Relative Acceleration in Spatial Mechanisms

2012 ◽  
Vol 4 (1) ◽  
Author(s):  
Ian S. Fischer
Keyword(s):  
Closed Loop ◽  
Number Representation ◽  
Automatic Computation ◽  
Dual Number ◽  
Spatial Mechanisms ◽  
Relative Acceleration ◽  
Set Up ◽  
Derivatives Of

A scheme applicable to automatic computation of the joint relative accelerations, the derivatives of joint speeds with respect to time, has been developed in the dual-number representation of the kinematics of spatial mechanisms. The equations which have been developed can be set up automatically by computer for any closed-loop mechanism of binary links. While the RCCC mechanism is given as an example, the scheme can be adapted for mechanisms with prismatic as well as revolute and cylindrical joints and can be readily further developed to consider other types of joints.

Static Equilibrium of Spatial Mechanisms With Cylindrical Joints

2008 ◽  
Vol 130 (6) ◽  
Author(s):  
Ian S. Fischer
Keyword(s):  
Input Data ◽  
Closed Loop ◽  
Static Equilibrium ◽  
Spatial Mechanisms ◽  
Cylindrical Joint ◽  
Set Up

The components of force and torque acting on a joint of a link in static equilibrium are partitioned according to the type of joint so that the equations of static equilibrium can be set up automatically by computer where the type of each joint has been specified in the input data. Special attention is given to the cylindrical joint, and the implications of the geometry of an intermediate link with a cylindrical joint on both ends are examined. While the methodology is demonstrated for the RCCC mechanism, which features a revolute input joint and cylindrical intermediate and output joints, it is adaptable to closed-loop mechanisms of binary links with any kind of joint in any position.

The application of compound proportional resonant control strategy in multiple PV inverters system

2018 ◽  
Vol 32 (34n36) ◽  
pp. 1840098
Author(s):  
Yuan Li ◽  
Huifang Shen ◽  
Chao Xiong ◽  
Yaofei Han ◽  
Guofeng He
Keyword(s):  
Control Strategy ◽  
Closed Loop ◽  
Control Strategies ◽  
Integrated Control ◽  
Reference Signal ◽  
Loop Model ◽  
Harmonic Compensation ◽  
Feed Forward ◽  
Feed Forward Control ◽  
Set Up

In order to eliminate the effect on the grid current caused by the background harmonic voltage and the reference signal on the grid connected multi-inverter, this paper adopts the double closed-loop feed-forward control strategy. This strategy is based on the inductor voltage and the grid-connected current, and the integrated control strategy of quasi-proportional resonance loop parallel to a specific harmonic compensation loop. Based on the closed-loop model of multiple inverters, the change curves of the transfer function of the two control strategies are compared with the feed-forward control and the composite proportional resonance. The two corresponding control methods are used to analyze the current quality of the multi-inverter impact. Finally, the MATLAB/Simulink simulation model is set up to verify the proposed control strategies. The simulation results show that the proposed method can achieve better tracking of the sinusoidal command signal at the fundamental frequency, and enhance the anti-interference ability of the system at the 3rd, 5th, and 7th harmonic frequency.

Implications of Using Dual Number Derivatives With a Numerical Solution

2013 ◽  
Author(s):  
Suryanarayana R. Pakalapati ◽  
Hayri Sezer ◽  
Ismail B. Celik
Keyword(s):  
Automatic Differentiation ◽  
Numerical Solutions ◽  
Computer Code ◽  
Model Parameters ◽  
Model Parameter ◽  
Systematic Assessment ◽  
Dual Number ◽  
Advection Diffusion Equation ◽  
Model Equations ◽  
Derivatives Of

Dual number arithmetic is a well-known strategy for automatic differentiation of computer codes which gives exact derivatives, to the machine accuracy, of the computed quantities with respect to any of the involved variables. A common application of this concept in Computational Fluid Dynamics, or numerical modeling in general, is to assess the sensitivity of mathematical models to the model parameters. However, dual number arithmetic, in theory, finds the derivatives of the actual mathematical expressions evaluated by the computer code. Thus the sensitivity to a model parameter found by dual number automatic differentiation is essentially that of the combination of the actual mathematical equations, the numerical scheme and the grid used to solve the equations not just that of the model equations alone as implied by some studies. This aspect of the sensitivity analysis of numerical simulations using dual number auto derivation is explored in the current study. A simple one-dimensional advection diffusion equation is discretized using different schemes of finite volume method and the resulting systems of equations are solved numerically. Derivatives of the numerical solutions with respect to parameters are evaluated automatically using dual number automatic differentiation. In addition the derivatives are also estimated using finite differencing for comparison. The analytical solution was also found for the original PDE and derivatives of this solution are also computed analytically. It is shown that a mathematical model could potentially show different sensitivity to a model parameter depending on the numerical method employed to solve the equations and the grid resolution used. This distinction is important since such inter-dependence needs to be carefully addressed to avoid confusion when reporting the sensitivity of predictions to a model parameter using a computer code. A systematic assessment of numerical uncertainty in the sensitivities computed using automatic differentiation is presented.

Identification of principal screws of two- and three-screw systems

2007 ◽  
Vol 221 (12) ◽  
pp. 1701-1715 ◽  
Author(s):  
J-S Zhao ◽  
F Chu ◽  
Z-J Feng
Keyword(s):  
Screw Theory ◽  
Coordinate Systems ◽  
Third Order ◽  
Analytical Methodology ◽  
Partial Derivatives ◽  
Spatial Mechanisms ◽  
Analysis Theory ◽  
Definition Of ◽  
Derivatives Of ◽  
Homogeneous Linear

The current paper proposes a unified analytical methodology to identify the principal screws of two- and three-screw systems. Based on the definition of the pitch of a screw, it first obtains an identical homogeneous quadric equation. According to functional analysis theory, it is known that the partial derivatives of an identical quadric equation with respect to its variables must be zero. Therefore, the paper deduces a set of linear homogeneous equations that are made up of the partial derivatives of the quadric equation. With the existing criteria of non-zero solutions for homogeneous linear algebra equations, it ultimately obtains the formulas of the principal pitches and the associated principal screws of the system. The most outstanding contribution of this methodology is that it proposes a unified analytical approach to identify the principal pitches and the principal coordinate systems of the second-order and the third-order screw systems. This should be a new contribution to the screw theory and will boost its applications to the kinematics analysis of robots and spatial mechanisms.

Two in one: bifunctional derivatives of trolox acting as antimalarial and antioxidant agents

2020 ◽  
Vol 12 (20) ◽  
pp. 1845-1854
Author(s):  
Florence Souard ◽  
Edwige Nicolle ◽  
Delphine Cressend ◽  
Alexis Valentin ◽  
Ahcène Boumendjel
Keyword(s):  
Antioxidant Activity ◽  
Ascorbic Acid ◽  
In Vivo Studies ◽  
Chemical Libraries ◽  
Falciparum Strain ◽  
Antioxidant Agents ◽  
One Step ◽  
Set Up ◽  
Derivatives Of

Background: The aim of the present work was to set-up compounds that are able to act simultaneously as antimalarial and antioxidants. Trolox, a known antioxidant was chosen as a core structure to ensure the antioxidant activity and contribute to antiplasmodial effect. Results: Ten compounds were prepared in one step and evaluated on chloroquino-sensitive (3D7) and chloroquino-resistant (FcB1) strains of Plasmodium falciparum. The most active compound (3d) shows antiplasmodial activity in the range of chloroquine against chloroquino-sensitive and chloroquino-resistant P. falciparum strain. The antioxidant activity of (3d) was conducted through four tests and was found to be more potent than trolox itself and L-ascorbic acid. Conclusion: Compound (3d) can be considered as an excellent lead molecule for further in vivo studies. This study paves the way for building large chemical libraries to be investigated in the field of malaria.

A Digital Computer Model for Optimal Programming of Hemodialytic Treatment

1988 ◽  
Vol 11 (4) ◽  
pp. 235-242 ◽  
Author(s):  
C. Lamberti ◽  
E. Sarti ◽  
A. Santoro ◽  
M. Spongano ◽  
P. Zucchelli ◽  
...  
Keyword(s):  
Mathematical Model ◽  
Closed Loop ◽  
Clinical Results ◽  
Pressure Regulation ◽  
Clinical Tests ◽  
Experimental Protocol ◽  
Dialysis Unit ◽  
Optimal Programming ◽  
Set Up ◽  
Arterial Pressure Regulation

A mathematical model of hydroelectrolyte exchanges and arterial pressure regulation in the human body during dialysis has been set up. It is conceived as a tool for a new dialysis unit which will be able to “interpret” the signals supplied by suitable instruments connected to the patient and modify the machine set-points in real time in order to obtain clinical results defined by the physician. The main aim is the prevention of hypotensive episodes during treatment. An experimental protocol has been developed for parameter estimation of each patient during a single dialysis. Clinical tests illustrated the model's ability to fit the patient's state during dialysis. This is the first step in the more general task of validation of the model, necessary for the achievement of a closed-loop dialysis unit.

scholarly journals Distance-Based Formation Control for Quadrotors with Collision Avoidance via Lyapunov Barrier Functions

2020 ◽  
Vol 2020 ◽  
pp. 1-17
Author(s):  
Jawhar Ghommam ◽  
Luis F. Luque-Vega ◽  
Maarouf Saad
Keyword(s):  
Collision Avoidance ◽  
Tracking Control ◽  
Formation Control ◽  
Closed Loop ◽  
Group Formation ◽  
Closed Loop System ◽  
Relative Localization ◽  
Formation Pattern ◽  
Set Up ◽  
The Stability

In this paper, group formation control with collision avoidance is investigated for heterogeneous multiquadrotor vehicles. Specifically, the distance-based formation and tracking control problem are addressed in the framework of leader-follower architecture. In this scheme, the leader is assigned the task of intercepting a target whose velocity is unknown, while the follower quadrotors are arranged to set up a predefined rigid formation pattern, ensuring simultaneously interagent collision avoidance and relative localization. The adopted strategy for the control design consists in decoupling the quadrotor dynamics in a cascaded structure to handle its underactuated property. Furthermore, by imposing constraints on the orientation angles, the follower will never be overturned. Rigorous stability analysis is presented to prove the stability of the entire closed-loop system. Numerical simulation results are presented to validate the proposed control strategy.

scholarly journals Impact of Component Dispersion in DC to DC Low-Power Low-Voltage Power Converter Array

Electronics ◽  
2019 ◽  
Vol 8 (9) ◽  
pp. 917
Author(s):  
Jean-Christophe CREBIER ◽  
Theo LAMORELLE ◽  
Silvain MARACHE ◽  
Thanh Hai PHUNG ◽  
Van-Sang NGUYEN ◽  
...  
Keyword(s):  
Closed Loop ◽  
Low Voltage ◽  
Power Converter ◽  
Point Of View ◽  
Statistical Point ◽  
Loop Control ◽  
In Series ◽  
And Performance ◽  
Set Up ◽  
The Impact

The paper deals with arrays of numerous power conversion cells, associated in series and/or in parallel to build larger step up or step down direct current (DC)/DC isolated converters. The work focuses on the impact of the spread and distribution of the conversion cell characteristics on the characteristics and performance of the power converter array (PCA). Based on a characterization protocol, about 130 conversion standard cells (CSC) are characterized and classified from a statistical point of view. Three families are defined and representatives are chosen and implemented in various configurations, in open and closed loop control, to analyze the impact of their spread characteristic over the global converter, the PCA. The paper is based on an extended practical set up and protocols, all described in details. Guidelines on CSCs implementation with respect to their dispersion are provided at the end on the paper.

Modeling the Systematic Uncertainty of Photogrammetric Tracking of Human Motion

1997 ◽  
Vol 119 (2) ◽  
pp. 358-361 ◽  
Author(s):  
S. B. Bortolami ◽  
P. O. Riley ◽  
D. E. Krebs
Keyword(s):  
Uncertainty Modeling ◽  
Human Locomotion ◽  
Human Motion ◽  
Tracking Data ◽  
Total Uncertainty ◽  
Rotation Matrices ◽  
Self Consistent ◽  
Consistent Manner ◽  
Set Up ◽  
Derivatives Of

We address bias errors of photogrammetric tracking of four SELSPOT-II® cameras using active marker photogrammetry in a 2 m × 2 m × 2 m viewing volume for human locomotion measurements. We present uncertainty modeling regarding the first stage of equipment set up, which provides the camera frame to global frame rotation matrices and the distances among cameras. We also characterize the uncertainty due to the camera distortions of the bare system as compared to published performances achieved with a camera correction procedure. The particular approach is to qualify performances of photogrammetric tracking during routine operation and to identify the nature and magnitude of the uncertainty due to equipment set up and camera distortions as part of the total uncertainty in a self-consistent manner. We found that uncertainty of the camera frame to global frame rotation matrices produced rotation of the image and uncorrected camera hardware uncertainty produced dilatation or compression of the image twice the magnitude of that seen with camera correction. However, camera resolution remains as an equally important factor limiting the accuracy of photogrammetric tracking that can not be easily reduced numerically. In conclusion, the analysis elucidates how uncertainty propagates to numerical derivatives of the tracking data and prepares the groundwork for future development.

scholarly journals Open source modules for tracking animal behavior and closed-loop stimulation based on Open Ephys and Bonsai

2018 ◽  
Author(s):  
Alessio Paolo Buccino ◽  
Mikkel Elle Lepperød ◽  
Svenn-Arne Dragly ◽  
Philipp Häfliger ◽  
Marianne Fyhn ◽  
...  
Keyword(s):  
Open Source ◽  
Real Time ◽  
Closed Loop ◽  
Low Cost ◽  
Data Formats ◽  
Behavioral Tracking ◽  
Real Time Tracking ◽  
Set Up ◽  
And Behavior ◽  
Closed Loop Stimulation

AbstractObjectiveA major goal in systems neuroscience is to determine the causal relationship between neural activity and behavior. To this end, methods that combine monitoring neural activity, behavioral tracking, and targeted manipulation of neurons in closed-loop are powerful tools. However, commercial systems that allow these types of experiments are usually expensive and rely on non-standardized data formats and proprietary software which may hinder user-modifications for specific needs. In order to promote reproducibility and data-sharing in science, transparent software and standardized data formats are an advantage. Here, we present an open source, low-cost, adaptable, and easy to set-up system for combined behavioral tracking, electrophysiology and closed-loop stimulation.ApproachBased on the Open Ephys system (www.open-ephys.org) we developed multiple modules to include real-time tracking and behavior-based closed-loop stimulation. We describe the equipment and provide a step-by-step guide to set up the system. Combining the open source software Bonsai (bonsai-rx.org) for analyzing camera images in real time with the newly developed modules in Open Ephys, we acquire position information, visualize tracking, and perform tracking-based closed-loop stimulation experiments. To analyze the acquired data we provide an open source file reading package in Python.Main resultsThe system robustly visualizes real-time tracking and reliably recovers tracking information recorded from a range of sampling frequencies (30-1000Hz). We combined electrophysiology with the newly-developed tracking modules in Open Ephys to record place cell and grid cell activity in the hippocampus and in the medial entorhinal cortex, respectively. Moreover, we present a case in which we used the system for closed-loop optogenetic stimulation of entorhinal grid cells.SignificanceExpanding the Open Ephys system to include animal tracking and behavior-based closed-loop stimulation extends the availability of high-quality, low-cost experimental setup within standardized data formats serving the neuroscience community.

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