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The overtaking process for autonomous vehicles must prioritize both efficiency and safety, with safe distance being a crucial parameter. To address this, we propose an automatic overtaking path planning method based on minimal safe distance, ensuring both maneuvering efficiency and safety. This method combines the steady movement and comfort of the constant velocity offset model with the smoothness of the sine function model, creating a mixed-function model that is effective for planning lateral motion. For precise longitudinal motion planning, the overtaking process is divided into five stages, with each stage's velocity and travel time calculated. To enhance the control system, the model predictive control (MPC) algorithm is applied, establishing a robust trajectory tracking control system for overtaking. Numerical simulation results demonstrate that the proposed overtaking path planning method can generate smooth and continuous paths. Under the MPC framework, the autonomous vehicle efficiently and safely performs automatic overtaking maneuvers, showcasing the method's potential to improve the performance and reliability of autonomous driving systems. [ABSTRACT FROM AUTHOR]

In this paper, we investigated the technical problem of the recovery of overlength and heavy load conveying booms of self-unloading ships. A method of folding the conveying boom with a hydraulic-four-bar mechanism is presented, and by using a mathematical model for the optimization of folding velocity stationary with ADAMS software, the optimization data and results were obtained. The multi-objective optimization index is introduced, and the multi-objective optimization problem is discussed. The results of the multi-objective optimization showed that parameters such as angular velocity and the change of angular acceleration of the conveyor boom were optimized. The paper has manufactured the connecting rod mechanism, and developed the self-discharging folding conveyance equipment. Through practical application, we determined that the developed folding conveying equipment had the advantages of smooth movement and high folding efficiency.

Automated tape placement (ATP) is an important automated process adopted for the fabrication of large composite components. Trajectory planning is the key link of ATP, which directly affects the precision and efficiency of the layup process and the quality of final products. Presently, most existing trajectory optimization methods for ATP focus on smooth surfaces. Nevertheless, as commercial CAD/CAM software generally uses NURBS (Non-uniform Rational B-Splines) for modelling, the difficulty of finding the solution and the low efficiency associated with the calculation process are inevitable. The discrete methods provide alternatives for designing layup trajectories, whereas their accuracy is seldom analysed. Furthermore, a path optimization algorithm for eliminating gap problems while preventing wrinkles on discrete models is rarely reported. In this paper, the adjustment of layup trajectories for ATP is considered on triangular meshes. First, the triangular mesh is reconstructed as a Nagata patch to recover the original geometry with good accuracy. Then, a numerical method for tracing desired paths on the Nagata patch set is provided and the computation efficiency is validated. Next, two optimization methodologies are proposed to improve the layup of composite tapes while avoiding wrinkles. Finally, the presented two strategies are examined on a discrete hyperbolic surface and a discrete freeform surface and some of the results are delivered. [ABSTRACT FROM AUTHOR]

Due to the small center distance, the dynamic performance of small modulus gear transmissions was very sensitive to the center distance errors. In addition, the intermediate gears were often designed to rotate at high speed on the fixed shaft, and there were clearances between the gear center hole and the shaft. Therefore, the calculation model of the gear mesh characteristic parameters and time-varying mesh stiffness under the influences of the center distance errors and the shaft hole fit clearances was established, and the influence laws of the two factors mentioned on the mesh stiffness were investigated. The results show that the center distance errors will change the contact degree and meshing stiffness of the gear pairs. The shaft hole clearance causes the actual center distance to fluctuate periodically around the theoretical center distance, which leads to the coexistence of the strengthening and weakening regions of the meshing stiffness in the whole cycle. The influences of center distance errors and shaft hole it clearances both superimposed and weakened each other in different angle ranges, resulting in the difference in meshing stiffness of each gear tooth, and the risk of inducing greater vibration and different noise. [ABSTRACT FROM AUTHOR]

Purpose: This paper aims to propose a novel origami structure with the characteristic of geometric nonunique relation, and apply it to the design of a new quasi-zero stiffness (QZS) vibration isolator. Methods: A tube-like structure is proposed by combining four six-panel non-Euclidean rigid origami patterns. According to the kinematic analysis, the geometric nonunique relation of the tube-like structure is discussed. By introducing eight mechanical tension springs, the tube-like structure can be transformed into a QZS structure, which is used to design a QZS vibration isolator. Then the force–compression relationship and stiffness of the vibration isolator are derived utilizing the energy method. To verify the vibration isolation performance, the displacement transmissibility under the harmonic displacement excitation is derived using the harmonic balance method and numerical simulation. Results: There is an obvious geometric nonunique relation between the height and side-opening width of the tube-like structure. Static analysis shows that three design parameters have significant influences on the mechanical response of the tube-like structure with springs. The result of the dynamic analysis verifies the low-frequency vibration isolation performance of the proposed QZS isolator outperforms the corresponding linear isolator. Conclusions: The proposed tube-like structure has the characteristic of geometric nonunique relation, which can be used to design the structure with QZS mechanical response. The proposed QZS vibration isolator based on the tube-like structure can be used for low-frequency vibration isolation. [ABSTRACT FROM AUTHOR]