Heading Angles Research Articles

Research on Tightly Coupled Multi-Antenna GNSS/MEMS Single-Frequency Single-Epoch Attitude Determination in Urban Environment

GNSS-only attitude determination is difficult to perform well in poor-satellite-tracking environments such as urban areas with high and dense buildings or trees. In addition, it is harder to resolve integer ambiguity in the case of single-frequency single-epoch process mode. In this contribution, a low-cost MEMS gyroscope is integrated with multi-antenna GNSS to improve the performance of the attitude determination. A new tightly coupled (TC) model is proposed, which uses a single filter to achieve the optimal estimation of attitude drift, gyro biases and ambiguities. In addition, a MEMS-Attitude-aided Quality-Control method (MAQC) for GNSS observations is designed to eliminate both the carrier multipath errors and half-cycle slips disturbing ambiguity resolution. Vehicle experiments show that in GNSS-friendly scenarios, the Ambiguity Resolution (AR) success rate of the proposed model with MAQC can reach 100%, and the accuracy of attitudes are (0.12, 0.2, 0.2) degrees for heading, pitch and roll angles, respectively. Even in harsh scenarios, the AR success rate increases from about 67% for the GNSS only case to above 90% after coupling GNSS tightly with MEMS, and it is further improved to about 98% with MAQC. Meanwhile, the accuracy and continuity of attitude determination are effectively guaranteed.

Onboard and External Magnetic Bias Estimation for UAS through CDGNSS/Visual Cooperative Navigation.

This paper describes a calibration technique aimed at combined estimation of onboard and external magnetic disturbances for small Unmanned Aerial Systems (UAS). In particular, the objective is to estimate the onboard horizontal bias components and the external magnetic declination, thus improving heading estimation accuracy. This result is important to support flight autonomy, even in environments characterized by significant magnetic disturbances. Moreover, in general, more accurate attitude estimates provide benefits for georeferencing and mapping applications. The approach exploits cooperation with one or more “deputy” UAVs and combines drone-to-drone carrier phase differential GNSS and visual measurements to attain magnetic-independent attitude information. Specifically, visual and GNSS information is acquired at different heading angles, and bias estimation is modelled as a non-linear least squares problem solved by means of the Levenberg–Marquardt method. An analytical error budget is derived to predict the achievable accuracy. The method is then demonstrated in flight using two customized quadrotors. A pointing analysis based on ground and airborne control points demonstrates that the calibrated heading estimate allows obtaining an angular error below 1°, thus resulting in a substantial improvement against the use of either the non-calibrated magnetic heading or the multi-sensor-based solution of the DJI onboard navigation filter, which determine angular errors of the order of several degrees.

Fuzzy logic based air-to-air combat algorithm for unmanned air vehicles

Unmanned combat air vehicles (UCAV) are finding increasing use in military applications due to their autonomy, processing capabilities and low cost with respect to manned flights. In order to use the UCAVs in the air to air combat, required algorithms must be carefully designed to enhance them with aerial combat competence. There are challanges for the design of this kind of an algorithm such as real-time operability and the case with inadequate number of sensors on the UAVs. In this paper a novel attack algorithm is introduced for UCAVs, with the assumption that in order to launch an effective attack the pursuer aircraft must be able to follow the target aircraft from behind with a predetermined distance. The attack algorithm consists of navigation and reference velocity calculation steps. In navigation part the reference values for bank, heading and flight path angles are computed. In velocity generation part, a PID based method and a fuzzy inference based method are employed to compute the reference velocity of the pursuer and the results obtained with these two approaches are compared. The performance of this algorithm is assessed with simulations performed in three different scenarios with different initial conditions for the pursuer and the target. Simulation results show that the effectiveness of the proposed fuzzy inference based air to air attack algorithm is better in action with respect to PID based algorithm since various effects that cause the change in velocity, can be incorporated into the fuzzy inference mechanism.

Autonomous Fuzzy Heading Control for a Multi-Wheeled Combat Vehicle

This paper introduces the design and the implementation of a heading angle tracking controller using fuzzy logic for a scaled Autonomous Multi-Wheeled Combat Vehicle (AMWCV) to navigate in outdoor environments. The challenge of designing this control system is to control the steering of the front four wheels individually to obtain the correct heading angle of the vehicle. The main contribution of the paper can be summarized in the fact that it is designing four fuzzy controllers for navigation and tracking the desired heading angle while at the same time while controlling the steering of the front four wheels individually. The AMWCV is capable of forwarding and backward movement where all eight wheels are powered individually. The different heading angles are used and simulated using MATLAB software to evaluate the performances of the developed algorithms. In addition, the performance of the developed controllers is validated in the presence of noise and disturbance in order to evaluate the robustness of the controller's Simulation results show the performances and demonstrate that the developed controllers are effective in predicting the desired heading angle changes.

Yaw Control of a Hovering Flapping-Wing Aerial Vehicle With a Passive Wing Hinge

Flapping-wing insect-scale robots (<;$500 mg) rely on small changes in drive signals supplied to actuators to generate angular torques. Previous results on vehicles with passive wing hinges have demonstrated roll, pitch, and position control, but they have not yet been able to control their yaw (heading) angle while hovering. To actuate yaw, the speed of the downstroke can be changed relative to the upstroke by adding a second harmonic signal at double the fundamental flapping frequency. Previous work has shown that pitching dynamics of a passive spring-like wing hinge reduces the aerodynamic drag available to produce yaw torque. We introduce three innovations that increase yaw actuation torque: 1) a new two-actuator robot fly design that increases the moment arm, 2) wider actuators that increase the operating frequency, and 3) a phase shift to the second harmonic signal. We validated these results through simulation and experiment. Further, we present the first demonstration of yaw angle control on a passive-hinge vehicle in a controlled flight. Our new robot fly design, UW Robofly-Expanded, weighs 160 mg (two toothpicks) and requires only two piezo actuators to steer itself.

The use of inertial measurement units for analyzing change of direction movement in sports: A scoping review

Change of direction movement is common in sports and the ability to perform this complex movement efficiently is related to athlete's performance. Wearable devices have been used to evaluate aspects of change of direction movement, but so far there are no clear recommendations on specific metrics to be used. The aims of this scoping review were to evaluate the reliability and validity of inertial measurement unit sensors to provide information on change of direction movement and to summarize the available evidence on inertial measurement units in analyzing change of direction movement in sports. A systematic search was employed in MEDLINE (Ovid), CINAHL (EBSCO host), SPORTDiscus (EBSCO host), EMBASE and Cochrane Database of Systematic Reviews and Web of Science to identify eligible studies. A complementary grey literature search was employed to locate non-peer reviewed studies. The risk of bias of the studies evaluating validity and/or reliability was evaluated using the AXIS tool. The initial search identified 15,165 studies. After duplicate removal and full-text screening 49 studies met the inclusion criteria, with 11 studies evaluating validity and/or reliability. There are promising results on the validity and reliability, but the number of studies is still small and the quality of the studies is limited. Most of the studies were conducted with pre-planned movements and participants were usually adult males. Varying sensor locations limits the ability to generalize these findings. Inertial measurement units (IMU) can be used to detect change of direction (COD) movements and COD heading angles with acceptable validity, but IMU measured or derived kinetic or kinematic variables present inconsistency and over-estimation. Studies can be improved with larger sample sizes and agreement on the metrics used and sensor placement. Future research should include more on-field studies.

Route-Planning Method for Plant Protection Rotor Drones in Convex Polygon Regions.

Aiming at the problem of low operating efficiency due to the poor endurance of plant protection rotor drones and the small volume of pesticide carried, this paper proposes a route-planning algorithm for convex polygon regions based on the initial heading angle. First, a series of coordinate conversion methods ranging from the Earth coordinate system to the local plane coordinate system are studied. Second, in the local plane coordinate system, a route generation method based on subregion is proposed; therefore, multiple routes can be generated with different initial heading angles. Lastly, the optimal route and the best initial heading angle can be obtained after the comparison according to the three evaluation criteria: number of turns, route distance, and pesticide waste rate. The simulation results show that, compared with the common grid method, the route generation method based on subregion reduces the route distance and pesticide waste rate by 2.27% and 13.75%, respectively. Furthermore, it also shows that, compared with the route generated by the initial heading angle of 0°, the optimal route reduces the number of turns, route distance, and pesticide waste rate by 60%, 17.65%, and 38.18%, respectively. The route was optimized in three aspects and reached the best overall result using this method, which in turn proved its feasibility.

Algorithm for Control of Unmanned Aerial Vehicles in the Process of Visual Tracking of Objects with a Variable Movement’s Trajectory

The purpose of the research was to create an algorithm for determining and correcting the output parameters of the navigation module and the flight-navigation complex of unmanned aerial vehicles which provides control of an aviation gyro-stabilized platform with a multispectral optoelectronic system during flight and tracking various objects of observation.Principles of control of an aviation technical vision system located on an unmanned aerial vehicle on a two-degree gyro-stabilized platform with the possibility of full turn around two perpendicular axes along the course and pitch are considered. Stability of tracking of observation objects at a distance of up to 10000 m is ensured by the use of a multispectral optoelectronic system including a rangefinder, thermal imaging and two visual channels.Analysis of the object of observation and the method of its support are carried out. An algorithm is proposed for integrating a Global Navigation Satellite System and a strapdown inertial navigation system based on the extended Kalman filter which includes two stages of calculations, extrapolation (prediction) and correction. Specialized software in theFreeRTOSv9.0 environment has been developed to obtain a navigation solution: latitude, longitude and altitude of the unmanned aerial vehicle in theWGS-84 coordinate system, as well as the pitch, heading and roll angles; north, east and vertical components of velocities in the navigation coordinate system; longitudinal, vertical and transverse components of free accelerations and angular velocities in the associated coordinate system based on data from the receiving and measuring module of the Global Navigation Satellite System and data from the 6-axis MEMS sensorSTIM300.

Numerical investigation of ship motions in cross waves using CFD

A computational fluid dynamics (CFD) based Unsteady Reynolds Averaged Navier–Stokes and Volume of Fluid model solver is adopted to estimate ship motion responses in bi-directional cross waves. The characteristics of cross waves are analyzed theoretically and by CFD verification at first. Then ship nonlinear motion responses and green water on deck induced by cross waves are systematically analyzed by adopting a S175 containership model sailing in different cross wave conditions such as various wave lengths, wave heading angles and forward speeds. Finally, ship safe navigational strategy is explored and corresponding operational guidance is proposed to ensure the safety of ships when encountering cross waves.

Rapid Algorithm for Generating Entry Landing Footprints Satisfying the No-Fly Zone Constraint

An online estimation algorithm of landing footprints based on the drag acceleration-energy profile is proposed for an entry hypersonic vehicle. Firstly, based on the Evolved Acceleration Guidance Logic for Entry (EAGLE), drag acceleration-energy profiles are designed. To track the drag acceleration-energy profile obtained by the interpolation, a drag acceleration tracking law is designed. Secondly, based on the constraint model of the no-fly zone, flying around strategies are proposed for different conditions, and a reachable area algorithm is designed for no-fly zones. Additionally, by interpolating the minimum and maximum drag acceleration profiles, the terminal heading angle constraint is designed to realize the accurate calculation of the minimum and maximum downrange ranges by adjusting the sign of the bank angle. In this way, the distribution of landing footprints is more reasonable, and the boundary of a reachable area is more accurate. The simulation results under typical conditions indicate that the proposed method can calculate landing footprints for different situations rapidly and with the good adaptability.

Observer-based motion control system for the approach ship with propeller and rudder in the process of underway replenishment

To avoid collisions between guide ship and approach ship during the underway replenishment process, it is important to maintain a certain distance between them. Based on trajectory tracking requirements, a control strategy suitable for engineering applications is proposed for an approach ship without velocity measurements. First, considering the effects of wind, waves, currents, hydrodynamic interactions and the highline cable system, models are established for the two ships. Second, a leader-follower approach is used to maintain the expected longitudinal and transverse distances between the two ships. Third, an extended state observer is designed according to the position, heading, propeller speed and rudder angle of the approach ship. Two time-varying parameters in the observer are estimated in the controller design process. Therefore, the linear speeds, yaw rate, and total system uncertainties can be observed. Fourth, the propeller speed and rudder angle, other than the surge force and steering moment, are considered as the control inputs, which are constructed by the command filter backstepping method. The stability of the proposed control system is verified. Finally, a simulation is performed to demonstrate the effectiveness of the proposed method.

An Improved Multi-Platform Stacked D-InSAR Method for Monitoring the Three-Dimensional Deformation of the Mining Area

The acquisition of information on fine surface three-dimensional deformation in a goaf is of great significance for the in-depth understanding of the law of mining subsidence and guiding the safe production and ecological restoration of the mining area. In this paper, three platform SAR satellite images are used for stacked D-InSAR processing to obtain the information on surface deformation in three line-of-sight directions. An improved three-dimensional decomposition model is proposed based on the difference between the COSMO-SkyMed and TerraSAR-X satellite heading angles, which are very small. The proposed method is verified by evaluating the three-dimensional deformation of the ground surface during the mining process at the 132610 working face in Fengfeng Mining District, Handan City, Hebei Province. The accuracy of the three-dimensionally decomposed vertical settlement results is verified with the leveling data of the same period. The accuracy of 0.82 cm is achieved, and the maximum subsidence is approximately 16 cm. Combining the high-precision terrain information obtained from the unmanned aerial vehicle photogrammetry data and the deformation law of inclined coal seam mining, the horizontal movement of the 132610 working face is analyzed to prove the feasibility of the proposed method.

Investigation into the control strategy for a long spine of Edinburgh Duck modules, using an efficient numerical model

An efficient numerical model of a spine of ten Edinburgh duck modules is developed. The spine joints and duck modules are modelled using a linear approach based on the theory of generalized modes, which mitigates the need for a more computationally expensive time- domain solver. This approach also allows for computation of the shear forces acting on the spine joints, and has the added benefit of enabling the use of complex conjugate control. The resulting hydrodynamic model is verified for a three duck spine against an alternative implementation that uses a nonlinear multibody solver to enforce the joint motions. A conservative weighted motion constraint is imposed on the controlled degrees of freedom of the ten duck spine, in order to ensure results stay within the bounds of the linear theory. Pertinent sections of the theory underpinning the constrained complex conjugate control method are elaborated upon for the case in which not all degrees of freedom are controlled. An implementation of this control method for a solo duck is compared against a result from the literature, in order to confirm the suitability of the choice of duck design in this study. The control force coefficients that maximise the absorbed power, subject to the motion constraint, are computed for the ten duck spine over a range of wave periods and wave heading angles. The resulting dynamics of the spine of ducks are explored, with particular emphasis on aspects related to the power extraction and forces acting within the system.

Practical observer-based path following control of the guide ship with propeller and rudder in the underway replenishment

ABSTRACT A path following control strategy is proposed for the guide ship in the underway replenishment without velocity measurements. Firstly, the detailed models of the ship and external disturbances are established. Secondly, an extended state observer is designed to estimate the linear speeds and yaw rate of the ship based on the information of position, heading, propeller speed and rudder angle. With the estimated linear speeds, the sideslip angle led by the disturbances is obtained and thus can be compensated by the update law of the desired heading. Also, an augmented state in this observer is constructed to approximate the system uncertainties and disturbances. Thirdly, two command filter backstepping controllers companied with the observer are proposed to directly control the propeller and rudder, respectively. For the proposed control system, its stability is proved by using the Lyapunov theory. Finally, the effectiveness of the proposed method is demonstrated by a simulation example.

A Novel Inertial-Visual Heading Determination System for Wheeled Mobile Robots

Finding an alternative way to replace the magnetic compass to determine the robot heading angle indoor is always a challenge in the robotics society. This brief proposes a structurally simple yet efficient nonmagnetic heading determination system, which can be used in the planar indoor environment with abundant ferromagnetic and electromagnetic interferences, by the combination of gyroscope and vision. The gyroscope is utilized to perceive the yaw rate, whereas a downward-looking camera is used to capture the prelaid auxiliary strips to acquire the absolute angle of the robot heading. Due to the existence of pseudomeasurement, varying noise statistical characteristics, and asynchronization between state propagation and measurement, the existing Kalman filters cannot be applied to fuse the gyroscopic and visual data. Therefore, a novel fusion algorithm named pseudomeasurement-resistant adaptive asynchronous Kalman filter is proposed, which is experimentally verified to be efficient in the environment with various interferences.

Heading angle estimation using rotating magnetometer for mobile robots under environmental magnetic disturbances

The heading angle plays a vital role in the localization and mapping of mobile robots. It is generally obtained by fusing measurements from gyroscope and magnetometer. However, ferromagnetic objects in real-world environments will disturb the magnetic field and will, therefore, cause significant errors in the estimated heading angles. This work proposes a novel method that employs a rotating magnetometer to detect ambient spatial magnetic disturbances and corrects the heading angle. The algorithm is based on the extended Kalman filter (EKF). Firstly, a criterion named spatial disturbance index is defined to characterize the disturbance quantitatively. And then the magnetometer measurement error covariance of the EKF is tuned adaptively according to the proposed criterion, so that a relatively reliable heading angle can be obtained even under strong spatial dynamic magnetic disturbances. In addition, the estimated heading angle can quickly restore to the correct value when the spatial disturbances disappear. The proposed algorithm has the benefit of adjusting the fusing degree of gyroscope and magnetometer adaptively to reject spatial disturbances and avoid the adverse impact of inherent gyroscope drift. The algorithm is evaluated under static and dynamic conditions in real-world indoor/outdoor environments. The results show that our algorithm outperforms the conventional EKF with fixed measurement error covariance and also the algorithm using only gyroscope.

인공지능 학습을 통한 제한된 센서 융합기반의 헤딩각 추정을 이용한 차량의 후진 자율 주행의 정확도 개선

This paper aims to improve the performance of the BDAS (Backward Driving Assist System) using a sensor fusion technique. The existing BDAS has a 1-m positional deviated error, which is based on the estimation of the vehicle’s heading and path from the steering angle sensor. To reduce the deviated error to less than 0.5 m, the use of rear-wheel sensors is proposed to estimate the heading angle through sensor fusion. After characterizing the steering-angle sensor, rear-wheel sensor, and yaw-rate sensor, data from different road conditions are collected. These data are learned by a neural network to generate appropriate heading angles. As a result of experiments conducted using an actual car, the backward driving error is reduced by half, within 0.5 m.

Precise vehicle dynamic heading and pitch angle estimation using time-differenced measurements from a single GNSS antenna

The attitude information of ground vehicles, i.e., heading and pitch information, can be used for many transport applications. This information can be determined through various solutions of onboard sensors, including magnetic sensors, inertial sensors, GNSS equipment, and their combinations. In order to find a cost-effective solution, we propose here a new toolbox named Vehicle Attitude Determination toolbox from the Intelligent Transportation And Geomatics group (iTAG_VAD) that determines vehicle dynamic heading and pitch using only one single-frequency GPS antenna, reducing costs while retaining an acceptable heading and pitch accuracy. In this toolbox, by using the constraints of the vehicle motion and road geometry, two variations in a time-differenced measurement model, i.e., Time-Differenced Carrier Phase (TDCP) and Time-Differenced Pseudorange (TDPR), are developed for heading and pitch determination. The results show that both proposed TDCP- and TDPR-based models are able to provide an accurate heading and pitch estimation with a root mean square error below the one-degree level, which is sufficient for many land-based applications. We describe the toolbox and its implementation in MATLAB in detail.

Hydrodynamic Simulation of the Semi-Submersible Wind Float by Investigating Mooring Systems in Irregular Waves

The present study aims to implement the software ANSYS AQWA to discuss the hydrodynamic analysis of the DeepCwind semi-submersible floating platform in waves based on the potential flow theory by considering the second-order wave exciting force. In this study, the linearized potential-flow hydrodynamic radiation and diffraction problems in the frequency domain were firstly solved by adopting the three-dimensional panel method. Subsequently, the hydrodynamic coefficients and wave loading data were transformed to time domain forms by the Cummins time domain equation as a system loading input. Furthermore, the quadratic transfer function (QTF) matrices with different frequencies and directions deduced based on the near field integration over the mean wetted hull surface were adopted for the calculation of slow-drift forces. In order to represent the damping in a real system for modeling potential flow without Morison’s elements, an additional quadratic damping matrix was added to capture the viscous drag. Eventually, both of the dynamic mooring model based on the lump-mass (LM) approach and the quasi-static mooring model based on the multi-segmented, quasi-static (MSQS) approach are introduced to discuss the mooring effect on the platform hydrodynamics. The effect of wave heading angles on the platform motion is considered as an influential parameter as well.

Time-energy efficient guidance strategy for a realistic 3D interceptor: An adaptive robust time-delayed control approach with input saturation

To achieve successful interception of a target by a missile with efficient time-energy utilization and robustness against external disturbances, a consolidated guidance approach has been proposed in this manuscript. Time-energy efficiency has been accomplished by employing Sine-Cosine algorithm to generate a near-optimal reference trajectory for the pitch and yaw heading angles. Thereafter, an adaptive robust time delayed controller has been designed to track the reference trajectory thus providing robustness towards uncertainties. To incorporate realistic aspect in the interceptor scenario, input saturation has been considered for the lateral acceleration of the missile. Stability analysis has been performed using a suitable Lyapunov function which proves Uniformly Ultimately Bounded (UUB) stability of the system through the proposed control approach. The efficacy of the proposed methodology has been verified through simulations involving various engagement scenarios. The simulation results demonstrate the superior tracking performance of the proposed method in the presence of time-varying disturbances.