Onboard Avionics Research Articles

Platform and State Estimation Design of a Small-Scale UAV Helicopter System

This paper presents the development of a small-scale unmanned aerial vehicle (UAV) helicopter system based on a Raptor 90 hobby helicopter. Firstly, onboard avionics system and ground station are designed carefully. The onboard avionics system mainly consists of sensors, flight control board, RF modem, and power supply system. The ground station comprises a computer and a RF modem. The main function of ground station is to monitor the status of onboard avionics. To avoid the effect of noises, some efficient sensor data processing and integrated navigation algorithms are designed and implemented on the onboard avionics. As a result, the constructed system exhibits low weight, small size, antivibration, and low power consumption; the essential information for system identification and automatic control can be easily acquired. Several ground and flight tests have been performed to verify the feasibility and reliability of the total system. The results show that it is sufficient for system identification and automatic control.

Robust Motion Controller Design and Implementation for Unmanned Helicopter

In this paper a novel robust controller is investigated for unmanned helicopter. Based on signal compensation theory, robust controllers are designed to enhance both rotational and translational tracking performance, as well as robust performance over parameter uncertainty and external disturbance. The designed robust controllers are time invariant and easy to realize. The full controllers are implemented on onboard avionics of a small scale unmanned helicopter THeli260 developed by Tsinghua University. Real flight experiments are successfully carried out, which shows advantage of designed robust controller.

Role of avionics in trajectory-based operations

Air Traffic Management automation systems are being developed and fielded to assist controllers in handling more aircraft and larger airspace per controller. Many of these systems are time-based and built upon predicting the aircraft trajectories as accurately as possible. Trajectories of multiple aircraft are strategically deconflicted by modifying appropriate trajectories and issuing corresponding clearances to the aircraft. However, disturbances and modeling errors will cause aircraft to deviate from their predicted trajectories and controllers will need to take action to keep trajectories free from conflict. The associated increase in workload will reduce the usefulness of these automation systems. On-board avionics can help improve the accuracy of the trajectory prediction system in three ways: (1) sharing aircraft state information to improve the performance of the ground trajectory prediction system, (2) sharing airborne prediction results and allowable minimum and maximum arrival times at key route waypoints, and, finally, (3) by applying feedback control onboard the aircraft to autonomously correct for disturbances encountered in flight. This presents an analysis of trajectory dispersion with and without airborne time of arrival control, presents an operational concept for air/ground trajectory negotiation, discusses integration with airborne merging and spacing algorithms, and raises concerns about challenges in implementing this integrated solution.

A technology for scheduling of data exchange over bus with centralized control in onboard avionics systems

In this paper, the problem of automatic scheduling of data exchange over a channel with centralized control in real-time avionics (RTA) systems is addressed. Examples of such channels are MIL STD-1553B multiplex data bus and Fibre Channel FC-AE-1553. Scheduling algorithms implementing greedy strategy and ant colony method are presented and evaluated experimentally. These algorithms support customization for specific requirements of the target onboard RTA system. Results of experimental evaluation demonstrate that the ant colony algorithm outperforms greedy algorithms on most of the considered classes of input data, with realistic technological requirements to data exchange. The proposed technology for data exchange scheduling is implemented in a tool system. Two case studies of industrial application of the system to the development of onboard real-time systems are described.

LINKMAV, A PROTOYPE ROTARY WING MICRO AERIAL VEHICLE

This paper provides an overview about the design of the LinkMAV rotary wing autonomous Micro Aerial Vehicle. The paper describes the flying platform, the main problems related to aerodynamics and propulsion, the onboard avionics and the flight control system, including the autonomous navigation algorithms. We also describe the sensor chosen for the MAV05 competition, held in Garmisch Partenkirchen, and a high level system and multi-modal interface providing more advanced autonomy in terms of collision free path planning and in-flight mission reconfiguration.

SMART-1: Development and lessons learnt

SMART-1 is the first of the small missions for advanced research and technology as part of ESA's science programme “Cosmic vision”. It was successfully launched on September 27, 2003 and is presently traveling towards its destination, the Moon. The main objective of the mission, to demonstrate solar electric primary propulsion for future Cornerstones (such as Bepi-Colombo), has already been achieved. At the time of writing the electric propulsion system has been working already for more than 3400 h and has provided a Delta-V to the spacecraft of more than 2500 m/s. The other technology objectives are also being fulfilled by the verification of the proper functioning of such on-board experiments like the X-Ka band transponder, the X-ray spectrometer, the near IR spectrometer, the laser link, etc. The scientific objectives are related to lunar science and will be fulfilled once the spacecraft enters its operational lunar orbit, currently expected for January 2005. SMART-1 lunar science investigations will include studies of the chemical composition of the Moon, of geophysical processes, environment and high-resolution studies in preparation for future steps of lunar exploration. SMART-1 has been an innovative mission in many aspects and we are now drawing some preliminary conclusions about the lessons to be learnt. The paper describes the spacecraft and the technology elements with particular emphasis to the technology nature of the mission. The on-board avionics employs many novel designs for spacecraft, including a serial CAN bus for data communication, autonomous star trackers and extensive use of auto-code generation for implementing the attitude control system and the failure, detection, isolation and recovery (FDIR). Finally, the orbital operation phase currently ongoing, including the routine electric propulsion operations and the instrument commissioning, is providing a wealth of data and lesson-learnt useful for future autonomous planetary missions.

DEIS UAV: GNC Design and Avionics Implementation Issues

The School of Aerospace Engineering of the Forli Branch of the University of Bologna is currently developing an Unmanned Aerial Vehicle (UAV) which, thanks to a partially autonomous flight capability, aims to be a very low cost and compact flying platform capable of performing significant flight tests of general GNC algorithms or mission oriented experiments. The development activity includes the project, the synthesis and the assembly of the on-board avionics equipment, together with the software implementation for both data collection and some basic GNC algorithms. A demonstrative application will be the test of some integrity monitoring functions and algorithms using data collected during some flights.

パラフォイルによる滑空・着陸技術の予備検討(S68-3 ハイブリッドロケットおよび回収技術,S68 学生による宇宙活動)

The goal of this study is to develop an autonomous guidance and control system for prospective spacecraft recovery using parafoils. As the first phase of such efforts, a parafoil flight experiment vehicle equipped with a propulsion system for running and taking off by itself was designed and fabricated, with the aim of acquiring know-how of handling parafoils and designing/fabricating vehicles. In addition, on-board avionics for measuring parafoil flight dynamics were designed and fabricated. Preliminary flight experiments were carried out in Muroran/Furthermore, a plan of establishing a system for lifting the vehicles up to an altitude and releasing them for parafoil opening and gliding is outlined.

Optical fiber wavelength division multiplexing

During flight, aircraft avionics transmit and receive RF signals to/from antennas over coaxial cables. As the density and complexity of onboard avionics increases, the electromagnetic interference (EMI) environment degrades proportionately, leading to decreasing signal-to-noise ratios (SNRs) and potential safety concerns. The coaxial cables are inherently lossy, limiting the RF signal bandwidth while adding considerable weight. To overcome these limitations, we have investigated a fiber optic communications link for aircraft that utilizes wavelength division multiplexing (WDM) to support the simultaneous transmission of multiple signals (including RF) over a single optical fiber. Optical fiber has many advantages over coaxial cable, particularly lower loss, greater bandwidth, and immunity to EMI. In this paper, we demonstrate that WDM can be successfully used to transmit multiple RF signals over a single optical fiber with no appreciable signal degradation. We investigate the transmission of FM and AM analog modulated signals, as well as FSK digital modulated signals, over a fiber optic link (FOL) employing WDM. We present measurements of power loss, delay, SNR, carrier-to-noise ratio (CNR), total harmonic distortion (THD), and bit error rate (BER). Our experimental results indicate that WDM is a fiber optic technology suitable for avionics applications.

Optimal flight management system utilization with ATC automation

The requirements and design philosophy for developing ground-based automation planning and control advisory concepts to best serve aircraft with flight management systems (FMS) are defined. Analytical results are presented that are based on the comparison of operational data with the user-preferred trajectories to identify flying-time variabilities in various segments of arriving flights. En route descents, terminal maneuvering areas, and the final approaches are considered to determine the impact of aircraft and environmental factors on flying times essential for traffic planning. Simple time-estimation algorithms based on FMS-defined speed schedules and prevailing winds are presented for estimating flying times during en route descents. Automation, planning and control concepts are developed that utilize flexible route structures and a speed-control strategy to permit the aircraft maximum use of FMS and onboard avionics in all operating conditions. >

Aeronautical satellite data link concept, design, and flight test results

The MITRE Corporation has conducted a three-year study of aeronautical satellite communications that culminated in a set of flight tests over the North Atlantic during August of 1985. The flight tests required the cooperation of four organizations in addition to MITRE: The Communications Satellite Corporation (COMSAT), Rockwell International, Ball Aerospace and Avantek. A test aircraft, equipped with a specially designed satellite data link terminal and antenna configuration, was flown from Cedar Rapids, Iowa across the North Atlantic to Iceland, and north of Iceland to 75° latitude. The purpose of the flight tests was to measure the performance of a full duplex aeronautical satellite data link (ASDL) using the International Maritime Satellite Organization's (INMARSAT's) spacecraft and earth station at Southbury, Connecticut, and to demonstrate potential applications. The data link operates at 200 bits-per-second (bps), uses forward error correction (FEC) coding, and employs a terminal monitor that provides interfaces to on-board avionics, data recording equipment, and an industry-standard personal computer (PC). The PC serves as a user terminal as well as a real-time monitor of bit-error-rate (BER) performance. In addition to channel propagation and BER experiments, demonstrations of potential applications of an oceanic ASDL system were conducted. A standard commercial airline data link management unit (MU) was used to communicate data over the ASDL using standard protocols. The interface to the MU allowed access to data from two distinct navigation systems: an inertial navigation system (INS) and a Global Positioning System (GPS) receiver. Aircraft position data was transmitted from the aircraft to the earth station on an automatic basis to simulate automatic dependent surveillance (ADS) of oceanic air space. This paper is divided into three sections: 1) A discussion of background issues, such as the motivation for the reported research and development, and important operational ASDL system design topics; 2) a detailed description of the developed ASDL design; and 3) a description of the test program and a preliminary summary of the results.

A Microprocessor-Based Automatic Test Controller (ATC)

An 8085-based ATC with IEEE-STD-488 interface has been designed and developed for the batch-testing of on-board avionics units like pre-amplifiers.