The Experts below are selected from a list of 22290 Experts worldwide ranked by ideXlab platform
Yimin Shao - One of the best experts on this subject based on the ideXlab platform.
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fault feature analysis of Planetary Gear system with tooth root crack and flexible ring Gear rim
Engineering Failure Analysis, 2015Co-Authors: Zaigang Chen, Yimin ShaoAbstract:Abstract Planetary Gear transmission has a wide application in different areas due to its advantages such as compactness, large torque-to-weight ratio, reduced noise and vibrations. However, its dynamic responses are much more complex due to the complicated structures and relative motions, which make it difficult in the fault feature extractions at the view point of fault detection. Better understanding on the dynamic features of a Planetary Gear transmission and the corresponding internal excitation sources will benefit the fault feature extractions. In this paper, an analytical model for mesh stiffness calculation is developed based on the potential energy principle and uniformly curved Timoshenko beam theory, which enables exploring the effects of the tooth root crack fault and the flexible ring Gear rim on the dynamic responses. Based on the developed model, the frequency spectrum structures of the Planetary Gear transmission can be revealed and analyzed theoretically in the presence of tooth crack and flexible ring Gear. A case study is performed to demonstrate the effectiveness of the developed model, where the tooth root cracks are seeded in a tooth of the sun, planet, and ring Gears. The simulated results indicate that the complicated modulation phenomenon can be observed where the causes of different frequency components can be revealed. This study is expected to be able to give some theoretical guidance on the identification of vibration sources for Planetary Gear transmissions.
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dynamic simulation of Planetary Gear set with flexible spur ring Gear
Journal of Sound and Vibration, 2013Co-Authors: Zaigang Chen, Yimin Shao, D SuAbstract:Abstract Ring Gear is a key element for vibration transmission and noise radiation in the Planetary Gear system which has been widely employed in different areas, such as wind turbine transmissions. Its flexibility has a great influence on the mesh stiffness of internal Gear pair and the dynamic response of the Planetary Gear system, especially for the thin ring cases. In this paper, the flexibility of the internal ring Gear is considered based on the uniformly curved Timoshenko beam theory. The ring deformation is coupled into the mesh stiffness model, which enables the investigation on the effects of the ring flexibility on the mesh stiffness and the dynamic responses of the Planetary Gear. A method about how to synthesize the total mesh stiffness of the internal Gear pairs in multi-tooth region together with the ring deformation and the tooth errors is proposed. Numerical results demonstrate that the ring thickness has a great impact on the shape and magnitude of the mesh stiffness of the internal Gear pair. It is noted that the dynamic responses of the Planetary Gear set with equally spaced supports for the ring Gear are modulated due to the cyclic variation of the mesh stiffness resulted from the presence of the supports, which adds more complexity in the frequency structure.
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dynamic simulation of Planetary Gear with tooth root crack in ring Gear
Engineering Failure Analysis, 2013Co-Authors: Zaigang Chen, Yimin ShaoAbstract:Abstract Planetary Gear is widely used in different areas due to its advantages such as compactness, large torque-to-weight ratio, large transmission ratios, reduced noise and vibrations. However, the tooth faults like cracks are seldom concentrated. In this paper, a mesh stiffness model of internal Gear pair with a tooth root crack in the ring Gear is derived based on the potential energy principle. The mesh stiffness model is incorporated into the dynamic model of a one-stage Planetary Gear set with 21-degree-of-freedom (DOF) to investigate the effect of the internal Gear tooth root crack. The crack cases with different dimensions are designed in this paper to demonstrate their influences on the mesh stiffness and the dynamic performance of the Planetary Gear set. The simulated results show that bigger reduction in mesh stiffness is caused by the growth in the crack size. And the impulsive vibrations and sidebands can be observed in the dynamic response of the Planetary Gear set in time and frequency domains, respectively. Both their amplitudes increase as the crack propagation which supply the possibility for them to be the indicators in the condition monitoring and fault diagnosis of Planetary Gear system.
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dynamic features of a Planetary Gear system with tooth crack under different sizes and inclination angles
Journal of Vibration and Acoustics, 2013Co-Authors: Zaigang Chen, Yimin ShaoAbstract:Planetary Gears are widely used in the industry due to their advantages of compactness, high power-to-weight ratios, high efficiency, and so on. However, Planetary Gears such as that in wind turbine transmissions always operate under dynamic conditions with internal and external load fluctuations, which accelerate the occurrence of Gear failures, such as tooth crack, pitting, spalling, wear, scoring, scuffing, etc. As one of these failure modes, Gear tooth crack at the tooth root due to tooth bending fatigue or excessive load is investigated; how it influences the dynamic features of Planetary Gear system is studied. The applied tooth root crack model can simulate the propagation process of the crack along tooth width and crack depth. With this approach, the mesh stiffness of Gear pairs in mesh is obtained and incorporated into a Planetary Gear dynamic model to investigate the effects of the tooth root crack on the Planetary Gear dynamic responses. Tooth root cracks on the sun Gear and on the planet Gear are considered, respectively, with different crack sizes and inclination angles. Finally, analysis regarding the influence of tooth root crack on the dynamic responses of the Planetary Gear system is performed in time and frequency domains, respectively. Moreover, the differences in the dynamic features of the Planetary Gear between the cases that tooth root crack on the sun Gear and on the planet Gear are found.
Jung Jun Park - One of the best experts on this subject based on the ideXlab platform.
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A serial-type dual actuator unit with Planetary Gear train: Basic design and applications
IEEE ASME Transactions on Mechatronics, 2010Co-Authors: Byeong Sang Kim, Jae-bok Song, Jung Jun ParkAbstract:Control of a robot manipulator in contact with the environment is usually conducted by a direct feedback control system using a force-torque sensor or an indirect impedance control scheme. Although these methods have been successfully applied to many applications, simultaneous control of force and position cannot be achieved. To cope with such problems, this paper proposes a novel design of a dual actuator unit (DAU) composed of two actuators and a Planetary Gear train to provide the capability of simultaneous control of position and stiffness. Since one actuator controls position and the other actuator modulates stiffness, the DAU can control the position and stiffness simultaneously at the same joint. Both the torque exerted on the joint and the stiffness of the environment can be estimated without an expensive force sensor. Various experiments demonstrate that the DAU can provide good performance for position tracking, force estimation, and environment estimation.
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Double actuator unit with Planetary Gear train for a safe manipulator
Proceedings - IEEE International Conference on Robotics and Automation, 2007Co-Authors: Byeong Sang Kim, Jung Jun Park, Jae-bok SongAbstract:Control of a robot manipulator in contact with the environment is usually conducted by the direct feedback control system using a force-torque sensor or the indirect impedance control scheme. Although these methods have been successfully applied to many applications, simultaneous control of force and position cannot be achieved. Furthermore, collision safety has been of primary concern in recent years with emergence of service robots in direct contact with humans. To cope with such problems, redundant actuation has been used to enhance the performance of a position/force controller. In this paper, the novel design of a double actuator unit (DAU) composed of double actuators and a Planetary Gear train is proposed to provide the capability of simultaneous control of position and force as well as the improved collision safety. Since one actuator controls position and the other actuator modulates stiffness, DAU can control the position and stiffness simultaneously at the same joint. The torque exerted on the joint can be estimated without an expensive torque/force sensor. DAU is capable of detecting dynamic collision by monitoring the speed of the stiffness modulator. Upon detection of dynamic collision, DAU immediately reduces its joint stiffness according to the collision magnitude, thus providing the optimum collision safety. It is shown from various experiments that DAU can provide good performance of position tracking, force estimation and collision safety. I.
Young Soo Yang - One of the best experts on this subject based on the ideXlab platform.
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design of a non circular Planetary Gear train system to generate an optimal trajectory in a rice transplanter
Journal of Engineering Design, 2007Co-Authors: Young Soo YangAbstract:The transplanting accuracy of a rice transplanter for picking, conveying and transplanting seedlings mainly depends on the trajectory as well as the return motion of the hoe. The trajectory of the hoe has to be optimized in treating seedlings for a prevailing soil condition. For better transplanting accuracy, a Planetary-Gear-train system, instead of the four-bar linkage system is used to design a transplanting mechanism. This study proposes a theoretical design method for a transplanting mechanism; the method designs non-circular Gears of a Planetary-Gear-train system for the hoe to trace a prescribed trajectory. An optimization method was used to determine the arm length and tool length; inverse kinematics to determine the configuration angles of the two links and the roll contact condition in transmitting motion between the Gears; and a linearization approach to obtain the shapes of the Gears. Based on the proposed method, the shapes of the Gears and the lengths of the tools of the Planetary-Gear-train...
Byeong Sang Kim - One of the best experts on this subject based on the ideXlab platform.
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A serial-type dual actuator unit with Planetary Gear train: Basic design and applications
IEEE ASME Transactions on Mechatronics, 2010Co-Authors: Byeong Sang Kim, Jae-bok Song, Jung Jun ParkAbstract:Control of a robot manipulator in contact with the environment is usually conducted by a direct feedback control system using a force-torque sensor or an indirect impedance control scheme. Although these methods have been successfully applied to many applications, simultaneous control of force and position cannot be achieved. To cope with such problems, this paper proposes a novel design of a dual actuator unit (DAU) composed of two actuators and a Planetary Gear train to provide the capability of simultaneous control of position and stiffness. Since one actuator controls position and the other actuator modulates stiffness, the DAU can control the position and stiffness simultaneously at the same joint. Both the torque exerted on the joint and the stiffness of the environment can be estimated without an expensive force sensor. Various experiments demonstrate that the DAU can provide good performance for position tracking, force estimation, and environment estimation.
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Double actuator unit with Planetary Gear train for a safe manipulator
Proceedings - IEEE International Conference on Robotics and Automation, 2007Co-Authors: Byeong Sang Kim, Jung Jun Park, Jae-bok SongAbstract:Control of a robot manipulator in contact with the environment is usually conducted by the direct feedback control system using a force-torque sensor or the indirect impedance control scheme. Although these methods have been successfully applied to many applications, simultaneous control of force and position cannot be achieved. Furthermore, collision safety has been of primary concern in recent years with emergence of service robots in direct contact with humans. To cope with such problems, redundant actuation has been used to enhance the performance of a position/force controller. In this paper, the novel design of a double actuator unit (DAU) composed of double actuators and a Planetary Gear train is proposed to provide the capability of simultaneous control of position and force as well as the improved collision safety. Since one actuator controls position and the other actuator modulates stiffness, DAU can control the position and stiffness simultaneously at the same joint. The torque exerted on the joint can be estimated without an expensive torque/force sensor. DAU is capable of detecting dynamic collision by monitoring the speed of the stiffness modulator. Upon detection of dynamic collision, DAU immediately reduces its joint stiffness according to the collision magnitude, thus providing the optimum collision safety. It is shown from various experiments that DAU can provide good performance of position tracking, force estimation and collision safety. I.
Robe G Parke - One of the best experts on this subject based on the ideXlab platform.
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nonlinear dynamics and stability of wind turbine Planetary Gear sets under gravity effects
European Journal of Mechanics A-solids, 2014Co-Authors: Yi Guo, J Kelle, Robe G ParkeAbstract:Abstract This paper investigates the dynamics of wind turbine Planetary Gear sets under the effect of gravity using a modified harmonic balance method that includes simultaneous excitations. This modified method along with arc-length continuation and Floquet theory is applied to a lumped-parameter Planetary Gear model including gravity, fluctuating mesh stiffness, bearing clearance, and nonlinear tooth contact to obtain the dynamic response of the system. The calculated dynamic responses compare well with time domain-integrated mathematical models and experimental results. Gravity is a fundamental vibration source in wind turbine Planetary Gear sets and plays an important role in the system dynamic response compared to excitations from tooth meshing alone. Gravity causes nonlinear effects induced by tooth wedging and bearing-raceway contacts. Tooth wedging, also known as a tight mesh, occurs when a Gear tooth comes into contact on the drive-side and back-side simultaneously and it is a source of planet-bearing failures. Clearance in carrier bearings decreases bearing stiffness and significantly reduces the lowest resonant frequencies of the translational modes. Gear tooth wedging can be prevented if the carrier-bearing clearance is less than the tooth backlash.
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analytical investigation of tooth profile modification effects on Planetary Gear dynamics
Mechanism and Machine Theory, 2013Co-Authors: Cheonjae Ahk, Robe G ParkeAbstract:Abstract This study investigates the impact of tooth profile modification on spur Planetary Gear vibration. An analytical model is proposed to capture the excitation from tooth profile modifications at the sun–planet and ring–planet meshes. The accuracy of the proposed model for dynamic analysis is correlated against a benchmark finite element analysis. Perturbation analysis yields a closed-form approximation of the vibration response with tooth profile modifications. The perturbation solution is used to investigate the effects of tooth profile modification. The tooth profile modification parameters that minimize response are readily obtained. Static transmission error and dynamic response are minimized at different amounts of profile modification, which contradicts common practical thinking regarding the correlation between static transmission error and dynamic response. Contrary to expectations, the optimal sun–planet and ring–planet tooth profile modifications that minimize response when applied individually may increase dynamic response when applied simultaneously. System parameters such as mesh stiffness and mesh phase significantly affect the influence of tooth profile modification.
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suppression of planet mode response in Planetary Gear dynamics through mesh phasing
Journal of Vibration and Acoustics, 2006Co-Authors: Vijaya Kuma Ambarisha, Robe G ParkeAbstract:This work analytically derives design rules to suppress certain harmonics of planet mode response in Planetary Gear dynamics through mesh phasing. Planet modes are one of three categories of Planetary Gear vibration modes. In these modes, only the plantes deflect while the carrier, ring, and sun Gears have no motion (Lin, J., and Parker, R. G., 1999, ASME J. Vib. Acoust., 121, pp. 316-321; J. Sound Vib, 233(5), pp. 921-928). The dynamic mesh forces are not explicitly modeled for this study; instead, the symmetry of Planetary Gear systems and Gear tooth mesh periodicity are sufficient to establish rules to suppress planet modes. Thus, the conclusions are independent of the mesh modeling details, Planetary Gear systems with equally spaced planets and with diametrically opposed planet pairs are examined. Suppression of degenerate mode response in purely rotational degree-of-freedom models achieved in the limit of infinite bearing stiffness is also investigated. The mesh phasing conclusions are verified by dynamic simulations of various Planetary Gears using a lumped-parameter analytical model and by comparisons to others' research.
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Planetary Gear parametric instability caused by mesh stiffness variation
Journal of Sound and Vibration, 2002Co-Authors: Robe G ParkeAbstract:Abstract Parametric instability is investigated for Planetary Gears where fluctuating stiffness results from the changing contact conditions at the multiple tooth meshes. The time-varying mesh stiffnesses of the sun–planet and ring–planet meshes are modelled as rectangular waveforms with different contact ratios and mesh phasing. The operating conditions leading to parametric instability are analytically identified. Using the well-defined properties of Planetary Gear vibration modes, the boundaries separating stable and unstable conditions are obtained as simple expressions in terms of mesh parameters. These expressions allow one to suppress particular instabilities by adjusting the contact ratios and mesh phasing. Tooth separation from parametric instability is numerically simulated to show the strong impact of this non-linearity on the response.
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a physical explanation for the effectiveness of planet phasing to suppress Planetary Gear vibration
Journal of Sound and Vibration, 2000Co-Authors: Robe G ParkeAbstract:Abstract The effectiveness of planet phasing to suppress Planetary Gear vibration in certain harmonics of the mesh frequency is examined based on the physical forces acting at the sun–planet and ring–planet meshes. The analysis does not rely on assumptions of the nature of the dynamic excitation (e.g., static transmission error or time-varying mesh stiffness) or on an underlying dynamic model. Instead, the inherent system symmetries imply distinct relationships between the forces at the multiple meshes. These relationships lead naturally to simple rules for when a particular harmonic of mesh frequency is suppressed in the dynamic response. An important implication is that certain expected resonances when a mesh frequency harmonic and a natural frequency coincide are suppressed. Systems with equal planet spacing and those with unequally spaced, diametrically opposed planets are considered. In both cases, a substantial number of mesh frequency harmonics are suppressed naturally without optimization of the phasing. The phenomena are demonstrated with a dynamic finite element/contact mechanics simulation.
