service life of the planetary reducer in a hub drive system largely depends on the system reliability design. Aimed at the problems of lower credibility and inadequate depth in the reliability allocation, based on improved FMECA formulas and order statistics theory, an advanced reliability allocation method of the planetary reducer is proposed. The basic characteristics of the planetary reducer are analyzed, and FMECA formulas with the positive failure correlation modifying operator are presented, which indicate that the subsystem complexity and the failure occurrence change in the same direction as the failure correlation degree, respectively. Simultaneously, based on the Gumbel Copula function and order statistics theory, the reliability allocation model is established to assign reliability design indices to parts of the planetary reducer. By comparing the subsystem reliability allocation weights obtained by different methods, results show that the allocation result of the proposed method is more credible. It will be helpful to accomplish the deeper reliability allocation and improve the service life of the planetary reducer.

Copyright of Journal of Mechanical Strength / Jixie Qiangdu is the property of Zhengzhou Research Institute of Mechanical Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The mining dump truck has a large load capacity, low running speed, and the characteristics of low speed and high torque. The planetary wheel reducer can meet this demand, which is widely used in such vehicles. According to the structural characteristics of a 170-ton vehicle two-stage planetary gear reducer, the reliability of planetary gear transmission at all levels was analysed, and the system parameters were optimized on this basis. The multi-objective optimization design method was used to transform the maximum reliability of the system into the maximum reliability of the gears at all levels, and the constraints are established based on the actual processing, operation, installation, assembly and other working conditions. The MATLAB multi-objective optimization module was used to solve the analysis, and the best gear design parameters were obtained after rounding. Under different operating conditions, the planetary reducer before and after optimization was compared and analysed to obtain the reliability and service life of the entire deceleration system after optimization. The analysis results show that: after the parameter optimization of the planetary reducer, the transmission efficiency is 0.946, and the transmission ratio of the system is 30.54, which meets the actual use requirements. The reliability coefficient of the contact strength of the tooth surface of the secondary sun gear is 2.52, the reliability coefficient of the bending fatigue strength of the root of the secondary inner ring gear is 2.59, and the reliability of the secondary gear is 0.989. The reliability is obviously improved. The safety factor of the main parts is high. The service life of each gear of the whole secondary reduction system meets the design requirements. The analysis content and results provide reference for the optimization design and reliability analysis of similar planetary gear systems [ABSTRACT FROM AUTHOR]

In many robotic applications, the joint is required to have a small volume, low weight and high torque output. In this paper, based on the finite element analysis (FEA), a 36-slot 40-pole outer rotor surface-mounted permanent magnet (OR-SPM) motor with concentrated winding is designed for the exoskeleton robot. The fractional slot concentrated winding (FSCW) is employed to reduce end winding height, leading better portability. Since the motor is relatively flat, the 3D end effect is critical to the electromagnetic performances. Special attention is paid to 3D end effect during the multi-objective optimization of the OR–SPM motor. In order to increase the ending torque output, the planetary reducer is located between OR–SPM motor and load, and then system level optimization covering motor and reducer is carried out to achieve best torque output. In addition, the force impendence control method with parameter self-adaptive capability is proposed to improve user experience of the exoskeleton robot, where the key parameters in the algorithm vary according to different actions of the exoskeleton. In addition, the inertia of load is calculated using the parameter identification based on least squares method. Finally, the prototype of the joint is fabricated and tested to validate the above FEA results and control method. The user experience of the exoskeleton robot is also covered. [ABSTRACT FROM AUTHOR]

Aiming at the requirements of large radial size， large load-bearing load and high precision of the thin-walled gear ring of a planetary reducer for a high-altitude rescue vehicle， the deformation of the thin-walled gear ring during processing and heat treatment is analyzed， and the cause of the deformation of the workpiece is found. A solution is developed， the process route of thin-walled ring gear processing and heat treatment is optimized. By using Deform heat treatment simulation software， the optimized heat treatment route is simulated， and the feasibility of the optimized scheme is verified. This optimization scheme improves the accuracy of the workpiece， meets the requirements of a certain high-altitude rescue vehicle planetary reducer to work normally under complex working conditions， and ensures the safe and stable operation of mechanical equipment. Engineering practice shows that this optimization scheme is suitable for low-speed and heavy-duty high-altitude rescue vehicle slewing mechanism reducer， and has high economic and practicality.

A cycloidal planetary reducer, which fulfils both high reduction ratio and low vibration in a thin and small body, had been proposed to cope with the further downsizing of DC motors. The reduction mechanism is inspired by the intellectual toy ‘Spirograph’ and structurally based on a planetary reducer. Instead of the internal gear of the planetary reducer, output plate with skid epitrochoid groove is introduced. The sun gear is connected to the input shaft and the planetary carrier works as a stator. The planetary gear has a pin that fits in the groove of the output plate. According to the rotation of the planetary gear, the output plate revolves in the counter direction with a speed in inverse proportional to the number of the skid epitrochoid. The prototype can realize higher reduction ratio compared to the planetary reducer without unpleasant vibration that is unavoidable in the cycloidal reducer. It is confirmed that the idling torque is very small with 0.006Nm, and the torque transmission efficiency is acceptable with 73%. But the torque fluctuation caused by the cam motion by the pin and groove is remarkable, which will be forthcoming challenges.

The current research of robots is mainly developing in lightweight, fast speed and large load. The characteristics of flexible robots are mainly reflected in flexible joints and links. However, flexible joints are often assumed to be simply linear. Since the joint of the planetary reducer also needs to consider the flexible deformation and nonlinearity of the structure, this assumption is not applicable to the assumption of this joint. Therefore, considering coupling properties of the more accurate structure and friction, the joints and the flexible links, a more accurate dynamic model of the flexible robot is established. Furthermore, the accuracy of motion and positioning for the flexible robot under the influence of many factors is analyzed. The research is of great significance for flexible robot control. Firstly, the structure of the two-stage planetary gear reducer is analyzed. Using Newton's Euler and force balance principles, the dynamic model of its joint reducer was constructed. Secondly, taking the Euler–Bernoulli beam as the object, using the Lagrange method and the structural damping formula, the coupling dynamic model of the flexible robot is established. Based on the virtual work and variational principles, the input matrix is further modified by friction. Finally, Using MATLAB and the experiment platform, the validity of the coupling dynamics is verified. And then, taking the flexible deformation, the clearance, and friction of the reducer as the influencing factors, the influence characteristics of the flexible robot are analyzed. [ABSTRACT FROM AUTHOR]

A novel 2K-H internal meshing abnormal cycloidal gear (ACG) planetary reducer is proposed to tackle the rotor vector (RV) reducer problems, such as complex over-positioning structure, high manufacturing and assembly accuracy requirements. The composite tooth profile of epicycloid-involute-hypocycloid is adopted as the tooth profile of the reducer. The aim of this study was to investigate the meshing principle of such gear and evaluate its transmission characteristics. The meshing principle of tooth profile of the ACG is described. According to the gear geometry theory, the mathematical model of conjugate tooth profile of ACG pair was derived based on the contact path. And the influence of design parameters on the ACG tooth profile were also carried out. Moreover, the non-interference condition of the ACG pair was derived, and then meshing characteristics of the ACG pair were analyzed by numerical example, such as contact ratio, sliding ratio, and meshing efficiency. The bending and contact stresses of the ACG pair were also evaluated by comparing with those of involute pair. The results show that, the ACG has good transmission characteristics, such as small sliding ratio, high transmission efficiency. Compared with the involute gear, the bending and contact stresses of the ACG are reduced. The study lays a theoretical foundation for the optimization design of the ACG and the improved reliability of the ACG reducer. [ABSTRACT FROM AUTHOR]

The joint motor is one of the core components of the foot robot，and its dynamic response directly affects the performance of the robot. Among them，the planetary reducer is a precision mechanical transmission mechanism，and its transmission accuracy is closely related to the deformation of key parts. Therefore，by using Adams，a rigid-flexible coupling dynamics simulation model of the joint motor is established to simulate the transient output characteristics during the startup process. In the model，the key parts are flexibly processed，and the motion pair constraints between the parts are set. The Hertz contact theory is used to calculate the contact stiffness coefficient of the planetary gear and the sun gear and the inner gear ring. The simulation results show that the dynamic characteristics of the joint motor are closely related to the acceleration time and inertial load. A larger acceleration time and a smaller inertial load are beneficial to improve its dynamic performance.

The backlash of the planetary reducer was an important index that affected the transmission accuracy and smoothness of the reducer, and it was also the main parameter for dividing the accuracy grade. Aiming at the problems of inaccurate torque loading, poor compatibility, and low measurement efficiency that were common in backlash detection equipment, an automatic detection device for the backlash of the reducer was developed. First, a mechanical structure with a simple structure and suitable for operation of multiple models was designed to improve the compatibility of the device;then combining the precision servo system with the high-precision torque sensor, the torque loading closed-loop feedback system was constructed to realize the precise and dynamic torque loading, and the PLC control system was developed to realize the automation of the work process and improve the detection efficiency. Finally, a comparative measurement experiment was designed, and the device was analyzed for the measurement system. The test results show that the repeatability and reproducibility of the measurement device is 0. 218, the total variation TV is 1. 219, and the measurement variation accounts for the percentage of the total variation in the process. The GRR value is 17. 9%, indicating that the device has good detection performance and can be used to detect the backlash of a medium-precision reducer. [ABSTRACT FROM AUTHOR]

In order to study reliability of planetary reducer of shearer cutting unit under influence of multiple factors, taking the MG400/951-WD shearer as research object, the load curve of spiral drum is calculated according to force analysis of pick and measurement result of coal sample mechanical properties. The load is applied to the model of cutting unit for simulation, and stress information of planet carrier and planet shaft is obtained. The reliability information of planet carrier and planet shaft is obtained by building a stress-reliability Gaussian membership function. Based on orthogonal test, influence law and significance degree of Protodyakonov coefficient of coal, traction speed of shearer and cutting depth of spiral drum on reliability of planetary reducer are analyzed. It is concluded that traction speed of shearer has the greatest influence on the reliability of planetary reducer, followed by Protodyakonov coefficient of coal, and the cutting depth has the least influence on the reliability of planetary reducer. With the increase of the Protodyakonov coefficient of coal, the decrease of the reliability of planetary reducer increases, and the decrease trend of the reliability becomes more obvious. With the increase of traction speed and cutting depth, the decrease of planetary reducer reliability tends to be gentle.

This paper proposes a modified harmonic cam, which is used to design a harmonic drive. Conventional harmonic drives using a sinusoidal cam type pertain to an elastic body concept and are thus difficult to design and evaluate. Unlike the conventional sinusoidal cam, the proposed harmonic cam involves a combination of four arcs. Such cams can be designed based on a rigid body concept, and thus, the tooth profile can be designed and analyzed using the established gear theory. The novel harmonic cam is designed by exploiting four-arc combinations, and guides for designing harmonic drives with involute and cycloid angular teeth are presented. A harmonic drive with a difference of two teeth between the circular spline and flex spline is designed. The operation, tooth engagement, and interference are validated through a mock-up production using a 3D printer and gear simulation program. The findings can facilitate the facile design and manufacturing of harmonic drives.

In order to solve the problem of large vibration and noise caused by the unsteady gear transmission of the traveling reducer under actual working conditions, the two-stage planetary reducer was taken as the object. A three-dimensional model was established through Pro/E software and a dynamic model was established based on the multi-body dynamics simulation software ADAMS to study the dynamics of the reducer transmission system. The results showed that according to the formula of transmission ratio, the theoretical speed of each component was compared with the simulation speed, and the correctness of the model was verified. The simulation analysis of multi-group damping coefficients showed that appropriate damping coefficients could improve the stability of the system, and the optimal damping coefficient was 0.1 % K. According to the dynamic simulation analysis based on the optimal damping coefficient, the meshing impact of the secondary planetary wheel and gear ring were the main source of vibration. In actual production, different lubrication methods could be selected to reduce the meshing impact of the gear. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Mine Automation is the property of Industry & Mine Automation Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Aiming at the difficulties in the selection of planetary reducer in an enterprise,a planetary reducer selection software is developed to improve the efficiency of selection. The software is developed based on Visual Basic 6. 0 and Access 2013,the XML format is used for formula storage. By analyzing the selection process and the factors of the selection,the required parameters are selected,the calculation formula of motor-reducer-load transmission process is analyzed and deduced. The database,calculation module,auxiliary function module and planetary reducer selection system are designed. Finally,the feasibility of the planetary reducer selection system is verified by concrete examples.

The 3-stage planetary reducer with closed-loop control is adopted in CE-3 lunar rover wheel drive mechanism.Aiming at the problem that the speed stability of drive mechanism does not satisfy the design requirements,the factors affecting the speed stability of planetary reducer are systematically analyzed,and methods and measures minimizing the inequality of load sharing of planetary gear sets are studied carefully.Through troubleshooting and numerical simulations,the causation is uncovered as follows:the first stage sun gear radial runout exceeds the allowed range.Then two solutions are proposed:the first one is to redesign the first stage sun gear into a floating sun gear,the second one is to improve the machining precision of the first stage sun gear.And the second solution is adopted because it is smaller and lighter than the first one.Then much ground simulation tests which are conducted at the room condition,high-temperature vacuum condition and low-temperature vacuum condition demonstrate that the speed stability of drive mechanism satisfies the design requirements.At last,the effectiveness of the proposed method is validated by the telemetry parameters of lunar rover moving on the moon surface.

The main task of the third Chinese lunar exploration project is to obtain soil samples that are greater than two meters in length and to acquire bedding information from the surface of the moon. The driving component is the power output unit of the drilling system in the lander; it provides drilling power for core drilling tools. High temperatures can cause the sensors, permanent magnet, gears, and bearings to suffer irreversible damage. In this paper, a thermal analysis model for this driving component, based on the thermal network method (TNM) was established and the model was solved using the quasi-Newton method. A vacuum test platform was built and an experimental verification method (EVM) was applied to measure the surface temperature of the driving component. Then, the TNM was optimized, based on the principle of heat distribution. Through comparative analyses, the reasonableness of the TNM is validated. Finally, the static temperature field of the driving component was predicted and the "safe working times" of every mode are given. [ABSTRACT FROM AUTHOR]

Based on FEM/BEM method, the analysis model of vibration and acoustic radiation properties of planetary reducer box is established in this paper, and the vibration and acoustic radiation properties of planetary reducer box is analyzed. First of all, the finite element analysis model is established in ABAQUS. Secondly, the acoustic radiation boundary element model is built through the VA-one, then calculate the sound pressure distribution of the surface and sound field of the box, the noise spectrum and field and modal contribution degree of radiation noise of the box is also calculated. And the influence law of the main structural parameters on radiation noise properties is studied, which can provide technical support for the structural scheme design of planetary reducer box. [ABSTRACT FROM AUTHOR]

In the paper, new design of planetary reducer with herringbone gear is suggested. This design will allow reducing dimensions of planetary mechanisms. Characteristics of the suggested reducer design are described, and it is compared with standard reducer. [ABSTRACT FROM AUTHOR]