Steering Wheel AGV Path Tracking Control Based on Improved Pure Pursuit Model

Aiming at the path tracking problem of the AGV transfer platform of an Optical module installing and calibrating system, this paper designs a pure pursuit control strategy in which the preview distance changes adaptively according to the current speed of AGV and the curvature of the reference path. Firstly, AGV kinematics model and pure pursuit model are established according to the geometric relationship. Then fitness function is established with tracking deviation and steering stability, and Particle swarm optimization (PSO) algorithm is used to optimize the preview distance of pure pursuit model of AGV under various working conditions. During the tracking process, AGV selects the optimal preview distance according to the curvature of the reference path and the current speed. The simulation experiment results show that the improved pure pursuit control strategy containing curvature information of reference path can improve the adaptability of AGV when it is tracking complex path, guaranteeing tracking accuracy and steering stability.

Cooperative Pursuit Control for Multiple Underactuated Underwater Vehicles with Time Delay in Three-Dimensional Space

SUMMARY In this paper, the k-valued logic control network is introduced to study the cooperative pursuit control problem of multiple underactuated underwater vehicles (UUVs) with time delay in three-dimensional space. The semi-tensor product of matrices is used to solve the complex calculation problem of the large dimension matrix. The influence of communication delay on multiple UUVs’ optimization and cooperative pursuit control is expressed in a matrix. Under the leadership of evader UUV, the control algorithm can ensure that all the pursuit UUVs reach the desired position. The stability of the closed loop system is proved.

Driverless Bus Path Tracking Based on Fuzzy Pure Pursuit Control with a Front Axle Reference

Currently, since the model of a driverless bus is not clear, it is difficult for most traditional path tracking methods to achieve a trade-off between accuracy and stability, especially in the case of driverless buses. In terms of solving this problem, a path-tracking controller based on a Fuzzy Pure Pursuit Control with a Front Axle Reference (FPPC-FAR) is proposed in this paper. Firstly, the reference point of Pure Pursuit is moved from the rear axle to the front axle. It relieves the influence caused by the ignorance of the bus’s lateral dynamic characteristics and improves the stability of Pure Pursuit. Secondly, a fuzzy parameter self-tuning method is applied to improve the accuracy and robustness of the path-tracking controller. Thirdly, a feedback-feedforward control algorithm is devised for velocity control, which enhances the velocity tracking efficiency. The proportional-integral (PI) controller is indicated for feedback control, and the gravity acceleration component in the car’s forward direction is used in feedforward control. Finally, a series of experiments is conducted to illustrate the excellent performances of proposed methods.

The Association Between Stalking and Violence in a Sample of Spanish Partner Violence Cases

The present descriptive study analyzes stalking in a sample of 278 Spanish court cases involving partner violence and contrasts the benefits of the new bill article 172ter, which criminalizes stalking, compared with the Organic Law 1/2004 on partner violence. Thirty-seven percent (37%) of the total sample included stalking behaviors, which manifested in intimidatory (60%) and controlling (45%) unwanted verbal communications (62%) and physical approaches (42%) that ended violently in a third of the cases (35%). Cases involving violent stalking, non-violent stalking, and physical violence without stalking were compared. A closer look at violent stalking cases uncovered that intimacy-seeking stalking behavior was concurrent with face-to-face aggression with a sharp object, whereas pursuit/control and invasive behavior were associated with property invasion and damage. Data not only support the contention that stalking should be criminalized regardless of the type of stalking behavior but also indicate that differences in the behavior might warrant different management interventions.