• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.10
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• pp.2130-2141
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• 2002

A unique technique to estimate the magnitude or contribution ratio of each stage backlash in a system with a two-stage gear reducer is proposed. The concept to estimate the magnitude or contribution ratio of each stage backlash is based on the change of frequency response characteristic, in particular, the change of anti-resonant frequency and resonant frequency, due to the change of each stage backlash magnitude, even though the total backlash magnitude of a system with a two-stage gear reducer is constant. The validity of the technique is verified in a seeker gimbal and satisfactory results are obtained. It is thought that the diagnosis and maintenance of the manufacturing machines and systems with two-stage gear reducers will become more efficient and economical by virtue of the proposed technique.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.12 no.12
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• pp.921-928
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• 2002

Main sources of the nitration of a gear-pair system are backlash and transmission error, the difference between required and actual rotation during gear meshing. This paper presents the nonlinear dynamic characteristics of gear motions due to the existence of backlash and periodic variation of meshing stiffness, which is assumed as a one-term harmonic component. Gear motions are classified as three types with the consideration of backlash. Each response is calculated using the harmonic balance method and confirmed by numerical integration. The responses with the increase of the rotating speed show abrupt changes in its magnitude for the variation of the preload, exciting force, and damping coefficient. The result also shows that there is a chaotic motion with some specific design parameters and operating conditions In gear diving system. Consequently the design of gear driving system with low nitration and noise requires the study on the effects of nonlinear dynamic characteristics due to stiffness variation and backlash.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.20 no.7
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• pp.677-684
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• 2010

Backlashes of gears provide gears for good lubrication and for removal of the interference between teeth by the wear and manufacturing errors. The backlash is the strong nonlinear factor to gears. This study deals with nonlinear modeling of helical gears with backlash. Excitation of helical gears comes from torque variation, the tooth surface error, and the periodical change of mesh stiffness. To study the effect of torque fluctuation, equation of motion for the single degree of freedom torsional model of helical gears with the periodical change of mesh stiffness and the backlash was derived. The Newmark beta method and the Newton-Raphson method were used to obtain the nonlinear behaviors of mesh forces of helical gears. All excitation frequencies initially caused the tooth separation and single-sided impacts of the gear pair and eventually led to the normal tooth contact. However, some special excitation frequencies caused the single-sided impacts in the entire time as well as the initial time. Damping increase reduced the duration of single-sided impacts, and the backlash increase caused those in the entire time domain.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.1
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• pp.89-99
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• 2014

This paper presents the experimental torque disturbance analysis of a missile hatch system by spline backlash. The missile hatch system uses a spline and gear train for vertical elevation of the heavy hatch. The spline used for the rotation shaft of the hatch is generally used for automotive driving parts that transmit high amounts of power. It has an angular backlash, which results in jerks. Backlash of the hatch spline influences hatch swinging. The spline backlash and hatch swing are experimentally analyzed by measuring the hatch's rotation angle and acceleration. Hatch swing is visually observable for a short period, and it is measured by measuring the rotation angle variation and hatch acceleration. The shape of fluctuation and duration time of hatch angle variation are similar to those of torque. This shows that the hatch swing due to spline backlash generates torque disturbances.

• Journal of the Korea Society for Simulation
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• v.24 no.3
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• pp.45-54
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• 2015

This paper presents the influence of backlash can be greatly increased on the frequency response characteristic which is presented as the angular velocity of a motor to the motor input voltage, if the motor input voltage is adequately reduced. And, this paper verifies theoretically, analytically and experimentally the availability on the method of detecting the change of backlash magnitude by investigating on the change of the anti-resonance and resonance frequencies in the frequency response characteristic due to the change of backlash magnitude. The amount of change of anti-resonance frequency is more useful that of resonance frequency when detecting the change of backlash magnitude, because the change of anti-resonance frequency can be measured more stable. This paper also shows the sharp change of resonance frequency can be investigated when the motor input voltage is enough reduced. The work will be useful for the further research on the backlash estimation method of a servo system with a gear reducer.

• Journal of the Korean Society for Precision Engineering
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• v.19 no.6
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• pp.119-127
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• 2002

The paper presents the effect of the backlash magnitude and the supplied voltage of motor on the gear reduction servo system. The bandwidth of the system depends heavily on the supplied voltage of motor as well as the backlash magnitude. Specially, the bandwidth of the system increases as the supplied voltage of motor increases. 1t is shown that the system has the bandwidth of zero backlash in case of motor supplied voltage is infinite. It is also found that the magnitude of the supplied voltage of motor is very important in case of the analysis of the system bandwidth.

• Journal of Power System Engineering
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• v.21 no.4
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• pp.77-83
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• 2017

The aim of this paper is to solve the chattering and delayed response problems caused by gear backlash. In the gear mechanism based systems, for example, in robot systems, the actuators provide the reduction gear with motors to transfer effectively electric power to mechanical power. Therefore, the gear backlash exists and is an unavoidable fact which makes many undesirable problems. In this paper, the authors try to make a solution for this issue and, introduce several control methods which are PID only, PID with Smith predictor and super-twisting algorithm based SMC(sliding mode control). Each control method is applied to the real plant in which strong backlash is included. By comparison results, it is clear that SMC gives the best control performance with little backlash effects. Also, the usefulness and effectiveness of proposed control method is verified by experiment.

• Journal of the Korea Institute of Military Science and Technology
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• v.11 no.2
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• pp.125-135
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• 2008

Backlash in the actuator is one of the most important nonlinearities that limit the performance of speed and position control of mechanical systems. In this paper, we propose disturbance observers in order to estimate the effect of nonlinearities and cancel them subsequently. As a result the disturbance observers make the nonlinear system behave linearly. And finally we show that the disturbance observers guarantee the system robustness and the performance to reject the effect of backlash in the face of parameter uncertainties.

• Transactions of the Korean Society of Automotive Engineers
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• v.6 no.3
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• pp.88-96
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• 1998

The rattle noise is the most significant in many kinds of manual gearbox nioses, which is generated at the idle stage of the engine operation. The main torsional vibrat- ion source of the driveline is the fluctuation of the engine torque. The gear rattle is impacts generating in the backlash of the free gear due to this torsional vibration. Many researchers reported the clutch torsional characteristic optimization method to reduce the idle gear rattle but only few of them give sufficient consideration to the system parameters like gear backlash, drag torque, system inertia, inertia distribution, engine torque fluctuation, idle engine rotation speed, and accessory load. In this paper, influence rate of system parameters on the gear rattle is presented and counterplans like backlash reduction, drag torque increase, inertia addition, inertia distribution modification and engine torque characteristic control are suggested.

• Proceedings of the KIEE Conference
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• 2005.07d
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• pp.2471-2473
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• 2005

We present a receding horizon control [RHC] algorithm for compensation of backlash at the input of a stable linear system under control rate constraints. The problem is posed as a receding horizon optimal control [RHOptC] problem for a piecewise affine [PWA] system by modelling the backlash nonlinearity as a PWA system with a state space partition consisting of three regions. The RHC problem involves solving, at each step, $3^N$ quadratic programmes[QP], where N is the optimization horizon. This strategy leads, at the cost of some performance degradation, to much smaller computational load since a feasible rather than optimal solution has to be obtained at each step.