Trajectory Synthesis and Inverse Dynamics Formulation for Minimal Vibrational Excitation for Flexible Structures based on Trajectory Patterns

1993 ◽  
Author(s):  
Q. Tu ◽  
J. Rastegar ◽  
F. Tangerman
Keyword(s):  
Inverse Dynamics ◽  
Vibrational Excitation ◽  
Flexible Structures

Trajectory Pattern Method Based Trajectory Synthesis and Inverse Dynamics Formulation for Minimal Vibrational Excitation for Flexible Structures

1996 ◽  
Author(s):  
Q. Tu ◽  
J. Rastegar
Keyword(s):  
Inverse Dynamics ◽  
Vibrational Excitation ◽  
Flexible Structures ◽  
Frequency Component ◽  
High Frequency Component ◽  
Flexible Beam ◽  
Dynamics Model ◽  
Trajectory Pattern ◽  
Point To Point ◽  
Trajectory Pattern Method

Abstract A new approach to trajectory synthesis and formulation of the inverse dynamics model of flexible structures for point to point motions with minimal high frequency component of the actuating torques (forces) is presented. Trajectories are synthesized such that the flexible structure comes to rest undeformed at the completion of motion. The developed method is based on the Trajectory Pattern Method. In this approach, an appropriate trajectory pattern is selected and described in parametric form. The inverse dynamics model of the system is formulated in terms of the trajectory parameters. The trajectory patterns used are in terms of a number of basic sinusoidal time functions and their harmonics. The basic frequencies are selected such that the harmonics appearing in the actuating torques do not excite the natural modes of vibration of the system. For each motion, the trajectory parameters are determined for minimal amplitudes of the higher actuating torque harmonics, noting that from the vibration and control points of view, such trajectories are more desirable. The higher harmonics refers to the harmonics of the actuating torques with frequencies above the highest trajectory harmonic frequency. As an example, a flexible beam undergoing large displacements and rotations in a plane is considered. The effectiveness of the approach is illustrated by an example.

Bernstein-Be´zier Harmonics and Their Application to Robot Trajectory Synthesis With Minimal Vibrational Excitation

1996 ◽  
Vol 118 (4) ◽  
pp. 509-514 ◽  
Author(s):  
Q. J. Ge ◽  
J. Rastegar
Keyword(s):  
Dynamic Response ◽  
High Frequency ◽  
High Speed ◽  
Inverse Dynamics ◽  
Robot Manipulator ◽  
Vibrational Excitation ◽  
Significant Source ◽  
Polynomial Curves ◽  
Robot Trajectory

For a given high-speed machinery, a significant source of the internally induced vibrational excitation is the presence of high frequency harmonics in the trajectories that the system is forced to follow. This paper presents a Bernstein-Be´zier form of harmonic trajectory patterns for synthesizing low-harmonic trajectories. Similar to Bernstein-Be´zier polynomial curves, Bernstein-Be´zier harmonic trajectories can be defined either explicitly using Bernstein-Be´zier basis harmonics or recursively using the harmonic deCasteljau algorithm. The second part of the paper demonstrates how a Bernstein-Be´zier trajectory can be combined with the inverse dynamics of a robot manipulator for synthesizing a joint trajectory that demands “minimal” dynamic response from its actuators. An example involving a planar 2R robot is also presented.

Intelligent Sensor Fault Detection of Vibration Control for Flexible Structures

1999 ◽  
Vol 11 (6) ◽  
pp. 524-530 ◽  
Author(s):  
Masahiro Isogai ◽  
◽  
Fumihito Arai ◽  
Toshio Fukuda ◽  
◽  
...  
Keyword(s):  
Fault Detection ◽  
Vibration Control ◽  
Inverse Dynamics ◽  
Fault Tolerant ◽  
Flexible Structures ◽  
Space Structures ◽  
Sensor Fault ◽  
Intelligent Sensor ◽  
Proposed Model ◽  
Sensor Fault Detection

Vibration control for flexible structures such as arms and space structures has been widely studied. We proposed model-based decentralized control for flexible structures by decoupling mode quantities of other links. If a failure occurs, control performance drops due to parameter error between the model and plant. We must consider device fault detection and controller reconfiguration. We propose a fault-tolerant system using inverse dynamics constructed by neural network for sensor fault detection and NN adaptive control for the actuator fault to reconfigure control to compensate for parameter changes due to actuator faults. The effectiveness of our proposal is shown through simulation.

Direct inverse control for active vibration suppression using artificial neural networks

2020 ◽  
pp. 107754632092425
Author(s):  
William Camilo Ariza-Zambrano ◽  
Alberto Luiz Serpa
Keyword(s):  
Neural Networks ◽  
Artificial Neural Networks ◽  
Inverse Dynamics ◽  
Vibration Suppression ◽  
Control Method ◽  
Flexible Structures ◽  
Plate Model ◽  
Inverse Control ◽  
Application Problem ◽  
Artificial Neural

In this article, a control method based on artificial neural networks applied to the vibration control of flexible structures is presented. The direct inverse control method is used. This method consists in the identification of the inverse dynamics of the plant using an artificial neural network to be used as the controller. An application example is proposed, and two problem variations are treated. The application problem is based on a cantilever plate model. The plate model is obtained using the finite element method. For the first problem, the controller is designed using the full-order plant model. In the second example, a model reduction is made to evaluate the performance of this technique applied to control problems with dynamic uncertainties. The results were evaluated according to the time response and frequency response of the closed-loop system. To compare the results obtained using the control method based on artificial neural networks, the previous examples were also solved using the [Formula: see text] control method. The obtained results show that the control method based on the inverse model using neural networks is effective in solving this kind of problem.

Simultaneous Trajectory Tracking and Vibration Reduction of Distributed Parameter Systems Through Inverse Dynamics

1993 ◽  
Author(s):  
R. Ledesma ◽  
S. Devasia ◽  
E. Bayo
Keyword(s):  
Trajectory Tracking ◽  
Inverse Dynamics ◽  
Vibration Reduction ◽  
Flexible Structures ◽  
Three Dimensional ◽  
Distributed Parameter ◽  
Structural Vibrations ◽  
Inverse Dynamic ◽  
Open Chain ◽  
Recursive Procedure

Abstract This paper addresses the problem of inverse dynamics for three-dimensional articulated flexible structures with both lumped and distributed actuators. A recursive procedure is presented for computing the lumped inverse dynamic torques and the distributed piezoelectric actuator inputs for simultaneously tracking a prescribed end-point trajectory and reducing motion-induced vibrations in the articulated structure. The procedure sequentially solves for the non-causal inverse dynamic torques and piezoelectric voltages applied to each link in the open-chain articulated structure, starting from the last element in the chain and proceeding to the base element. The method allows trajectory tracking wherein controllability of the structural vibrations is assured in all possible configurations through the use of only one motor at each intermediate joint and three motors at the ground. Numerical simulation shows that the elastic vibrations can be reduced significantly through the use of distributed actuators while at the same time satisfying the trajectory tracking requirement through the use of inverse dynamics.

Progress in high-resolution CRYO-SEM imaging of viral particles

1996 ◽  
Vol 54 ◽  
pp. 818-819
Author(s):  
Ya Chen ◽  
Geoffrey Letchworth ◽  
John White
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
High Resolution ◽  
Structural Information ◽  
Signal To Noise Ratio ◽  
Flexible Structures ◽  
Simian Virus ◽  
Topographic Features ◽  
Viral Particles ◽  
Scanning Electron

Low-temperature high-resolution scanning electron microscopy (cryo-HRSEM) has been successfully utilized to image biological macromolecular complexes at nanometer resolution. Recently, imaging of individual viral particles such as reovirus using cryo-HRSEM or simian virus (SIV) using HRSEM, HV-STEM and AFM have been reported. Although conventional electron microscopy (e.g., negative staining, replica, embedding and section), or cryo-TEM technique are widely used in studying of the architectures of viral particles, scanning electron microscopy presents two major advantages. First, secondary electron signal of SEM represents mostly surface topographic features. The topographic details of a biological assembly can be viewed directly and will not be obscured by signals from the opposite surface or from internal structures. Second, SEM may produce high contrast and signal-to-noise ratio images. As a result of this important feature, it is capable of visualizing not only individual virus particles, but also asymmetric or flexible structures. The 2-3 nm resolution obtained using high resolution cryo-SEM made it possible to provide useful surface structural information of macromolecule complexes within cells and tissues. In this study, cryo-HRSEM is utilized to visualize the distribution of glycoproteins of a herpesvirus.

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