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The purpose of this paper is to consider the process of design and implementation of an enhanced fuzzy H_∞ (EFH_∞) estimation algorithm to determine the attitude and heading angles of ground vehicles, which are frequently affected by considerable exogenous disturbances. To detect the changes of disturbances, a fuzzy system is designed based on expert knowledge and experiences of a navigation engineer. In the EFH_∞ estimator, the intensity bounds of disturbances affecting the measurements are updated using a heuristic combination of three change‐detection indices. Performance of the proposed estimator is evaluated by Monte‐Carlo simulations and field tests of three kinds of vehicles using a manufactured attitude‐heading reference system (AHRS). In both simulations and real tests, the proposed estimator results in a superior performance compared to those of the recently developed and standard H_∞ estimators.

Design, implementation and real tests of the EFH_∞ estimator are considered for an AHRS specialized for vehicular applications. In the AHRS, three‐axis accelerometers (TAA) and three‐axis magnetometers (TAM) may be affected by large disturbances due to non‐gravitational accelerations and local magnetic fields. Therefore, the design parameters of EFH_∞ estimator including the theoretic bound of disturbance intensity and the attenuation level are adaptively tuned using a fuzzy combination of three change‐detection indices. Once a sensor is affected by an exogenous disturbance, the fuzzy system will increase the scale factor of the corresponding measurement disturbance to place more confidence on the data of the AHRS dynamics including measurements of gyros with respect to the data coming from the TAA and TAM.

An intelligent fault detector is proposed for considering changes of disturbances to adjust the upper bounds of the estimator's disturbances and the length of data to update the fuzzy system inputs. The EFH_∞ estimator is suitable to attenuate the effects of disturbances changes on accurate estimation of the attitude and heading angles, intelligently.

The paper provides a fuzzy state estimator for adaptively adjusting the theoretic disturbance matrices according to the actual intensity of the disturbances affecting the AHRS dynamics and the measurement sensors.

This study aims to design an optimized algorithm for low-cost pedestrian navigation system (PNS) to correct the heading drift and altitude error, thus achieving high-precise pedestrian location in both two-dimensional (2-D) and three-dimensional (3-D) space.

A novel heading correction algorithm based on smoothing filter at the terminal of zero velocity interval (ZVI) is proposed in the paper. This algorithm adopts the magnetic sensor to calculate all the heading angles in the ZVI and then applies a smoothing filter to obtain the optimal heading angle. Furthermore, heading correction is executed at the terminal moment of ZVI. Meanwhile, an altitude correction algorithm based on step height constraint is proposed to suppress the altitude channel divergence of strapdown inertial navigation system by using the step height as the measurement of the Kalman filter.

The verification experiments were carried out in 2-D and 3-D space to evaluate the performance of the proposed pedestrian navigation algorithm. The results show that the heading drift and altitude error were well corrected. Meanwhile, the path calculated by the novel algorithm has a higher match degree with the reference trajectory, and the positioning errors of the 2-D and 3-D trajectories are both less than 0.5 per cent.

Besides zero velocity update, another two problems, namely, heading drift and altitude error in the PNS, are solved, which ensures the high positioning precision of pedestrian in indoor and outdoor environments.

Rzeszów University of Technology has undertaken the task of designing and providing of equipment to a flying laboratory. This paper presents basic design principles of the Inertial Reference Unit (IRU) which employs measuring signals from the Fiber Optic Gyros (FOG), accelerometers and electronic compass module. A microcomputer follows the algorithm of complementary filtration for of calculating the Euler angles for the aircraft attitude (pitch, roll and heading), angular rates, and linear accelerations. The correction systems that minimize error of the steady‐state measuring have been employed. The results of computer simulations, lab tests and selected flight tests have also been presented. The Inertial Reference Unit μIRU‐1 was tested in flight on board of the general aviation aircraft PZL‐110 “Koliber”. It has been confirmed that metrological properties of the system are appropriate for the purposes of teaching process. Currently, a modified version of the unit is being prepared. The new IRU is planned as a main reference unit for integrated flight control system of general aviation aircraft.

This paper aims to present a proposal of a simple analytical redundancy method using for virtual attitude reference system design. The main idea of the project is applied typical on‐board general aviation aircraft equipment for solving pitch and bank angles.

The presented solution is based on satellite navigation and air data computer signals, which are independent from basic attitude and heading reference system. The concept described is related to the kinematics relations and aerodynamic forces formulas.

The paper shows that the virtual attitude sensors are used by failure detection and reconfiguration subsystem and as a standby attitude reference system for general aviation aircraft equipped with augmentation control system applied for improving safety and efficiency handling qualities of aircraft.

This solution allows improvements in operating properties of already existing and newly designed executive aircraft, as well as establishing a higher level of flight safety.

AT the present day the operations of civil transport aeroplanes are severely restricted under conditions of poor visibility and not infrequently flights have to be diverted or cancelled. The work of the Blind Landing Experimental Unit of the Ministry of Aviation in the development of a system of automatic landing for military aircraft has been described elsewhere.1 A flight control system is described in this paper, which given the necessary azimuth guidance signals from ground based installations, will extend the advantages of automatic landings into the civil field.

Attitude and heading are very important measurements on board aircraft. In modern solutions they are measured by the attitude and heading reference system (AHRS). In some small unmanned systems, the GPS track angle is used for heading corrections instead of the magnetometer; then, the system measures the track angle instead of heading. With a temporary lack of correction signals, the measurement error increases very quickly. Similarly, a quick increase in the measurement error is observed when a magnetic heading sensor used for correction stops working properly. This study aims to propose measurement of the roll angle for yaw angle correction.

AHRS algorithms were designed; typical maneuvers were analyzed. The method was verified by simulation and in flight testing analysis. For quantitative analyses, a performance index was proposed.

The method enables reduction of the yaw angle error caused by the gyros bias error. This study presents the idea, results of simulations and flight testing data analysis and discusses advantages and limitations of the presented method.

The presented methodology can be implemented in AHRS systems for manned and unmanned aircraft.

This study enables more accurate measurement of the yaw angle in the case of missing correction signals.

Using the backdrop of an (apparently) extended visit to the West Indies, analogies with key concerns of internal audit are drawn. An unusual and refreshing way of exploring the main themes ‐ a discussion between Bill and Jack on tour in the islands ‐ forms the debate. Explores the concepts of control, necessary procedures, fraud and corruption, supporting systems, creativity and chaos, and building a corporate control facility.

Using the backdrop of an (apparently) extended visit to the West Indies, analogies with key concerns of internal audit are drawn. An unusual and refreshing way of exploring the main themes ‐ a discussion between Bill and Jack on tour in the islands ‐ forms the debate. Explores the concepts of control, necessary procedures, fraud and corruption, supporting systems, creativity and chaos, and building a corporate control facility.

A distinction must be drawn between a dismissal on the one hand, and on the other a repudiation of a contract of employment as a result of a breach of a fundamental term of that contract. When such a repudiation has been accepted by the innocent party then a termination of employment takes place. Such termination does not constitute dismissal (see London v. James Laidlaw & Sons Ltd (1974) IRLR 136 and Gannon v. J. C. Firth (1976) IRLR 415 EAT).

The purpose of this paper is to employ an extended Kalman filter for implementing an AHRS (attitude and heading reference system) with acceleration compensation, thereby improving the reliability of such systems, since this removes the usual restrictive assumption that the vehicle is undergoing a non‐accelerated maneuver.

MARG (magnetic, acceleration and rate gyros) sensors constitute the basic hardware, which are integrated by the Kalman filter. The error dynamics for attitude and gyro biases is obtained in the navigation frame, providing a much simpler approach than usually taken in the literature, since it relies on direct quaternion differentiation. The state vector associated to the error dynamics possesses six components: three are associated to the quaternion error and three concern gyro bias estimates.

The AHRS is implemented in an ARM (Advanced RISC Machine) processor and tested with experimental data. The accelerated case is treated by two complementary approaches: by changing the noise variance in the Kalman filter, and by obtaining an acceleration information from GPS (global positioning system) velocity measurements. Experimental results are presented and the performance is compared with commercial ARHS systems.

The proposed AHRS can be implemented with low cost MARG sensors, and GPS aiding, with use for instance in UAV (unmanned aerial vehicle) and small aircrafts' attitude estimation, for navigation and control applications.

Usually the AHRS designs employ as states total gyro bias and Euler angles, or quaternion, and do not consider the accelerated case. Here the state is comprised by gyro bias and quaternion error variables, which attenuates the effect of nonlinearities, and two complementary procedures tackle the accelerated case: acceleration correction by using a GPS derived acceleration signal and change in the output noise covariance used by the Kalman filter.