Dynamics and control of a spacecraft with a moving, pulsating ball in a spherical cavity

A model with two interacting bodies, for a spacecraft with liquid, has been developed. The spacecraft without liquid is the "tank" and is characterized by its inertial properties and the location and size of a spherical cavity. In the cavity is located the "slug", a sphere of uniform density with a variable radius. At the point of contact...

On the simulation of fluid spacecraft interactive dynamics

The present report contains a study on the simulation of interactive fluid spacecraft dynamics. The equations of motion of the two dimensional full tank case as well as the corresponding finite different discretized equations are presented. The numerical solution of this system is studied. Results are presented for a number of cases. Based on...

A study on methods to compare measured and calculated modal data

Fokker Space and Systems and the National Aerospace Laboratory NLR performed a study to integrate more systematically the experimental and analytical analysis of the dynamic behaviour of structures. The study focused on the correlation of experimental and analytical data, matrix and parameter updating methods. In this paper an overview will be...

Dynamics motion simulation of the Hermes robot arm subjected to constraints

During operations with a manipulator arm situations will occur when the manipulator end-effector is, or comes, in contact with its environment. The dynamics equations, which describe the motion of the manipulator, can be represented by an ordinary differential equation for the free motion and an additional algebraic (in)equality for the motion...

Linear recursive formulation of flexible multi-body space system dynamics

Numerical simulation of the dynamics of multi-body systems constitutes a central part in the design and analysis of modern space-based systems. The report focuses on the development of a recursive formulation of the dynamics of flexible spacecraft-robotmanipulator systems, suitable for efficient numerical simulation. The rather well-established...

Modelling dynamical systems with equality state-space constraints

A mathematical theory for modelling dynamical systems with equality state-space constraints is presented. The dynamic behaviour of these systems is represented by a combination of differential and algebraic equations. It Is shown that the freedom offered by control is essential to obtain other, mathematically equivalent formulations. The notion...

Numerical solution of dynamical systems with equality state-space constraints

Numerical simulation of constrained dynamical systems is known to exhibit stability problems even when the unconstrained system can be simulated in a stable manner. We show that not the constraints themselves, but the transformation of a continuous set of equations to a discrete set of equations is the true source of the stability problem....

Study on efficient numerical time-integration methods for simulation of multi-body systems

This report describes the results of an evaluation of numerical integration schemes to be used for the digital simulation of second order ordinary differential equations (ODE's) which are characteristic for multibody systems such as space manipulators. The study focuses on dedicated schemes for this type of systems. Main attention is paid to the...

Quasi-recursive dynamics equations for spacecraft-based flexible robotic manipulators

The report contains the development of the dynamics equations of a spacecraftmanipulator system with chain topology. The spacecraft may be flexible. The attached manipulator consists of an arbitrary number of links, connected by single degree-of-freedom rotational joints. None, any, or all of the links may be flexible. A rigid or flexible...

Equivalent flexibility modelling for the recursive simulation of robot manipulator dymamics

The report focuses on the mathematical modelling of the dynamics of spacecraft based manipulators displaying structural flexibility in their links. The equations of motion must be cast in a form suitable for efficient numerical simulation. Equations of motion found in literature are usually written in the form of an augmented system of...

Flexible space-based robot modelling and real-time simulation

The Hermes manipulation system (HERA) is a sophisticated space manipulator system, which has to perform tasks ranging from berthing to tool operation in various operational modes from fully automatic to purely manual. Development and qualification of such a space-based manipulator must be supported by computer simulation facilities. The HERA...

A reference model for the dynamics of a flexible, spacecraft-based manipulator

The objective of the study is to develop the equations of motion of a single link, flexible manipulator, attached to an orbiting spacecraft. A payload may be attached to the end-effector of the manipulator. Starting point is d'Alembert's principle, with displacements described by hybrid coordinates. The equations of motion for the two-body...

Dynamics of flexible spacecraft: an analysis approaches towards mathematical model order reduction

Increases in size and mechanical complexity of spacecraft result in increased complexity of the mathematical model which describes the spacecraft dynamics. This results in turn in increased computational effort, in increased difficulties in understanding the characteristics of the spacecraft dynamics, and in increased difficulties in the design...

Methoden voor het verbeteren van dynamische modellen van constructies

A survey of computational methods to improve dynamic analytical models described in the literature is made. Both the matrix methods and the optimal correction method of the dynamic model using the measured modes are discussed.

Towards digital computer simulation of the dynamics of flexible spacecraft

Software design for digital computer simulation of the dynamics of flexible spacecraft equipped with actuators and sensors, should take into account two properties of the overall system: (i) s.ampled-data control of the spacecraft leads to discontinuous inputs (forcing functions) in the differential equations of motion, thereby requiring...

Some investigations on the notching procedtire used in shaker tests on satellites

The notching procedure as used in the shaker test on a satellite is critically examined. In stead of the notching procedure an alternative test set-up, in which the dynamic interaction between launcher and spacecraft is taken into account, has been proposed and investigated for a simple model of launcher and satellite. Using this test set-up the...