scholarly journals Backlash Identification in Two-Mass Systems by Delayed Relay Feedback

2019 ◽  
Vol 141 (6) ◽  
Author(s):  
Michael Ruderman ◽  
Shota Yamada ◽  
Hiroshi Fujimoto
Keyword(s):  
System Model ◽  
Complex Dynamic ◽  
Relay Feedback ◽  
Mass System ◽  
Velocity Feedback ◽  
Detection And Identification ◽  
In Series ◽  
Machine Elements ◽  
The One ◽  
Toothed Gears

Backlash, also known as mechanical play, is a piecewise differentiable nonlinearity which exists in several actuated systems, comprising, e.g., rack-and-pinion drives, shaft couplings, toothed gears, and other machine elements. Generally, the backlash is nested between the moving parts of a complex dynamic system, which handicaps its proper detection and identification. A classical example is the two-mass system which can approximate numerous mechanisms connected by a shaft (or link) with relatively high stiffness and backlash in series. Information about the presence and extent of the backlash is seldom exactly known and is rather conditional upon factors such as wear, fatigue, and incipient failures in the components. This paper proposes a novel backlash identification method using one-side sensing of a two-mass system. The method is based on the delayed relay operator in feedback that allows stable and controllable limit cycles to be induced and operated within the (unknown) backlash gap. The system model, with structural transformations required for the one-side backlash measurements, is given, along with the analysis of the delayed relay in velocity feedback. Experimental evaluations are shown for a two-inertia motor bench that has coupling with backlash gap of about 1 deg.

Modeling, Actuation, and Control of an Active Fluid Vibration Isolator

1997 ◽  
Vol 119 (1) ◽  
pp. 52-59 ◽  
Author(s):  
M. J. Panza ◽  
D. P. McGuire ◽  
P. J. Jones
Keyword(s):  
Electrical Power ◽  
Fluid Pressure ◽  
Space Representation ◽  
Vibration Isolator ◽  
Mass System ◽  
Integral Control ◽  
Active Fluid ◽  
State Space Representation ◽  
In Series ◽  
And Control

An integrated mathematical model for the dynamics, actuation, and control of an active fluid/elastomeric tuned vibration isolator in a two mass system is presented. The derivation is based on the application of physical principles for mechanics, fluid continuity, and electromagnetic circuits. Improvement of the passive isolator performance is obtained with a feedback scheme consisting of a frequency shaped notch compensator in series with integral control of output acceleration and combined with proportional control of the fluid pressure in the isolator. The control is applied via an electromagnetic actuator for excitation of the fluid in the track connecting the two pressure chambers of the isolator. Closed loop system equations are transformed to a nondimensional state space representation and a key dimensionless parameter for isolator-actuator interaction is defined. A numerical example is presented to show the effect of actuator parameter selection on system damping, the performance improvement of the active over the passive isolator, the robustness of the control scheme to parameter variation, and the electrical power requirements for the actuator.

Analytic Form Solution of the Direct Position Analysis of a Wide Family of Three-Legged Parallel Manipulators

2005 ◽  
Vol 128 (1) ◽  
pp. 264-271 ◽  
Author(s):  
Raffaele Di Gregorio
Keyword(s):  
Analytic Form ◽  
Parallel Manipulators ◽  
Analytical Form ◽  
Form Solution ◽  
Kinematic Chains ◽  
Position Analysis ◽  
In Series ◽  
The One ◽  
Generic Structures ◽  
Wide Family

A wide family of parallel manipulators (PMs) is the one that groups all PMs with three legs where the legs become kinematic chains constituted of a passive spherical pair (S) in series with either a passive prismatic pair (P) or a passive revolute pair (R) when the actuators are locked. The topologies of the structures generated by these manipulators, when the actuators are locked, are ten. Two out of these topologies are the SR-2PS topology (one SR leg and two PS legs) and the SP-2RS topology (one SP leg and two RS legs). This paper presents two algorithms. The first one determines all the assembly modes of the SR-2PS structures. The second one determines all the assembly modes of the SP-2RS structures. The presented algorithms can be applied without changes to solve, in analytical form, the direct position analysis (DPA) of all the parallel manipulators that generate a SR-2PS structure or a SP-2RS structure when the actuators are locked. In particular, the closure equations of two generic structures, one of type SR-2PS and the other of type SP-2RS, are written. The eliminants of the two systems of equations are determined and the solution procedures are presented. Finally, the proposed procedures are applied to real cases. This work demonstrates that (i) the DPA solutions of any PM that becomes a SR-2PS structure are at most eight, and (ii) the DPA solutions of any PM that becomes a SP-2RS structure are at most sixteen.

HELICITY AMPLITUDES FOR COLLIDING BEAM SCATTERING OF TWO SPIN 1/2 PARTICLES

1993 ◽  
Vol 08 (30) ◽  
pp. 5383-5407
Author(s):  
T.B. ANDERS ◽  
A.O. BARUT ◽  
W. JACHMANN
Keyword(s):  
Center Of Mass ◽  
Mass System ◽  
Intermediate Transformation ◽  
Beam System ◽  
Pair Annihilation ◽  
Helicity Amplitudes ◽  
Reaction Channels ◽  
Invariant Coupling ◽  
Exchange Scattering ◽  
The One

As a generalization and extension of the extensive tables of polarization asymmetries given in a previous work,1 we present here tables of helicity amplitudes for the scattering of two spin 1/2 particles in the colliding beam system (i.e. two incoming particles with opposite directions but not necessarily of equal momenta). The particles belonging to the same current may have different masses in order to describe particle excitations. The amplitudes are given for six different basic couplings connecting two vector vertices, a vector vertex at the one current and a derivative vector vertex at the other current, two derivative vector vertices, two tensor vertices, and two scalar vertices. The vertices include axial couplings by factors of type 1+cγ5. The amplitudes are written as expressions with 16 components in the six different reaction channels, namely the scattering of two fermions, of two antifermions, and of a fermion and an antifermion, the pair creation by pair annihilation, as well as the exchange scattering for two identical fermions or antifermions. The formulas may be used for an analysis which extracts the invariant coupling functions from the experimental data obtained in the colliding beam system directly without an intermediate transformation to the center of mass system.

scholarly journals The city as a theatre of characters. John Hejduk’s Masques

2021 ◽  
Vol 9 (2) ◽  
pp. 51
Author(s):  
Luca Cardani
Keyword(s):  
Design Research ◽  
Strong Connection ◽  
Theoretical Design ◽  
In Series ◽  
Place Of Origin ◽  
The One ◽  
The City ◽  
General Work ◽  
Different Parts

The architectural work of John Hejduk (1929-2000) is marked by theoretical-design research, collected in series with titles and periods. Among these series the one entitled Masques, developed since about 1979, can be considered the nucleus of his research on the architecture of the city and the place of origin of his language of construction later developed in his realized buildings. This paper analyses the dense network of references and analogies established by Hejduk to create his Masques, trying to fix its origin in the idea of the city as a theatre of characters composed of architecture. Starting from the name chosen for the title of this series, the paper tries to trace the threads that lead from the general work of the various projects of the Masques series, to the reflections and ideas that produced it. Then, it comes back again to the observation of architecture and of a case study (Security, 1989), to understand and explain its meaning and the compositional methods involved into the process of genesis of form. Through the entire work named Masques, and its recognizable link with the buildings and installation realized around the world, Hejduk has built an archive of architectural prototypes ready to construct different parts of the city, thus highlighting the strong connection that his work establishes with reality in order "to conceive it, represent it and finally realize it".

Modeling, Actuation, and Control of an Active Fluid Vibration Isolator

1995 ◽  
Author(s):  
Michael J. Panza ◽  
Dennis P. McGuire ◽  
Peter J. Jones
Keyword(s):  
Electrical Power ◽  
Fluid Pressure ◽  
Space Representation ◽  
Vibration Isolator ◽  
Mass System ◽  
Integral Control ◽  
Active Fluid ◽  
State Space Representation ◽  
In Series ◽  
And Control

Abstract An integrated mathematical model for the dynamics, actuation, and control of an active fluid/elastomeric tuned vibration isolator in a two mass system is presented. The derivation is based on the application of physical principles for mechanics, fluid continuity, and electromagnetic circuits. Improvement of the passive isolator performance is obtained with a feedback scheme consisting of a frequency shaped notch compensator in series with integral control of output acceleration and combined with proportional control of the fluid pressure in the isolator. The control is applied via an electromagnetic actuator for excitation of the fluid in the track connecting the two pressure chambers of the isolator. Closed loop system equations are transformed to a nondimensional state space representation and a key dimensionless parameter for isolator-actuator interaction is defined. A numerical example is presented to show the effect of actuator parameter selection on system damping, the performance improvement of the active over the passive isolator, the robustness of the control scheme to parameter variation, and the electrical power requirements for the actuator.

Micromachined Snap-In Resonators

2012 ◽  
Vol 2012 (DPC) ◽  
pp. 001920-001935 ◽  
Author(s):  
Colin Stevens ◽  
Robert Dean ◽  
Chris Wilson
Keyword(s):  
Resonant Frequency ◽  
Proof Mass ◽  
Pressure Sensors ◽  
Mass System ◽  
Dc Voltage ◽  
Movable Electrode ◽  
Mems Resonators ◽  
Spring Force ◽  
In Series ◽  
Fixed Electrode

MEMS resonators have many applications, including micromachined gyroscopes, resonating pressure sensors and RF devices. Typically, MEMS resonators consist of a proof mass and suspension system that allows the proof mass motion in one or two directions. Micromachined actuators provide kinetic energy to the proof mass, usually at its resonant frequency. In the simplest resonators, the actuators are driven with an AC signal at or near the resonant frequency. In more complex resonators, the actuator-proof mass system is placed in an amplifier feedback circuit so that the electromechanical system self-resonates. MEMS parallel plate actuators (PPAs) are simple to realize, yet complex nonlinear variable capacitors. If a DC voltage is applied in attempt to move the proof mass greater than 1/3 of the electrode rest gap distance, the device becomes unstable and the electrodes snap into contact. A current limiting resistor is often placed in series with the PPA to limit short circuit current due to a snap-in event. Consider the effect of placing a large resistor, on the order on 10 meg-Ohms, in series with the PPA. Then apply a DC voltage across the resistor-PPA pair of sufficient voltage to cause snap-in. Once the electrostatic force (ES) exceeds the spring force (SF), the electrodes will accelerate toward each other. The capacitance between the electrodes swells as the separation distance shrinks. Since the large resistor limits the charging rate of the capacitor, the voltage across it drops. Once the SF exceeds the EF, the momentum of the movable electrode brings it into contact with the fixed electrode, discharging the capacitor. The movable electrode then accelerates away from the fixed electrode while the resistor slowly allows recharging. After recharging, the cycle repeats resulting in stable oscillation. This resonator requires only a DC power supply, a resistor and a MEMS PPA.

Larval development of ovine Neostrongylus linearis in four experimentally infected mollusc species

1994 ◽  
Vol 68 (3) ◽  
pp. 207-210 ◽  
Author(s):  
M.Y. Manga-González ◽  
M.P. Morrondo-Pelayo
Keyword(s):  
Post Infection ◽  
The Other ◽  
Snail Species ◽  
Intermediate Hosts ◽  
Cepaea Nemoralis ◽  
In Series ◽  
Mollusc Species ◽  
Higher Temperature ◽  
The One ◽  
First Time

AbstractDevelopment of Neostrongylus linearis larvae was studied in the snail intermediate hosts Oestophora (Oestophora) barbula, Oestophorella buvinieri, Cepaea nemoralis and Helix (Cryptomphalus) aspersa. The molluscs of each species, all adults, were divided into groups of 40 for infection purposes. The infection doses for the first two snail species were 90 and 50 first stage larvae (L1) of N. linearis, respectively. For C. nemoralis two batches were tested: one with 200 L1 kept at 19°C and the other with 250 L1 at a temperature of 21°C. The same was done with Helix (C.) aspersa with 200 L1 at a temperature of 21°C, on the one hand and 300 L1 at 24°C on the other. One or two molluscs of each species were killed in series from the 6th day post-infection (p.i.) until the 44th. Percentage values for total larvae (1, 2 and 3) and L3 were higher with the lower dose for C. nemoralis, whilst the same was true with the higher dose in Helix (C.) aspersa. In both cases, the higher temperature appeared to contribute to cycle acceleration. Using one way analysis of variance, statistically significant differences were detected between the species of molluscs tested concerning percentages of L1 which penetrated, total larvae and L3. According to our results, the decreasing order of susceptibility of these species of molluscs as experimental intermediate hosts of N. linearis is: O. buvinieri, Oestophora (O.) barbula, C. nemoralis and Helix (C.) aspersa. It is the first time that Oestophora (O.) barbula and Oestophorella buvinieri have been named as experimental intermediate hosts of N. linearis.

Direct Position Analysis in Analytical Form of Parallel Manipulators Generating Structures With Topology SR-2PS

2004 ◽  
Author(s):  
Raffaele Di Gregorio
Keyword(s):  
Parallel Manipulator ◽  
Parallel Manipulators ◽  
Analytical Form ◽  
Solution Procedure ◽  
Generic Structure ◽  
Kinematic Chains ◽  
Position Analysis ◽  
In Series ◽  
The One ◽  
Wide Family

A wide family of parallel manipulators (PMs) is the one that groups all the PMs with three legs where the legs become kinematic chains constituted of a passive spherical pair (S) in series with either a passive prismatic pair (P) or a passive revolute pair (R) when the actuators are locked. The topologies of the structures generated by these manipulators, when the actuators are locked, are ten. One out of these topologies is the SR-2PS topology (one SR leg and two PS legs). This paper presents an algorithm that determines all the assembly modes of the structures with topology SR-2PS in analytical form. The presented algorithm can be applied without changes to solve, in analytical form, the direct position analysis of any parallel manipulator which generates a SR-2PS structure when the actuators are locked. In particular, the closure equations of a generic structure with topology SR-2PS are written. The eliminant of this system of equations is determined and the solution procedure is presented. Finally, the proposed procedure is applied to a real case. This work demonstrates that the solutions of the direct position analysis of any parallel manipulator which generates a SR-2PS structure when the actuators are locked are at most eight.

A Structure-Based Biomechanical Model for the Effect of Dissolution of Muscle Cells on Pig Arteries: Elastin Associated With Muscle and Extracellular Matrix

2011 ◽  
Author(s):  
Aristotelis Agianniotis ◽  
Alexander Rachev ◽  
Nikos Stergiopulos
Keyword(s):  
Extracellular Matrix ◽  
Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Biomechanical Model ◽  
Muscle Cells ◽  
In Series ◽  
Minor Part ◽  
The Media ◽  
The One ◽  
A Minor

We developed a structure-based model of the arterial wall to explain the effect of dissolution of smooth muscle cells (SMC) on the mechanical behavior of the artery and to obtain a better understanding of the interaction between the different wall components. Pressure-radius curves and dimensions of zero-stress configuration were measured in 5 control and 5 decellularized porcine common carotid arteries. We found that 13% of elastin is associated with the smooth muscle cells (SMC) whereas the rest 87% is associated with the extracellular matrix (ECM). Further, we found that the elastin related to SMC and the one related to the ECM have circumferential prestretches of 2.04 and 0.89, respectively. We conclude that the majority of elastic in the media is linked to ECM and is under compression at zero load, whereas a minor part is linked to VSM and is under tension (SMC related) at its zero load state. Upon chemical dissolution of the muscle cells elastin in series with SMC do not bear load allowing elastin connected to ECM to release its compressive prestress, leading to the expansion of the artery.

scholarly journals Fundamental study on countermeasures against subharmonic vibration of order 1/2 in automatic transmissions for cars

2018 ◽  
Vol 211 ◽  
pp. 13004
Author(s):  
Fumiya Takino ◽  
Takahiro Ryu ◽  
Takashi Nakae ◽  
Kenichiro Matsuzaki ◽  
Risa Ueno
Keyword(s):  
Piecewise Linear ◽  
Vibration Reduction ◽  
System Model ◽  
Torsional Vibrations ◽  
Fundamental Study ◽  
Automatic Transmissions ◽  
Linear Spring ◽  
Low Stiffness ◽  
Subharmonic Vibration ◽  
The One

In automatic transmissions for cars, a damper is installed in the lock-up clutch to absorb torsional vibrations caused by combustion in the engine. Although a damper with low stiffness reduces the torsional vibration, low-stiffness springs are difficult to use because of space limitations. To address this problem, dampers have been designed using a piecewise-linear spring having three different stages of stiffness. However, a nonlinear subharmonic vibration of order 1/2 occurs because of the nonlinearity of the piecewise-linear spring in the damper. In this study, we experimentally and analytically examined a countermeasure against the subharmonic vibration by increasing the stages of the piecewise-linear spring using the one-degree-of-freedom system model. We found that the gap between the switching points of the piecewise-linear spring was the key to vibration reduction. The experimental results agreed with results of the numerical analyses.

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