scholarly journals Nonlinear control of parallel manipulators for very high accelerations without velocity measurement: stability analysis and experiments on Par2 parallel manipulator

Robotica ◽  
2014 ◽  
Vol 34 (1) ◽  
pp. 43-70 ◽  
Author(s):  
Guilherme Sartori Natal ◽  
Ahmed Chemori ◽  
François Pierrot
Keyword(s):  
Stability Analysis ◽  
Parallel Manipulator ◽  
Parallel Manipulators ◽  
High Gain ◽  
Velocity Estimation ◽  
Estimation Methods ◽  
Mechanical Vibrations ◽  
State Observers ◽  
The Stability ◽  
Very High

SUMMARYThis paper presents a comparison between control/state estimation methods applied on Par2 parallel manipulator for pick-and-place applications as well as a discussion about the mechanical vibrations issue that may become important when reaching very high accelerations. Real-time experiments were performed first to compare two controllers (a linear Proportional-Derivative controller and a nonlinear/adaptive Dual Mode (DM) controller) complied with the same High-Gain Observer (HGO) to estimate articular velocities, and second to compare three state observers (a Lead-lag-based, an Alpha-beta-gamma (ABG) and an HGO) complied with the same nonlinear DM controller. The stability analysis of the Par2 robot under the control of the proposed DM controller (complied with the HighGO for joint velocity estimation) is also provided. Some small mechanical vibrations were noted when reaching 20 G acceleration, which means that it can become an important issue for higher accelerations. Some suggestions are then made for future investigations to avoid/damp these vibrations.

scholarly journals Stability Analysis of a High Stone Retaining Wall: A Case of Eskipazar/Turkey

2017 ◽  
Vol 3 (2) ◽  
pp. 26
Author(s):  
İnan Keskin
Keyword(s):  
Stability Analysis ◽  
Slope Stability ◽  
Retaining Wall ◽  
Retaining Walls ◽  
Stone Masonry ◽  
The North ◽  
Index Terms ◽  
Natural Stones ◽  
The Stability ◽  
Very High

Abstract— The use of natural stones in retaining wall has been a tradition and common practice throughout human history. Stone retaining walls are load bearing retaining walls, which have long been analyzed by considering the equilibrium of forces and moments applied to the wall treated as a rigid solid. Stone retaining walls can be designed for the provision of some slope stability. This paper provides a review of stability analysis of high stone retaining walls. This paper provides a review of stability analysis of high stone retaining walls using Geo5 software. The stone retaining wall examined in this study is located in Karabük (Turkey). The study area was located near of the North Anatolian Fault Line (NAF) which are the most important fault lines in Turkey. For that reason, the stability analyzes were carried out considering the earthquake situation. The stone retaining wall is made of traverten type rock. This rock is a commonly observed rock type. The height of the analyzed wall is 10 m. A 5 kPa uniformly distributed load was adopted in the stability analysis to accommodate for the heaviest loading condition during construction. The analysis with Geo5 found a wall factor of safety 1.78. At this value, it shows that the wall will stable although it is very high.   Index Terms— Stone masonry walls, slope stability, Geo5, Turkey

Stability Analysis for ESO in Frequency Domain Based on Description Function Methodology

2010 ◽  
Vol 439-440 ◽  
pp. 629-634
Author(s):  
Geng Liang ◽  
Hui Wan ◽  
Xing Zhou ◽  
Wen Li
Keyword(s):  
Stability Analysis ◽  
Frequency Domain ◽  
State Observer ◽  
Tracking Performance ◽  
Stability Conditions ◽  
Nonlinear Parameters ◽  
Analysis Methodology ◽  
State Observers ◽  
Linear State ◽  
The Stability

Expanded State Observer (ESO) can be used in the control of plants with uncertainties to achieve better effects. Many theoretical and practical researches have been done on design of systems equipped with ESO. Nevertheless, those on the stability of ESO are relatively rare. In this paper, stability analysis for ESO was conducted based on the methodology of description function. Stability conditions for nonlinear ESO with (2+1)th order were presented. It was proved in this paper that stability conditions that were same with that of linear state observers could be obtained and better tracking performance could be achieved if nonlinear parameters were chosen appropriately. The proposed analysis methodology was also applicable for nonlinear ESO with (n+1)th order.

Equivalent Noise Dose Obtained Through Hearing Aids in the Classrooms of Hearing-Impaired Children

1990 ◽  
Vol 21 (3) ◽  
pp. 147-150
Author(s):  
Ronald A. Wilde
Keyword(s):  
Hearing Aids ◽  
High Gain ◽  
Hearing Impaired ◽  
Deaf Children ◽  
Impaired Children ◽  
Very High ◽  
Hearing Impaired Children

A commercial noise dose meter was used to estimate the equivalent noise dose received through high-gain hearing aids worn in a school for deaf children. There were no significant differences among nominal SSPL settings and all SSPL settings produced very high equivalent noise doses, although these are within the parameters of previous projections.

A Low-Noise, High-Gain Quasi-Millimeter-Wave Receiver MMIC with a Very High Degree of Integration Using 3D-MMIC Technology

2011 ◽  
Vol E94-C (10) ◽  
pp. 1548-1556 ◽  
Author(s):  
Takana KAHO ◽  
Yo YAMAGUCHI ◽  
Kazuhiro UEHARA ◽  
Kiyomichi ARAKI
Keyword(s):  
Millimeter Wave ◽  
High Gain ◽  
Low Noise ◽  
High Degree ◽  
Very High ◽  
Millimeter Wave Receiver

Stability Analysis of the Nanjung Water Diversion Twin Tunnels based on Convergence Measurement

2019 ◽  
Vol 1 (1) ◽  
pp. 49-60
Author(s):  
Simon Heru Prassetyo ◽  
Ganda Marihot Simangunsong ◽  
Ridho Kresna Wattimena ◽  
Made Astawa Rai ◽  
Irwandy Arif ◽  
...  
Keyword(s):  
Stability Analysis ◽  
Convergence Rate ◽  
Critical Strain ◽  
Convergence Rates ◽  
Strain Analysis ◽  
Water Diversion ◽  
Tunnel Face ◽  
Tunnel Stability ◽  
The Stability ◽  
Twin Tunnels

This paper focuses on the stability analysis of the Nanjung Water Diversion Twin Tunnels using convergence measurement. The Nanjung Tunnel is horseshoe-shaped in cross-section, 10.2 m x 9.2 m in dimension, and 230 m in length. The location of the tunnel is in Curug Jompong, Margaasih Subdistrict, Bandung. Convergence monitoring was done for 144 days between February 18 and July 11, 2019. The results of the convergence measurement were recorded and plotted into the curves of convergence vs. day and convergence vs. distance from tunnel face. From these plots, the continuity of the convergence and the convergence rate in the tunnel roof and wall were then analyzed. The convergence rates from each tunnel were also compared to empirical values to determine the level of tunnel stability. In general, the trend of convergence rate shows that the Nanjung Tunnel is stable without any indication of instability. Although there was a spike in the convergence rate at several STA in the measured span, that spike was not replicated by the convergence rate in the other measured spans and it was not continuous. The stability of the Nanjung Tunnel is also confirmed from the critical strain analysis, in which most of the STA measured have strain magnitudes located below the critical strain line and are less than 1%.

Stability of bounded rapid shear flows of a granular material

1996 ◽  
Vol 308 ◽  
pp. 31-62 ◽  
Author(s):  
Chi-Hwa Wang ◽  
R. Jackson ◽  
S. Sundaresan
Keyword(s):  
Growth Rate ◽  
Stability Analysis ◽  
Granular Material ◽  
Bulk Density ◽  
Particulate Material ◽  
Dominant Mode ◽  
Marginal Stability ◽  
Sheared Layer ◽  
The Stability ◽  
Unusual Type

This paper presents a linear stability analysis of a rapidly sheared layer of granular material confined between two parallel solid plates. The form of the steady base-state solution depends on the nature of the interaction between the material and the bounding plates and three cases are considered, in which the boundaries act as sources or sinks of pseudo-thermal energy, or merely confine the material while leaving the velocity profile linear, as in unbounded shear. The stability analysis is conventional, though complicated, and the results are similar in all cases. For given physical properties of the particles and the bounding plates it is found that the condition of marginal stability depends only on the separation between the plates and the mean bulk density of the particulate material contained between them. The system is stable when the thickness of the layer is sufficiently small, but if the thickness is increased it becomes unstable, and initially the fastest growing mode is analogous to modes of the corresponding unbounded problem. However, with a further increase in thickness a new mode becomes dominant and this is of an unusual type, with no analogue in the case of unbounded shear. The growth rate of this mode passes through a maximum at a certain value of the thickness of the sheared layer, at which point it grows much faster than any mode that could be shared with the unbounded problem. The growth rate of the dominant mode also depends on the bulk density of the material, and is greatest when this is neither very large nor very small.

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