Attitude Error Research Articles

A GNSS/IMU/Vision Ultra-Tightly Integrated Navigation System for Low Altitude Aircraft

In order to solve the problem of poor anti-interference ability of GNSS/IMU ultra-tight integrated navigation system under high dynamic and harsh environments, a visual assisted GNSS/IMU ultra-tight integrated navigation method is studied. The attitude and position information provided by binocular vision are introduced into the GNSS/IMU ultra-tight integrated navigation system. The state equation of the traditional ultra-tight integrated navigation system is used as the state equation of the visual assisted GNSS/ IMU ultra-tight integrated navigation system. Meanwhile, the pseudorange of SINS and GNSS, the difference of pseudorange rate, the platform misalignment angle of SINS, the position and attitude error of SINS and vision are used as the measurement information of the ultra-tight combination of GNSS/IMU assisted by vision. On this basis, the fuzzy control method is used to replace the traditional federated Kalman filter to fuse the information of the navigation structure of the two self-filters, and the navigation method is simulated and verified by C #. The simulation results show that the computational system performance is improved 52% by using the fuzzy control method compared with the traditional federal Kalman filter method, and the attitude error is significantly reduced in the ultra-tight integrated navigation system with visual assistance. When the GNSS signal is interfered by strong noise, the tracking accuracy of GNSS/IMU ultra-tight integrated navigation system assisted by binocular vision can effectively reduce the navigation error. And the position and velocity errors of the system are kept within 5.0m/s and 0.3m/s, respectively, which effectively solves the navigation problem of low altitudeaircraft in the case of GNSS signal occlusion or interference.

Rapid star identification algorithm for fish-eye camera based on PPP/INS assistance

AbstractThe fish-eye star sensor with a field of view (FOV) of 180° is an important piece of equipment for attitude determination, which improves the visibility of stars significantly. However, it also brings the star identification (star-ID) difficulties because of imprecise calibrations. Thus, a fish-eye star-ID algorithm supported by the integration of the precise point positioning/inertial navigation system (PPP/INS) is proposed. At first, a reference star map is generated in combination with the distortion model of the fish-eye camera based on the position and attitude information from the PPP/INS. Then the star points are extracted in a specific neighbourhood of the reference star points. Subsequently, the extracted star points are individually tested and identified according to angular distance error. Finally, the real-time precise attitude is determined based on the star-ID results. Experimental results show that, 270–310 stars can be identified in a fish-eye star map with an average time of 0.03 s if the initial attitude error is smaller than 1.5° and an attitude determination accuracy better than 10″ can be achieved by support from PPP/INS.

Adaptive Fault-Tolerant Attitude Tracking Control for Flexible Spacecraft With Guaranteed Performance Bounds

Fault-tolerant attitude tracking control for rigid-flexible coupled spacecraft is studied in this article. Taking actuator faults, measurement errors of attitude and angular velocity, unmeasured modal displacements, model uncertainties, and external disturbances into consideration, an adaptive fault-tolerant attitude tracking control is designed. Then, based on the sequential Lyapunov method, the stability of the closed-loop system is analyzed showing that if the attitude and angular velocity measurement errors are bounded, then successively less conservative bounds on the attitude tracking error and the angular velocity error can be obtained.

A Trident Quaternion Framework for Inertial-Based Navigation—Part II: Error Models and Application to Initial Alignment

This work deals with error models for trident quaternion framework proposed in the companion paper (Part I) and further uses them to investigate the odometer-aided static/in-motion inertial navigation attitude alignment for land vehicles. By linearizing the trident quaternion kinematic equation, the left and right trident quaternion error models are obtained, which are found to be equivalent to those derived from profound group affine. The two error models are used to design their corresponding extended Kalman filters (EKF), namely, the left-quaternion EKF (LQEKF) and the right-quaternion EKF (RQEKF). Simulations and field tests are conducted to evaluate their actual performances. Owing to the high estimation consistency, the L/RQEKF converge much faster in the static alignment than the traditional error model-based EKF, even under arbitrary large heading initialization. For the in-motion alignment, the L/RQEKF possess much larger convergence region than the traditional EKF does, although they still require the aid of attitude initialization so as to avoid large initial attitude errors.

LINE OF SIGHT AUTO-CALIBRATION FOR CO3D ROLLING SHUTTER MATRIX DETECTOR

Abstract. The accurate calibration of the line of sight (LOS) is very important for a high-resolution imaging satellite, especially in a system as Co3D, whose mission is to produce 3D elevation models. A calibration error immediately translates into an altimetry error. Co3D has a matrix and the reading of the lines is done in rolling shutter, each line is read at a different date. So, the geometry of the image is affected by the dynamic perturbations of the attitude during the acquisition time.The objective of the study is to propose a calibration method accurate to 0.1 pixel at 90 percentile. The images needed for calibration must only require one or two satellite passes over the same site, and be compatible with the pointing agility. The method must be robust to residual errors in attitude knowledge.The assumptions of the simulations have been modified in this article to keep the performance of Co3D confidential.

Spherical actuator attitude measurement method based on multi-to-one WPT modeling

The measurement system of contact spherical actuator has the disadvantages of large friction resistance and poor rotor positioning accuracy. The structure or calculation of non-contact attitude measurement system is complicated. In order to solve the above problems, a multi-to-one wireless power transmission (WPT) spherical actuator attitude measurement method is proposed. The model of mutual inductance(MI) is built. This method effectively shortens the time of finite element analysis(FEA). Three motion states (spin, yaw and tilt) of actuator rotor are analyzed by using this measurement method. Compared with the micro electro mechanical system (MEMS) and fast complementary filter (FCF), the initial attitude error of this method is about 50% of that of the other two methods. Compared with MEMS method, the average angle error of WPT method is reduced by 35%. Experimental results show that this method has good real-time performance and repeatability.

Attitude measurement of multi-DOF actuator based on multiple-inputs and single-output WPT system modeling

Multi-DOF actuators are used in bionics where their flexibility is limited by changing batteries or wired charging methods. In order to realize flexible power supplement and accurate attitude measurement, a multiple-inputs and single-output wireless power transmission (WPT) attitude measurement method is proposed. Traditional contact measurement methods have large friction resistance, and some non-contact measurement methods are complicated in structure or calculation. In order to solve the above problems, the receiving coil is installed inside the rotor. When the rotor rotates, the receiving angle is offset from the multi-transmitting coil outside the stator. The receiving coil can transmit power with multi-angle rotation and has good space tolerance. The rotor position is measured by estimating mutual inductance accurately. This method effectively reduces the time of finite element analysis. Three types of exercise are tested (yaw, spin, and tilt). Compared with micro-electromechanical system and fast complementary filter methods, the average angle error of the proposed WPT method is reduced by 36%, 24% and 40% respectively, and the initial attitude error is about 50% of that of the other two methods. Experiments show that this method can accurately measure the attitude of the rotor of the multi-DOF actuator.

Adaptive actor-critic learning-based robust appointed-time attitude tracking control for uncertain rigid spacecrafts with performance and input constraints

This paper addresses the prescribed performance attitude tracking control problem for a rigid spacecraft with input constraint and bounded disturbance on the special orthogonal group (SO(3)). By introducing a proper pseudo-Morse function as the attitude error function, the tracking problem on matrix manifold SO(3) is reformulated as an equivalent stabilization problem in the associated Lie algebra (so(3)). To on-line compensate the system uncertainties, an actor-critic neural network (NN) architecture is incorporated into the controller design process. The critic NN intends to reconstruct the long-term integral cost function and evaluate the prescribed performance attitude tracking quality. Based on the output of the critic NN, the actor NN is utilized to reconstruct the unknown system uncertainties and generate the auxiliary compensation control. By introducing the actor-critic architecture into the logarithm barrier Lyapunov function method, a model-free attitude tracking controller is proposed. Furthermore the input saturation limit is considered to support the normal operation of the rigid spacecraft. Besides, an adaptive robustifying term is designed to enhance the disturbance attenuation performance. By incorporating the Lyapunov stability analysis, we prove that the designed adaptive robust controller can ensure that all signals are uniformly ultimately bounded (UUB), and prescribed performance constraints are not destroyed. Finally, numerical simulations are included to verify the performance of the proposed adaptive robust tracking control strategy with intelligent actor-critic learning mechanism.

Distributed Coordinated Control for Fixed-Wing UAVs With Dynamic Event-Triggered Communication

Compared with most existing results concerning unmanned aerial vehicles (UAVs) wherein two-degree or only attitude/longitudinal dynamics are considered, this paper proposes an event-based fault-tolerant coordinated control (FTC) for multiple fixed-wing UAVs such that the consensus tracking of velocity and attitude is achieved in the presence of actuator faults, external disturbances and modeling uncertainties. More precisely, as opposed to static event-triggered communication mechanisms, a dynamic event-triggered communication mechanism (DECM) is devised to schedule the connected communications while avoiding the unnecessary information exchanges among UAVs, which reduces the communication burden and saves on the network resources. Meanwhile, the Zeno phenomenon is excluded in terms of guaranteeing that the period between two consecutive triggering communication is lower bounded by a positive constant. Moreover, the actuator fault, external disturbance as well as model uncertainty are treated as the lumped disturbances and estimated via the disturbance observer technique. By strict Lyapunov arguments, all closed-loop signals are proved to be uniformly ultimately bounded (UUB) and the tracking errors of velocity and attitude converge to a residual set around origin. Finally, simulation results are presented to illustrate the validity and superiority of proposed event-based control scheme.

INDOOR ATTITUDE ESTIMATION USING EQUIPPED GYROSCOPES AND DEPTH SENSORS

Abstract. Attitude estimation is central to a wide range of applications such as robotics, virtual reality and mobile smart devices. With the development of sensor technologies, these application devices are often equipped with gyroscopes and depth sensors. In this paper, we propose a novel method to fuse gyroscope and depth information for drift-free and robust attitude estimation in structured indoor applications. Our method relies on the depth information and the Manhattan world assumption to estimate the absolute orientation, which is then fused to correct the accumulated error of the gyroscope-determined attitude. We first utilize the mean shift algorithm on the unit sphere to align the surface normals from the depth measurements with the orthogonal planar structures of the Manhattan world. Therefore, the orientation estimates are drift-free and absolute with respect to the Manhattan world. We then fuse the orientation estimates with the gyroscope measurements in an error-state Kalman filter manner to further improve the attitude estimation accuracy and robustness. We validate the performance of our method on public datasets, demonstrating the robustness and accuracy of the method for attitude estimation.

An Adaptive Three-Axis Attitude Estimation Method Based on Multi-Sensor Fusion for Optoelectronic Platform

Optoelectronic platform is an important payload in the field of aerospace and widely used in geographic mapping, measurement, and positioning. In order to obtain high-precision attitude measurement, gyro and accelerometer are applied in the feedback loop of light of sight (LOS) control system of optoelectronic platform. Aiming at compensating for gyro drift and maneuvering acceleration disturbance, an adaptive 3-axis attitude estimation method is proposed in this paper. An adaptive threshold criterion is designed by applying the accelerometer data in the sliding window. The threshold is determined in real time to judge whether the maneuvering acceleration exists. If it exists, the angular attitude error is compensated for by the gyro drift model. Otherwise, the angular attitude error is compensated by multi-sensor fusion. Furthermore, a phase-lag-free low pass filter (LPF) is applied to compensate for the phase lag error introduced in the above attitude estimation process. Compared with the angular attitude calculated by gyro, the root mean square error (RMSE) of the proposed method in roll, pitch, and yaw attitude decreased 44.23%, 49.91%, and 46.21%, respectively. In addition, the proposed method can estimate the attitude accurately without obvious phase lag when the maneuvering acceleration disturbance exists. The focus of this paper is to improve the performance of LOS motion control system of optoelectronic platform from the perspective of sensor signal processing. This method is suitable for aerospace applications with high-precision measurement and positioning requirements without maneuver interference, drift error and phase lag.

Rapid Reduction Dimensionality Transfer Alignment Method Based on CKF for SINS of Ship-borne Aircraft with GNSS Assistance

Abstract Aiming at the problem of rapid transfer alignment of inertial navigation system in shipborne environment with large azimuth misalignment angle, a dimension reduction fast transfer alignment scheme of shipborne aircraft inertial navigation system based on CKF algorithm is designed. Firstly, the nonlinear attitude error equation, velocity error equation and position error equation of the Global Navigation Satellite System (GNSS) assisted strapdown inertial navigation system in the case of large azimuth misalignment are analyzed. Secondly, the nonlinear dimensionality reduction rapid transfer alignment state equation and measurement equation are derived. Finally, the CKF algorithm is simulated and verified, and compared with EKF algorithm and UKF algorithm. The simulation results show that the reduced dimension fast transfer alignment method of shipborne aircraft inertial navigation system based on CKF algorithm can complete the estimation of attitude error angle in 80s, with horizontal estimation error of 1’ and azimuth error of 4’, and the estimation accuracy is equivalent to EKF and UKF, with less calculation and better rapidity.

Globally Stable Attitude Control and Quasi-Static Disturbance Estimation in the Presence of Aerodynamic Dissipation

In this letter, we design and verify a novel nonlinear attitude controller for small fixed-wing unmanned aerial vehicles (UAVs) in the presence of dissipation. The attitude controller is designed using quaternions, which provide the physical insight for the control design by relating it to the geometry of rotations. We also show how the controller can be suitably modified to adaptively estimate quasi-static disturbances and compensate for aerodynamic damping by incorporating suitable refinements to the controller. The performance of the controller is then verified using simulations that demonstrate global stability against arbitrarily large initial attitude errors.

Application of Weld Scar Recognition in Small-Diameter Transportation Pipeline Positioning System

In order to improve the positioning accuracy of the pipeline inspection gauge (PIG), a pipeline positioning method, based on weld location, is proposed. The position of the welding scar is recognized by wavelet transform modulus maxima (WTMM). Equidistant welding scars provide positioning references to the strap-down inertial navigation system (SINS)/dead reckoning (DR) navigation system, which is the positioning algorithm in PIG. The following improvements have been made in relation to prior research. First, we suggest a selection strategy for the optimal mother wavelet and decomposition level; based on the strategy, WTMM can recognize the collision response between the PIG and submerged weld in the burst noise for the inertial measurement unit (IMU) output. Then, characteristic position (CP), which is the site of the weld scar, and non-holonomic constraints are utilized to decrease the position and the attitude error. By doing such, the SINS/DR/CP algorithm is proposed. The positioning error of the modified algorithm is 0.129% in the experiment, which performs better than other algorithms.

A SINS/CNS integrated navigation scheme with improved mathematical horizon reference

Strap-down inertial navigation system (SINS) and celestial navigation system (CNS) integrated navigation have been widely applied in ships, aircraft and spacecraft etc. However, in practice, its performance is highly depending on the horizon reference accuracy, which is usually difficult to guarantee. In this work, we propose a SINS/CNS integrated navigation scheme based on a novel mathematical horizon reference (MHR) determination method. More specifically, inertial coordinate system is used in constructing the MHR, where the attitude and position errors could be decoupled and compensated, respectively. Then, a more accurate MHR could be established, thus resulting in better navigation results. Comparative numerical simulations for a maneuvering flight have been conducted, and it is shown the proposed approach has the best converging speed as well as the highest navigation precision compared with SINS and existing MHR-based SINS/CNS schemes, and all-state optimal estimation could be achieved, thus enabling fully autonomous and high-precision navigation.

Advancing the Solar Radiation Pressure Model for BeiDou-3 IGSO Satellites

In the absence of detailed surface information, empirical solar radiation pressure (SRP) models, such as the five-parameter Empirical CODE Orbit Model (ECOM1) and its extended version-ECOM2, are widely used for modeling SRP forces acting on GNSS satellites. This study shows that the orbits of BeiDou-3 Inclined Geosynchronous Orbit satellites (IGSOs) determined with the ECOM1 model suffer from systematic once-per-revolution radial orbit errors, which can be partly reduced by the ECOM2 model. To eliminate such orbit errors, the BeiDou-3 IGSO optical coefficients are solved by using an adjustable box-wing (ABW) model and then introduced into an a priori box-wing SRP model to enhance the ECOM1 model (ECOM1 + BW). In the ABW solution, in addition to satellite body and solar panels, the contributions of the communication payloads installed on BeiDou-3 IGSO ±X panels on the SRP are also considered, which markedly improves the stability of the optical coefficient estimates. The efficiency of the developed a priori box-wing model is demonstrated through eliminated once-per-revolution radial orbit errors and decreased day boundary discontinuities. However, the orbit solutions still show significant degradations during eclipse seasons. The results of the first yaw-attitude analysis for eclipsing BeiDou-3 IGSOs show that their yaw behaviors are the same as those of BeiDou-3 CAST (China Academy of Space Technology) MEOs (Medium Earth Orbit satellites), and have been well considered in the study. This rules out the possibility that attitude errors are the potential reason for the orbit deterioration. By introducing a once-per-revolution sine term in the Sun direction (Ds term) and keeping Ds active during the Earth’s shadow transitions to the ECOM1 + BW model, the orbit performance inside the eclipse seasons is significantly improved and can be comparable to that outside the eclipse seasons.

The pre-process DV-UKF algorithm for high-precision attitude measurement with low-cost inertial sensor

PurposeThe purpose of this paper is to propose a high-precision attitude solution to solve the attitude drift problem caused by the dispersion of low-cost micro-electro-mechanical system devices in strap-down inertial navigation attitude solution of micro-quadrotor.Design/methodology/approachIn this study, a three-stage attitude estimation scheme that combines data preprocessing, gyro drifts prediction and enhanced unscented Kalman filtering (UKF) is proposed. By introducing a preprocessing model, the quaternion orientation is calculated as the composition of two algebraic quaternions, and the decoupling feature of the two quaternions makes the roll and pitch components independent of magnetic interference. A novel real-time based on differential value (DV) estimation algorithm is proposed for gyro drift. This novel solution prevents the impact of quartic characteristics and uses the iterative method to meet the requirement of real-time applications. A novel attitude determination algorithm, the pre-process DV-UKF algorithm, is proposed in combination with UKF based on the above solution and its characteristics.FindingsCompared to UKF, both simulation and experimental results demonstrate that the pre-process DV-UKF algorithm has higher reliability in attitude determination. The dynamic errors in the three directions of the attitude are below 2.0°, the static errors are all less than 0.2° and the absolute attitude errors tailored by average are about 47.98% compared to the UKF.Originality/valueThis paper fulfils an identified need to achieve high-precision attitude estimation when using low-cost inertial devices in micro-quadrotor. The accuracy of the pre-process DV-UKF algorithm is superior to other products in the market.

Learning‐based super‐twisting sliding‐mode control for space circumnavigation mission with suboptimal reaching under input constraints

AbstractThe problem of attitude‐orbit synchronous finite‐time control for the space circumnavigation (SCN) mission with input constraints is investigated in this research article. A novel terminal sliding‐mode (TSM) manifold with nonsingular first derivative is developed to ensure that the sliding‐mode reduced‐order system is practical finite‐time stable. Then, the learning‐based adaptive dynamic programming (ADP) technique is adopted to design a super‐twisting sliding‐mode control scheme, so that the proposed TSM is suboptimal reached. Especially, benefited from the introduction of two nonlinear performance indexes, the proposed sliding‐mode control strategy satisfies the saturation constraint of the propulsion system, and the weight update rate of the actor‐critic (AC) network will not be too large, even if the initial value of the system is too large. Finally, the simulation results show that both attitude and orbital tracking errors in the SCN mission are forced to converge to a small neighborhood containing the origin synchronously under input saturation constraints.

Improved attitude estimation accuracy by data fusion of a MEMS MARG sensor and a low-cost GNSS receiver

To obtain precise and continuous attitude information, this paper proposed a data fusion scheme that exploits the complementary advantages of a microelectromechanical system (MEMS) magnetic, angular rate, and gravity (MARG) sensor and a low-cost global navigation satellite system (GNSS) receiver. A quaternion-based error state Kalman filter is designed to integrate the different data sources, where the attitude error and gyro bias variation are taken as the error states. The gyro-measured angular rates are continuously integrated to propagate the attitude quaternion, while the accelerometer and magnetometer readings or the GNSS pitch and heading angles estimated by the precise carrier phase observations are utilized to perform the measurement update. The system kinematic model remains constant when the aiding source changes, only the measurement model alternates accordingly. A vehicular dynamical test was conducted to evaluate the proposed algorithm, the test results show that the attitude estimation accuracy of the integrated algorithm is apparently improved.

Position and attitude tracking control using CCW and SNI system theory with applications to multi-agent systems

This paper considers position and attitude tracking control. Counterclockwise (CCW) input–output maps from force and torque to position and attitude are established for rigid-body position and attitude motion. Using the properties of counterclockwise systems and negative imaginary (NI) systems, a stabilizing strictly negative imaginary (SNI) controller is shown to drive the tracking errors in position and attitude to zero. In addition, a method to synthesize the strictly negative imaginary controller in a H∞-optimal sense is presented. The control laws are then extended to the formation control problem in multi-agent systems. Numerical results are included.