Engineering Test Satellite VI Research Articles

Attitude Control of an Artificial Satellite Using H∞ and Two-Degree-of-Freedom Control -On-Orbit Experiments Using ETS-VI-

In this paper, results of attitude control experiments using Engineering Test Satellite VI (ETS-VI) on orbit are introduced. ETS-VI is a three-axis-stabilized satellite launched by the National Space Development Agency of Japan (NASDA) in August 1994. Identification and attitude control experiments on orbit were one of the ETS-VI mission programs and were carried out from January to March in 1995. The attitude controllers were designed using H∞ control method and two-degree-of-freedom control method. Experimental results show the effectiveness of these controllers for artificial satellite control.

ETS-VI Magnetic Field Observations of the Near-Earth Magnetotail during Substorms

The magnetic field experiment on board ETS-VI (the Engineering Test Satellite-VI) and initial results from the experiment are presented. ETS-VI was launched on August 28, 1994 and has been placed in anear equatorial orbit with a perigee of 2.3Re, an apogee of 7.1Re, an inclination of 13.4°, and an orbital period of 14.4 hours. The spacecraft is three-axis stabilized. The magnetic field experiment on board the satellite consists of a triaxial fluxgate magnetometer. The magnetometer has a sampling interval of 3 s, and except near perigee, it is operated in the mode having a ±256 nT dynamic range and a 0.125 nT resolution. We have examined the magnetometer data obtained at radial distances from 5.0 to 7.1Re, magnetic latitudes from-10° to 25°, and local times from 14 MLT through midnight to 04 MLT, to study magnetic field variations associated with substorms. Substorm-associated field variations are easily seen at larger radial distances and at local times later than 19 MLT. Using 92 substorm events that occurred in the 21-01 MLT sector, we have constructed the average field configuration during the growth phase. The magnetic field becomes highly taillike and its intensity increases at high latitudes (> 10°), while the field intensity decreases at lower latitudes (<10°). The field configuration suggests that the inner edge of the growth phase current system is located near the synchronous altitude at the end of the growth phase.

技術試験衛星VI型による通信実験

技術試験衛星VI型による通信実験

ETS-VI On-Orbit Identification Experiments. 1st Report. Impulse Excitation.

System parameter identification and attitude control experiments (FLEX) have been conducted as one of the bus experiments of Engineering Test Satellite-VI (ETS-VI) launched in August, 1994 by H-II rocket. The objectives of the identification experiment are to evaluate typical identification methods both in the frequency and time domains, to compare the identified parameters with the ones established in the ground test before launch and to construct the standards for designing attitude controller. This paper shows the results of the system parameter identification experiment using impulse excitation by gas jet thrusters for the attitude/orbital control system. Measurement data from attitude control system and paddle mounted accelerometers are down-linked by telemetry and analyzed by the Eigensystem Realization Algorithm (ERA) to identify flexible modal parameters.

モード合成法によるＥＴＳ‐ＶＩのモーダルパラメータ同定

A component mode synthesis technique based on experimentally determined modal parameters is applied to the solar array paddle of Engineering Test Satellite-VI. The paddle structure is divided into four parts and six flexible connective parts. In the synthesis, the measured frequencies are modified by the gravity and atmospheric effects.

技術試験衛星ＶＩ型による柔構造制御実験

技術試験衛星ＶＩ型による柔構造制御実験

Development of multibeam phased array antenna on ets‐vi for s‐band intersatellite communications

AbstractThis paper describes the S‐band intersatellite communication (SIC) antenna to be carried on the Engineering Test Satellite VI scheduled for launch in 1994, to undertake the first intersatellite data relay experiments in Japan. The SIC antenna is an on‐board formed multibeam phased array antenna, the first of this kind in the world to be carried on a satellite. The SIC antenna is capable of simultaneous data relays to several orbiting satellites (user satellites) by means of an electrically scanned beam. With an on‐board microprocessor, the location of a user satellite can be computed, and the beam is pointed toward that direction automatically.In comparison with the system used in the data relay satellite of the United States, the on‐board beam‐forming system has several advantages, such as the effective use of power and frequency in the case in which the number of user satellites is small, as in Japan. In this paper, the function and the configuration of an SIC antenna are described first. Next, analysis of the antenna is presented, including the effect of the phase and amplitude errors caused by temperature fluctuations. Further, as the main components, the newly developed broadband microstrip antenna, a small beam‐forming network with small phase errors, and the phase shifter controller making the computation of the orbit of the user satellite are presented. Finally, the total test results of the on‐board model of the SIC antenna are described.

Deployment Performance and Reliability Prediction of Large Deployable Antenna for Satellite Use.

A method to predict the deployment performance and reliability of satellite antennas is proposed. The gravity cancellation method is selected to minimize gravitational effect on deployment performance. Unwanted torque about the hinge axis is calculated using measured misalignment data in ground deployment testing. Parameters of the equation of deployment motion are identified by curve fitting of measured angle-time or angular velocity-time relationship. The comparison between calculated unwanted torque and the identified one shows good agreement. Therefore, in-orbit deployment performance can be predicted by deleting effects unique to ground testing. The deployment reliability prediction method is based on driving and resistive torque generated by constituent parts of deployment mechanisms. Torque measurements show that each part torque distribution can be fitted to the normal distribution. Deployment reliability can be calculated as a probability that driving torque distribution is greater than resistive torque distribution. Prediction methods are applied to the deployable antennas for Engineering Test SatelliteVI (ETS-VI), scheduled for launch in 1994.

Ground verification of deployment dynamics of large deployable spacestructures

This paper describes a precise verification procedure for antenna-deployment mechanisms using ground-deployment test data. Ground-deployment tests are carried out for a communication antenna reflector for the Engineering Test Satellite VI (ETS-VI). The antenna-deployment mechanism studied consisted of a bearing, a helical spring, a chassis, and a latch mechanism. The characteristics of individual parts were measured under space and ground conditions. Then the initial characteristic of a deployment mechanism is statistically predicted. Ground verification of a deployment mechanism is usually difficult because of atmospheric and gravitational effects especially at the system level. Therefore, a new verification procedure is employed. Two kinds of suspending system are developed to compensate for gravity effects. The characteristics of a deployment mechanism can be estimated by identifying system parameters for the equation of deployment motion. This estimation procedure covers all development stages, so that a characteristic history of a deployment mechanism can be easily obtained. Atmospheric and gravitational effects on deployment motion are taken into account as system parameters. It is clarified that all mechanical parts retain their initial characteristics during assembly and environmental testing.

38-GHz-band high-power MMIC amplifier module for satellites on board use

The design and development results of 38-GHz high-power MMIC amplifier modules for use in the solid-state power amplifier (SSPA) to be carried aboard Engineering Test Satellite VI in 1993 are presented. This amplifier will be used in millimeter-wave intersatellite communication experiments. For the development of this amplifier, high-power, highly reliable FETs with 0.25- mu m-long gates were designed. The FET large-signal impedance was accurately measured using an improved load-pull method and MMIC transformers. The measurements were used to design two types of MMICs: one composed of two FET cells with 600- mu m-wide gates and the other of four FET cells with 400- mu m-wide gates. A two-stage amplifier package consisting of two of these MMICs that can be used at 38 GHz is also developed. A P/sub o/(1 dB) of 25 dBm and a gain of 11 dB are obtained. A 38-GHz test conducted during chip screening achieves a high production yield without circuits adjustment.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

On-board multibeam deployable antennas using Ka, C, andS frequency bands

The configuration, on-ground tests, and design verification results for the multibeam antenna flight model for Engineering Test Satellite-VI (ETS-VI) are described for onboard multibeam antennas with thirteen and five beams for the Ka- and S-bands, respectively. The antennas feature Ka-band frequency reuse in alternate beams through use of a cluster horn; shared use of a reflector for two frequency bands using a novel frequency selective surface (FSS); large, lightweight deployable main reflectors with diameters of 3.5 m and 2.5 m; and a highly accurate antenna-pointing control system consisting of RF sensors and an antenna-pointing mechanism to drive the subreflector. >

ETS-VI multibeam satellite communications systems

Satellite systems are expected to play an important role in constructing economical and highly reliable communications networks in combination with terrestrial networks, and to provide attractive new communications services promptly and widely. Multibeam satellite communications technology is one of the most important technologies for improving system economy and transmission capacity for satellite communications. The multibeam satellite communications experiments are planned to be conducted using Engineering Test Satellite-VI (ETS-VI) to be launched in 1993. This paper describes the ETS-VI multibeam satellite communications systems.

Compact equipment for on-board communications subsystem supervisory and control system

Onboard equipment for the communications subsystem supervisory and control (CSC) system of a next-generation multibeam high-capacity communications satellite is discussed. In order to keep the equipment as compact, lightweight, and low in power consumption as possible, an onboard data bus system using four kinds of LSIs was developed. It will be carried on-board the Japanese Engineering Test Satellite VI for launch in 1993. Configuration and functions of the CSC equipment, design philosophy of the LSIs, and characteristics of the LSIs developed are discussed.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

A Study on the Prediction Method for Dynamic Response of a Large Spacecraft in Acoustic Environments.

A new method has been developed to predict the dynamic response of a large spacecraft in acoustic environment during launching. In this study, emphasis was placed on the importance of the effects of the equipment masses attached to spacecraft panels. These effects are not taken into account in traditional methods, such as Statistical Energy Analysis (SEA). It is shown that the dependence on frequencies of equipment responses differs from that for responses of bare sections of the same panels. Emphasis was also placed on the effects of change of radiation efficiency of a panel due to equipment attached to the panel. When the number of equipment attached to a panel is large, the effect of radiation effiency change on the panel response is extremely important. The new method has been applied to predict the dynamic response of a model panel of Engineering Test Satellite-VI (ETS-VI). Agreement between predicted results and measurements is excellent.

Pyroelectric infrared detector for precision earth sensor

Two new types of infrared detectors have been developed for the precision earth sensor in the three axis stabilized satellite, Engineering Test Satellite VI (ETS-VI). Both detectors have a pair of infrared sensing elements, each of which is made of a pyroelectric material and mounted on an immersion lens. A-type element is a flake of lead titanate ceramic, and B-type is a sputtered epitaxial film of calcium-modified lead titanate. The precision earth sensor consists of a scanning mirror and an infrared telescope containing an objective lens, plus either type of infrared detector. Detectivity of each type at 120Hz, which is the nominal frequency of the earth sensor's signal, is 1.5×109Hz1/2/W(A-type) and 2.7×109Hz1/2/W(B-type) at 14∼16.25μm. Each value is 2.5 and 4.5 times as high as the previous model in ETS-V. A-type detector passed the space environmental test and the random error cf attitude measurement was 0.03 deg with the preliminary model of the earth sensor being ahead of the breadboard model. This measurement accuracy is nearly equal to that of the foremost earth sensor. A-type was chosen as the detector for ETS-VI. The random error of the earth sensor with B-type detector is 0.012deg, smaller than a half of the A-type sensor's error. Investigation of B-type is being continued in order to confirm its reliability for space use.

NASDA's Long-Range Plan and Automatic Control

A long-range plan of NASDA's space development, until the beginning of the 21st century and thereafter, is outlined, and automatic control-related features and technologies of the space systems appearing in this long-range plan are described. Currently, NASDA is developing world-level rockets and satellites such as the H-II rocket and the Engineering Test Satellite-VI (ETS-VI). And, NASDA is about to develop the Japanese Experiment Module (JEM) participating in the International Space Station (ISS) program. In the future, NASDA intends to place emphasis on the development of the space infrastructure including such future space systems as the H-II Orbiting Plane (HOPE), the H-II derived rockets, the Rocket Plane (RP), space-to-space transportation systems, the Data Relay and Tracking Satellite (DRTS), manned space facilities, various platforms, etc. And, the space infrastructure around the earth will be extended to the moon and planets. The space infrastructure will be developed economically by employing unmanned systems as much as possible, safely by employing fully-automatic, manned systems, and efficiently by promoting international cooperation with autonomy.

Attitude Control System for Engineering Test Satellite-VI

This paper deals with the Attitude Control System design of the Engineering Test Satellite-VI (ETS-VI). The ACS of ETS-VI is required to provide high attitude control accuracy, high reliability (10 years operational life), excellent operational capability and highly on-borad operational automation. The ACS is designed to meet above requirements. In design results, the high attitude control accuracy of ± 0.05 deg in roll/pitch and ± 0.15 deg in yaw is achieved in on-orbit and the ACS has highly on-borad operational automation functions for the normal and the contingency including the fault-tolerant system. In simulation results, the design results are confirmed.

Design and development of the engineering test satellite-VI

Engineering Test Satellite-VI (ETS-VI) has being developed since 1987 in order to establish the spacecraft bus technology, which is required for the large operational communication and broadcasting spacecraft in 1990s, and to conduct the on-orbit communication experiments for developing the advanced satellite communication technology, which is needed in the future. The ETS-VI will be launched in the Summer of 1992 by the second test flight of H-II launch vehicle (two-stage rocket), which is being developed in parallel with the ETS-VI development. The basic design of the ETS-VI was completed in September 1988, and the detail design phase and manufacturing and test phase have begun. In this paper are described the summary of the ETS-VI program objectives, development plan, on-board experiment, system and subsystem design configured as the results of the basic design, development status and the results of breadboard model testing for the major subsystems are described.

ＥＴＳ‐ＶＩ搭載Ｓバンド衛星間通信用機器システム

The S-band inter-satellite communication system for Japan's Engineering Test Satellite-VI (ETS-VI) to be launched in 1992, is presented. The S-band inter-satellite communication equipment system (SIC) provides a multibeam array antenna with 19 microstrip antenna elements, which is being developed in Japan for an experiment S-band intersatellite data relay and tracking satellite system. The SIC has the compatibility with NASA's S-band multiple access system in Tracking and Data Relay Satellite System (TDRSS) to access to user satellite in TDRSS. The SIC provides an on-board microprocessor for directing the beams to any desired user satellite and on-board beamforming networks. This paper describes performances of the SIC and the experimental S-band inter-satellite communication system using the SIC.

ＥＴＳ−ＶＩ搭載Ｓバンド衛星間通信用オンボード軌道計算追尾システム

On-board orbit calculation and tracking system of the S band inter-satellite communication equipment (SIC) for Japan's Engineering Test Satellite-VI (ETT-VI) to be launched in 1992, is presented. The SIC provides a multibeam phased array antenna with 54 phase shifters for beam pointing. The beams are directed to any desired user satellites automatically by controlling 54 phase shifters according to results of on-board orbit calculations by an on-board microprocessor. As accurate on-board beam pointing is required in inter-satellite communications, this paper describes a method of on-board orbit calculation and estimations of beam pointing errors caused by using the system considering perturbations.