Inverse Dynamics Algorithm for Space Robots

1996 ◽  
Vol 118 (3) ◽  
pp. 625-629 ◽  
Author(s):  
Subir Kumar Saha
Keyword(s):  
Efficient Algorithm ◽  
Dynamic Models ◽  
Inverse Dynamics ◽  
Recursive Algorithm ◽  
Space Robot ◽  
Orthogonal Complement ◽  
Free Base ◽  
Space Robots ◽  
Primary Body ◽  
Kinematic Models

An efficient algorithm for the inverse dynamics of free-flying space robots, consisting of a serial manipulator mounted on a free-base, e.g., a spacecraft, is presented. The kinematic and dynamic models are based on the concepts of the Primary Body (PB) and the Natural Orthogonal Complement, respectively, reported elsewhere. In this paper, besides the efficiency, the usefulness of the PB in deriving different kinematic models and selecting an efficient one is pointed out. Moreover, it is shown that a recursive algorithm for the inverse dynamics of the space robot at hand can be developed even without the consideration of the momenta conservation principle.

Parametric Kinematic Tolerance Analysis of Planar Pairs With Multiple Contacts

1996 ◽  
Author(s):  
Elisha Sacks ◽  
Leo Joskowicz
Keyword(s):  
Efficient Algorithm ◽  
Tolerance Analysis ◽  
Parametric Model ◽  
Worst Case ◽  
Multiple Contacts ◽  
Work Cycle ◽  
Computer Aided ◽  
Kinematic Models ◽  
Range Of Variation ◽  
Different Parts

Abstract We present an efficient algorithm for worst-case limit kinematic tolerance analysis of planar kinematic pairs with multiple contacts. The algorithm extends computer-aided kinematic tolerance analysis from mechanisms in which parts interact through permanent contacts to mechanisms in which different parts or part features interact at different stages of the work cycle. Given a parametric model of a pair and the range of variation of the parameters, it constructs parametric kinematic models for the contacts, computes the configurations in which each contact occurs, and derives the sensitivity of the kinematic variation to the parameters. The algorithm also derives qualitative variations, such as under-cutting, interference, and jamming. We demonstrate the algorithm on a 26 parameter model of a Geneva mechanism.

scholarly journals Constraining families of dynamic models using geological, geodetic and strong ground motion data: the Mw 6.5, October 30th, 2016, Norcia earthquake, Italy

2021 ◽  
Author(s):  
Elisa Tinti ◽  
Emanuele Casarotti ◽  
Thomas Ulrich ◽  
Duo Li ◽  
Taufiqurrahman Taufiqurrahman ◽  
...  
Keyword(s):  
Dynamic Models ◽  
Central Italy ◽  
Kinematic Model ◽  
Seismic Wave Propagation ◽  
Dynamic Rupture ◽  
Friction Coefficients ◽  
Multiple Faults ◽  
Central Italy Earthquake ◽  
Trade Offs ◽  
Kinematic Models

The 2016 Central Italy earthquake sequence is characterized by remarkable rupture complexity, including highly heterogeneous slip across multiple faults in an extensional tectonic regime. The dense coverage and high quality of geodetic and seismic data allow to image intriguing details of the rupture kinematics of the largest earthquake of the sequence, the Mw 6.5 October 30th, 2016 Norcia earthquake, such as an energetically weak nucleation phase. Several kinematic models suggest multiple fault planes rupturing simultaneously, however, the mechanical viability of such models is not guaranteed.Using 3D dynamic rupture and seismic wave propagation simulations accounting for two fault planes, we constrain 'families' of spontaneous dynamic models informed by a high-resolution kinematic rupture model of the earthquake. These families differ in their parameterization of initial heterogeneous shear stress and strength in the framework of linear slip weakening friction.First, we dynamically validate the kinematically inferred two-fault geometry and rake inferences with models based on only depth-dependent stress and constant friction coefficients. Then, more complex models with spatially heterogeneous dynamic parameters allow us to retrieve slip distributions similar to the target kinematic model and yield good agreement with seismic and geodetic observations. We discuss the consistency of the assumed constant or heterogeneous static and dynamic friction coefficients with mechanical properties of rocks at 3-10 km depth characterizing the Italian Central Apennines and their local geological and lithological implications. We suggest that suites of well-fitting dynamic rupture models belonging to the same family generally exist and can be derived by exploiting the trade-offs between dynamic parameters.Our approach will be applicable to validate the viability of kinematic models and classify spontaneous dynamic rupture scenarios that match seismic and geodetic observations at the same time as geological constraints.

scholarly journals Kinematic signatures of triaxial stellar systems

1993 ◽  
Vol 153 ◽  
pp. 407-408
Author(s):  
Richard Arnold ◽  
Tim De Zeeuw ◽  
Chris Hunter
Keyword(s):  
Velocity Field ◽  
Dynamic Models ◽  
Elliptical Galaxies ◽  
Velocity Fields ◽  
Stellar Systems ◽  
Viewing Angle ◽  
Upper Limit ◽  
Wide Range ◽  
Triaxial Stellar Systems ◽  
Kinematic Models

Analytic dynamic models of triaxial stellar systems, such as elliptical galaxies and galactic bulges, can be used to calculate the velocity fields of systems in a wide range of potentials without the need for orbit integrations. We present results from a first application of these models, in the form of velocity fields projected onto the sky. The appearance of the velocity field depends strongly on the viewing angle. Thin orbit models provide a theoretical upper limit to streaming in all possible kinematic models in a given potential.

DELTA: a simple and efficient parallel robot

Robotica ◽  
1990 ◽  
Vol 8 (2) ◽  
pp. 105-109 ◽  
Author(s):  
F. Pierrot ◽  
C. Reynaud ◽  
A. Fournier
Keyword(s):  
Inverse Kinematics ◽  
Research Team ◽  
Dynamic Models ◽  
Inverse Dynamics ◽  
Parallel Robot ◽  
Parallel Robots ◽  
Kinematic Parameters ◽  
Mechanical Structure ◽  
Serial Robots ◽  
École Polytechnique

SummaryThe DELTA parallel robot, designed by an EPFL (Ecole Polytechnique Fédérale de Lausanne) research team, is a mechanical structure which has the advantage of parallel robots and ease of serial robots modeling. This paper presents solutions for a complete modeling of the DELTA parallel robot (direct and inverse kinematics, inverse statics, inverse dynamics), with few arithmetic and trigonometric operations. Our method is based on a satisfactory choice of kinematic parameters and on a few restricting hypotheses for the static and dynamic models. We give some details of each model, we present some computation results and we put the emphasis on some particular points, showing the capabilities of this mechanical structure.

Hardware Experiments of Autonomous Space Robot – A Demonstration of Truss Structure Assembly –

2000 ◽  
Vol 12 (4) ◽  
pp. 343-350 ◽  
Author(s):  
Kei Senda ◽  
◽  
Yoshisada Murotsu ◽  
Akira Mitsuya ◽  
Hirokazu Adachi ◽  
...  
Keyword(s):  
Experimental System ◽  
Space Robot ◽  
Truss Structure ◽  
Two Dimensional ◽  
Air Bearings ◽  
Vision Sensor ◽  
Space Robots ◽  
Automatic Construction ◽  
System A ◽  
Structure Assembly

This paper addresses an experimental system simulating a free-flying space robot, which has been constructed to study autonomous space robots. The experimental system consists of a space robot model, a frictionless table system, a computer system, and a vision sensor system. The robot model composed of two manipulators and a satellite vehicle can move freely on a two-dimensional planar table without friction by using air-bearings. The robot model has successfully performed the automatic truss structure construction including many jobs, e.g., manipulator berthing, component manipulation, arm trajectory control avoiding collision, assembly considering contact with the environment, etc. The experiment demonstrates the possibility of the automatic construction and the usefulness of space robots.

scholarly journals Trajectory Planning with Pose Feedback for a Dual-Arm Space Robot

2016 ◽  
Vol 2016 ◽  
pp. 1-9 ◽  
Author(s):  
Yicheng Liu ◽  
Kedi Xie ◽  
Tao Zhang ◽  
Ning Cai
Keyword(s):  
Trajectory Planning ◽  
Path Tracking ◽  
Space Robot ◽  
End Effector ◽  
Planning Algorithm ◽  
Kinematic Models ◽  
Simulation Results ◽  
Singular Configuration ◽  
Theoretical Analyses ◽  
Dual Arm

In order to obtain high precision path tracking for a dual-arm space robot, a trajectory planning method with pose feedback is proposed to be introduced into the design process in this paper. Firstly, pose error kinematic models are derived from the related kinematics and desired pose command for the end-effector and the base, respectively. On this basis, trajectory planning with pose feedback is proposed from a control perspective. Theoretical analyses show that the proposed trajectory planning algorithm can guarantee that pose error converges to zero exponentially for both the end-effector and the base when the robot is out of singular configuration. Compared with the existing algorithms, the proposed algorithm can lead to higher precision path tracking for the end-effector. Furthermore, the algorithm renders the system good anti-interference property for the base. Simulation results demonstrate the effectiveness of the proposed trajectory planning algorithm.

Dynamics of Serial Multibody Systems Using the Decoupled Natural Orthogonal Complement Matrices

1999 ◽  
Vol 66 (4) ◽  
pp. 986-996 ◽  
Author(s):  
S. K. Saha
Keyword(s):  
Multibody Systems ◽  
Degrees Of Freedom ◽  
Inverse Dynamics ◽  
Equations Of Motion ◽  
Kinematic Chain ◽  
Rigid Bodies ◽  
Dynamic Equations ◽  
Orthogonal Complement ◽  
Forward Dynamics ◽  
Velocity Constraints

Constrained dynamic equations of motion of serial multibody systems consisting of rigid bodies in a serial kinematic chain are derived in this paper. First, the Newton-Euler equations of motion of the decoupled rigid bodies of the system at hand are written. Then, with the aid of the decoupled natural orthogonal complement (DeNOC) matrices associated with the velocity constraints of the connecting bodies, the Euler-Lagrange independent equations of motion are derived. The De NOC is essentially the decoupled form of the natural orthogonal complement (NOC) matrix, introduced elsewhere. Whereas the use of the latter provides recursive order n—n being the degrees-of-freedom of the system at hand—inverse dynamics and order n3 forward dynamics algorithms, respectively, the former leads to recursive order n algorithms for both the cases. The order n algorithms are desirable not only for their computational efficiency but also for their numerical stability, particularly, in forward dynamics and simulation, where the system’s accelerations are solved from the dynamic equations of motion and subsequently integrated numerically. The algorithms are illustrated with a three-link three-degrees-of-freedom planar manipulator and a six-degrees-of-freedom Stanford arm.

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