Search results for "Cartesian coordinate system"
showing 10 items of 39 documents
Identification and control design for path tracking of hydraulic loader crane
2017
The controlled operation of hydraulic machines with multiple degrees of freedom is challenging due to complex nonlinear dynamics of cylinder actuators, in addition to multibody dynamics like in the case of hydraulic manipulators. This paper addresses the system identification and control design for path tracking of a standard hydraulic loader crane. The kinematics of the crane is solved for operation in the vertical plane and generation of trajectories for the tool tip to be followed. A frequency response measurements and analysis have been done for dynamics modeling of both hydraulic cylinders actuating main boom and jib. The static dead-zone type input non-linearity has been identified an…
Identification of Objects Based on Generalized Amplitude-Phase Images Statistical Models
2017
The article presents the dynamical objects identification technology based on statistical models of amplitude-phase images (APIm) – multidimensional data arrays (semantic models) and statistical correlation analysis methods using the generalized discrete Hilbert transforms (DHT) – 2D Hilbert (Foucault) isotropic (HTI), anisotropic (HTA) and total transforms – AP-analysis (APA) to calculate the APIm. The identified objects are modeled with 3D airplanes templates rotated in space around the center of Cartesian coordinate system. The DHT domain system of coordinates displaying the plane projections (2D flat images) remains to be space-invariant. That causes the anisotropic properties of APIm a…
Regularization of spherical and axisymmetric evolution codes in numerical relativity
2007
Several interesting astrophysical phenomena are symmetric with respect to the rotation axis, like the head-on collision of compact bodies, the collapse and/or accretion of fields with a large variety of geometries, or some forms of gravitational waves. Most current numerical relativity codes, however, can not take advantage of these symmetries due to the fact that singularities in the adapted coordinates, either at the origin or at the axis of symmetry, rapidly cause the simulation to crash. Because of this regularity problem it has become common practice to use full-blown Cartesian three-dimensional codes to simulate axi-symmetric systems. In this work we follow a recent idea idea of Rinne…
The Gender of the Cartesian Mind, Body, and Mind-Body Union
2019
The chapter examines what we can know about gender from the perspective of the three primary notions introduced by Descartes in his correspondence with Princess Elisabeth of Bohemia. The first section discusses how the primitive notion of the mind strengthens the idea that “the mind has no sex”, an idea that was further developed by the Cartesian and early feminist François Poulain de la Barre. The next section focuses on the notion of the body and analyses what Descartes has to say about gender in his anatomical writings. The little known posthumously published notes Primae cogitationes circa generationem animalium receive particular attention. Here Descartes assumes a difference between t…
Development of Point-to-Point Path Control in Actuator Space for Hydraulic Knuckle Boom Crane
2020
This paper presents a novel method for point-to-point path control for a hydraulic knuckle boom crane. The developed path control algorithm differs from previous solutions by operating in the actuator space instead of the joint space or Cartesian space of the crane. By operating in actuator space, almost all the parameters and constraints of the system become either linear or constant, which greatly reduces the complexity of both the control algorithm and path generator. For a given starting point and endpoint, the motion for each actuator is minimized compared to other methods. This ensures that any change in direction of motion is avoided, thereby greatly minimizing fatigue, jerky motion,…
An improved immersed boundary method for curvilinear grids
2009
Abstract In the present paper we propose an extension of the direct-forcing immersed boundary technique, recently developed and employed by Verzicco and co-authors [Fadlun EA, Verzicco R, Orlandi P, Mohd-Yusof J. Combined immersed-boundary finite-difference methods for three-dimensional complex flow simulations. J Comput Phys 2000;161:35–60; Verzicco R, Fatica M, Iaccarino G, Moin P, Khalighi B. Large eddy simulation of a road vehicle with drag-reduction devices. AIAA J 2002;40(12):2447–55; Cristallo A, Verzicco R. Combined immersed boundary/large-eddy-simulations of incompressible three-dimensional complex flows. Flow Turbul Combust 2006;77(1–4):3–26.] and successively improved by Balaras …
Weighted Extrapolation Techniques for Finite Difference Methods on Complex Domains with Cartesian Meshes
2016
The design of numerical boundary conditions in high order schemes is a challenging problem that has been tackled in different ways depending on the nature of the problem and the scheme used to solve it numerically. In this paper we propose a technique to extrapolate the information from the computational domain to ghost cells for schemes with structured Cartesian Meshes on complex domains. This technique is based on the application of Lagrange interpolation with weighted filters for the detection of discontinuities that permits a data dependent extrapolation, with high order at smooth regions and essentially non oscillatory properties near discontinuities. This paper is a sequel of Baeza et…
High order normal form construction near the elliptic orbit of the Sitnikov problem
2011
We consider the Sitnikov problem; from the equations of motion we derive the approximate Hamiltonian flow. Then, we introduce suitable action–angle variables in order to construct a high order normal form of the Hamiltonian. We introduce Birkhoff Cartesian coordinates near the elliptic orbit and we analyze the behavior of the remainder of the normal form. Finally, we derive a kind of local stability estimate in the vicinity of the periodic orbit for exponentially long times using the normal form up to 40th order in Cartesian coordinates.
Multi-Objective Design of Optimisation of a Class of PKMs - The 3-DOF Gantry-Tau
2010
The main contribution of this paper is the use of the evolutionary multi-objective methodology based on the com plex search algorithm and geometric approaches to optimise a parallel kinematic structure. The design optimisation scheme includes the kinematic (collisions free workspace), elastostatic (Cartesian stiffness in the Y direction) and elastodynamic (first resonance frequency) properties of the PKM as the objectives. The optimisation constraints are the support frame lengths, actuator positions, end-effector’s kinematic parameters and the robot’s arm lengths. The optimisation results are presented in this paper.
Assessment of a high-resolution central scheme for the solution of the relativistic hydrodynamics equations
2004
We assess the suitability of a recent high-resolution central scheme developed by Kurganov & Tadmor (2000) for the solution of the relativistic hydrodynamics equations. The novelty of this approach relies on the absence of Riemann solvers in the solution procedure. The computations we present are performed in one and two spatial dimensions in Minkowski spacetime. Standard numerical experiments such as shock tubes and the relativistic flat-faced step test are performed. As an astrophysical application the article includes two-dimensional simulations of the propagation of relativistic jets using both Cartesian and cylindrical coordinates. The simulations reported clearly show the capabili…