scholarly journals Kinematic error of a harmonic drive

2018 ◽  
Vol 224 ◽  
pp. 01039 ◽  
Author(s):  
Igor Lyuminarsky ◽  
Stanislav Lyuminarsky
Keyword(s):  
Mathematical Model ◽  
Kinematic Error ◽  
Harmonic Drive ◽  
Elastic Interactions ◽  
Wave Generator ◽  
Flexible Gear

The article deals with the causes for kinematic error of harmonic drives. The error was determined theoretically using a mathematical model of a drive accounting elastic interactions of the drive elements. The paper identifies the main cause for the inherent kinematic error of a harmonic drive featuring a cam wave generator: a variation in a flexible gear deformation at rolling of flexible bearing balls. It was established that the highest kinematic error of a drive is significantly lower than the first harmonic of a flexible gear generating error. There is obtained a cam displacement dependence of the highest kinematic error for VZP-80 drive.

The Influence of the Angular Coordinate of a Fixed Gear Wheel on the Kinematic Error of a Harmonic Drive

2019 ◽  
pp. 3-8
Author(s):  
I.E. Lyuminarsky ◽  
S.E. Lyuminarsky ◽  
Y.S. Ivanov
Keyword(s):  
Angular Position ◽  
Gear Wheel ◽  
Elastic Interaction ◽  
Design Stage ◽  
Theoretical Studies ◽  
Kinematic Error ◽  
Harmonic Drive ◽  
Accuracy Class ◽  
Wave Generator ◽  
Manufacturing Errors

When designing harmonic drives, it is important to address the issue of reducing the kinematic error of the drive occurring due to the deformation of the flexible gear, radial oscillations of the cam, manufacturing and installation errors of the gears. Conventionally, this problem is solved by increasing the accuracy class of the gears and the parts where manufacturing errors impact the accuracy of cam installation. A mathematical model is proposed that enables researchers to study the dependency of the kinematic error of the harmonic drive on various factors already at the design stage. Calculation techniques are developed that take into account elastic interaction between the main elements of the drive as well as manufacturing and installation errors. The results of theoretical studies of the influence of the angular position of the flexible and rigid gears on the kinematic error of a harmonic drive with a cam wave generator are presented. The possibility of reducing the kinematic error by turning the fixed gear is proven.

Influence of wave generator profile on the pure kinematic error and centrodes of harmonic drive

2016 ◽  
Vol 104 ◽  
pp. 100-117 ◽  
Author(s):  
Federico Gravagno ◽  
Victor Hugo Mucino ◽  
Ettore Pennestrì
Keyword(s):  
Kinematic Error ◽  
Harmonic Drive ◽  
Wave Generator

Mathematical Model of Dynamic-Kinematic Error of a Harmonic Drive

2021 ◽  
pp. 48-54
Author(s):  
I.E. Lyuminarsky ◽  
S.E. Lyuminarsky ◽  
V.V. Balasanyan
Keyword(s):  
Mathematical Model ◽  
Frequency Response ◽  
Rotation Frequency ◽  
Elastic Interaction ◽  
Gear Train ◽  
Kinematic Error ◽  
Resonant Frequencies ◽  
Urgent Task ◽  
Wave Generator

Reducing the kinematic error when designing a high-precision drive with a harmonic gear train (HGT) is an urgent task. Currently, a large number of studies have been conducted to determine this parameter, but the effect of the wave generator rotation frequency on the kinematic error of the HGT has been considered insufficiently. A mathematical model is proposed for determining the frequency response of the HGT dynamic-kinematic error, taking into account the elastic interaction of its elements and the error of the cam mounting. The results of the calculated determination of the frequency response of a HGT with a cam wave generator are presented. The presence of several resonant frequencies that occur due to periodic changes in the relative position of the HGT elements and the vector of the cam mounting error is defined. It is proved that the two main resonant frequencies are caused by the rotation of the vector of the cam mounting error relative to the large axis of the wave generator and the balls of the flexible bearing.

Kinematic Error, Compliance, and Friction in a Harmonic Drive Gear Transmission

1993 ◽  
Author(s):  
Timothy D. Tuttle ◽  
Warren P. Seering
Keyword(s):  
Rotational Velocity ◽  
Operating Conditions ◽  
Kinematic Error ◽  
Harmonic Drive ◽  
Static Stiffness ◽  
Drive Gear ◽  
Experimental Examination ◽  
Transmission Properties ◽  
Highly Nonlinear ◽  
Wave Generator

Abstract In this experimental examination, the behavior of harmonic-drive kinematic error, compliance, and friction was characterized. In particular, kinematic error was confirmed to appear primarily at frequencies that were multiples of the wave-generator rotational velocity, and static stiffness measurements were found to yield a range of profiles that could be highly nonlinear. Additional measurements of static and dynamic friction demonstrated that energy dissipation in harmonic drives varies nonlinearly with velocity and can escalate during system resonance. Due to the inseparable interaction between harmonic-drive kinematic error, compliance and friction, transmission properties often showed significant variation with operating conditions and were difficult to characterize accurately.

A Wave Generator of New Concept for Flex Gear of Harmonic Drive With Pure Involute Tooth Gear Pairs

2000 ◽  
Author(s):  
R. Maiti ◽  
A. K. Roy
Keyword(s):  
New Wave ◽  
Harmonic Drive ◽  
Tooth Gear ◽  
Circular Arcs ◽  
Wave Generator ◽  
Accurate Performance ◽  
Involute Gears ◽  
Cam Profile ◽  
Engagement And Disengagement ◽  
Made In

Abstract A new wave generator (or cam) is proposed (Maiti, Patent 1995) to drive the flex gear of strain wave gearing i.e., harmonic drives with gear pairs of pure involute profiles. The cam profile is made of circular arcs at the two contact zones and shifted elliptical curves for the other zones. The geometric constniction is made in such a way that tip interference is properly avoided for both engagement and disengagement with nominally stubbed or full depth involute gears. The theories are established to verify other geometric and gearing conditions. Evidently, in the existing products (all are patented design) the profiles are non-involute and none of them offers ideal gear kinematics. It is expected that this new harmonic drive will offer the best gearing kinematics and will have desired accurate performance.

Deformation of Flexspline under Transmission Force in Harmonic Drive

2010 ◽  
Vol 97-101 ◽  
pp. 3536-3539 ◽  
Author(s):  
Xiao Xia Chen ◽  
Shu Zhong Lin ◽  
Jing Zhong Xing
Keyword(s):  
Elastic Deformation ◽  
Shell Element ◽  
Beam Element ◽  
Tangential Displacement ◽  
Harmonic Drive ◽  
Ansys Software ◽  
Neutral Layer ◽  
Experimental Distribution ◽  
Wave Generator ◽  
Tangential Forces

Method to investigate the elastic deformation of a flexspline in harmonic driver was developed under assembly force from wave generator and transmission force. Shell element and tapered beam element were applied to model the flexspline cone and the teeth on the flexspline respectively. Forced displacement of the flexspline in assembly state was imposed by contact analysis between the flexspline and wave generator. According to experimental distribution of tangential forces in transmission state, applying forces at the teeth tips on the flexspline in mesh state, deformation distribution under transmission torque loading was obtained. Simulations of assembly state and transmission state were realized in ANSYS software. In three sections of tooth ring vertical to the axis, the deformation distributions of the flexspline under specified displacement in assembly state were compared with the theory results. Deformation between tip of tooth and neutral layer in assembly state and in transmission state were compared respectively. The deformation results agreed well with the theory results in assembly state, while difference was found in tangential displacement on tooth tips in transmission state, which may influence mesh property evidently under transmission loading.

scholarly journals Study on Lubrication Characteristics of Novel Forced Wave Generator of Harmonic Drive without Flexible Bearing

Materials ◽  
2021 ◽  
Vol 15 (1) ◽  
pp. 215
Author(s):  
Hongli Jia ◽  
Hongbing Xin
Keyword(s):  
The Novel ◽  
Harmonic Drive ◽  
Design And Optimization ◽  
Forced Wave ◽  
Gap Ratio ◽  
Optimal Value ◽  
Wave Generator ◽  
Computational Fluid Dynamics Cfd ◽  
Lubrication Characteristics ◽  
Cfd Method

In contrast to the conventional forced wave generator which consists of cam and flexible bearing in harmonic drive, the novel forced wave generator retains cam but cancels flexible bearing. In this article, the lubrication characteristics of the novel forced wave generator in harmonic drive is studied. First, an elliptical sliding bearing (ESB) model of simplified structure between the novel forced wave generator and the flex spline is established. Further, the computational fluid dynamics (CFD) method is employed to study the effect of some factors on the lubrication characteristics of the ESB model including elliptical gap ratio, width, and rotational speed. According to the analysis, the elliptical gap ratio has a great impact and its optimal value is 3, which is used in the design of the novel forced wave generator. Last, the practical design of the novel forced wave generator in harmonic drive is given, which can provide a basis for design and optimization of a forced wave generator without flexible bearing of the harmonic drive.

A High-Fidelity Harmonic Drive Model

2011 ◽  
Vol 134 (1) ◽  
Author(s):  
Curt Preissner ◽  
Thomas J. Royston ◽  
Deming Shu
Keyword(s):  
Model Simulation ◽  
Viscous Friction ◽  
Phenomenological Approach ◽  
Kinematic Error ◽  
Harmonic Drive ◽  
Hysteresis Model ◽  
Hysteresis Behavior ◽  
Model Sets ◽  
In Series ◽  
Drive Model

In this paper, a new model of the harmonic drive transmission is presented. The purpose of this work is to better understand the transmission hysteresis behavior while constructing a new type of comprehensive harmonic drive model. The four dominant aspects of harmonic drive behavior—nonlinear viscous friction, nonlinear stiffness, hysteresis, and kinematic error—are all included in the model. The harmonic drive is taken to be a black box, and a dynamometer is used to observe the input/output relations of the transmission. This phenomenological approach does not require any specific knowledge of the internal kinematics. In a novel application, the Maxwell resistive-capacitor hysteresis model is applied to the harmonic drive. In this model, sets of linear stiffness elements in series with Coulomb friction elements are arranged in parallel to capture the hysteresis behavior of the transmission. The causal hysteresis model is combined with nonlinear viscous friction and spectral kinematic error models to accurately represent the harmonic drive behavior. Empirical measurements are presented to quantify all four aspects of the transmission behavior. These measurements motivate the formulation of the complete model. Simulation results are then compared to additional measurements of the harmonic drive performance.

scholarly journals Global Sensitivity Analysis of Chosen Harmonic Drive Parameters Affecting Its Lost Motion

Materials ◽  
2021 ◽  
Vol 14 (17) ◽  
pp. 5057
Author(s):  
Slavomir Hrcek ◽  
Frantisek Brumercik ◽  
Lukas Smetanka ◽  
Michal Lukac ◽  
Branislav Patin ◽  
...  
Keyword(s):  
Sensitivity Analysis ◽  
Global Sensitivity Analysis ◽  
Important Variable ◽  
Design Parameters ◽  
Harmonic Drive ◽  
Global Sensitivity ◽  
Output Torque ◽  
Wave Generator ◽  
Spline Finite Element ◽  
Geometry Parameter

The aim of the presented study was to perform a global sensitivity analysis of various design parameters affecting the lost motion of the harmonic drive. A detailed virtual model of a harmonic drive was developed, including the wave generator, the flexible ball bearing, the flexible spline and the circular spline. Finite element analyses were performed to observe which parameter from the harmonic drive geometry parameter group affects the lost motion value most. The analyses were carried out using 4% of the rated harmonic drive output torque by the locked wave generator and fixed circular spline according the requirements for the high accuracy harmonic drive units. The described approach was applied to two harmonic drive units with the same ratio, but various dimensions and rated power were used to generalize and interpret the global sensitivity analysis results properly. The most important variable was for both harmonic drives the offset from the nominal tooth shape.

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