Showing papers on "Angular velocity published in 2006"
TL;DR: A new quaternion-based feedback control scheme for exponential attitude stabilization of a four-rotor vertical takeoff and landing aerial robot known as a quadrotor aircraft is proposed and the model-independent PD controller, without compensation of the Coriolis and gyroscopic torques, provides asymptotic stability for the problem.
Abstract: In this paper, we propose a new quaternion-based feedback control scheme for exponential attitude stabilization of a four-rotor vertical takeoff and landing aerial robot known as a quadrotor aircraft. The proposed controller is based upon the compensation of the Coriolis and gyroscopic torques and the use of a PD/sup 2/ feedback structure, where the proportional action is in terms of the vector quaternion and the two derivative actions are in terms of the airframe angular velocity and the vector quaternion velocity. We also show that the model-independent PD controller, where the proportional action is in terms of the vector-quaternion and the derivative action is in terms of the airframe angular velocity, without compensation of the Coriolis and gyroscopic torques, provides asymptotic stability for our problem. The proposed controller as well as some other controllers have been tested experimentally on a small-scale quadrotor aircraft.
982 citations
TL;DR: In this article, the role of thermal wind balance and tachocline-induced entropy variations in maintaining the solar differential rotation is discussed, and the relative amplitude of the imposed entropy variations is of order 10 � 5, corresponding to a latitudinal temperature variation of about 10 K.
Abstract: Three-dimensional simulations of solar convection in spherical shells are used to evaluate the differential rotation that results as thermal boundary conditions are varied. In some simulations a latitudinal entropy variation is imposed at the lower boundary in order to take into account the coupling between the convective envelope and the radiative interior through thermal wind balance in the tachocline. The issue is whether the baroclinic forcing arising from tachocline-induced entropy variations can break the tendency for numerical simulations of convection to yield cylindrical rotation profiles, unlike the conical profiles deduced from helioseismology. As the amplitude of the imposed variation is increased, cylindrical rotation profiles do give way to more conical profiles that exhibit nearly radial angular velocity contours at midlatitudes. Conical rotation profiles are maintained primarily by the resolved convective heat flux, which transmits entropy variations from the lower boundary into the convective envelope, giving rise to baroclinic forcing. The relative amplitude of the imposed entropy variations is of order 10 � 5 , corresponding to a latitudinal temperature variation of about 10 K. The role of thermal wind balance and tachoclineinduced entropy variations in maintaining the solar differential rotation is discussed. Subject headingg convection — Sun: interior — Sun: rotation
290 citations
15 May 2006
TL;DR: Experimental results, for flight data from the HoverEyecopy UAV, demonstrate the efficiency of the proposed nonlinear complimentary filter exploiting the structure of special orthogonal group S0(3).
Abstract: This paper considers the question of obtaining high quality attitude estimates from typical low cost inertial measurement units for applications in control of unmanned aerial vehicles. A nonlinear complimentary filter exploiting the structure of special orthogonal group S0(3) is proposed. The filter is expressed explicitly in terms of direct and untreated measurements. For a typical low cost inertial measurement where two inertial directions are measured (gravitational and magnetic fields) along with angular velocity, it is shown that the filter is well conditioned. If only a single direction is available (typically the gravitational field) along with angular velocity, it is shown that the full gyro bias vector is correctly estimated and that the estimated orientation converges to a set consistent with the measurements. Experimental results, for flight data from the HoverEyecopy UAV, demonstrate the efficiency of the proposed filter
212 citations
TL;DR: This study provides an accurate, inexpensive and simple method to measure the kinematics of movements similar to rising from a chair using low-pass filtering of the accelerometer signal.
158 citations
Patent•
30 Nov 2006
TL;DR: In this paper, an angular velocity sensor was designed to reduce the effect of detouring drive signals while preventing a vibrator from being upsized and a signal processing circuit from being complicated, and the oscillation circuit consisted of a CV conversion circuit, a phase adjustment circuit, and an amplitude adjustment circuit.
Abstract: PROBLEM TO BE SOLVED: To provide an angular velocity sensor for reducing the effect of detouring drive signals while preventing a vibrator from being upsized and a signal processing circuit from being complicated. SOLUTION: This angular velocity sensor 80 comprises a vibrator 10 having a movable part 14 movable in two directions orthogonal to each other. An oscillation circuit 50 is connected to a drive electrode 22 and a monitor electrode 24 existing in the X direction of the movable part 14, the oscillation circuit 50 comprising a CV conversion circuit 52, a phase adjustment circuit 54, and an amplitude adjustment circuit 56. CV conversion circuits 60 and 62 are connected to detection electrodes 38 and 40 existing in the Y direction of the movable part 14 while connecting the conversion circuits 60 and 62 to an angular velocity signal processing circuit 64. In designing the vibrator 10, an electrostatic coupling capacitance Cc between the drive electrode 22 and the monitor electrode 24 is set to be equal to or less than 1/30 of detection capacitance of the monitor electrode 24. COPYRIGHT: (C)2007,JPO&INPIT
139 citations
TL;DR: In this article, the effects of magnetic fields on the evolution of differentially rotating neutron stars were studied in axisymmetry using their recently developed codes which integrate the coupled Einstein-Maxwell-MHD equations.
Abstract: We study the effects of magnetic fields on the evolution of differentially rotating neutron stars, which can be formed in stellar core collapse or binary neutron star coalescence. Magnetic braking and the magnetorotational instability (MRI) both act on differentially rotating stars to redistribute angular momentum. Simulations of these stars are carried out in axisymmetry using our recently developed codes which integrate the coupled Einstein-Maxwell-MHD equations. We consider stars with two different equations of state (EOS), a gamma-law EOS with $\ensuremath{\Gamma}=2$, and a more realistic hybrid EOS, and we evolve them adiabatically. Our simulations show that the fate of the star depends on its mass and spin. For initial data, we consider three categories of differentially rotating, equilibrium configurations, which we label normal, hypermassive and ultraspinning. Normal configurations have rest masses below the maximum achievable with uniform rotation, and angular momentum below the maximum for uniform rotation at the same rest mass. Hypermassive stars have rest masses exceeding the mass limit for uniform rotation. Ultraspinning stars are not hypermassive, but have angular momentum exceeding the maximum for uniform rotation at the same rest mass. We show that a normal star will evolve to a uniformly rotating equilibrium configuration. An ultraspinning star evolves to an equilibrium state consisting of a nearly uniformly rotating central core, surrounded by a differentially rotating torus with constant angular velocity along magnetic field lines, so that differential rotation ceases to wind the magnetic field. In addition, the final state is stable against the MRI, although it has differential rotation. For a hypermassive neutron star, the MHD-driven angular momentum transport leads to catastrophic collapse of the core. The resulting rotating black hole is surrounded by a hot, massive, magnetized torus undergoing quasistationary accretion, and a magnetic field collimated along the spin axis\char22{}a promising candidate for the central engine of a short gamma-ray burst.
132 citations
TL;DR: In this article, two spots were detected at different latitudes (200, 315) rotating with different periods (11.35 days, 11.55 days), from which they derived a differential rotation coefficient, k = 0.11, in agreement with the prediction by Brown and coworkers for a young Sun-like star having roughly twice the solar angular velocity.
Abstract: The Microvariability and Oscillations of STars (MOST) photometric satellite observed three rotations of Eri continuously in late 2005. We detected two spots (Δm ~ 0.01) at different latitudes (200, 315) revolving with different periods (11.35 days, 11.55 days), from which we derive a differential rotation coefficient, k = 0.11, in agreement with the prediction by Brown and coworkers for a young Sun-like star having roughly twice the solar angular velocity. The light curve was analyzed with the program StarSpotz, a modification of SPOTMODEL by Ribarik and coworkers. The best-fitting value for the inclination angle i = 30° ± 3° is compatible with inclinations already estimated for the disk (~25°) and planetary orbit (262). The inclination also leads to an equatorial rotation speed of 3.42 km s-1 and the photometric value of v sin i = 1.7 km s-1. When compared with spectroscopically determined values, the photometric v sin i allows, in principle, an independent estimate of the macroturbulent velocity. Both spots would have distorted the radial velocity curve ~±10 m s-1 by the Rossiter-McLaughlin effect, which is similar to the stellar radial velocity "noise" detected by others. Details of the StarSpotz model and of the uniqueness tests that we applied in order to arrive at a best solution and realistic estimates of errors in the derived parameters are given.
105 citations
INAF1
TL;DR: In this paper, the authors considered the case of RS CVn binary systems and found that the surface angular velocity variation of the secondary component required by Applegate's hypothesis is between 4 and 12 per cent, i.e. too large to be compatible with the observations and that the kinetic energy dissipated in its convection zone ranges from 4 to 43 times that supplied by the stellar luminosity along one cycle of the orbital period modulation.
Abstract: The orbital period modulation, observed in close binary systems with late-type secondary stars, is considered in the framework of a general model that allows us to test the hypothesis proposed by Applegate. It relates the orbital period variation to the modulation of the gravitational quadrupole moment of their magnetically active secondary stars produced by angular momentum exchanges within their convective envelopes. By considering the case of RS CVn binary systems, it is found that the surface angular velocity variation of the secondary component required by Applegate's hypothesis is between 4 and 12 per cent, i.e. too large to be compatible with the observations and that the kinetic energy dissipated in its convection zone ranges from 4 to 43 times that supplied by the stellar luminosity along one cycle of the orbital period modulation. Similar results are obtained for other classes of close binary systems by applying a scaling relationship based on a simplified internal structure model. The effect of rapid rotation is briefly discussed finding that it is unlikely that the rotational quenching of the turbulent viscosity may solve the discrepancy. Therefore, the hypothesis proposed by Applegate is not adequate to explain the orbital period modulation of close binary systems with a late-type secondary.
103 citations
TL;DR: In this paper, the authors show that coherent motions of points in Yemen, Bahrain, Oman, and Iran allow them to estimate a geodetically constrained angular velocity for the Arabian plate (52.59°N, 15.74°W, 0.461°/Myr in ITRF2000).
Abstract: During the last 10 years, a network of about 30 GPS sites was measured in Djibouti, East Africa. Additional points were also measured in Yemen, Oman, Ethiopia, Iran, and on La Reunion island. Merged with data from the available International GPS Service permanent stations scattered on the different plates in the area (Eurasia, Anatolia, Africa, Arabia, Somalia), this unique data set provides new insight on the current deformation in the Africa-Somalia-Arabia triple junction area and on the Arabian plate motion. Here we show that coherent motions of points in Yemen, Bahrain, Oman, and Iran allow us to estimate a geodetically constrained angular velocity for the Arabian plate (52.59°N, 15.74°W, 0.461°/Myr in ITRF2000). This result differs significantly from earlier determinations and is based upon our vectors in Yemen. They provide new additional data and better geometry for angular velocity determination. Combined with the African and Somalian motions, this new angular velocity results in predicted spreading rates in the Red Sea and the Gulf of Aden which are 15-20% lower than those measured from oceanic magnetic anomalies and thus averaged over the last 3 Myr. With respect to Eurasia, the geodetic motion of Arabia is also about 30% slower than predicted by NUVEL-1A. On the basis of the kinematic results presented here and on other evidence for a similar slower geodetic rate of the Indian plate, we suggest that the whole collision zone between Africa, Arabia, India on one hand and Eurasia on the other hand has slowed down in the last 3 Myr.
102 citations
TL;DR: The maximum voluntary knee extensor torque that can be exerted may be modelled accurately as the product of functions defining the maximum torque and the maximum voluntary activation level.
101 citations
TL;DR: In this article, the first toroidal rotation measurements in TCV ohmic L-mode plasmas with no external momentum injection were presented, and the toroidal velocity profile of the fully stripped carbon species is measured by active charge eXchange Recombination Spectroscopy with a temporal resolution of typically 90 ms and a spatial resolution of 2.5 cm, about 1/10 of the plasma radius.
Abstract: The first toroidal rotation measurements in TCV ohmic L-mode plasmas with no external momentum injection are presented. The toroidal velocity profile of the fully stripped carbon species is measured by active Charge eXchange Recombination Spectroscopy with a temporal resolution of typically 90 ms and a spatial resolution of 2.5 cm, about 1/10 of the plasma radius. The observed carbon velocity is of the order of the deuterium diamagnetic drift velocity and up to 1/5 of the deuterium thermal velocity. It is directed opposite to plasma current in the electron diamagnetic toroidal drift direction. The profile reverses when reversing the plasma current. The angular velocity profile is flat, or hollow, inside the sawtooth inversion radius and decreases quasi linearly towards the plasma edge. By vertically shifting the plasma magnetic axis within the TCV vessel the plasma edge velocity profile was measured with high resolution. Such experiments confirm that, close to the limiter, the stationary rotation velocity is close to zero or somewhat positive (co-current directed). This suggests that the angular momentum is not driven from the plasma edge. The maximum carbon velocity scales as v(phi,Max) [km s(-1)] = -12.5T(i)/I-p [eV/kA] for a significant range of densities and values of the edge safety factor. Comparison with neoclassical predictions show that the TCV plasma rotation is mainly driven by radial electric fields, with a negligible contribution from the toroidal electric fields. The neoclassical theory of small toroidal rotation quantitatively and qualitatively disagrees with the experimental observation. An alternative empirical equation for the angular momentum flux, able to reproduce the measured stationary profile outside the inversion radius, is proposed.
Patent•
15 Jun 2006
TL;DR: In this article, the angular velocity sensor is provided with a closed channel 2 through which an electro-conjugate fluid (ECF) circulates; a positive electrode and a negative electrode as driving parts for circulating ECF; diaphragms 6 and 8 provided as part of the closed channel; and strain detectors 11 and 13 for detecting strains of the diaphrasms6 and 8.
Abstract: PROBLEM TO BE SOLVED: To provide an angular velocity sensor capable of achieving compactness, improving sensitivity, and heightening resistance to shocks by using the Coriolis force which occurs in a circulating fluid. SOLUTION: The angular velocity sensor is provided with a closed channel 2 through which an electro-conjugate fluid (ECF) circulates; a positive electrode and a negative electrode as driving parts for circulating ECF; diaphragms 6 and 8 provided as part of the closed channel 2; and strain detectors 11 and 13 for detecting strains of the diaphragms 6 and 8. COPYRIGHT: (C)2006,JPO&NCIPI
TL;DR: In this article, a direct torque control space vector modulation (DTC-SVM) scheme using SVM does not use coordinate transforms or current controllers to achieve DTC and is demonstrated experimentally.
Abstract: At high angular velocity, the induction motor is operated in the field weakening range due to the voltage limit of the inverter. Field oriented vector control (FOC) is unsuitable for this operation duetocoupling, non-linearities,andsaturationof linear current controllers. A proposed direct torque control space vector modulation (DTC–SVM) scheme using SVM does not use coordinate transforms or current controllers to achieve DTC. Control of the stator flux vector allows for dynamic change in the torque in all regions,including field weakening with the six-step operation. This paper describes the torque control dynamic in the field weakening range, using a step change in stator flux vector magnitude and it’s angular velocity. The method is demonstrated experimentally.
TL;DR: In this article, the authors studied the collapse of rotating molecular cloud cores with inclined magnetic fields, based on three-dimensional numerical simulations, where the magnetic field and rotation axis change their directions as the cloud collapses.
Abstract: We studied the collapse of rotating molecular cloud cores with inclined magnetic fields, based on three-dimensional numerical simulations.The numerical simulations start from a rotating Bonnor-Ebert isothermal cloud in a uniform magnetic field. The magnetic field is initially taken to be inclined from the rotation axis. As the cloud collapses, the magnetic field and rotation axis change their directions. When the rotation is slow and the magnetic field is relatively strong, the direction of the rotation axis changes to align with the magnetic field, as shown earlier by Matsumoto & Tomisaka. When the magnetic field is weak and the rotation is relatively fast, the magnetic field inclines to become perpendicular to the rotation axis. In other words, the evolution of the magnetic field and rotation axis depends on the relative strength of the rotation and magnetic field. Magnetic braking acts to align the rotation axis and magnetic field, while the rotation causes the magnetic field to incline through dynamo action. The latter effect dominates the former when the ratio of the angular velocity to the magnetic field is larger than a critical value \Omega_0/ B_0 > 0.39 G^1/2 c_s^-1, where B_0, \Omega_0, G, and c_s^-1 denote the initial magnetic field, initial angular velocity, gravitational constant, and sound speed, respectively. When the rotation is relatively strong, the collapsing cloud forms a disk perpendicular to the rotation axis and the magnetic field becomes nearly parallel to the disk surface in the high density region. A spiral structure appears due to the rotation and the wound-up magnetic field in the disk.
TL;DR: The investigation of dust structure formed in glow discharge in an external longitudinal magnetic field with induction up to 400 G applied is presented and the occurrence of structure transformation and its phase transition of the meltinglike type in the magnetic field is shown.
Abstract: The investigation of dust structure formed in glow discharge in an external longitudinal magnetic field with induction up to 400 G applied is presented in this work. The dust structure starts to rotate in the magnetic field. The angular-velocity magnitude is one to two orders larger than one in other discharge types. Its dependence on the magnetic field is nonmonotonic. The rotation direction inverses with an increase of the magnetic induction value up to a certain magnitude B0. In close range of induction around B0 and under certain conditions the rotation of the upper and lower parts of the structure in the opposite direction is observed. Rotation is caused by the ion-drag force. The inversion of rotation direction relates with the change of plasma flows in the area of their formation in stratum with the magnetic field applied. The effect of ion flows was investigated in two additional experiments on the observation of structure rotation onset and on gravity-driven probing of stratum. The angular-velocity unhomogeniety allowed us to investigate shearing and to observe melting of the dust crystal. The correlation functions approach showed the occurrence of structure transformation and its phase transition of the meltinglike type in the magnetic field.
TL;DR: In this paper, the authors established a methodology for obtaining the general solution to the spacecraft relative motion problem by utilizing the Cartesian configuration space in conjunction with classical orbital elements, and derived useful metrics for quantification of the minimum, maximum, and mean distance between spacecraft for commensurable and noncommensurable mean motions.
Abstract: This paper establishes a methodology for obtaining the general solution to the spacecraft relative motion problem by utilizing the Cartesian configuration space in conjunction with classical orbital elements. The geometry of the relative motion configuration space is analyzed, and the relative motion invariant manifold is determined. Most importantly, the geometric structure of the relative motion problem is used to derive useful metrics for quantification of the minimum, maximum, and mean distance between spacecraft for commensurable and noncommensurable mean motions. A number of analytic solutions as well as useful examples are provided, illustrating the calculated bounds. A few particular cases that yield simple solutions are given. Nomenclature a = semimajor axis E = eccentric anomaly E = follower orbit e = eccentricity F = follower perifocal frame f = true anomaly I = inertial frame i = inclination Jk = Bessel function L = leader-fixed frame M = mean anomaly n = mean motion n0 = fundamental frequency R = leader position vector R = relative motion invariant manifold r = follower position vector W = distance function α = normalized semimajor axis μ = gravitational constant ρ = relative position vector � = right ascension of the ascending node ω = argument of periapsis ω = angular velocity vector |·| = vector norm �·� = signal norm Superscripts � = leader ∗ = relative orbital element
TL;DR: In this paper, the authors investigated the equilibrium, stability and pure rolling problems of a sphere moving on a flat plane with special reference to a few force models which are commonly used in the discrete element method and here categorized into two types: with and without rolling friction.
TL;DR: In this paper, a feedback controller using only one single-gimbal variable-speed control moment gyro is presented that drives all three components of the angular velocity of a rigid spacecraft to zero, while at the same time a spacecraft body-axis points along an arbitrary inertial direction.
Abstract: Complete attitude control of a spacecraft is not possible with only one single-gimbal variable-speed control moment gyro due to the conservation of angular momentum. However, partial attitude control without violating the angular momentum conservation principle is still possible. In this paper feedback controllers using only one single-gimbal variable-speed control moment gyro are presented that drive all three components of the angular velocity of a rigid spacecraft to zero, while at the same time a spacecraft body-axis points along an arbitrary inertial direction. To solve this problem, we first introduce a pair of angles to parametrize all feasible final spacecraft orientations at rest without violating the angular momentum constraint Based on this parametrization, an LQR control law is designed to locally achieve the control objective. Afterwards, a multistage control law is proposed to achieve the same control objective for large initial conditions.
TL;DR: Simulation results demonstrates that bulk modulus should be considered as a variable parameter to obtain a more realistic model and a PID controller is insufficient in presence of variable bulkModulus, whereas a fuzzy controller provides robust angular velocity control.
Abstract: In this paper, we examine the performance of PID (proportional integral derivative) and fuzzy controllers on the angular velocity of a hydrostatic transmission system by means of Matlab-Simulink. A very novel aspect is that it includes the analysis of the effect of bulk modulus on system control. Simulation results demonstrates that bulk modulus should be considered as a variable parameter to obtain a more realistic model. Additionally, a PID controller is insufficient in presence of variable bulk modulus, whereas a fuzzy controller provides robust angular velocity control.
Patent•
12 Jul 2006TL;DR: In this paper, a walking assist device (200) generates a first motion oscillator (shoulder joint angular speed) dΦS/dt, and a first oscillator x pulling each other while reflecting characteristic angular speed ωM.
Abstract: A device for assisting motion of a user in an appropriate rhythm in view point for bringing user’s motion rhythm close to a target rhythm while totally harmonizing each motion rhythm of the user at different part of the body with a rhythm for assisting user’s motion. The inventive walking assist device (200) generates a first motion oscillator (shoulder joint angular speed) dΦS/dt, and a first oscillator x pulling each other while reflecting characteristic angular speed ωM. On the other hand, a new characteristic angular speed ωM is set based on the phase difference (first phase difference) δθ1 between the first motion oscillator dΦH/dt and the first oscillator x. Furthermore, a second oscillator y oscillating in rhythm reflecting the characteristic angular speed ωM is generated based on a second motion oscillator (hip joint angular speed) ΦH. An assist oscillator z is generated based on the second oscillator y and a force variable F depending on the assist oscillator z acts on the body of the user.
TL;DR: A completely general three-dimensional dynamic model is presented to study the sets of free throw release angle, velocity, angular velocity, and lateral deviation angle that result in success (capture), as well as underhand free throws and those using an under-inflated ball.
Abstract: A completely general three-dimensional dynamic model is presented for the motion of basketball shots that may contact the rim, the backboard, the bridge between the rim and board, and possibly the board and the bridge simultaneously. Non-linear ordinary differential equations with six degrees of freedom describe the ball angular velocity and ball centre position. The model includes radial ball compliance and damping and contains five sub-models: purely gravitational flight, and ball-rim, ball-bridge, ball-board, and ball-bridge-board contact. Each contact sub-model has both slipping and non-slipping motions. Switching between the sub-models depends on the reaction force at, and velocity of, the contact point. Although the model can be used to study shots from any point on the court, we here use it to study the sets of free throw release angle, velocity, angular velocity, and lateral deviation angle that result in success (capture), as well as underhand free throws and those using an under-inflated ball. Free throw shots with larger backspin, lower inflation pressures, and underhand release conditions are shown to result in larger capture percentages.
TL;DR: In this paper, the exact equation of spin motion in a cylindrical coordinate system with allowance for electric dipole moments of particles has been derived, which is convenient for analytical calculations of spin dynamics in circular storage rings when the configuration of main fields is simple enough.
Abstract: The exact equation of spin motion in a cylindrical coordinate system with allowance for electric dipole moments of particles has been derived. This equation is convenient for analytical calculations of spin dynamics in circular storage rings when the configuration of main fields is simple enough. The generalized formula for the influence of a vertical betatron oscillation on the angular velocity of spin rotation has been found. This formula agrees with the previously obtained result and contains an additional oscillatory term that can be used for fitting. The relative importance of terms in the equation of spin motion is discussed.
TL;DR: This paper addresses the problem of a rigid body, with unknown inertia matrix, tracking a desired angular velocity reference using adaptive feedback control using sixth-order dynamic compensator and a Lyapunov argument is used to guarantee that asymptotic tracking is achieved globally.
Abstract: This paper addresses the problem of a rigid body, with unknown inertia matrix, tracking a desired angular velocity reference using adaptive feedback control. The control law, which has the form of a sixth-order dynamic compensator, does not require knowledge of the inertia of the rigid body. A Lyapunov argument is used to guarantee that asymptotic tracking is achieved globally. Furthermore, an analytical expression for an upper bound on the magnitude of the required torque is presented for a given reference signal. Next, sufficient conditions on the reference signal are given under which asymptotic identification of the inertia matrix is achieved. Reference signals that satisfy these sufficient conditions are characterized and simulation results that illustrate the control algorithm are presented for a constant spin about a fixed axis and for sinusoidal spins about the body axes. The controller is implemented on an experimental testbed, and experiments are performed for several commanded reference signals. The experimental results demonstrate the tracking performance of the controller, and parameter convergence is observed
Patent•
14 Feb 2006TL;DR: In this article, a free fall detection device capable of detecting a fall accompanied by rotation is provided, which is based on a waveform of an acceleration signal output from the acceleration detection unit and an angular velocity signal from the angular velocity detection unit.
Abstract: A free fall detection device capable of detecting a fall accompanied by rotation is provided. A fall accompanied by rotation is detected based on a waveform of an acceleration signal output from the acceleration detection unit and an angular velocity signal output from the angular velocity detection unit. A gravity center acceleration of the device to be protected is calculated from the acceleration detected by the acceleration detection unit and from the angular velocity detected by the angular velocity detection unit. Even when the device being protected rotates as it falls, the fall of the device can be detected from the detected acceleration or angular velocity. Further, by calculating the gravity center acceleration not affected by the rotation, it is possible to detect a fall of the device with high precision even if the device rotates as it falls.
TL;DR: In this paper, a detailed account on the circuit and control design of a buck converter driven DC motor is given, as well as the steps of design, as for example the choice of the coil, the switching devices employed, all in view of the control objective: tracking control of the DC motor's shaft angular velocity.
TL;DR: In this article, the authors present self-consistent numerical simulations of the Sun's convection zone and radiative interior using a two-dimensional model of the solar equatorial plane.
Abstract: We present self-consistent numerical simulations of the Sun's convection zone and radiative interior using a two-dimensional model of the solar equatorial plane. The background reference state is a one-dimensional solar structure model. Turbulent convection in the outer convection zone continually excites gravity waves that propagate throughout the stable radiative interior and deposit their angular momentum. We find that angular velocity variations in the tachocline are driven by angular momentum transported by overshooting convective plumes rather than nonlinear interaction of waves. The mean flow in the tachocline is time dependent but not oscillatory in direction and not like a quasi-biennial oscillation (QBO). Since the forcing in this shallow region cannot be described by simple linear waves, it is unlikely that the interaction of such waves is responsible for the solar cycle or the 1.3 yr oscillation. However, in the deep radiative interior, the interaction of low-amplitude gravity waves, continually excited by the overshooting plumes, is responsible for the angular velocity deviations observed there, which do resemble a very low amplitude QBO. Near the center of the model Sun the angular velocity deviation is about 2 orders of magnitude greater than that in the bulk of the radiative region and reverses its direction (prograde to retrograde or vice versa) in the opposite sense of the angular velocity deviations that occur in the tachocline. Our simulations thus demonstrate how angular velocity variations in the solar core are linked to those in the tachocline, which themselves are driven by convective overshooting.
TL;DR: A new method of velocity analysis using dual Euler angles and its application in studying rotational contribution from upper extremity segments to club head speed during a golf swing is presented, suggesting the suitability of using the Dual Euler method in analyzing a kinematic chain motion.
TL;DR: In this paper, the fundamental solution of the time dependent Navier-Stokes equations in three dimensions is obtained. But the solution of these problems is restricted to a class of functions that includes the classical Lebesgue spaces Lp(R3), 1 < p < ∞.
Abstract: Explicit formulae for the fundamental solution of the linearized time dependent Navier–Stokes equations in three spatial dimensions are obtained. The linear equations considered in this paper include those used to model rigid bodies that are translating and rotating at a constant velocity. Estimates extending those obtained by Solonnikov in [23] for the fundamental solution of the time dependent Stokes equations, corresponding to zero translational and angular velocity, are established. Existence and uniqueness of solutions of these linearized problems is obtained for a class of functions that includes the classical Lebesgue spaces Lp(R3), 1 < p < ∞. Finally, the asymptotic behavior and semigroup properties of the fundamental solution are established.
TL;DR: In this paper, boundary layer flow analysis of a micropolar fluid on a fixed or continuous moving plane surface is considered. And the results indicate that the effect of the material parameter on skin friction and heat transfer depends on the velocity ratio of the plate and the fluid.
Abstract: The present paper deals with the analysis of boundary-layer flow of a micropolar fluid on a fixed or continuous moving plane surface. Both parallel and reverse moving surfaces to the free stream are considered. The resulting system of nonlinear ordinary differential equations is solved numerically using the Keller-box method. Numerical results are obtained for skin friction coefficient, local Nusselt number, velocity, angular velocity, and temperature profiles. The results indicate that the effect of the material parameter on skin friction and heat transfer depends on the velocity ratio of the plate and the fluid.PACS No.: 47.15.Cb
TL;DR: In this paper, the authors present a velocity equation to be compiled by general-purpose software and applicable to any mechanism topology, and the motion space of the manipulator is obtained from the velocity equation.