Abstract. A 5-DOF dynamic model of vehicle shimmy system with clearance in universal joint of steering handling mechanism is presented. The sub model of cross shaft universal joint with clearance is built based on Hertz' theory, and two-state model is applied to describe the contact force. The sub model of the universal joint is combined with the simplified dynamic model of steering system, and a 5-DOF dynamic model of vehicle shimmy system with consideration of assembling clearance in universal joint of steering handling mechanism is presented. Based on this model, numerical analysis is carried out to evaluate the influence of clearance in universal joint on the dynamic behavior of the vehicle shimmy system. The results show that the clearance and some other parameters, such as vehicle speed, have coupled contribution to the dynamic behavior of the vehicle shimmy system. The conclusions provide theoretical basis for effective attenuation of vehicle shimmy, especially for those in-service vehicles.

Indoor localization services are emerging as an important application of the Internet of Things, which drives the development of related technologies in indoor scenarios. In recent years, various localization algorithms for different indoor scenarios have been proposed. The indoor localization algorithm based on fingerprints has attracted much attention due to its good performance without extra hardware devices. However, the occurrence of fingerprint mismatching caused by the complexity and variability of indoor scenarios is unneglectable, which degrades localization accuracy. In this article, by combining weighted kernel norm and L2,1-norm, a joint-norm robust principal component analysis (JRPCA in brief) assisted indoor localization algorithm is proposed, which can improve the localization accuracy through aggregating the reference points (RPs) and conducting robust feature extraction based on clustering. More specifically, a one-way hierarchical clustering termination method is proposed to obtain reasonable RP clusters adaptively according to the preset RPs. A two-phase fingerprint matching algorithm of JRPCA based on clustering is proposed to further increase the difference between similar RPs, thus facilitating rapid identification and reinforcing localization accuracy. To validate the proposed algorithm, extensive experiments are conducted in real indoor scenarios. The experimental results confirm that the proposed cluster-based JRPCA algorithm outperforms other existing algorithms in terms of robustness and accuracy.

Increasing attention has been paid to high-precision indoor localization in dense urban and indoor environments. Previous studies have shown single indoor localization methods based on WiFi fingerprints, surveillance cameras or Pedestrian Dead Reckoning (PDR) are restricted by low accuracy, limited tracking region, and accumulative error, etc., and some defects can be resolved with more labor costs or special scenes. However, requesting more additional information and extra user constraints is costly and rarely applicable. In this paper, a two-stage indoor localization system is presented, integrating WiFi fingerprints, the vision of surveillance cameras, and PDR (the system abbreviated as iWVP). A coarse location using WiFi fingerprints is done advanced, and then an accurate location by fusing data from surveillance cameras and the IMU sensors is obtained. iWVP uses a matching algorithm based on motion sequences to confirm the identity of pedestrians, enhancing output accuracy and avoiding corresponding drawbacks of each subsystem. The experimental results show that the iWVP achieves high accuracy with an average position error of 4.61 cm, which can effectively track pedestrians in multiple regions in complex and dynamic indoor environments.

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