An improved airborne wind measurement technique for the NAE twin otter

Airborne wind measurement techniques currently being used onboard the NAE Twin Otter Atmospheric Research Aircraft are described and their fundamentallimitations are discussed. In particular, a recently acquired L TN-90-1 00 strapdown inertial reference system (IRS) demonstrates significant low frequency Schuier oscillations in its velocity...

CAESAR, a CCD airborne experimental scanner for applications in remote sensing radiometric and geometric calibration

Within the framework of the National Remote Sensing Programme, an airborne push-broom scanner was developed in The Netherlands by the National Aerospace Laboratory NLR and the Institute for Applied Physics TNO-TH (TPD). With the development of this scanner, named CAESAR, two objectives were fulfilled: technical knowledge about CCD detectors and...

A modular and versatile acquisition, recording and preprocessing system for airborne remote sensing

The National Aerospace Laboratory "NLR" is the operator of an aircraft which can be equipped with either a SLAK, a multl spectral scanner or a TVbased scanner. The airborne recording equipment la designed to accommodate these various sensors. The general airborne system setup is: the sensor, a dedicated digitizing unit and an Interface to a High...

Crop identification with microwaves (SLAR-data of 1985)

Microwaves (i.e. X-band SLAR) have been used in The Netherlands for many years within ROVE to identify agricultural crops. This report deals with data acquisition, preprocessing and classification of agricultural crops in The Netherlands using the Dutch Digital SLAR. With internal and external calibration of the instrument satisfactory results...

Testing of spacecraft attitude and orbit control systems

The testing of Spacecraft Attitude and Orbit Control Subsystems is described from the early design up to in-flight, inclusive. Main topics dealt with are: description of three generic AOCS test classes, model philosophy, standardization, subsystem static test methods, subsystem dynamic test methods, generic test equipment and test facilities....

In-flight attitude estimations and control experiments with Iras based on modern control theory

One of the research activities of the Space Division of the National Aerospace Laboratory NLR is the application of modern estimation and control theory to spacecraft attitude control problems. Algorithms for spacecraft state estimation and attitude control, as well as for inertial-optical attitude determination have been developed previously...

Reliability aspects of software for digital avionics

Modern commercial transport aircraft contain digital avionics systems for more and more safety critical functions. The reliability and safety of those new systems depend on the hardware reliability and on the reliability of the embedded software. In this report, an overview is given of available methods and techniques to develop reliable...

Application of model following control and estimation techniques to attitude control of manoeuvring spacecraft Part I: Theory and simulation results

This document presents an approach to sampled data, on-board estimation and control of the attitude motion of manoeuvring spacecraft. Algorithms which are developed include: a - model following control of attitude manoeuvres b - estimation of spacecraft state (attitude, angular velocity, disturbance torque) c - optical-inertial attitude...

Application of model following control and estimation techniques to attitude control of manoeuvring spacecraft Part II: Simulation software description

This document describes two computer programs developed during a study of the application of modern control techniques in the area of spacecraft attitude control. Theory and simulation results are described in part I of this report. In part II a general overview of the tasks of the simulation program is presented, and program design aspects are...

Trends in airline avionics

Modern avionics are an integral part of the aircraft. They provide the functions of communication, navigation, energy management, identification, weather, terrain, and collision avoidance, the presentation of flight and warning data as well as aircraft guidance and stabilization. New developments in micro-electronics and display technology...

IRAS on-board software

The infra Red Astronomical Satellite IRAS will be laimched in February I98I for a mission of one year duration. The purpose of the mission is to produce a full sky catalogue in the infrared waveband. The IRAS satellite will be equipped with an on-board computer system to control the satellite and to execute the measurements necessary to fulfil...

In-orbit experiment with an attitude control algorithm for ANS based on modern control principles

The existing fine attitude system of the Astronomical Netherlands Satellite was designed on the basis of conventional digital control techniques. The possibility of a more advanced approach is presented in this report. As an example, an alternative control algorithm for the scan mode has been developed with the use of state estimation and state...