Single Antenna Global Positioning System Research Articles

A Novel In-Motion Alignment Method Based on Trajectory Matching for Autonomous Vehicles

The field of automatic driving has always been a research hotspot. Based on inertial and odometer, dead reckoning is used to navigate for L4 and above level autonomous vehicles with less human intervention when GPS is blocked. The navigation accuracy is mainly determined by the alignment error and the drift accumulated over time. In this paper, we proposed a novel method to achieve initial alignment of inertial navigation for L4 and above level autonomous vehicles. The alignment is accomplished with a MEMS inertial measurement unit (MIMU) and single antenna global positioning system real-time kinematic (GPS-RTK). By matching the trajectory obtained from MIMU dead reckoning with the trajectory obtained from RTK, the initial heading angle is obtained, and the heading angle accuracy is improved through multiple iterations. In the case of RTK precision decreasing, the MIMU can still achieve lane-level navigation after the initial alignment. Because the alignment is accomplished in motion, there is no need for additional static alignment time before the vehicle starts. The field experiment results show that the method could achieve fast initial alignment in a few seconds in moving state with an alignment accuracy of 0.05°.

Attitude Determination Method by Fusing Single Antenna GPS and Low Cost MEMS Sensors Using Intelligent Kalman Filter Algorithm

For meeting the demands of cost and size for micronavigation system, a combined attitude determination approach with sensor fusion algorithm and intelligent Kalman filter (IKF) on low cost Micro-Electro-Mechanical System (MEMS) gyroscope, accelerometer, and magnetometer and single antenna Global Positioning System (GPS) is proposed. The effective calibration method is performed to compensate the effect of errors in low cost MEMS Inertial Measurement Unit (IMU). The different control strategies fusing the MEMS multisensors are designed. The yaw angle fusing gyroscope, accelerometer, and magnetometer algorithm is estimated accurately under GPS failure and unavailable sideslip situations. For resolving robust control and characters of the uncertain noise statistics influence, the high gain scale of IKF is adjusted by fuzzy controller in the transition process and steady state to achieve faster convergence and accurate estimation. The experiments comparing different MEMS sensors and fusion algorithms are implemented to verify the validity of the proposed approach.

Application of a Single-Antenna GPS–Based Attitude Estimation on the Stability Control of a Small Unmanned Aerial Vehicle

AbstractAttitude estimation is an important issue in the autonomous flight of an unmanned aerial vehicle (UAV) system. However, for a micro-sized UAV with a wingspan of less than 2 m, a high performance Attitude and Heading Reference System (AHRS) is usually too heavy and large, whereas a low-cost AHRS of suitable size and weight may easily give erroneous attitude data. In this study, a single-antenna global positioning system (GPS)–based attitude estimation method, called pseudoattitude, in combination with the angular rate data given by the onboard gyroscopes, is applied to solve the problem. That is, the pseudoattitude estimated by the GPS velocity data provides a reference attitude with some time lag, whereas the gyroscope’s angular rate is integrated with the aid of a proposed complementary filter to eliminate the time lag problem. An experimental method is then developed to determine the filter parameters by a static ground test of the GPS and flight test data with postprocessing and analysis. A fuz...

Attitude estimation based on fusion of gyroscopes and single antenna GPS for small UAVs under the influence of vibration

An attitude estimation method is presented for small unmanned aerial vehicles (UAVs) powered by a piston engine which is the major source of vibration. Vibration of the engine significantly degrades the accuracy of the inertial measurement unit, especially for low-cost sensors that are based on micro electro-mechanical system. Therefore, a vibration model for a small UAV is proposed in order to examine the influence of vibration on attitude estimation with different sensors. The model is derived based on spectrum analysis with short-time Fourier transform. The vibration is compared with the drift of the gyroscope in order to examine the impact on attitude estimation. An attitude estimation method that fuses the gyroscopes and single antenna global positioning system (GPS) is proposed to mitigate the influence of engine vibration and gyroscope drift. The quaternion-based extended Kalman filter is implemented to fuse the sensors. This filter fuses the angular rates measured by the gyroscopes and the pseudo-attitude derived from the GPS velocity to estimate the attitude of the UAV. Simulations and experiment results indicate that the proposed method performs well both in short-term and long-term accuracy even though the gyroscopes are affected by drift and vibration noise, while the pseudo-attitude contains severe noise.

Application of fuzzy logic controller and pseudo‐attitude to the autonomous flight of an unmanned aerial vehicle

This paper presents the application of the proposed autopilot and navigation system to an unmanned aerial vehicle (UAV). The autopilot is based on fuzzy control and the navigation system is composed of a single antenna global positioning system (GPS) and gyroscopes, which implies that no other inertial navigation system (INS) is needed for this system. The autopilot consists of four fuzzy logic controllers, which control the altitude, pitch, heading, and roll respectively, and it is capable of performing waypoint navigation and trajectory following. The navigation system supplies the position and the estimated attitude of the aircraft. The estimated attitude is fused from the angular rates measured by the gyroscopes and the pseudo‐attitude derived from the GPS velocity solution, and this fusion is via the quaternion‐based extended Kalman filter (EKF). Ultimately, the feasibility and performance of the resulting autopilot and navigation system are verified through flight simulation of the SP‐80 UAV. The simulation results demonstrate the successful autonomous flight of this UAV, using the autopilot and navigation system, even under the influence of wind disturbance.

Pitch and roll attitude estimation of a small-scaled helicopter using single antenna GPS with gyroscopes

A method is presented for estimating the roll and pitch attitude of a small-scaled unmanned helicopter based on the velocity measurements of the global positioning system (GPS). The small-scaled helicopter is a radio controlled (RC) model which is readily available and affordable for academic laboratories as a research platform. Only one single antenna GPS receiver is equipped on the RC helicopter to acquire the velocity measurements needed for the attitude estimation. The velocity information is recorded by the onboard computer for post-processing. An attitude and heading reference system (AHRS) is used to provide the reference attitudes. The required angular rates and heading for this study are also given by the gyroscopes and compass of the AHRS for the sake of system’s simplification. The Kalman filter is applied to estimate the helicopter’s accelerations by using the GPS velocity measurements. The estimated accelerations form the fundamental elements of synthesizing the pseudo-roll and the pseudo-pitch. With some legitimate simplifications and assumptions, the relation between the helicopter’s attitudes and the accelerations estimated from the GPS velocity measurements can be developed. Furthermore, to enhance the accuracy of the pseudo-attitudes, the angular rates acquired from the gyroscopes are incorporated into the estimation algorithm of pseudo-attitudes by using a complementary filter.

Experimental Study on the Estimation of Lever Arm in GPS/INS

Lever-arm uncertainty can be an important error source in the integration of the Global Positioning System (GPS) and inertial navigation system (INS). This paper presents both numerical and experimental studies on the estimation of the lever arm in the integration of a very-low-grade inertial measurement unit (IMU) with an accurate single-antenna GPS measurement system. Covariance simulation results showed that maneuvers play an important role on the estimation of the lever arm and attitude. The length of the lever arm has a rather insignificant effect on the estimation of these. Experimental tests conducted with a low-cost microelectromechanical system (MEMS) IMU and a carrier-phase differential GPS (CDGPS) measurement system showed that the lever arm can be estimated with centimeter-level accuracy. The test results confirmed that angular motions and horizontal accelerations improve the estimates of the lever arm and yaw angle, respectively.

Applications of Global Positioning System Velocity-Based Attitude Information

Applications of aircraft attitude information obtained from single-antenna global positioning system (GPS) receiver measurements are discussed. A recently introduced framework to synthesize attitude information from GPS velocity vector measurements is reviewed. The framework combines the benee ts of high-quality GPS velocity measurementswithanovelvelocity-vector-basede ightcontrolparadigmtoprovideameansforthehumanoperator orautopilottoclosetheaircrafte ightcontrolloop.Threepossibleapplicationsofthisnovelconceptarediscussed.A single-antenna GPS-based backup attitude indicator is evaluated in e ight and compared to thetraditional attitude indicator. In addition, single-antenna GPS-based autopilot and tunnel-in-the-sky trajectory guidance systems are demonstrated in e ight. Unlike traditional attitude indicators and autopilot and trajectory guidance systems, these applications rely solely on the information obtained from a single-antenna GPS receiver. This concept thus has signie cant system integration and cost advantages and makes a number of glass-cockpit capabilities affordable to the General Aviation aircraft community.