Identification of Coulomb Friction in Robot Drives and Other Mechanical Systems Through Observation of Third Harmonic Generation

1994 ◽  
Vol 208 (5) ◽  
pp. 329-336 ◽  
Author(s):  
D J Brookfield
Keyword(s):  
Coulomb Friction ◽  
Robot Control ◽  
Control Strategies ◽  
Harmonic Component ◽  
Experimental Tests ◽  
Third Harmonic ◽  
The Third ◽  
Drive Systems ◽  
Driving Torque ◽  
Frictional Behaviour

One of the main difficulties in introducing improved robot control strategies is a lack of knowledge of the frictional behaviour of robot drive systems. The aim of the present paper is to describe a technique for the identification of Coulomb friction based on the response of the robot drive to a sinusoidal driving torque The presence of a third harmonic component in the resulting velocity is a consequence of the Coulomb non-linearity and it is shown theoretically, through computer simulation and in experimental tests, that the coefficient of Coulomb friction can be estimated from the amplitude of the third harmonic component. The identification method is shown to be applicable to any mechanical system that can be subjected to a sinusoidal forcing torque or force.

Imaging Cracks in Bones Using Acoustic Nonlinearity: A Simulation Study

2011 ◽  
Vol 97 (5) ◽  
pp. 728-733
Author(s):  
Yang Liu ◽  
Xiasheng Guo ◽  
Zhao Da ◽  
Dong Zhang ◽  
Xiufen Gong
Keyword(s):  
Time Reversal ◽  
Three Dimensional ◽  
Harmonic Component ◽  
Ultrasonic Signal ◽  
Long Bone ◽  
Third Harmonic ◽  
Acoustic Nonlinearity ◽  
The Third ◽  
Nonlinear Approach ◽  
Radial Depth

This article proposes an acoustic nonlinear approach combined with the time reversal technique to image cracks in long bones. In this method, the scattered ultrasound generated from the crack is recorded, and the third harmonic nonlinear component of the ultrasonic signal is used to reconstruct an image of the crack by the time reversal process. Numerical simulations are performed to examine the validity of this approach. The fatigue long bone is modeled as a hollow cylinder with a crack of 1, 0.1, and 0.225 mm in axial, radial and circumferential directions respectively. A broadband 500 kHz ultrasonic signal is used as the exciting signal, and the extended three-dimensional Preisach-Mayergoyz model is used to describe the nonclassical nonlinear dynamics of the crack. Time reversal is carried out by using the filtered third harmonic component. The localization capability depends on the radial depth of the crack.

Analysis of error motions of axial locking-prevention hydrostatic spindle

2018 ◽  
Vol 233 (1) ◽  
pp. 3-17
Author(s):  
Penghai Zhang ◽  
Yaolong Chen
Keyword(s):  
Significant Influence ◽  
Harmonic Component ◽  
Necessary Condition ◽  
Third Harmonic ◽  
The Third ◽  
Fourth Harmonic ◽  
Radial Error ◽  
Tilt Error ◽  
Error Motion ◽  
Error Averaging

Hydrostatic spindles are widely used in precision optical grinder and lathe. Their high precision comes from the error averaging effect of oil film. The purpose of this paper is to give the quantitative analysis of the error averaging effect for a newly developed axial locking-prevention hydrostatic spindle. An approximate error motion model of the hydrostatic spindle is established to analyze the internal relationship between the geometric errors of the shaft and the error motions of the spindle including radial, tilt and axial error motions. The theoretical analysis shows that, the roundness errors of the two journals have a major impact on error motions while the coaxiality errors of two journals, the perpendicularity errors of front thrust plate and the coaxiality errors of the land of back thrust bearing, have no significant influences on error motions. The elliptical component of roundness errors of the two journals has significant influence on the axial error motion but no influence on the pure radial and tilt error motions, resulting into the fourth harmonic component of axial error motion. The trilobal component of roundness errors of the two journals has significant influence on the pure radial and tilt error motions but no influence on the axial error motion, resulting in the third harmonic component of pure radial and tilt error motions. The changes of recess pressures are not necessary condition for the error motions. Additionally, the experiment analysis shows that, the third harmonic component is the main part of the measured radial error motion and the third, fourth harmonic components are the main parts of the measured face error motion, which can be reasonably explained by the theory. The model proposed in this paper can be used to guide the precision design and optimization of hydrostatic spindle.

scholarly journals A Tool for the Development of Robot Control Strategies

2007 ◽  
Vol 6 (2) ◽  
Author(s):  
Luiz Carlos Figueiredo ◽  
Gilcésar Ávila ◽  
Francisco Reinaldo ◽  
Rui Camacho ◽  
Demétrio R. Magalhães ◽  
...  
Keyword(s):  
Robot Control ◽  
Control Strategies ◽  
Experimental Tests ◽  
Traction Motors

In this paper we report as the development of a tool in to develop and set control strategies as a fast and easy way. Additionally, a tricycle robot with two traction motors was built to test the strategies produced with the tool. Experimental tests have shown an advantage in the use of such tool.

scholarly journals Sensorless Control for Non-Sinusoidal Five-Phase Interior PMSM Based on Sliding Mode Observer

2021 ◽  
Vol 23 (6) ◽  
pp. 445-454
Author(s):  
Youssouf Mini ◽  
Ngac Ky Ngac Ky ◽  
Eric Semail
Keyword(s):  
Control Strategy ◽  
Sliding Mode ◽  
Sensorless Control ◽  
Harmonic Component ◽  
Sliding Mode Observer ◽  
Third Harmonic ◽  
The Third ◽  
Three Phase ◽  
Interior Permanent Magnet ◽  
Harmonic Components

This paper proposes a sensorless control strategy based on Sliding Mode Observer (SMO) for a Five-phase Interior Permanent Magnet Synchronous Machine (FIPMSM), with a consideration of the third harmonic component. Compared to conventional three-phase machines, the third harmonic of back electromotive force (back-EMF) contains more information. Thus, in this paper, the first and third harmonic components of the five-phase machine are considered to estimate the rotor position which is necessary for the vector control. Simulation results are shown to verify the feasibility and the robustness of the proposed sensorless control strategy.

Third-Order Hydrodynamic Loads on an Oscillating Vertical Cylinder in Water

1999 ◽  
Vol 121 (1) ◽  
pp. 16-21 ◽  
Author(s):  
M. Markiewicz ◽  
P. Łe¸tkowski ◽  
O. Mahrenholtz
Keyword(s):  
Harmonic Component ◽  
Vertical Cylinder ◽  
Offshore Structures ◽  
Third Order ◽  
Earthquake Excitation ◽  
Hydrodynamic Loads ◽  
Third Harmonic ◽  
The Third ◽  
Steep Waves ◽  
Order Components

The third-harmonic component of the third-order hydrodynamic loads on a vertical circular cylinder oscillating in water is calculated by a conventional perturbation method within the framework of a potential theory. Although the third-order forces are expressed in terms of the first, second, and third-order components of the velocity potential, the latter is not directly required for the calculation. It is replaced by a properly defined linearized radiation potential via Haskind-like theorem. The results of the study are applicable to the analysis of high-frequency resonances of deepwater offshore structures under earthquake excitation or under steep waves (ringing problem).

A New Control Strategy of Five-Phase Permanent-Magnet Motor Drives with a Third Harmonic Current Injection

2011 ◽  
Vol 464 ◽  
pp. 191-194
Author(s):  
Guo Hai Liu ◽  
Li Hao Yan ◽  
Duo Zhang ◽  
Wen Xiang Zhao
Keyword(s):  
Permanent Magnet ◽  
Harmonic Component ◽  
Motor Drives ◽  
Permanent Magnet Motor ◽  
Harmonic Current ◽  
Third Harmonic ◽  
Torque Density ◽  
Brushless Dc ◽  
The Third ◽  
Three Phase

In this paper, a five-phase permanent-magnet (PM) brushless dc (BLDC) motor is investigated, which has almost trapezoidal back electromotive force(EMF) due to its concentrated windings. Since the third harmonic component in the magnetic field is utilized, the presented five-phase BLDC motors have a higher torque density over conventional three-phase ones, in which the third harmonic current is injected. This paper proposes a new five-phase transformation system, by which the vector control is easily applicable to five-phase BLDC motors. Finally, the results verify the validity of the proposed method.

scholarly journals Ultrafast Third-Order Nonlinear Optical Response Excited by fs Laser Pulses at 1550 nm in GaN Crystals

Materials ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3194
Author(s):  
Adrian Petris ◽  
Petronela Gheorghe ◽  
Tudor Braniste ◽  
Ion Tiginyanu
Keyword(s):  
Harmonic Generation ◽  
Nonlinear Optical ◽  
Laser Pulses ◽  
Third Harmonic Generation ◽  
High Repetition Rate ◽  
Third Order ◽  
Third Harmonic ◽  
The Third ◽  
High Repetition ◽  
Gan Crystal

The ultrafast third-order optical nonlinearity of c-plane GaN crystal, excited by ultrashort (fs) high-repetition-rate laser pulses at 1550 nm, wavelength important for optical communications, is investigated for the first time by optical third-harmonic generation in non-phase-matching conditions. As the thermo-optic effect that can arise in the sample by cumulative thermal effects induced by high-repetition-rate laser pulses cannot be responsible for the third-harmonic generation, the ultrafast nonlinear optical effect of solely electronic origin is the only one involved in this process. The third-order nonlinear optical susceptibility of GaN crystal responsible for the third-harmonic generation process, an important indicative parameter for the potential use of this material in ultrafast photonic functionalities, is determined.

scholarly journals Indirect Feedback Measurement of Flow in a Water Pumping Network Employing Artificial Intelligence

Sensors ◽  
2020 ◽  
Vol 21 (1) ◽  
pp. 75
Author(s):  
Thommas Kevin Sales Flores ◽  
Juan Moises Mauricio Villanueva ◽  
Heber P. Gomes ◽  
Sebastian Y. C. Catunda
Keyword(s):  
Artificial Intelligence ◽  
Nonlinear Models ◽  
Control Strategies ◽  
Experimental Tests ◽  
Feedback System ◽  
Indirect Measurement ◽  
High Price ◽  
Maximum Relative Error ◽  
Pumping System ◽  
Water Pumping

Indirect measurement can be used as an alternative to obtain a desired quantity, whose physical positioning or use of a direct sensor in the plant is expensive or not possible. This procedure can been improved by means of feedback control strategies of a secondary variable, which can be measured and controlled. Its main advantage is a new form of dynamic response, with improvements in the response time of the measurement of the quantity of interest. In water pumping networks, this methodology can be employed for measuring the flow indirectly, which can be advantageous due to the high price of flow sensors and the operational complexity to install them in pipelines. In this work, we present the use of artificial intelligence techniques in the implementation of the feedback system for indirect flow measurement. Among the contributions of this new technique is the design of the pressure controller using the Fuzzy logic theory, which rules out the need for knowing the plant model, as well as the use of an artificial neural network for the construction of nonlinear models with the purpose of indirectly estimating the flow. The validation of the proposed approach was carried out through experimental tests in a water pumping system, fully automated and installed at the Laboratory of Hydraulic and Energy Efficiency in Sanitation at the Federal University of Paraiba (LENHS/UFPB). The results were compared with an electromagnetic flow sensor present in the system, obtaining a maximum relative error of 10%.

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