This paper presents a novel sideslip angle estimator based on the pseudo-multi-sensor fusion method. The
kinematics-based and dynamics-based sideslip angle estimators are designed for sideslip angle estimation.
Also, considering the influence of ill-conditioned matrix and model uncertainty, a novel sideslip angle estimator
is proposed based on the wheel speed coupling relationship using a modified recursive least squares
algorithm. In order to integrate the advantages of above three sideslip angle estimators, drawing lessons
from the multisensory information fusion technology, a novel thinking of sideslip angle estimator design is
presented through information fusion of pseudo-multi-sensors. Simulations and experiments were carried
out, and effectiveness of the proposed estimation method was verified.
The accuracy and reliability of Kalman filter are easily affected by the gross errors in observations. Although robust Kalman filter based on equivalent weight function models can reduce the impact of gross errors on filtering results, the conventional equivalent weight function models are more suitable for the observations with the same noise level. For Precise Point Positioning (PPP) with multiple types of observations that have different measuring accuracy and noise levels, the filtering results obtained with conventional robust equivalent weight function models are not the best ones. For this problem, a classification robust equivalent weight function model based on the t-inspection statistics is proposed, which has better performance than the conventional equivalent weight function models in the case of no more than one gross error in a certain type of observations. However, in the case of multiple gross errors in a certain type of observations, the performance of the conventional robust Kalman filter based on the two kinds of equivalent weight function models are barely satisfactory due to the interaction between gross errors. To address this problem, an improved classification robust Kalman filtering method is further proposed in this paper. To verify and evaluate the performance of the proposed method, simulation tests were carried out based on the GPS/BDS data and their results were compared with those obtained with the conventional robust Kalman filtering method. The results show that the improved classification robust Kalman filtering method can effectively reduce the impact of multiple gross errors on the positioning results and significantly improve the positioning accuracy and reliability of PPP.
The authors studied the fracture mechanical properties under half-symmetric loading in this paper. The stress distribution around the crack tip and the stress intensity factor of three kinds of notched specimens under half symmetric loading were compared. The maximum tensile stress σmax of double notch specimens was much greater than that of single notch specimens and the maximum shear stress τmax was almost equal, which means that the single notch specimens were more prone to Mode II fractures. The intensity factors KII of central notch specimens were very small compared with other specimens and they induced Mode I fractures. For both double notch and single notch specimens, KII was kept at a constant level and did not change with the change of a/h, and KII was much larger than KI. KII has the potential to reach its fracture toughness KIIC before KI and Mode II fractures occurred. Rock-like materials were introduced to produce single notch specimens. Test results show that the crack had been initiated at the crack tip and propagated along the original notch face, and a Mode II fracture occurred. There was no relationship between the peak load and the original notch length. The average value of KIIC was about 0.602 MPa×m1/2, and KIIC was about 3.8 times KIC. The half symmetric loading test of single notch specimens was one of the most effective methods to obtain a true Mode II fracture and determine Mode fracture toughness.
In the process of coal extraction, a fractured zone is developed in the overburden above the goaf. If
the fractured zone is connected with an aquifer, then water inrush may occur. Hence, research and analysis
of the height of overburden fractured zone (HOFZ) are of considerable significance. This study focuses
on the HOFZ determination in deep coal mining. First, general deformation failure characteristics of
overburden were discussed. Second, a new method, numerical simulation by orthogonal design(NSOD),
have been proposed to determinate the HOFZ in deep coal mining. Third, the validity of NSOD is verified
in the practical application, compared with empiric al formula in Chinese Regulations and in-situ test.
These three methods were applied to determine the HOFZ of working face No. 111303 in No. 5 coal
mine. The pre dicted HOFZ of NSOD is found to be similar to the result of the in-situ test (8.9% relative
error), whereas the HOFZ calculated by the empirical formula has extremely large error (25.7% relative
error). Results show that the NSOD can reliably predict the HOFZ in deep coal mining and reduce time
and expenses required for in-situ test.
Reliable estimation of longitudinal force and sideslip angle is essential for vehicle stability and active safety control. This paper presents a novel longitudinal force and sideslip angle estimation method for four-wheel independent-drive electric vehicles in which the cascaded multi-Kalman filters are applied. Also, a modified tire model is proposed to improve the accuracy and reliability of sideslip angle estimation. In the design of longitudinal force observer, considering that the longitudinal force is the unknown input of the electric driving wheel model, an expanded electric driving wheel model is presented and the longitudinal force is obtained by a strong tracking filter. Based on the longitudinal force observer, taking into consideration uncertain interferences of the vehicle dynamic model, a sideslip angle estimation method is designed using the robust Kalman filter and a novel modified tire model is proposed to correct the original tire model using the estimation results of longitudinal tire forces. Simulations and experiments were carried out, and effectiveness of the proposed estimation method was verified.