A harmonic drive model considering geometry and internal interaction

2016 ◽  
Vol 231 (4) ◽  
pp. 728-743 ◽  
Author(s):  
Chuang Zou ◽  
Tao Tao ◽  
Gedong Jiang ◽  
Xuesong Mei ◽  
Junhui Wu
Keyword(s):  
Ball Bearing ◽  
Experimental Results ◽  
Torsional Stiffness ◽  
Harmonic Drive ◽  
Low Velocity ◽  
New Model ◽  
Internal Interaction ◽  
Drive Systems ◽  
Assembly Error ◽  
Drive Model

A new harmonic drive model considering the geometry, internal interactions and assembly error of key parts is proposed in this paper. In this model, a single tooth pair is used to represent the transmission mechanism of harmonic drive. The meshing stiffness between the flexspline and the circular spline, the torsional stiffness of the flexspline cylinder, and the radial stiffness of the thin-walled ball bearing are included and formulated. The kinematic error is fitted using a low-velocity test, and its generating mechanism is analysed. The friction of the harmonic drive is formulated at the tooth meshing section and at the ball bearing, where its parameters are identified based on experimental results. Based on the new model, velocity step simulations are conducted. For comparison, velocity step experiments at eight different velocities from 60 to 3000 r/min are performed, and the simulation results are in good agreement with the experimental results. The new model reveals the dynamic behaviour of the harmonic drive system; therefore, it will be useful for the dynamic design and precision control of harmonic drive systems.

Improving Hole-Searching Accuracy for Peg-in-Hole Assembly With Manipulator Harmonic Drive Uncertainty

2019 ◽  
Author(s):  
Po-Yu Chen ◽  
Kuei-Yuan Chan
Keyword(s):  
Robot Manipulator ◽  
A Priori ◽  
Nonlinear Process ◽  
Harmonic Drive ◽  
Orientation Error ◽  
Transmission Errors ◽  
Drive Systems ◽  
Uncertainty Parameters ◽  
The Impact ◽  
Drive Model

Abstract Uncertainties of a robot manipulator include the inaccurate transformation between each coordinate, (e.g., robot base, flange, camera, tool, and workpiece) and the inherent variations within each links and mechanical components. In this work we consider the impact of harmonic drive uncertainty in peg-in-hole assembly. We investigate the accumulations of transmission errors within robot dynamic and nonlinear process in rotation. Models of manipulators with uncertainty parameters in harmonic drive systems are developed. The parameters in our harmonic drive model with uncertainty are identified through testing. The transformation metrics between each coordinate are also determined by detecting fiducial pattern and marker with well-calibrated camera. As a result we have a virtual robot model with parameters and uncertainties much closer to the real system. The simulation results show that the accuracy of hole-searching can reach 0.50 mm position error and 0.16 degree orientation error for hole locations that are not known as a priori.

Interaction of a Whirling Rotor with a Vibrating Stator across a Clearance Annulus

1968 ◽  
Vol 10 (1) ◽  
pp. 1-12 ◽  
Author(s):  
H. F. Black
Keyword(s):  
Dry Friction ◽  
Ball Bearing ◽  
Radial Symmetry ◽  
Experimental Results ◽  
Equilibrium Conditions ◽  
General Behaviour ◽  
Mass Unbalance ◽  
Jump Phenomena ◽  
Rotor Stator Interaction ◽  
Rotor Mass

Where a rotor runs within a clearance space, the clearance being comparable with rotor mass unbalance, the synchronous whirling behaviour of the rotor may be considerably affected by intermittent interaction with the stator at the clearance position. Discontinuity and jump phenomena may occur: in general, behaviour will be different with increasing speed from that with decreasing speed, and in either case zones may exist in which rotor-stator interaction is possible but not certain. In the analysis here presented, rotor and stator are regarded as linear multi-degree-of-freedom systems including damping; dry friction at the clearance space is taken into account. Discussion is limited to cases with radial symmetry, and interaction is assumed limited to the position of the clearance space. Polar receptances are used to establish equilibrium conditions with interaction, and speed zones are defined within which interaction may occur. Some hypothetical cases are fully explored, demonstrating that rotor-stator interactions may occur in a variety of forms and circumstances. Interactions with dry friction counterwhirling are also considered. Some experimental results on counterwhirl within a ball bearing are given and qualitatively compared with theory.

New model of dielectric strength of Debye relaxation in monohydroxy alcohols

2019 ◽  
Vol 33 (26) ◽  
pp. 1950313
Author(s):  
Li-Na Wang ◽  
Xing-Yu Zhao ◽  
Yi-Neng Huang
Keyword(s):  
Experimental Data ◽  
Exact Solution ◽  
High Temperature ◽  
Ising Model ◽  
Dielectric Spectroscopy ◽  
Dielectric Strength ◽  
Experimental Results ◽  
Debye Relaxation ◽  
New Model ◽  
Model Predictions

The Debye relaxation of dielectric spectroscopy exists extensively in monohydroxy alcohols, and the existing theory of the dielectric strength is obviously inconsistent with the experimental results. In this paper, we propose an Ising model of infinite free-rotating pseudospin chains and get the exact solution of the dielectric strength versus temperature. The model predictions are qualitatively consistent with the experimental results, especially the crossover from the low to the high-temperature Curie–Weiss law. The quantitative comparisons indicate that the model predictions can agree well with the experimental data below 250 K.

Speech Enhancement Using Heterogeneous Information

2018 ◽  
Vol 10 (3) ◽  
pp. 46-59
Author(s):  
Yan Xiong ◽  
Fang Xu ◽  
Qiang Chen ◽  
Jun Zhang
Keyword(s):  
Speech Enhancement ◽  
Experimental Results ◽  
Noisy Environments ◽  
Heterogeneous Information ◽  
New Model ◽  
Model Based ◽  
Single Stream

This article describes how to use heterogeneous information in speech enhancement. In most of the current speech enhancement systems, clean speeches are recovered only from the signals collected by acoustic microphones, which will be greatly affected by the acoustic noises. However, heterogeneous information from different kinds of sensors, which is usually called the “multi-stream,” are seldom used in speech enhancement because the speech waveforms cannot be recovered from the signals provided by many kinds of sensors. In this article, the authors propose a new model-based multi-stream speech enhancement framework that can make use of the heterogeneous information provided by the signals from different kinds of sensors even when some of them are not directly related to the speech waveform. Then a new speech enhancement scheme using the acoustic and throat microphone recordings is also proposed based on the new speech enhancement framework. Experimental results show that the proposed scheme outperforms several single-stream speech enhancement methods in different noisy environments.

Compression after Impact Performance of Composite Stiffened Panels

2011 ◽  
Vol 415-417 ◽  
pp. 2231-2235 ◽  
Author(s):  
Zhe Sun ◽  
Fei Xu ◽  
Wei Xie ◽  
Bo Wang
Keyword(s):  
Structural Damage ◽  
Initial Imperfection ◽  
Maximum Load ◽  
Experimental Results ◽  
Low Velocity Impact ◽  
Thickness Direction ◽  
Low Velocity ◽  
Stiffened Panels ◽  
Velocity Impact ◽  
Compression After Impact

Composite stiffened panels are widely used in the modern aircraft structure with the advantages of light weight, structural efficiency and good crack performance. But the stiffened panels have poor performance at thickness direction, especially for low-velocity impact. First of all, compressive tests were investigated and analyzed for two types of composite stiffened panels, which are integrated specimens and post-impact specimens. And the effect of low-velocity impact to the supporting capacity of composite stiffened panels was researched. Secondly，the finite element model was established to simulate the CAI (Compression After Impact)strength with the equivalent hole method. It is found that the analyze results match the experimental results well. According to the experimental results, structural damage and the maximum load caused by impact energy are scattering. Then the imperfect factors were introduced to reflect the initial imperfection, namely the initial deflection at thickness direction. The effect of different imperfect factors to the maximum load was discussed.

Adaptive Friction Compensation in Robot Manipulators: Low Velocities

1991 ◽  
Vol 10 (3) ◽  
pp. 189-199 ◽  
Author(s):  
C. Canudas de Wit ◽  
P. Noël ◽  
A. Aubin ◽  
B. Brogliato
Keyword(s):  
Coulomb Friction ◽  
Robot Manipulator ◽  
Robot Manipulators ◽  
Friction Compensation ◽  
Low Velocity ◽  
New Model ◽  
Friction Models ◽  
Computed Torque ◽  
Simple Models

This article analyzes the problem of modeling and compensation of friction at velocities close to zero. A new model, linear in parameters, which captures the downward bends at low velocity is used to adoptively compensate for friction. The need for this type of model is mainly motivated by instability phenomena that can be caused by overcompensation when simple models (such as Coulomb friction models) are used as a basis for the friction compensation. This model, in combination with an adaptive computed torque method, was tested experimentally in a robot manipulator.

Carriage Drift in Linear-Guideway Type Roller Bearings

2015 ◽  
Vol 137 (2) ◽  
Author(s):  
Hiroyuki Ohta ◽  
Taiki Kato ◽  
Soichiro Kato ◽  
Hideyuki Tajimi
Keyword(s):  
Ball Bearing ◽  
Roller Bearing ◽  
Experimental Results ◽  
Ball Bearings ◽  
Roller Bearings ◽  
Angular Displacements ◽  
Return Process

This study deals with carriage drift (which is the differences of the carriage displacements or angular displacements at a certain position on a rail during a forward and return process) in linear-guideway type roller bearings. First, the displacements and angular displacements of the carriage of the “nonrecirculating” linear roller and ball bearings under a reciprocating operation were measured. The experimental results showed that carriage drift (in the horizontal, vertical, yaw, and pitch directions) occurred in the roller bearing and not in the ball bearing. Next, in relationship to roller skew, the generating mechanism of carriage drift in roller bearings was examined by a multibody analysis (MBA), then the generating mechanism of carriage drift was explained. Finally, to reduce carriage drift by restricting the roller skew, an antiskewing brace (ASB) was developed.

A New Model to Describe Yield Surface Distortion Based on the Baltov and Sawczuk’s Model

2012 ◽  
Author(s):  
A. Nayebi ◽  
H. Rokhgireh
Keyword(s):  
Yield Surface ◽  
Kinematic Hardening ◽  
Experimental Results ◽  
Surface Model ◽  
New Model ◽  
Surface Distortion ◽  
Loading Direction ◽  
Reverse Loading ◽  
Reversed Loading ◽  
Yield Surface Distortion

In the present study Baltov and Sawczuk’s yield surface model is modified to represent compatible results with experimental observations. The proposed yield surface is determined during tension-torsion loading by considering kinematic hardening model and monotonic loading paths. The experimental results represent the nosed and flattened region in the loading and reverse loading direction respectively. The nosed region is dominant in tension than in torsion. The cross-effect is negligible in the small plastic strain amount. The Baltov and Sawczuk’s yield surface has nosed and flattened regions in both loading and reversed loading directions for negative and positive added material parameter respectively. Thus the elliptic Baltov and Sawczuk’s yield surface is modified by changing the sign of this parameter continuously from loading to reverse loading direction and the needed relations of the new model are obtained. The new model was able to predict properly the shape of yield surface. The experimental results compare well with the new model yield surface distortion predictions.

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