scholarly journals Attitude Determination Algorithms through Accelerometers, GNSS Sensors, and Gravity Vector Estimator

2018 ◽  
Vol 2018 ◽  
pp. 1-14 ◽  
Author(s):  
Raúl de Celis ◽  
Luis Cadarso
Keyword(s):  
Reference Frame ◽  
Velocity Vector ◽  
Reference Frames ◽  
Attitude Determination ◽  
The Body ◽  
Gravity Vector ◽  
New Approach ◽  
Spacecraft Navigation ◽  
Body Reference ◽  
Ballistic Projectiles

Aircraft and spacecraft navigation precision is dependent on the measurement system for position and attitude determination. Rotation of an aircraft can be determined measuring two vectors in two different reference systems. Velocity vector can be determined in the inertial reference frame from a GNSS-based sensor and by integrating the acceleration measurements in the body reference frame. Estimating gravity vector in both reference frames, and combining with velocity vector, determines rotation of the body. A new approach for gravity vector estimations is presented and employed in an attitude determination algorithm. Nonlinear simulations demonstrate that using directly the positioning and velocity outputs of GNSS sensors and strap-down accelerometers, aircraft attitude determination is precise, especially in ballistic projectiles, to substitute precise attitude determination devices, usually expensive and forced to bear high solicitations as for instance G forces.

scholarly journals Equivalence of Euler equations and torque-angular momentum relation

2021 ◽  
Vol 18 (1) ◽  
pp. 136
Author(s):  
V. Tanriverdi
Keyword(s):  
Angular Momentum ◽  
Rigid Body ◽  
Reference Frame ◽  
Euler Equations ◽  
Equations Of Motion ◽  
The Body ◽  
Moments Of Inertia ◽  
Body Reference ◽  
Stationary Reference Frame ◽  
Momentum Relation

Euler derived equations for rigid body rotations in the body reference frame and in the stationary reference frame by considering an infinitesimal part of the rigid body.Another derivation is possible, and it is widely used: transforming torque-angular momentum relation to the body reference frame.However, their equivalence is not shown explicitly.In this work, for a rigid body with different moments of inertia, we calculated Euler equations explicitly in the body reference frame and in the stationary reference frame and torque-angular momentum relation.We also calculated equations of motion from Lagrangian.These calculations show that all four of them are equivalent.

scholarly journals POINT CLOUD REFINEMENT WITH A TARGET-FREE INTRINSIC CALIBRATION OF A MOBILE MULTI-BEAM LIDAR SYSTEM

2016 ◽  
Vol XLI-B3 ◽  
pp. 359-366
Author(s):  
H. Nouiraa ◽  
J. E. Deschaud ◽  
F. Goulettea
Keyword(s):  
Reference Frame ◽  
Real Data ◽  
Point Clouds ◽  
The Body ◽  
Mobile Mapping ◽  
Extrinsic Calibration ◽  
Body Reference ◽  
3D Information ◽  
Calibration Parameters ◽  
Mapping Systems

LIDAR sensors are widely used in mobile mapping systems. The mobile mapping platforms allow to have fast acquisition in cities for example, which would take much longer with static mapping systems. The LIDAR sensors provide reliable and precise 3D information, which can be used in various applications: mapping of the environment; localization of objects; detection of changes. Also, with the recent developments, multi-beam LIDAR sensors have appeared, and are able to provide a high amount of data with a high level of detail. <br><br> A mono-beam LIDAR sensor mounted on a mobile platform will have an extrinsic calibration to be done, so the data acquired and registered in the sensor reference frame can be represented in the body reference frame, modeling the mobile system. For a multibeam LIDAR sensor, we can separate its calibration into two distinct parts: on one hand, we have an extrinsic calibration, in common with mono-beam LIDAR sensors, which gives the transformation between the sensor cartesian reference frame and the body reference frame. On the other hand, there is an intrinsic calibration, which gives the relations between the beams of the multi-beam sensor. This calibration depends on a model given by the constructor, but the model can be non optimal, which would bring errors and noise into the acquired point clouds. In the litterature, some optimizations of the calibration parameters are proposed, but need a specific routine or environment, which can be constraining and time-consuming. <br><br> In this article, we present an automatic method for improving the intrinsic calibration of a multi-beam LIDAR sensor, the Velodyne HDL-32E. The proposed approach does not need any calibration target, and only uses information from the acquired point clouds, which makes it simple and fast to use. Also, a corrected model for the Velodyne sensor is proposed. <br><br> An energy function which penalizes points far from local planar surfaces is used to optimize the different proposed parameters for the corrected model, and we are able to give a confidence value for the calibration parameters found. Optimization results on both synthetic and real data are presented.

scholarly journals On the Geodetic Rotation of the Major Planets, the Moon and the Sun

2009 ◽  
Vol 44 (2) ◽  
pp. 43-52
Author(s):  
G. Eroshkin ◽  
V. Pashkevich
Keyword(s):  
Angular Velocity ◽  
Reference Frame ◽  
Velocity Vector ◽  
Previous Investigation ◽  
The Body ◽  
The Other ◽  
The Sun ◽  
The Moon ◽  
Angular Velocity Vector

On the Geodetic Rotation of the Major Planets, the Moon and the SunThe problem of the geodetic (relativistic) rotation of the major planets, the Moon and the Sun was studied in the paper by Eroshkin and Pashkevich (2007) only for the components of the angular velocity vectors of the geodetic rotation, which are orthogonal to the plane of the fixed ecliptic J2000. This research represents an extension of the previous investigation to all the other components of the angular velocity vector of the geodetic rotation, with respect to the body-centric reference frame from Seidelmann et al. (2005).

Explaining Ground Effect Aerodynamics via a Real-Life Reference Frame

2014 ◽  
Vol 553 ◽  
pp. 229-234
Author(s):  
Philip Close ◽  
Tracie J. Barber
Keyword(s):  
Reference Frame ◽  
Reference Frames ◽  
Computational Simulation ◽  
Real Life ◽  
Computational Modelling ◽  
Ground Effect ◽  
The Body ◽  
Moving Body ◽  
Set Up ◽  
Insight Into

The principle of relative motion as the cause of forces on a body submersedin a uid is foundational in the study of uid mechanics. In aerodynamics the wind tunnelis used as a convenient and safe method by which to test the aerodynamic performance ofbodies. This body-stationary convention has carried over into the computational world withthe development of CFD, though there is no practical reason why the moving body/stationaryuid set-up that corresponds to reality cannot be used for computational modelling. This pointbecomes particularly important as the concept of ground e ect is introduced. With an extraboundary nearby it becomes harder to appropriatel y match the experimental set-up with reality,and the extra boundary condition also adds complexity to computational simulation. A studywas undertaken to compare the body-stationary and body-moving reference frames in grounde ect. The moving reference frame velocity elds allowed new insight into the aerodynamics ofground e ect.

Balancing the Mind

2012 ◽  
Vol 59 (6) ◽  
pp. 332-339 ◽  
Author(s):  
Caroline J. Falconer ◽  
Fred W. Mast
Keyword(s):  
Reference Frames ◽  
Body Schema ◽  
Vestibular Stimulation ◽  
The Body ◽  
Whole Body ◽  
Bottom Up ◽  
Mental Transformation ◽  
Body Reference ◽  
The Mind ◽  
Mental Transformations

The body schema is a key component in accomplishing egocentric mental transformations, which rely on bodily reference frames. These reference frames are based on a plurality of different cognitive and sensory cues among which the vestibular system plays a prominent role. We investigated whether a bottom-up influence of vestibular stimulation modulates the ability to perform egocentric mental transformations. Participants were significantly faster to make correct spatial judgments during vestibular stimulation as compared to sham stimulation. Interestingly, no such effects were found for mental transformation of hand stimuli or during mental transformations of letters, thus showing a selective influence of vestibular stimulation on the rotation of whole-body reference frames. Furthermore, we found an interaction with the angle of rotation and vestibular stimulation demonstrating an increase in facilitation during mental body rotations in a direction congruent with rightward vestibular afferents. We propose that facilitation reflects a convergence in shared brain areas that process bottom-up vestibular signals and top-down imagined whole-body rotations, including the precuneus and tempero-parietal junction. Ultimately, our results show that vestibular information can influence higher-order cognitive processes, such as the body schema and mental imagery.

scholarly journals Optimization-based Attitude Determination in Geodetic Applications

2020 ◽  
Vol 10 (1) ◽  
pp. 270-275
Author(s):  
Alexander Pesterev ◽  
Ivan Matrosov ◽  
Yury Morozov
Keyword(s):  
Rigid Body ◽  
Minimization Problem ◽  
Field Experiments ◽  
Attitude Determination ◽  
Traditional Approach ◽  
The Body ◽  
New Approach ◽  
Satellite Antenna ◽  
Initial Attitude ◽  
Magnetic Disturbances

AbstractA new approach to determining the attitude of a rigid body is suggested, which does not rely on the use of magnetometers. In the framework of this approach, the problem of determining the attitude reduces to solving a minimization problem for a function of three variables (angles characterizing the initial attitude of the body). The proposed method can be employed in precise geodetic measurements carried out with the use of a geodetic pole with a satellite antenna and an IMU installed on its top when, for some reasons, the surveyor cannot position the pole vertically (e.g., near walls or buildings). The use of the traditional approach, which relies on a compass and accelerometers, in this case does not ensure the desired accuracy of the attitude determination due to magnetic disturbances (both external ones and those induced by the receiver) affecting badly compass readings. The discussion is illustrated by results of field experiments.

scholarly journals POINT CLOUD REFINEMENT WITH A TARGET-FREE INTRINSIC CALIBRATION OF A MOBILE MULTI-BEAM LIDAR SYSTEM

2016 ◽  
Vol XLI-B3 ◽  
pp. 359-366
Author(s):  
H. Nouiraa ◽  
J. E. Deschaud ◽  
F. Goulettea
Keyword(s):  
Reference Frame ◽  
Real Data ◽  
Point Clouds ◽  
The Body ◽  
Mobile Mapping ◽  
Extrinsic Calibration ◽  
Body Reference ◽  
3D Information ◽  
Calibration Parameters ◽  
Mapping Systems

LIDAR sensors are widely used in mobile mapping systems. The mobile mapping platforms allow to have fast acquisition in cities for example, which would take much longer with static mapping systems. The LIDAR sensors provide reliable and precise 3D information, which can be used in various applications: mapping of the environment; localization of objects; detection of changes. Also, with the recent developments, multi-beam LIDAR sensors have appeared, and are able to provide a high amount of data with a high level of detail. <br><br> A mono-beam LIDAR sensor mounted on a mobile platform will have an extrinsic calibration to be done, so the data acquired and registered in the sensor reference frame can be represented in the body reference frame, modeling the mobile system. For a multibeam LIDAR sensor, we can separate its calibration into two distinct parts: on one hand, we have an extrinsic calibration, in common with mono-beam LIDAR sensors, which gives the transformation between the sensor cartesian reference frame and the body reference frame. On the other hand, there is an intrinsic calibration, which gives the relations between the beams of the multi-beam sensor. This calibration depends on a model given by the constructor, but the model can be non optimal, which would bring errors and noise into the acquired point clouds. In the litterature, some optimizations of the calibration parameters are proposed, but need a specific routine or environment, which can be constraining and time-consuming. <br><br> In this article, we present an automatic method for improving the intrinsic calibration of a multi-beam LIDAR sensor, the Velodyne HDL-32E. The proposed approach does not need any calibration target, and only uses information from the acquired point clouds, which makes it simple and fast to use. Also, a corrected model for the Velodyne sensor is proposed. <br><br> An energy function which penalizes points far from local planar surfaces is used to optimize the different proposed parameters for the corrected model, and we are able to give a confidence value for the calibration parameters found. Optimization results on both synthetic and real data are presented.

A Study on Mixed Kinetic-Kinematic Equations for Multibody Systems

2013 ◽  
Author(s):  
Sung-Soo Kim ◽  
Bongcheol Seo ◽  
Myungho Kim
Keyword(s):  
Angular Velocity ◽  
Velocity Vector ◽  
Reference Frames ◽  
Time Derivative ◽  
Kinetic Equations ◽  
Angular Acceleration ◽  
The Body ◽  
Integration Step ◽  
Angular Velocity Vector ◽  
The Relationship

In this paper, mixed kinetic-kinematic equations for a multibody system have been studied in order to resolve the difficulties of non-integrability of angular velocity vectors. As for the kinetic equations, the Newton-Euler equations of motion are considered. They are derived in terms of angular velocity and angular acceleration vectors expressed in the body fixed reference frames. As for the kinematic compatibility equations, two different equations are considered. One is from the relationship between the angular velocity vector and the time derivatives of Euler parameters. The other is from the relationship between the rotational orientation matrix, its time derivative, and the angular velocity vector. In order to investigate the accuracy of the solution methods using two different kinematic compatibility equations, simulations of a spherical pendulum model and a 1/6 robot vehicle model have been carried out. With different integration step-sizes, the constraint violation errors have been also investigated.

Relativistic coordinates’ transformations of accelerating reference frames. A new approach

2021 ◽  
Vol 34 (2) ◽  
pp. 174-177
Author(s):  
J. Deligiannis
Keyword(s):  
Reference Frame ◽  
Reference Frames ◽  
Twin Paradox ◽  
Constant Acceleration ◽  
New Approach

In this paper, Lorentz-type coordinates’ transformations are proposed to connect the coordinates of an accelerating reference frame with the coordinates of a fixed one. Next, these transformations are applied to accelerating frames of constant acceleration. Finally, the Lorentz-type transformations are applied to the twin paradox, in an attempt to describe how the acceleration affects this phenomenon.

scholarly journals Flexible egocentric and allocentric representations of heading signals in parietal cortex

2018 ◽  
Vol 115 (14) ◽  
pp. E3305-E3312 ◽  
Author(s):  
Xiaodong Chen ◽  
Gregory C. DeAngelis ◽  
Dora E. Angelaki
Keyword(s):  
Reference Frame ◽  
Parietal Cortex ◽  
Posterior Parietal Cortex ◽  
Reference Frames ◽  
The Body ◽  
Neural Representation ◽  
Body Orientation ◽  
Tuning Curves ◽  
The World ◽  
Posterior Parietal

By systematically manipulating head position relative to the body and eye position relative to the head, previous studies have shown that vestibular tuning curves of neurons in the ventral intraparietal (VIP) area remain invariant when expressed in body-/world-centered coordinates. However, body orientation relative to the world was not manipulated; thus, an egocentric, body-centered representation could not be distinguished from an allocentric, world-centered reference frame. We manipulated the orientation of the body relative to the world such that we could distinguish whether vestibular heading signals in VIP are organized in body- or world-centered reference frames. We found a hybrid representation, depending on gaze direction. When gaze remained fixed relative to the body, the vestibular heading tuning of VIP neurons shifted systematically with body orientation, indicating an egocentric, body-centered reference frame. In contrast, when gaze remained fixed relative to the world, this representation changed to be intermediate between body- and world-centered. We conclude that the neural representation of heading in posterior parietal cortex is flexible, depending on gaze and possibly attentional demands.

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