Journal articles: 'Gear-train backlash'

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Sommer, Andrew, Jim Meagher, and Xi Wu. "Gear Defect Modeling of a Multiple-Stage Gear Train." Modelling and Simulation in Engineering 2011 (2011): 1–8. http://dx.doi.org/10.1155/2011/754257.

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This study demonstrates the transient and steady state dynamic loading on teeth within a two-stage gear transmission arising from backlash and geometric manufacturing errors by utilizing a nonlinear multibody dynamics software model. Backlash between gear teeth which is essential to provide better lubrication on tooth surfaces and to eliminate interference is included as a defect and a necessary part of transmission design. Torsional vibration is shown to cause teeth separation and double-sided impacts in unloaded and lightly loaded gearing drives. Vibration and impact force distinctions between backlash and combinations of transmission errors are demonstrated under different initial velocities and load conditions. The backlash and manufacturing errors in the first stage of the gear train are distinct from those of the second stage. By analyzing the signal at a location between the two stages, the mutually affected impact forces are observed from different gear pairs, a phenomenon not observed from single pair of gears. Frequency analysis shows the appearance of side band modulations as well as harmonics of the gear mesh frequency. A joint time-frequency response analysis during startup illustrates the manner in which contact forces increase during acceleration.

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Hsu, Y.-L., and S.-G. Wang. "Minimizing angular backlash of a multistage gear train." Proceedings of the Institution of Mechanical Engineers, Part B: Journal of Engineering Manufacture 216, no. 4 (April 1, 2002): 565–69. http://dx.doi.org/10.1243/0954405021520256.

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An optimization model is constructed to select the optimum reduction ratios that minimize the total angular backlash of a gear train, under constraints on the total reduction ratio and available space. It is found that a proper layout of reduction ratios has a major effect on the total angular backlash of a gear train.

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Zhu, Zengbao, Longchao Cheng, Rui Xu, and Rupeng Zhu. "Impacts of Backlash on Nonlinear Dynamic Characteristic of Encased Differential Planetary Gear Train." Shock and Vibration 2019 (May 27, 2019): 1–15. http://dx.doi.org/10.1155/2019/9347925.

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A multifreedom tensional nonlinear dynamic equation of encased differential planetary gear train with multibacklash and time-varying mesh stiffness was developed in the present research. The nonlinear dynamic response was obtained by solving the formulated nonlinear dynamic equation, and the impacts of backlash on dynamic characteristics of the gear train were then analyzed by combining time process diagram, phase diagram, and Poincaré section. The results revealed that bilateral shock in meshing teeth was caused due to smaller backlash, thus causing dramatic changes in meshing force; hence, the gears were found to be in a chaotic state. Further, during stable motion state, no contact between intermeshing teeth with bigger backlash was noticed; thus, they were in a stable quasiperiodic motion state in the absence of teeth exciting force. Therefore, in order to avoid a bilateral shock in gears as well as to maintain gear teeth lubrication, a slightly bigger backlash is required. The backlash change in any transmission stage caused significant impacts on gear force and the motion state of its own stage; however, the impact on gear force of another stage was quite small, whereas the impact on the motion state of another stage was quite large.

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Litvin, F. L., D. Vecchiato, A. Demenego, E. Karedes, B. Hansen, and R. Handschuh. "Design of One Stage Planetary Gear Train With Improved Conditions of Load Distribution and Reduced Transmission Errors." Journal of Mechanical Design 124, no. 4 (November 26, 2002): 745–52. http://dx.doi.org/10.1115/1.1515797.

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The authors propose an approach for the design of one-stage planetary gear train with reduced transmission errors, localized bearing contact and improved conditions of distribution of load between the planetary gears. The planetary gear train is considered as a multi-body mechanical system of rigid bodies. The proposed approach is based: (i) on modification of geometry of gear tooth surfaces, and (ii) minimization and equalization of the backlash between the contacting gear tooth surfaces. The modification of geometry is accomplished: (i) by double-crowning of planetary gears, and (ii) by application of screw involute surfaces of the same direction of screws for the sun and the ring gears. The proposed geometry enables: (i) predesign of parabolic function of transmission errors for reduction of noise and vibration, and (ii) a simple method of regulation and equalization of the backlash between the gear tooth.

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Dankov, A. M. "PLANETARY CONTINUOUSLY ADJUSTABLE GEAR TRAIN WITH FORCE CLOSURE OF PLANET GEAR AND CENTRAL GEAR: FROM IDEA TO DESIGN." Science & Technique 17, no. 3 (May 31, 2018): 228–37. http://dx.doi.org/10.21122/2227-1031-2018-17-3-228-237.

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One of the reasons constraining use of a continuously adjustable gear train with compound poly-sector gear wheels in general and its most perspective version that is a planetary continuously adjustable gear train in particular is its design complexity. For example, a complex design of the mechanism for regulation of transmission gear ratio is specified by the use of involute gearing that requires a presence of backlash and bottom clearances for normal functioning and, therefore, autonomous but synchronous movement of a planet gear, as well as sectors of a central gear. In order to simplify the design of especially this mechanism for continuously adjustable gear train the paper justifies a transition to a backlash-free gearing and during this process either a planet gear or sectors of central gear are forcibly moving for regulation of the transmission ratio without losing contact with the mating element. Contact constancy of interacting elements under load is ensured by their force closure which is meant to overcome an action of gearing forces. The paper describes options for implementation of backlash-free gearing as a result of planet gear and central gear force closure, each variant is characterized by selection of active (controlled) and passive (execution of force closure) gear element. In the case of gear transmission with planet pinion coaxial tooth rims it is appropriate to implement a version with involute gearing, passive planet gear and active gear sectors of central gears. In the case of gear transmission with planet pinion opposite tooth rims the most acceptable option is with the cycloidal pin wheel gear, active planet gear and passive gear sectors of central gears. The paper proposes to carry out the force closure for teeth of gear components by means of an elastic element (a spring). A method for determination of parameters for an elastic element has been described depending on a planet gear design and the paper also shows simplification level in the gear design.

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Joshi, Yashodhan V., and Jordan E. Kelleher. "Gear Train Mesh Efficiency Study: The Effects of an Anti-Backlash Gear." SAE International Journal of Commercial Vehicles 7, no. 1 (April 1, 2014): 271–77. http://dx.doi.org/10.4271/2014-01-1769.

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Zhang, Lianchao, Hongbo Liao, Dapeng Fan, Shixun Fan, and Jigui Zheng. "Design optimization analysis of an anti-backlash geared servo system using a mechanical resonance simulation and experiment." Mechanical Sciences 12, no. 1 (March 17, 2021): 305–19. http://dx.doi.org/10.5194/ms-12-305-2021.

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Abstract. In many mechatronic systems, gear transmission chains are often used to transmit motion and power between motors and loads, especially for light, small but large torque output systems. Gear transmission chains will inevitably bring backlash as well as elasticity of shafts and meshing teeth. All of these nonlinear factors will affect the performance of mechatronic systems. Anti-backlash gear systems can reduce the transmission error, but elasticity has to be considered too. The aim of this paper is to find the key parameters affecting the resonance and anti-resonance frequencies of anti-backlash gear systems and then to give the design optimization methods of improving performance, both from element parameters and mechanical designing. The anti-backlash geared servo system is modeled using a two-inertia approximate model; a method of computing the equivalent stiffness of anti-backlash gear train is proposed, which comprehensively considers the total backlash of transmission chain, gear mesh stiffness, gear shaft stiffness and torsional spring stiffness. With the s-domain block diagram model of the anti-backlash geared servo system, the influences of four main factors on the resonance and anti-resonance frequencies of system are analyzed by simulation according to the frequency response, and the simulation analysis results dependent on torsional spring stiffness of anti-backlash gear pair and load moment of inertia variation are verified by the experiment. The errors between simulation and experimental results are less than 10 Hz. With these simulation and experiment results, the design optimization methods of improving the resonance and anti-resonance frequencies such as designing the center distance adjusting mechanism to reduce the initial total backlash, increasing the stiffness of torsional spring and lightweight design of load are proposed in engineering applications.

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Yang, Tianfu, Shaoze Yan, Wei Ma, and Zengyao Han. "Joint dynamic analysis of space manipulator with planetary gear train transmission." Robotica 34, no. 5 (July 30, 2014): 1042–58. http://dx.doi.org/10.1017/s0263574714002045.

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SUMMARYJoints of space manipulators are usually simplified as torsional springs in modeling motion equations, and the nonlinear behaviors of the reducer in the joints are generally neglected. In this study, a dynamic model of a space manipulator that considers the joints that are transmitted through a typical 2K-H planetary gear reducer is developed using the Lagrangian method. The backlash clearances, gear tooth profile error, and time-variant meshing stiffness are integrated into the process. The simulation results show that the backlash clearances lead to the accumulation of positioning errors in the space manipulator when the joints rotate back and forth. The tooth profile error is the main cause of severe acceleration fluctuations and meshing force impacts. These fluctuations influence torque instability, which may accelerate gear system failure.

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Blanche, J. G., and D. C. H. Yang. "Cycloid Drives With Machining Tolerances." Journal of Mechanisms, Transmissions, and Automation in Design 111, no. 3 (September 1, 1989): 337–44. http://dx.doi.org/10.1115/1.3259004.

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The cycloidal speed reducer, or cycloid drive, is an epicyclic gear train in which the profile of the planet gear is an epitrochoid and the annular sun gear has rollers as its teeth. The cycloid drive has very high efficiency and small size, in comparison with a conventional gear mechanism, making it an attractive candidate for limited space applications. On the other hand, in this type of transmissions there exist two major drawbacks, namely, backlash and torque ripple. Backlash, the angle through which the output shaft can rotate when the input shaft is held fixed, has a degrading effect on the output accuracy. Torque ripple, the variation in mechanical advantage as the input shaft rotates, causes vibrations and could lead to dynamic instability of the machinery. If the cycloid drive were manufactured to the ideal dimensions, there would be no backlash nor torque ripple. However, in reality, there will always be some machining tolerances. In this paper an analytical model is developed which models the cycloid drive with machining tolerances. Consequently, the effect of machining tolerances on backlash and torque ripple are investigated. It is found that both the backlash and the torque ripple are inherent periodic functions of the input crank angle.

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Donmez, Ata, and Ahmet Kahraman. "An experimental methodology to study engine gear rattle problems." INTER-NOISE and NOISE-CON Congress and Conference Proceedings 263, no. 3 (August 1, 2021): 3335–43. http://dx.doi.org/10.3397/in-2021-2377.

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Gear induced noise represents a major part of overall automotive drivetrain noise. Gear rattle noise is caused by strongly nonlinear dynamic behavior of the gear pair, primarily due to external torque of speed fluctuations under lightly loaded conditions. Such loading conditions cannot be generated by using the conventional gear dynamics test set-ups that employ power recirculating gearbox arrangements or conventional electric motors. In this paper, a new test set-up is introduced to emulate the actual torque/velocity fluctuations of the input and/or output members of a gear train through three-phase synchronous servo-motors. In addition to establishing backlash boundaries, a pair of absolute encoders are used to measure the relative motions of the gears as well as their impacts along the drive and coast sides flanks or gears. Torsional vibratory behavior of a gear pair is presented at different backlash values under several input/output fluctuation conditions along with the companion sound pressure measurements.

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Warnecke, Martin, and Musa Jouaneh. "Backlash Compensation in Gear Trains by Means of Open-Loop Modification of the Input Trajectory." Journal of Mechanical Design 125, no. 3 (September 1, 2003): 620–24. http://dx.doi.org/10.1115/1.1596241.

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This paper presents an approach to reduce the effect of the backlash nonlinearity in systems with relative cyclic motion. A compensation approach is developed to calculate a modified course of input motion for a desired velocity profile in systems with known backlash. The modified input trajectory contains accelerating and decelerating motion features to traverse the backlash area in minimal time. The method was proved with a dc-motor driven gear train. Results show that the output motion delay could be remarkably reduced. The time to overcome the backlash gap depends upon the desired velocity and the amount of backlash introduced to the system. Time savings between 43% and 74% could be measured with the utilized experimental setup. The proposed velocity compensation method is most efficient for low operating speeds and large mounting allowance between gears.

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Meng, Rui, Xin Cai, and Xingwen Guo. "A New Resultant Vibration Acceleration Model of a Planetary Gear Train and Fault Response Analysis." Shock and Vibration 2022 (February 27, 2022): 1–20. http://dx.doi.org/10.1155/2022/5243204.

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A new resultant vibration acceleration model is proposed to reveal its signal characteristics more accurately in the healthy and faulty state. First, an analytical lateral-torsional coupled dynamic model is developed with consideration of time-varying mesh stiffness and damping, static transmission error, and gear backlash. Then, the effect of gear backlash and damping on the system is analyzed, and a numerical velocity signal in the healthy and faulty state is carried out. Considering the effects of transmission paths, the resultant acceleration signal along the vertical direction is constructed as the weighted vibration summation. This signal includes a vertical component of the vibration along the meshing lines of both sun-planet and ring-planet pairs. Moreover, it also contains the vertical component of the planet gears, sun gear, and planet carrier acceleration relative to their own supporting bearings. Finally, the simulation results from the resultant signal model are experimentally validated and analyzed in both time and frequency domains.

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Al-Shyyab, A., K. Alwidyan, A. Jawarneh, and H. Tlilan. "Non-linear dynamic behaviour of compound planetary gear trains: Model formulation and semi-analytical solution." Proceedings of the Institution of Mechanical Engineers, Part K: Journal of Multi-body Dynamics 223, no. 3 (April 15, 2009): 199–210. http://dx.doi.org/10.1243/14644193jmbd197.

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A discrete, non-linear, time-varying, torsional dynamic model of a multi-stage planetary train that is formed by any number of simple planetary stages is proposed in this study. Each planetary stage has a distinct fundamental mesh frequency and any number of planets spaced in any angular positions. The model allows the analysis of the gear train in all possible power flow configurations suitable for various gear drive ratios. It includes periodic variation of gear mesh stiffnesses as well as clearance (backlash) non-linearities that allow tooth separations. Equations of motion for the general case are formulated and solved semi-analytically using a hybrid harmonic balance method (HBM) in conjugate with inverse Fourier transform. Relative mesh displacements along lines of action of individual gear pairs were used as the continuation parameters to pass singular points and ill-conditioned equations in their proximity. At the end, a case study of a two-stage planetary train is used to demonstrate the effectiveness of the model and solution methods. The HBM solutions are compared to those obtained by a direct numerical integration method to assess their accuracy.

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Xu, Lijiao, and Nan Chen. "Nonlinear dynamic study and vibration reduction of a power turret gear train with modified design parameters." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 229, no. 10 (August 12, 2014): 1745–59. http://dx.doi.org/10.1177/0954406214547092.

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This work presents the nonlinear dynamic characteristics and vibration reduction of a numerical control power turret three-stage gear transmission system composed of four spur gears. Considering translational and rotational motions, the nonlinear lumped-parameter and multi-degrees of freedom models of modified and unmodified transmission systems are introduced to study the dynamic behavior while the time-varying mesh stiffness and backlash of gear mesh pairs are involved as internal excitations. For the requirement of high speed and low vibration, high contact ratio by modifying design parameters is suggested in this study. By numerical method, the dynamic vibration responses are calculated. Results in the time and frequency domains show that the vibration amplitudes and mesh forces are efficiently decreased after modification. The influences of key parameters, such as mesh stiffness, damping, backlash, and torque on the dynamic response are also studied here. To demonstrate the effectiveness of the proposed model, the vibration tests are conducted by two physical prototypes of the power turret. The values of vibration acceleration at different tests points and speeds are obtained and analyzed. Experimental results validate that the vibration of turret is decreased by the design improvement of gear system.

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Wang, Michael Yu, Weijie Zhao, and Radhakrishnan Manoj. "Numerical Modelling and Analysis of Automotive Transmission Rattle." Journal of Vibration and Control 8, no. 7 (July 2002): 921–43. http://dx.doi.org/10.1177/10775402029594.

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This paper describes a research work on modelling and numerical analysis of torsional vibration in automotive manual transmissions. The focus of the effort is on a decoupling procedure for the numerical analysis of gear rattle. The power train model is specified into a linear sub-system and a non-linear sub-system that includes the strong nonlinearities of gear backlash and multi-stage clutch stiffness. The weak coupling of the sub-systems is then exploited for efficient numerical analysis. It is shown that the decoupled model yields an acceptable accuracy with a significant gain in computational efficiency when using an algorithm of numerical integration of stiff differential equations or a finite element in time algorithm. Numerical simulation results for a Daimler-Chrysler vehicle power train are given to illustrate the effectiveness of the proposed scheme.

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Sheng, Ruo Yu, Yong Wang, and Li Na Zhang. "Study on the Nonlinear Dynamics of a Single-Stage Gear Vibro-Impact System." Applied Mechanics and Materials 697 (November 2014): 161–67. http://dx.doi.org/10.4028/www.scientific.net/amm.697.161.

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A vibro-impact dynamic model of a typical single-stage spur gear train has been proposed in this study. The lumped parameter dynamic model includes the constant meshing stiffnesses, the linear time-invariant viscous damping values and the gear clearance (backlash) non-linearity allowing teeth separations. With taking account of the effect on impact of gear tooth when meshing, the dynamic equations of motion are solved for the steady period response by use of analytical method under given periodic motion conditions. The feasibility of the given periodic motion conditions is demonstrated by comparing the analytical results with that of numeric simulation method. A Poincaré map of the system is established. The stability and bifurcation of the system are studied using analytical methods. Finally, the theoretical analyses are verified using numerical simulation.

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Prajapat, Ganesh P., Pratyasa Bhui, Nilanjan Senroy, and Indra N. Kar. "Modelling and estimation of gear train backlash present in wind turbine driven DFIG system." IET Generation, Transmission & Distribution 12, no. 14 (August 14, 2018): 3527–35. http://dx.doi.org/10.1049/iet-gtd.2017.1377.

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Prajapat, Ganesh P., N. Senroy, and I. N. Kar. "Modeling and impact of gear train backlash on performance of DFIG wind turbine system." Electric Power Systems Research 163 (October 2018): 356–64. http://dx.doi.org/10.1016/j.epsr.2018.07.006.

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Sepehri, N., F. Sassani, P. D. Lawrence, and A. Ghasempoor. "Simulation and Experimental Studies of Gear Backlash and Stick-Slip Friction in Hydraulic Excavator Swing Motion." Journal of Dynamic Systems, Measurement, and Control 118, no. 3 (September 1, 1996): 463–67. http://dx.doi.org/10.1115/1.2801168.

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Inherent to any heavy-duty hydraulic machine operation with a large number of interconnected components are nonidealities such as gear backlash, friction and leakage. The swing motion of the operator’s cabin in an excavator is a typical example. In this paper we conduct a study comprising experimental, mathematical and simulation components to determine the degree to which these nonlinearities affect the performance of such machines. The inclusion of the conventional model of backlash in the simulation of the excavator swing motion is shown to be inefficient and unnecessary in terms of computation time and the final results. A new model which combines the fluid-flow and the gear train dynamics is developed. The study of contact and non-contact cases brings about proper sets of static and dynamic equations which efficiently simulate this phenomenon for the class of excavator machines under consideration. The inclusion of stick-slip friction model in the simulation shows two effects. Firstly, it causes a noticeable time-delay at the beginning of the swing motion. Secondly, it results in an overshoot during velocity control experiments. It is also shown that dry friction and leakage (cross-port or external) are as significant as gear backlash in determining the pressure patterns in the connecting hydraulic lines and, therefore, should not be overlooked, especially when the excavator cabin is brought to a stop. Often, this is the most important state event when accurate positioning is crucial. The simulation results are qualitatively supported by the experimental evidence. The experiments were performed on an instrumented teleoperated Caterpillar 215B excavator.

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Bai, S., and J. Angeles. "The design of spherical multilobe-cam mechanisms." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 223, no. 2 (February 1, 2009): 473–82. http://dx.doi.org/10.1243/09544062jmes1154.

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Cam—roller mechanisms can be used in transmissions and robotic devices as an alternative to their bevel-gear counterparts. As bevel gears are used to couple shafts of intersecting axes, their cam-mechanism replacements are bound to have intersecting axes as well. This means that the contact surface of the cam must be conical, which leads to spherical cam mechanisms. Compared with gear transmissions, cam—roller mechanisms feature low friction, low backlash, and high strength. However, cam mechanisms may end up with a high pressure angle if negative action, a motion in which the cam is driven by mechanism rollers, occurs. This article reports the design of transmissions with spherical multilobe cams (MLCs), as a means to reduce the pressure angle. The kinematics of MLC, including profile generation, undercutting-avoidance, and transmission-quality evaluation, is studied here. A case study has been included, in which the synthesis of a spherical MLC transmission is undertaken as a means to improve the transmission quality of a spherical epicyclic gear train. This train was introduced with the purpose of producing a singularity-free, unlimited-workspace pitch—roll wrist.

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Farshidianfar, A., M. Ebrahimi, and H. Bartlett. "Hybrid modelling and simulation of the torsional vibration of vehicle driveline systems." Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 215, no. 2 (February 1, 2001): 217–29. http://dx.doi.org/10.1243/0954407011525593.

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Vehicle drivelines are lightly damped non-linear systems possessing many degrees of freedom with dynamic interactions between the various subsystems. There are many sources of excitation such as torsional impact caused by the take-up of backlash in the power train system. Such sources of excitation exist in transmission backlash, in driveline splines and in pinion to ring gear contact in the differential. Abrupt application or release of the throttle in slowly moving traffic or rapid engagement of the clutch can be followed by noise and vibration responses referred to in the industry as ‘clonk’. This paper presents a method of modelling a vehicle driveline which can identify the phenomena known as ‘clonk’ and ‘shuffle’. This model is based on the assumption that vehicle drivelines can be considered as partially lumped and partially distributed, which for systems of this type is wholly appropriate. In doing this it is possible to derive an analytical solution to the governing equations, which has not been considered previously. The results from this model are compared with a totally lumped model of the vehicle driveline for comparison.

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Raviola, Andrea, Andrea De Martin, and Massimo Sorli. "A Preliminary Experimental Study on the Effects of Wear on the Torsional Stiffness of Strain Wave Gears." Actuators 11, no. 11 (October 24, 2022): 305. http://dx.doi.org/10.3390/act11110305.

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Strain wave gears, also known as harmonic drives, are employed in a wide range of fields such as robotics and aerospace, where light weights, precision, and reliability are essential to the correct execution of the tasks. For this reason, their understanding and optimization are of high interest for both academia and industry. Previous studies have been mainly focused on investigating and modeling the working principle of strain wave gears in nominal operating conditions. On the contrary, the present paper describes the results of an experimental campaign aimed to introduce wear in gears of two different suppliers and its impact on the gear torsional stiffness. Results show how the change in the gear performance strongly depends both on the gear manufacturer and the location of wear. For the analyzed components, a damaged wave generator–flexspline interface reduces the gear stiffness up to one-fourth of its nominal value, while the non-nominal shape of the teeth jeopardizes the gearbox performance, leading up to just 4% of the nominal stiffness values, and resulting in backlash. Such data can be used to properly model the presence of wear in strain wave gears and to train data-driven diagnostics and prognostics routines to effectively detect such a fault.

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Wang, Zhiwei, Yao Cheng, Guiming Mei, Weihua Zhang, Guanhua Huang, and Zhonghui Yin. "Torsional vibration analysis of the gear transmission system of high-speed trains with wheel defects." Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit 234, no. 2 (March 6, 2019): 123–33. http://dx.doi.org/10.1177/0954409719833791.

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The gear transmission system of a high-speed train is the key component, which delivers the traction torque from the motor to the wheelset. It couples with the vehicle system via the suspension system, gear meshing and the wheel–rail interface. The dynamic performance of the transmission system directly affects the operational reliability or even the running safety of high-speed trains. In this study, the effects of wheel polygonalisation and wheel flat on the dynamic responses of the transmission system are investigated through simulations of a novel vehicle dynamics model. This model integrates the flexible gearbox housing, the time-varying mesh stiffness and the nonlinear gear tooth backlash, and the track irregularities to obtain more realistic responses of the traction transmission systems in a vehicle vibration environment, from motors to wheelsets, under the effects of the wheel flat and polygonal wear. The field experimental tests are implemented for a vehicle running along a main high-speed railway line in China. Subsequently, the developed dynamics model is validated with good agreement between the experimental and the theoretical results. The calculated results revealed that wheel flat and wheel polygonal wear caused a high-frequency fluctuation of both the longitudinal creep force and the gear mesh force, causing a violent and complex torsional vibration of the gear transmission system. Moreover, the flexible deformation of the gearbox housing, especially its resonance due to the wheel polygonal wear, contributed to the torsional vibration of the gear transmission system.

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Frech, Michael, Theodor Mammen, and Bertram Lange. "Pointing Accuracy of an Operational Polarimetric Weather Radar." Remote Sensing 11, no. 9 (May 10, 2019): 1115. http://dx.doi.org/10.3390/rs11091115.

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Exact navigation of detected radar signals is crucial for usage of radar data in meteorological applications. The antenna pointing accuracy in azimuth and elevation of a polarimetric weather research radar depending on position of the sun is assessed using dedicated solar boxscans in a sequence of 10 min. The research radar of the German Meteorological Service (Deutscher Wetterdienst, DWD) is located at the meteorological observatory Hohenpeissenberg. It is identical to the 17 weather radars of the German weather radar network. A non-linear azimuthal variation of azimuthal pointing bias of up to 0.1 ∘ is found, which is significant as this is commonly viewed as the target pointing accuracy. This azimuthal variation can be attributed to the mechanical design of the drive train with the angle encoder. This includes the inherent backlash of the gear-drive assembly. The pointing bias estimates based on over 1000 boxscans from 26 days show a small case by case variability, which indicates that dedicated solar boxscans from one day are sufficient to characterize the pointing performance of a particular system. An azimuth and elevation range that is covered with this approach is limited and dependent on the time of the year. At Hohenpeißenberg, an azimuth range up to 50–300 ∘ was covered around summer solstice and about 90 boxscans were acquired. It is shown that the pointing bias based on solar boxscan data are consistent with results from the operational assessment of pointing bias using solar hits from operational scanning if we take into account the fact that the DWD operational scan definition has only a maximum elevation of 25 ∘ . The analysis of a full diurnal cycle of boxscans from four operational radar system shows that the azimuthal dependence of azimuth bias needs to be evaluated individually for each system. For one of the systems, the azimuthal variation of the pointing bias of about 0.2 ∘ seems related to the bull gear. A difference of the pointing bias for the horizontal and vertical polarization is an indication of beam squint and, eventually, that of a feed misalignment. Beam squint and, as such, the quality of the antenna assembly can easily be monitored with this method during the life-time of a weather radar.

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Li, Tongjie, and Rupeng Zhu. "Global Analysis of a Planetary Gear Train." Shock and Vibration 2014 (2014): 1–6. http://dx.doi.org/10.1155/2014/930350.

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By using the Poincaré-like cell-to-cell mapping method and shooting method, the global characteristics of a planetary gear train are studied based on the torsional vibration model with errors of transmission, time-varying meshing stiffness, and multiple gear backlashes. The study results reveal that the planetary with a certain set of parameters has four coexisting periodic orbits, which are P-1, P-2, P-4, and P-8, respectively. P-1 and P-2 motions are not of long-term stability, P-8 motion is of local stability, and P-4 motion is of global stability. Shooting method does not have the capacity of searching coexisting periodic orbits in a global scope, and it is easy to omit some periodic orbits which are far away from the main gropes of periodic orbits.

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Chen, Chao, Xiang Zhang, and Jorge Angeles. "Kinematic and Geometric Analysis of a Pure-Rolling Epicyclic Train." Journal of Mechanical Design 129, no. 8 (August 12, 2006): 852–57. http://dx.doi.org/10.1115/1.2735343.

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This paper reports an innovative design of epicyclic (planetary) cam trains based on pure-rolling contact, intended to overcome the drawbacks of gear trains, such as Coulomb friction and backlash. The kinematic relations of the mechanism with a given speed-reduction ratio are analyzed; accordingly, the profiles of the sun cam and ring cam, key elements of the mechanism, are obtained. Furthermore, the condition for undercutting avoidance of the ring cam is derived. For mechanical design, different layouts of the epicyclic cam trains are discussed for the structure and transmission optimization. Finally, an epicyclic cam-roller speed reducer is designed and prototyped.

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Li, Tong Jie, Ru Peng Zhu, and He Yun Bao. "Study on Dynamic Load Sharing Behavior of Two-Stage Planetary Gear Train Based on a Nonlinear Vibration Model." Applied Mechanics and Materials 86 (August 2011): 611–14. http://dx.doi.org/10.4028/www.scientific.net/amm.86.611.

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The nonlinear torsional vibration model of a two-stage planetary gear system is established taking errors of transmission, time varying meshing stiffness and multiple gear backlashes into account. The solution of the equations is determined by using ODE45. The influences of transmission errors on the load sharing behavior are assessed and some useful theoretical guidelines for the design of planetary gear systems are provided at last.

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Hasan, A. T., A. M. S. Hamouda, N. Ismail, I. Aris, and M. H. Marhaban. "Trajectory tracking for a serial robot manipulator passing through singular configurations based on the adaptive kinematics Jacobian method." Proceedings of the Institution of Mechanical Engineers, Part I: Journal of Systems and Control Engineering 223, no. 3 (December 18, 2008): 393–415. http://dx.doi.org/10.1243/09596518jsce655.

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This paper discusses the use of artificial neural networks (ANNs) as a method of trajectory tracking control for a robotic system. Using an ANN does not require any prior knowledge of the kinematics model of the system being controlled; the basic idea of this concept is the use of the ANN to learn the characteristics of the robot system rather than to specify an explicit robot system model. In this approach, disadvantages of some schemes such as the fuzzy learning control, for example, have been elevated. Off-line training was performed for a geometric trajectory that is free of obstacles. Studying the kinematics Jacobian of serial manipulators by using ANNs has two problems: one of these is the selection of the appropriate configuration of the network and the other is the generation of a suitable training dataset. In this approach, although this is very difficult in practice, training data were recorded experimentally from sensors fixed on each joint to overcome the effect of kinematics uncertainties present in the real world such as ill-defined linkage parameters, links flexibility, and backlashes in the gear train. Then two network configurations were compared to find the best configuration to be used. Finally, the simulation results were verified experimentally using a general six-degree-of-freedom (DOF) serial robot manipulator.

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Donmez, Ata, and Ahmet Kahraman. "An experimental and theoretical investigation of the influence of backlash on gear train vibro-impacts and rattle noise." Proceedings of the Institution of Mechanical Engineers, Part K: Journal of Multi-body Dynamics, October 31, 2022, 146441932211343. http://dx.doi.org/10.1177/14644193221134322.

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Rattling is a perennial gear noise problem observed in various powertrain components ranging from manual transmissions to engine balancers and timing gear trains. Under lightly loaded conditions, gear systems that are subjected to input and/or output torque fluctuations exhibit vibro-impacts as tooth separations and coast-side contacts take place in the presence of backlash. Experimental set-ups that can impose tightly controlled torque fluctuations to single or multi-mesh gear train are used here to determine the sensitivity of the rattling noise levels to the magnitudes of backlash within wide ranges of torque fluctuation parameters. Torsional discrete models of the experimental set-ups were used to simulate these rattling motions and to predict impact velocity-based rattle severity indexes as a function of both excitation parameters and backlash magnitudes. Single-mesh results show that the larger backlash values result in higher noise levels in most of the cases. In case of double-mesh systems, the resultant noise levels and the corresponding rattle indices exhibit different sensitivities to backlash magnitudes depending on the excitation conditions.

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Donmez, Ata, and Ahmet Kahraman. "Experimental and Theoretical Investigation of Vibro-impact Motions of a Gear Pair Subjected to Torque Fluctuations to Define a Rattle Noise Severity Index." Journal of Vibration and Acoustics 144, no. 4 (January 13, 2022). http://dx.doi.org/10.1115/1.4053264.

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Abstract Vibro-impacts are common in various automotive engine and transmission gear applications. They are known to cause excessive noise levels, often called rattling or hammering. Input and output fluctuations acting on such systems cause tooth separations and sequences of impacts allowed by backlash at the gear mesh interfaces. The fluctuations leading gear rattling have often been studied for specific applications with the excitations produced typically by an internal combustion engine. As such, rattle evaluations have been often empirical and specific to the systems considered. In this study, an experimental test setup of a gear pair is developed to emulate the same torque fluctuations in a laboratory environment. This setup is used to establish an impact velocity-based rattle severity index defined by the measured torsional behavior of the drive train that is shown to correlate well with the measured sound pressure levels. With that, a validated dynamic model of the experimental setup is employed to predict the same index to allow estimation of rattle noise outcome solely from a torsional dynamic model of the drivetrain. Predicted rattle severity indexes are shown to agree well with the measured ones within wide ranges of torque fluctuations and backlash magnitudes, allowing an assessment of rattle performance of a drivetrain solely from a torsional model.

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Abdulhady Jaber, Alaa, and Robert Bicker. "Fault Diagnosis of Industrial Robot Bearings Based on Discrete Wavelet Transform and Artificial Neural Network." International Journal of Prognostics and Health Management 7, no. 2 (November 11, 2020). http://dx.doi.org/10.36001/ijphm.2016.v7i2.2365.

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Industrial robots have long been used in production systems in order to improve productivity, quality and safety in automated manufacturing processes. An unforeseen robot stoppage due to different reasons has the potential to cause an interruption in the entire production line, resulting in economic and production losses. The majority of the previous research on industrial robots health monitoring is focused on monitoring of a limited number of faults, such as backlash in gears, but does not diagnose the other gear and bearing faults. Thus, the main aim of this research is to develop an intelligent condition monitoring system to diagnose the most common faults that could be progressed in the bearings of industrial robot joints, such as inner/outer race bearing faults, using vibration signal analysis. For accurate fault diagnosis, time-frequency signal analysis based on the discrete wavelet transform (DWT) is adopted to extract the most salient features related to faults, and the artificial neural network (ANN) is used for faults classification. A data acquisition system based on National Instruments (NI) software and hardware was developed for robot vibration analysis and feature extraction. An experimental investigation was accomplished using the PUMA 560 robot. Firstly, vibration signals are captured from the robot when it is moving one joint cyclically. Then, by utilising the wavelet transform, signals are decomposed into multi-band frequency levels starting from higher to lower frequencies. For each of these levels the standard deviation feature is computed and used to design, train and test the proposed neural network. The developed system has showed high reliability in diagnosing several seeded faults in the robot.

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Journal articles on the topic 'Gear-train backlash'

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