Pavel Paces

Analyses of Triaxial Accelerometer Calibration Algorithms

This paper proposes a calibration procedure in order to minimize the process time and cost. It relies on the suggestion of optimal positions, in which the calibration procedure takes place, and on position number optimization. Furthermore, this paper describes and compares three useful calibration algorithms applicable on triaxial accelerometer to determine its mathematical error model without a need to use an expensive and precise calibration means, which is commonly required. The sensor error model (SEM) of triaxial accelerometer consists of three scale-factor errors, three nonorthogonality angles, and three offsets. For purposes of calibration, two algorithms were tested-the Levenberg-Marquardt and the Thin-Shell algorithm. Both were then related to algorithm based on Matlab fminunc function to analyze their efficiency and results. The proposed calibration procedure and applied algorithms were experimentally verified on accelerometers available on market. We performed various analyses of proposed procedure and proved its capability to estimate the parameters of SEM without a need of precise calibration means, with minimum number of iteration, both saving time, workload, and costs.

Flight attitude track reconstruction using two AHRS units under laboratory conditions

The paper describes a performance analysis of two low-cost AHRS (Attitude and Heading Reference Systems), calibration procedures, and the verification of INS (Inertial Navigation System) mechanization algorithm using dedicated automatic measurement system based on a real-time flight simulation. The measurement system included the flight simulation software FlightGear (FG) that offered a wide range of aircraft dynamics and track simulation possibilities. The FG output data were converted into the form suitable for a servo-controlled Rotational-Tilt Platform (RoTiP) which provided corresponding motion for two AHRS units mounted on it and reference information from optical sensors. The output data of the AHRS units were collected, processed and evaluated to verify the units accuracy and reliability. The methodology and results based on the performance analyses are presented.

Summary of avionics technologies

Avionics has reached a century of development from which fundamental elements include navigation, power, architectures, and standards. AESS is committed to organizing and maintaining membership in the planning and development of electronics technology that enables ATM, safe transport, and economic viability. With the ASP, technology developments reported in DASC, PLANS, and ICNS will feature contemporary solutions and investigations of the avionics industry.

Integrated modular avionics onboard of small airplanes — Fiction or reality?

Integrated Modular Avionics begins a core part of aircraft electronic installations on military airplanes. Based on more available and powerful electronics this concept is introduced also in to the area of civil aviation despite of more demanding certification process. Modern electronics penetrate also into ultra-light class of airplanes that are more accessible to flying public. Accidents of small and ultra-light airplanes were analyzed in order to identify ways to improve flight safety of this category of airplanes. Proposed solutions and the main findings are introduced here together with the development, evaluation and various test results. This paper presents a set of tools that allow rapid development of IMA functions and of Synthetic Vision Information System displays. System evaluation is illustrated on an IMA function performing online search for the most suitable place for landing under emergency situations. This function is also used during standard approaches to cope with high accident rate occurring during landings. It is called Safe Landing Advisory function. The function provides guidance to a pilot and navigates him to the selected safe landing place, which is evaluated by data from different sources but the final decision to use or not use the advisory service still lays on pilot. The function was evaluated with help of our custom Ground Proximity Warning System, an airplane online tracking system and a Traffic Collision and Avoidance System. Evaluation was performed with help of a free flight full-motion simulator and during a glider contest in the Czech Republic.

A combined angle of attack and angle of sideslip smart probe with twin differential sensor modules and doubled output signal

This article presents a combined system for an angle of attack (AOA) and an angle of sideslip (AOS) measurements that will be integrated into an existing air data computer system (ADC) due to an early warning against loss of air lift followed by uncontrolled fall of an airplane. We present a set of probes for AOA and AOS measurement whose parameters, advantages and disadvantages are compared. The results were acquired by direct measurement of sensors and through a newly developed smart probe that contains a microcontroller for basic signal processing and a sensor module for the probes connection. Within the project time span, some probe types were simulated in computational fluid dynamic (CFD) software and twelve probes were manufactured and tested. The most promising probe is described in details and compared with other types, its transfer characteristics depending on its orientation with respect to the airstream, velocity of the airstream and temperature. A unique sensor interconnection method resulting in double amplitude measurement that is based on asymmetric connection of differential pressure sensors is presented.

Fusion of Smart-Sensor Standards and Sensors with Self-Validating Abilities

In airborne applications the high degree of reliability is required. Typical methods for assuring the reliability are development guides (DO178), testing, quality checking (AS9100) and certification processes. Despite these processes provide high level of safety and reliability of the products, the electronic devices can fail from different reasons. Also, one of the main present problems today is incompatibility of communication interfaces of so called smart sensors. This article proposes fusion of smart sensor standard IEEE 1451 and information necessary for sensor self-validation of sensor output. In this paper estimation of the feedback magnitude measured by an intelligent servomechanism system is presented. This system is being developed for a specific UAV application. The necessary data are saved within the TEDS memory of the extended IEEE 1451 standard. In the paper, following topics are discussed: methods of magnitudes validation and estimation, standards of smart sensors, the servopsilas implementation and employment in an UAV project, algorithms and data stored in the TEDS memory.

Development of a IEEE 1451 Standard Compliant Smart Transducer Network with Time Synchronization Protocol

The IEEE 1451 family of standards defines how transducers can be mapped to a target network based on an object model defined independently of the network. Presently one of these standards, the IEEE 1451.2, is under a revision process and within the primary enhancements already defined, alternate physical layers are envisaged. This paper presents an original solution by implementing the network capable application processor (NCAP) in a PC and using the universal serial bus (USB) to communicate with the Transducer Independent Interface (TIM). The IEEE 1588 (PTP) protocol is used to synchronize the real-time clock of two TIMs connected to the USB hub. Besides the design implementation of the proposed Transducer Independent Modules with USB communication, an application to determine the temporal precision of the two modules obtained with the protocol is also described in detail.

Pilot timeliness of safety decisions using information fusion situation awareness

Information fusion includes interaction between users (e.g., pilots) and machines (e.g., aircraft). As popularized by Boyd; the observe, orient, decide, act (OODA) paradigm captures a users decision making ability. The OODA model has been used as a method of a pilots situation awareness (SAW) in flying an aircraft. Improvements to the OODA model include the SAW model of perception, comprehension, and forecasting of events. SAW can include waypoint analysis, detecting emerging threats, as well as terrain navigation. In this paper, we analyze the timeliness of pilot actions to augment flight safety using the cognitive OODA (C-OODA) for engine outages. In a critical maneuver scenario, data collected and analyzed with the C-ODDA highlight pilot lead, immediate, delay, and no action responses which could shed light on cockpit control warnings.

Pressure based reference system for aircraft attitude measurement

This paper proposes a new system for aircraft attitude measurements. This measurement system can provide attitude reference measurements, in the other words Euler angles: pitch and roll angles, by a set of modified AHRS units and is aimed for ultra-light category of aircrafts. The principle uses measurement of differential pressure between atmospheric static pressure and reference pressure. The static pressure is measured at tips of aircraft wings by differential pressure sensors with regards to the reference volume. Theory describing behavior of the gas in the closed reference volume is described in the first part of the paper. Two different arrangements of the pressure reference system are described with their advantages and disadvantages. These two arrangements are modeled in Matlab Simulink and various ambient and inner influences are discussed in this part of the paper. Realization of different measurement system arrangements are presented in the next part of this paper. Parameters of the differential pressure sensors for the best performance of pressure based reference system are identified and different methods of data fusion from pressure based measurement system and the one axial accelerometer are described and discussed in the fourth part of this paper. Finally, the results from a roll angle measurement with the help of the pressure based reference system acquired during a test in a wind tunnel are presented and discussed.

Performance evaluation of two altimeters intended for euler angles measurement

This paper describes usage of two pressure altimeters to measure an airplane position angle, e.g. pitch or roll. The measurement relates to the properties of the standard atmosphere where the pressure descends with increasing altitude. The altitudes measured by two altimeters allow us to determine their mutual vertical difference. While we know the shortest distance between these two altimeters we can calculate the required positional angle of an airplane. There are multiple ways how to compose a measurement system using this principle. One possible solution is based on two absolute sensors. In this case the precision of the pressure sensors is the crucial parameter. In this article we describe sensor modules with wireless interface using two types of sensors and we evaluate their performance for the proposed position angle measurement application. There are two types of sensors compared in the article. First of them is a cheap MEMS sensor LPS001DL provided by ST microelectronics with no certification for aerospace applications and the second is an SP82 manufactured by Memscap company which is often used in digital altimeters (Air Data Computer) for aerospace applications. The article describes the wireless measurement modules, the data interface, the mechanism used for data exchange with a control station and the measurement results that are statistically analyzed and compared with expectations. The article summarizes technical and economic advantages and disadvantages of this method of positional angles measurement and their applicability for aviation.