A composite fixed-time sliding mode control scheme for Unmanned Ground Vehicles affected by external disturbances.

Accurate path-following control is crucial for Unmanned Ground Vehicles (UGV). However, influenced by external disturbances, UGV systems encounter challenges in meeting specific performance requirements, such as no overshoot and minimized chattering. In current sliding mode control (SMC) methods with disturbance observer (DOB), there still exists a serious chattering problem.

The Improved Method for Indoor 3D Pedestrian Positioning Based on Dual Foot-Mounted IMU System.

Micro-Electro-Mechanical System (MEMS) inertial sensors, characterized by their small size, low cost, and low power consumption, are commonly used in foot-mounted wearable pedestrian autonomous positioning systems. However, they also have drawbacks such as heading drift and poor repeatability. To address these issues, this paper proposes an improved pedestrian autonomous 3D positioning algorithm based on dual-foot motion characteristic constraints.

Multipath/NLOS Detection Based on K-Means Clustering for GNSS/INS Tightly Coupled System in Urban Areas.

Due to the massive multipath effects and non-line-of-sight (NLOS) signal receptions, the accuracy and reliability of GNSS positioning solution can be severely degraded in a highly urbanized area, which has a negative impact on the performance of GNSS/INS integrated navigation. Therefore, this paper proposes a multipath/NLOS detection method based on the K-means clustering algorithm for vehicle GNSS/INS integrated positioning. It comprehensively considers different feature parameters derived from GNSS raw observations, such as the satellite-elevation angle, carrier-to-noise ratio, pseudorange residual, and pseudorange rate consistency to effectively classify GNSS signals.

Investigating the survey instrument for the underground pipeline with inertial sensor and dead reckoning method.

To survey deep-buried and non-metallic pipelines without excavation, a pipeline survey instrument composed of a data collection and data processing part is developed. The data collection part is composed of a walking machine, a nine-axis micro-electro-mechanical system inertial measurement unit (MEMS-IMU) installed on the walking machine, odometers based on Hall magnetic switches, and a control/data storage circuit, while data processing is executed on the personal computer, where the attitude and trajectory are acquired with the complementary filter and dead reckoning on the collected data. Key technologies include the following: (1) the gyro-bias is estimated with the parking mode when there is no angular motion excitation; (2) a magnetometer is introduced to assist MEMS-IMU tracking azimuth changes; (3) calibration based on ellipsoid fitting is designed for magnetometers and accelerometers without any references; (4) stretching and rotation on calculated trajectory are executed with position information of both pipeline ends.

An Indoor DFEC Ranging Method for Homologous Base Station Based on GPS L1 and BeiDou B1 Signals.

High-precision navigation and positioning technology for indoor areas has become one of the research hotspots in the current navigation field. However, due to the complexity of the indoor environment, this technology direction is also one of the research difficulties. At present, our common indoor positioning methods are WIFI, Bluetooth, LED, ultrasound and pseudo satellite.

Fusion of GNSS and Speedometer Based on VMD and Its Application in Bridge Deformation Monitoring.

Real-time dynamic displacement and spectral response on the midspan of Jiangyin Bridge were calculated using Global Navigation Satellite System (GNSS) and a speedometer for the purpose of understanding the dynamic behavior and the temporal evolution of the bridge structure. Considering that the GNSS measurement noise is large and the velocity/acceleration sensors cannot measure the low-frequency displacement, the Variational Mode Decomposition (VMD) algorithm was used to extract the low-frequency displacement of GNSS. Then, the low-frequency displacement extracted from the GNSS time series and the high-frequency vibration calculated by speedometer were combined in this paper in order to obtain the high precision three-dimensional dynamic displacement of the bridge in real time.

Support Vector Machine for Regional Ionospheric Delay Modeling.

The distribution of total electron content (TEC) in the ionosphere is irregular and complex, and it is hard to model accurately. The polynomial (POLY) model is used extensively for regional ionosphere modeling in two-dimensional space. However, in the active period of the ionosphere, the POLY model is difficult to reflect the distribution and variation of TEC.

Improving Ambiguity Resolution for Medium Baselines Using Combined GPS and BDS Dual/Triple-Frequency Observations.

The regional constellation of the BeiDou navigation satellite system (BDS) has been providing continuous positioning, navigation and timing services since 27 December 2012, covering China and the surrounding area. Real-time kinematic (RTK) positioning with combined BDS and GPS observations is feasible. Besides, all satellites of BDS can transmit triple-frequency signals.

Real-Time PPP Based on the Coupling Estimation of Clock Bias and Orbit Error with Broadcast Ephemeris.

Satellite orbit error and clock bias are the keys to precise point positioning (PPP). The traditional PPP algorithm requires precise satellite products based on worldwide permanent reference stations. Such an algorithm requires considerable work and hardly achieves real-time performance.