Investigation of the Effect of Dimple Bionic Nonsmooth Surface on Tire Antihydroplaning

Inspired by the idea that bionic nonsmooth surfaces (BNSS) reduce fluid adhesion and resistance, the effect of dimple bionic nonsmooth structure arranged in tire circumferential grooves surface on antihydroplaning performance was investigated by using Computational Fluid Dynamics (CFD). The physical model of the object (model of dimple bionic nonsmooth surface distribution, hydroplaning model) and SST k-ω turbulence model are established for numerical analysis of tire hydroplaning. By virtue of the orthogonal table L16(45), the parameters of dimple bionic nonsmooth structure design compared to the smooth structure were analyzed, and the priority level of the experimental factors as well as the best combination within the scope of the experiment was obtained. The simulation results show that dimple bionic nonsmooth structure can reduce water flow resistance by disturbing the eddy movement in boundary layers. Then, optimal type of dimple bionic nonsmooth structure is arranged on the bottom of tire circumferential grooves for hydroplaning performance analysis. The results show that the dimple bionic nonsmooth structure effectively decreases the tread hydrodynamic pressure when driving on water film and increases the tire hydroplaning velocity, thus improving tire antihydroplaning performance

Hysteresis Compensation and Sliding Mode Control with Perturbation Estimation for Piezoelectric Actuators

Based on the background of atomic force microscope (AFM) driven by piezoelectric actuators (PEAs), this paper proposes a sliding mode control coupled with an inverse Bouc–Wen (BW) hysteresis compensator to improve the positioning performance of PEAs. The intrinsic hysteresis and creep characteristics degrade the performance of the PEA and cause accuracy loss. Although creep effect can be eliminated by the closed-loop control approach, hysteresis effects need to be compensated and alleviated by hysteresis compensators. For the purpose of dealing with the estimation errors, unmodeled vibration, and disturbances, a sliding mode control with perturbation estimation (SMCPE) method is adopted to enhance the performance and robustness of the system. In order to validate the feasibility and performance of the proposed method, experimental studies are carried out, and the results show that the proposed controller performs better than a proportional-integral-derivative (PID) controller at 1 and 2 Hz, reducing error to 1.2% and 1.4%, respectively

Design, Assembly, and Simulation of Flexure-Based Modular Micro-Positioning Stages

With flexure-based micro-positioning stages (MPSs) being in high demand for high-precision applications, the performance and cost of flexure-based MPSs are two issues that urgently need to be addressed. In addition, the current MPSs are being developed toward complex spatial configurations, which further precludes monolithic fabrication. To address the aforementioned issues, modular MPSs using designed standardized modules are introduced in this paper. Firstly, the motivations are described, followed by the modular design. In addition, a new assembly concept analogy with composing compounds is proposed for guiding module assembly, including some proposed planar and spatial configurations. For validation, the static and dynamic performances of modular MPSs with respect to different modules and materials are presented as case studies. The proposed modular MPSs can provide better flexibility and functionality for further applications

Identification of Preisach Model Parameters Based on an Improved Particle Swarm Optimization Method for Piezoelectric Actuators in Micro-Manufacturing Stages

The Preisach model is a typical scalar mathematical model used to describe the hysteresis phenomena, and it attracts considerable attention. However, parameter identification for the Preisach model remains a challenging issue. In this paper, an improved particle swarm optimization (IPSO) method is proposed to identify Preisach model parameters. Firstly, the Preisach model is established by introducing a Gaussian−Gaussian distribution function to replace density function. Secondly, the IPSO algorithm is adopted to Fimplement the parameter identification. Finally, the model parameter identification results are compared with the hysteresis loop of the piezoelectric actuator. Compared with the traditional Particle Swarm Optimization (PSO) algorithm, the IPSO algorithm demonstrates faster convergence, less calculation time and higher calculation accuracy. This proposed method provides an efficient approach to model and identify the Preisach hysteresis of piezoelectric actuators

Univariate Gaussian model for multimodal inseparable problems

It has been widely perceived that a univariate Gaussian model for evolutionary search can be used to solve separable problems only. This paper explores whether and how the univariate Gaussian model may also be used to solve inseparable problems. The analysis is followed up with experimental tests. The results show that the univariate Gaussian model stipulates no inclination towards separable problems. Further, it is revealed that the model is not only an efficient but also an effective method for solving multimodal inseparable problems. To verify its relative convergence speed, a restart strategy is applied to a univariate Gaussian model (the univariate marginal distribution algorithm) on inseparable problems. The results confirm that the univariate Gaussian model outperforms the five peer algorithms studied in this paper

Effect of Friction Model and Tire Maneuvering on Tire-Pavement Contact Stress

This paper aims to simulate the effects of different friction models on tire braking. A truck radial tire (295/80R22.5) was modeled and the model was validated with tire deflection. An exponential decay friction model that considers the effect of sliding velocity on friction coefficients was adopted for analyzing braking performance. The result shows that the exponential decay friction model used for evaluating braking ability meets design requirements of antilock braking system (ABS). The tire-pavement contact stress characteristics at various driving conditions (static, free rolling, braking, camber, and cornering) were analyzed. It is found that the change of driving conditions has direct influence on tire-pavement contact stress distribution. The results provide the guidance for tire braking performance evaluation