Planetary Gear Reducer Research Articles

An Electric Drive for a Drilling Rig Top Drive System

The operation of a drilling rig top drive system (TDS) in drilling practice at a great depth or during the construction of a drill pipe stand in the case of failure of one of two motors is considered. In the existing kinematic scheme of most domestic and foreign TDSs, the two motors are mechanically rigidly connected to the drive shaft through a gear reduction unit. It is proposed to replace the gearbox with rigid mechanical connections with a double planetary gear reducer and, thereby, ensure the operation of the electric drive with two independent mechanical channels. Such a kinematic scheme with independent mechanical channels makes it possible to provide the drilling rig operation at great depths in the case of failure of one of the drives and when constructing pipes when disassembling the drilling string. Due to a wider range of torque control for each of the two channels, in the case of failure of one of the drives, the proposed scheme implements the indicated operating modes at a reduced speed, avoiding expensive downtime. The static mechanical characteristics of the TDS for the existing and proposed systems are presented. The calculation of the mechanical converter providing the required gear ratios for each of the mechanical channels is performed. The operation of the control system and power distribution unit of two drives is considered.

An Electromagnetic Variable Stiffness Device for Semiactive Seat Suspension Vibration Control

This article introduces a rotary semiactive variable stiffness (VS) device, including its system design and model validation. A variable damping (VD) device and springs can form mechanical networks with specific topologies, and the VD device can control the equivalent stiffness of the network by varying its damping. The proposed rotary electromagnetic VS device consists of an electromagnetic VD device and a torsion spring, which are in series, while a planetary gear reducer is used to amplify the torque output of the VS device. The models of the electromagnetic VD and VS devices are both built and validated with tests. Then, a seat suspension applies the VS device by installing the device in the center of its scissors structure. Bump and random vibration experiments are implemented to validate the effectiveness of the proposed VS system for seat suspension vibration control. The new system has merits in controllability and energy efficiency. It is easier to design the controller than the conventional one with magnetorheological damper due to the linear damping of the electromagnetic VD device. Besides, the system energy consumption is low and has energy harvesting capability. The proposed semiactive electromagnetic VS device also has potential in other practical applicationss.

Integration of multi-axis platform with synchronous motion-sensing and virtual reality imagery for the depth of immersion

This paper presented a multi-axis synchronous motion-sensing platform with virtual reality (VR) to enhance the depth of immersion. Multidisciplinary technologies have been integrated in this system, such as interactive technology, spatial position, tactile stimulation, and scenario sensing, to build a complete system of multi-axis VR sensing mechanism. This platform was consisted of servo motors with precision planetary gear reducer, drivers, and three crank linkages under 3 degrees of freedom (DoF) for working on a larger range of motion and able to support higher loading with lower folding height. A servo motor with reducer was connected to each linkage to control and drive the platform directly. The kinematic analysis of motion types on a heave, roll, and pitch was applied to validate the motion of this platform. The target speeds of step response experiments were 1000 rpm, 800 rpm, and 600 rpm, respectively. The rising time was upgraded by 15–18% in the experiment of the position loop. The results show that Cascade design can improve the response of this system. In addition, Visual Studio C# and EtherCAT communication transmission with the motion control card were utilized to establish the motion control system and human machine interface (HMI) to check the system status immediately. Finally, the platform was combined with VR image content that we designed. The motion-sensing platform could receive fast dynamic response. The simulation and control feedback of the synchronous bi-directional control can be realized the immersion of the virtual image and real world motion interactively. This system could highly enhance the immersion experience.

High power density design for planetary gear transmission system

Planetary gear transmission system has been widely used in the field of aerospace equipment, automobiles, ships, etc. High power density design is an important development direction for transmission machinery, but there is a lack of systematic and deepening research in planetary gear transmission system field. Taken the most widely used 2K–H-type planetary gear transmission system as research object, a design method of high power density considering volume and efficiency is put forward. First, the transmission efficiency model of 2K–H-type planetary gear transmission system is built on the basis of calculation of single gear pair meshing efficiency instead of the look-up table method. Second, the volume model of 2K–H-type planetary gear transmission system is built according to the structure of gear. Finally, the smallest volume and the minimum power loss of 2K–H-type planetary gear transmission system are the target of optimization, and the linear-weighted combination method is used to construct target function. Taken a 2K–H-type planetary gear reducer in some machine tool as an example, the optimization is carried out. The results show that the power loss of optimized system is reduced by 11.42%, and the volume of system is reduced by 25.2%.

Multi-objective Reliability-based Design Optimization for Climbing drive System of Stair-climbing Wheelchair

The 2K-H planetary gear reducer is an important driving part in the climbing system of the stair-climbing wheelchair. Based on the conventional mechanical design parameters, the mathematical model of the reliability optimization of the planetary gear reducer is established by using the reliability theory and the computer optimization method. Seeking optimal design parameters by the optimization algorithm of Matlab software. On the basis of satisfying the reliability constraint, the purpose of reducing the volume of the reducer and increasing the transmission efficiency is realized. It provides a theoretical basis for further optimization of structural design.

Dynamic Analysis of Planetary Gear Reducer

This paper presents dynamic analysis of a three stage planetary gear reducer for operate a tower crane. Ordinary and planetary gears have been designed respecting the coaxial, neighboring and mounting conditions. Harmonic analysis has been processed to identify frequency response for displacements, strains and deformations. The aim of the study was to determine critical frequencies to avoid mechanical resonance phenomenon. The obtained results are based on the superposition method for solving the systems of differential equations resulting from the analysis with finite elements.

Optimization design on dynamic load sharing performance for an in-wheel motor speed reducer based on genetic algorithm

With the help of the genetic algorithm search technique as well as the two-dimensional simplified model of floating planetary gear set, the optimal design of the dynamic load sharing performance for an in-wheel motor planetary gear reducer is completed. Based on the internal and external incentive factors, the formula for calculating the average load factor is derived. Through the numerical calculation of the dynamic response of the planetary gear set, several design parameters which have significant influence on the performance of the reducer is determined. In the optimization process, a program based on Ishikawa algorithm to express the time-varying meshing stiffness in the dynamic equations for the optimization is achieved. The multi-objective including load sharing performance and volume optimization method is established. A comparison study on the single optimization is also carried out in this work. The research results and the optimization program can help the designer to improve the dynamic performance as well as the design properties of the planetary gear set.

Dynamic Performance Optimization of Coupled System for Four-stage Planetary Gear Reducer

Dynamic Performance Optimization of Coupled System for Four-stage Planetary Gear Reducer

Study on Tooth Micro-geometry Optimization of Rear Gear Set in 2 Speed Planetary Gear Reducer

Study on Tooth Micro-geometry Optimization of Rear Gear Set in 2 Speed Planetary Gear Reducer

Design of cycloid planetary gear drives with tooth number difference of two

The cycloid planetary gear reducers are widely applied in automation machinery. Even having the advantages of high gear ratio, multiple contact tooth pairs and shock absorbing ability, how to enlarge the power density of the drives is still the essential development work today. To this end, the concept of tooth number difference of two is proposed. The aim of the paper is to analyze systematically the loaded contact characteristic of such the cycloid planetary gear drives so as to evaluate the feasibility. A set of essential equations for the cycloid profile, the tooth contact and the specific sliding of the cycloid stage are at first derived in the paper. A loaded tooth contact analysis approach is extended from a developed model based on the influence coefficient method. The influences of the design parameters on the contact characteristics are systematically analyzed with an example. These results are also compared with the conventional drive having tooth number difference of one. The analysis results show that the proposed concept with a larger eccentricity and a smaller pin radius can not only effectively enlarge the contact ratio, but also reduce the specific sliding, the shared loads and the contact stress. Although the radial portion of the bearing load can be also reduced accordingly, the total periodical time-variant bearing load can not be reduced effectively by using the concept of tooth number difference of two.

Mechanical design of EFW Exo II: A hybrid exoskeleton for elbow-forearm-wrist rehabilitation.

The use of rehabilitation exoskeleton has become an important means for the treatment of stroke patients. A hybrid exoskeleton named EFW Exo II is developed for the motor function rehabilitation of elbow, forearm and wrist. The EFW Exo II is based on a parallel 2-URR/RRS mechanism and a serial R mechanism. It could fit both left and right arms for the symmetrical and open structure, and the distance between the elbow and wrist could automatically adjust for different forearm length. Details of the mechanical design are introduced. Brushless DC servo motors with planetary gear reducer are used as the actuators of the exoskeleton. Gear drive and belt drive are used for power transmission. A three dimensional force sensor is mounted in the handle to regulate the interaction between the exoskeleton and patient. The EFW Exo II can realize rehabilitation exercise for each joint and the ranges of motion meet the rehabilitation demands of daily living.

Study on Nonlinear Dynamic Characteristics of 2K-H Planetary Gear System

A 2K-H type planetary gear reducer with involute spur gear is adopted as the research object. Considering the time-varying meshing stiffness, the time-varying backlash of the gear meshing and the time varying pressure angle and other nonlinear factors, the lateral-torsional-swing coupled nonlinear dynamic model of the planetary gear transmission system is established. According to the equations of Lagrange, the dynamic differential equations are derived. By introducing the state variable, the second-order differential equation of the coupled system is reduced to the first-order differential equation. The fifth-order step-varying adaptive Runge-Kutta numerical integration method is used to solve the dynamic equation. Compared with the previous dynamic models, this nonlinear dynamic model for the planetary gear transmission system is more closely to the practical operating conditions of the transmission system, which has laid a foundation for further evaluating the dynamic characteristics of the planetary gear transmission system in the future

Research on Planetary Gear Reducer with Dynamic Torque Measurement

Torque is a main parameter of mechanical transmission system, while the dynamic torque measurement is a technical difficulty in mechanical test system. In order to improve the level of dynamic torque measurement technique, the authors synthetically analyzed the existing problems of the existing torque sensor, studied on the principle of planetary gear transmission, researched piezoelectric sensor performance, and then put forward the planetary gear reducer with torque self-inspection. To improve the design of planetary gear reducer and use piezoelectric force sensor in measuring the gear ring of torque, then calculate the torque of input shaft and output shaft, and transfer torque measurement and dynamic transmission into one, change the complex torque measurement into simple pressure measurement, simplify the torque measuring system, improve the dynamic performance of the torque measurement. The study indicates that the planetary gear reducer with torque self-inspection has such advantages as the simple principle of measurement, high sensitivity, high signal-to-noise ratio, reliable work, small impact by environmental factors, convenient maintenance and so on. It can greatly improve the detection accuracy and efficiency of torque measurement, and be widely used in all kinds of torque measurement field.

A study on loaded tooth contact analysis of a cycloid planetary gear reducer considering friction and bearing roller stiffness

A study on loaded tooth contact analysis of a cycloid planetary gear reducer considering friction and bearing roller stiffness

Modelling and modal analysis of a hoist equipped with two-stage planetary gear transmission system

The connection between a gear pair is commonly treated as constant stiffness in the literature of planetary gear transmission dynamics, leading to inaccurate results. Based on the theory of viscoelastic contact, according to low speed or stationary gear pairs have the characteristics of small relative sliding velocity, viscoelastic contact method is proposed to solve this problem. A hoist equipped with two-stage planetary gear reducer is used as research object to investigate the dynamic properties. The natural frequencies and corresponding vibration modes of this planetary gear transmission system are presented. Accordingly, the natural frequencies are recognized using operational modal analysis under ambient excitation, and the experimental studies are in close agreement with theoretical expectation. In addition, the dynamic behaviours of this planetary gear train are investigated.

Thermal analysis and experimental verification of the transmission in a lunar drilling system

A planetary gear reducer is used as the transmission in the main driving assembly of a lunar drilling system. The extreme temperature and vacuum environment on the moon can easily cause a large temperature increase of the transmission in the working environment. This effect can cause lubrication failure and a decrease in gear strength, as well as other problems. Based on the thermal network method (TNM) and finite element method (FEM), the temperature field of the transmission under various working environments is predicted. A vacuum test platform is built and an experimental verification method (EVM) is applied to measure the surface temperature of the transmission. Through comparative analysis, the accuracy of the theoretical method and overall heat transfer path are determined. The temperature rise exhibited a linear relationship with the rotating speed and the square root of the system load. Through theoretical analysis and experimental verification, the sampling task can be controlled by predicting the temperature.

洗浄と移動を両立する回転ブラシを複数有する自走洗浄ロボットの開発

In this report, design of new cleaning robot with light weight, compact, high maneuverability, and high cleaning efficiency is discussed. At first, as the robot with these characteristics, a robot with three brushes whose attitude angle is controlled by an active universal joint is proposed. As one rotational joint composing this universal joint, circular arc slider has been adopted, in order to avoid interference between mechanisms and a floor. Secondly, an experimental apparatus to investigated dynamic characteristics of the rotational brush is designed and fabricated. This apparatus is composed of one rotational brush, a DC motor with planetary gear reducer to rotate the brush, a AC servo motor with timing belt drive mechanism to translate the brush, a 6-axes force sensor to measure forces acting between the brush and floor and attitude angle adjustment mechanism of the brush. Relationships among translational velocity, rotational speed, and attitude angle have been investigated by using this apparatus. Then, based on these experimental results, dynamic model of the brush has been proposed, in order to design and control the cleaning robot. And using this proposed model, a prototype is designed and fabricated. Its size is about 400 mm and similar in size to room cleaning robot on the market. And its mobility and cleaning performance has been investigated.

1P2-N10 ハンドリング機能を有する劣駆動グリッパの開発

This paper presents the development of a selfadaptive and versatile gripper. This hand has three fingers and each of the fingers has a drive roller to realize handling function. The selfadaptability of the hand is obtained using underactuation. The underactuated mechanism is composed of three planetary gear reducer. Also, die way of using planetary gear reducer is not the same as the one used by other researchers. Firstly, the principle and mechanism of the gripper are proposed. Secondly, design parameters are determined using static force analysis about a finger contacting with an object. Finally, effectiveness of underactuated mechanism and design parameters are confirmed by performing simulations considering dynamic behaviour.

석탄 분쇄기용 유성감속기 케이싱의 거동에 관한 유한요소해석

In this study, the structural analysis and the modal analysis are conducted to investigate the stress level, the deformation characteristics and the natural modes of the casing of a planetary gear reducer for a 800kW grade pulverizer mill. The casing is subjected to the load, 2800 kN, from the lump coals in the pulverizing process. Because of the symmetry, the half portion of the reducer casing is modeled for the stress analysis. But the full model is used to find out the eigenvalues and natural modes for the modal analysis. The contact conditions are applied between the thrust pad bearing and the adjacent contacting parts. The results shows that the casing structure has the sufficient strength and stiffness to support the load under consideration. ANSYS version 15 is employed to perform the numerical study.

Analysis on Transmission Efficiency of Planetary Gear Reducer

A transmission efficiency calculation model of planetary geared reducer was proposed in this paper. The power losses of meshed surfaces of sun-planet gears and planet-ring gears were analyzed in detail. Finally, the mechanical power losses and transmission efficiency of the planetary gear reducer were simulated to illustrate the influence of rotational speed and torque on mechanical power loss and transmission efficiency.