标致307制动器结构设计

制动器是汽车主动安全系统中重要的执行机构。为研究一般制动器结构的设计方法,文章以标致307制动器为研究对象,分析制动器的结构特点,参考设计书对制动器尺寸和材料进行设计与校核。设计的制动器制动力为300 N,踏板全行程为117.6 mm,完成了标致307制动系的驱动机构和制动管路的布置并完成了三维图像建模。该设计方法具有普遍意义,可以推广到其他类似车型制动器的设计应用。

盘式制动器结构对汽车制动中热机耦合特性的影响分析

针对结构不同的盘式制动器,建立了在某紧急制动工况下制动盘的三维瞬态热机耦合计算模型,运用有限元方法模拟了盘式制动器的制动过程。通过分析比较不同结构对制动盘在紧急制动工况下温度场的径向分布、峰值热应力与热弹性变形情况,讨论了制动盘结构对制动效果的影响。结果表明:通风制动盘能够明显降低制动时制动盘温度和应力,对改善制动效能的恒定性具有积极作用。

浅谈电梯制动器的结构型式与检验检测

电梯制动器是电梯安全、可靠运行的重要部件,一旦发生故障,会造成电梯冲顶、坠落,甚至导致人员伤亡事故发生。本文就电梯制动器结构以及检验方法进行了分析。

电梯制动器的结构型式与检验检测

文本主要针对电梯制动器的结构型式与检验检测展开深入研究,结合电梯制动器的基本结构型式,然后又提出了几点切实可行的检验检测措施,如电梯制动器检验检测技术、检测电梯的电力系统、机械检验,通过以上措施,促使电梯制动器的检验检测水平获得提高。

一种行车和驻车变结构形式的鼓式制动器设计及计算

领从蹄鼓式制动器的特点是:效能因数稳定性高,但效能因数低;双向自增力鼓式制动器的特点是:效能因数稳定性低,但效能因数高。如果能设计一种制动器,它在行车制动时是领从蹄式,利用其效能因数稳定性高的优点,在驻车制动时变为双向自增力式,利用其效能因数高的优点,它将是一种很有应用价值的制动器。本文通过一个实例给出这种制动器的制动力矩计算过程,并指明其设计要点。

轻卡用楔式制动器的开发与研究

近年来随着国内法规的不断完善,国家相关部门对微型和轻型货车车做了相应的产品技术要求,车桥作为整车主要零部件总成,楔式制动器无论从结构还是性能上,都比凸轮结构具有一定的优势。

钳盘式电磁制动器失效分析

钳盘式电磁制动器具有结构简单、响应速度快、维护简单等特点,被广泛用于行车起升机构的制动部件。钳盘式电磁制动器一般由机械结构件与电控箱配合使用。电磁制动器在使用过程中,由于机械结构件磨损、电子元器件老化,电磁制动器偶尔会出现故障。当行车上制动器出现故障时,严重影响行车使用,容易出现安全事故。本文将从制动器结构及工作原理上对电磁制动器出现的故障进行失效分析,以帮助维修人员对故障进行快速排查,保障生产正常运行。

T型磁流变制动器的有效工作间隙位置对制动性能的影响

针对T型结构磁流变制动器工作间隙的位置和数量的不同对制动性能的影响,结合理论建模与模拟仿真分析,在同等外形尺寸、同种磁流变液材料的约束下,对T型结构磁流变制动器不同工作状态下的制动力矩和磁场分布进行了研究。基于工作间隙的不同位置和数量,进行了磁路的设计和制动力矩理论建模与计算;通过仿真结果和理论计算结果的对比,对不同位置的工作间隙所产生的制动力矩进行了分析。结果表明,当所使用磁流变液的材料、制动器的外形尺寸一致的情况下,对比制动力矩的仿真分析结果和理论计算结果,两者的相对差值在盘式工作状态下大于筒式工作状态。其中,盘式工作状态下,间隙A的相对差值最大;筒式工作状态下,间隙D的相对差值最小。进一步地,间隙D在单位磁动势下产生的制动力矩最大,表明该工作状态下制动器的能量利用率最高。研究结果为T型结构磁流变制动器的设计研究提供了理论参考。

电动夹轮器的发展与应用解析

电动夹轮器的出现极大地提高了防风制动装置的工作效率,由于其采用电能作为驱动,使其较传统夹轮器和液压轮边制动器而言更加清洁环保。本文在对电动轮边制动器与液压轮边制动器进行对比分析的基础上,剖析了电动夹轮器的工作原理,并根据电动夹轮器的结构特点解析了其在安装、调试及运行维护等方面所具有的优越性。

DAMAGES AND FAILURES OF SMART STRUCTURES

According to some observed dama ge phenomena in the smart structure systems, the issues related to the damage and failures of smart structures are addressed in this paper. A few possible damage patterns and the definition of the failure of the smart structures are given. It is pointed out that more attentions should be paid to the functional failures o f smart structures. The effects on the control the static deformation due to par tial debonding of PZT actuators are analyzed by the finite element method. Preli minary numerical results show that partial debonding of PZT actuators may have a p preciate reduction on their actuating ability thus reducing the control ability and accuracy of the smart structures.

Adaptive variable structure control based on backstepping for spacecraft with reaction wheels during attitude maneuver

An adaptive variable structure control method based on backstepping is proposed for the attitude maneuver problem of rigid spacecraft with reaction wheel dynamics in the presence of uncertain inertia matrix and external disturbances. The proposed control approach is a combination of the backstepping and the adaptive variable structure control. The cascaded structure of the attitude maneuver control system with reaction wheel dynamics gives the advantage for applying the backstepping method to construct Lyapunov functions. The robust stability to external disturbances and parametric uncertainty is guaranteed by the adaptive variable structure control. To validate the proposed control algorithm, numerical simulations using the proposed approach are performed for the attitude maneuver mission of rigid spacecraft with a configuration consisting of four reaction wheels for actuator and three magnetorquers for momentum unloading. Simulation results verify the effectiveness of the proposed control algorithm.

Partially Decentralized Controller Design via Model Predictive Control

An expansion procedure to design partially decentralized controllers via model predictive control is proposed in this paper. Partially decentralized control is a control structure that lies between a fully decentralized structure and a fully centralized one, and has the advantage of achieving comparable performance as a fully centralized controller but with simpler structure. The proposed method follows the expansion method proposed in a previous paper where internal model control (IMC) was used to design controllers for non-square subsystems. The method requires computing the pseudo-inverse of a non-square matrix via pseudo-inverse factors. Instead, the proposed method uses dynamic matrix control (DMC) to design PID controllers for non-square subsystems without using additional factors. The effectiveness of the proposed method is demonstrated on several chemical examples. Simulation results show that the proposed method is simple and can achieve better performance.

Semi-active Control with Variable Damper for Pier-Beam Transversal Vibration

In this paper, the method of semi-active control with variable damper is presented to deal with the relatively poor transversal seismic condition of bridge. Based on the LQR control algorithm the control effectiveness for transverse vibration of pier-beam structure of bridge are discussed. Taking the structure as a multiple-degree of freedom system, the calculating model of structure-variable damper system is set up and the differential equation is derived, combined with practical example the control system is simulated and studied by various semi-active control algorithms and passive strategy with MATLAB. The results show that the semi-active control with variable damper can decrease the transverse vibration effectively and the control effect is obvious.

Experimental and Simulation-based Investigation of a Velocity Controller Extension on a Ball Screw System

The background of this contribution is the enhancement of the achievable accuracy of servo-screw-presses. Therefore, the paper is concerned with the improvement of the dynamic precision for direct driven servo axes which is still restricted by structural vibrations. For this purpose, a ball screw test rig was analyzed for which the standard cascade control structure was extended by an additional velocity feedback. This structural extension has the potential to improve the controller performance significantly due to a better damping of low frequent vibrations. Furthermore, a parametric dynamic model for the control structure was derived to investigate the effects of the controller extension. For this analysis, the influences of the used tuning factors and filters is discussed in the frequency domain based on bode plots. The results of these cognitions are transferred to the time domain and illustrated by step responses. In addition, an evaluation by the criterion of the IAE （integral of absolute error） and the Prony analysis is carried out. Finally, the results are experimentally verified at the ball screw test rig. The paper closes with the conclusions.

A New Model Parameter Identification Technique for Magnetorheological Dampers

Magnetorheological （MR） Dampers offer rapid variation in damping properties, making them ideal in semi-active control of structures. They potentially offer highly reliable operation and can be viewed as fail safe, in that in the worst case, they become passive dampers. Perfect understanding of the response is necessary when implementing these in operation in conjunction with a control mechanism. There are many models used to predict the behavior of MR dampers. One of these is the Bouc-Wen model. It is extremely popular as it is numerically tractable, very versatile and can exhibit a wide range of hysteretic behavior. It is necessary to first identify the characteristic parameters of the model before response prediction is possible. However, characteristic parameters identification of the Bouc-Wen model needs an experimental base, which has its own limitations. The extraction of these characteristic parameters by trial and error and optimization techniques leaves significant difference between observed and simulated results. This paper deals with a new approach to extract characteristic parameters for the Bouc-Wen model.

Active control of fluctuating pressure induced by blade-vortex interaction

It is well known that interactions between the leading edge of a blade and incoming vortical structures produce a sharp rise in fluctuating pressure nearby,contributing significantly to the noise production in various types of rotorcrafts.To suppress this fluctuating pressure and subsequently induced noise,as the first step,active control of interactions between an airfoil and incoming cylinder-generated vortices,which mimics the practical phenomenon,was experimentally investigated.The essence of the control is to create a local perturbation,using piezo-ceramic actuators,on the surface near the leading edge of the airfoil,thus modifying the airfoil-vortex interactions.Both open-and closed-loop methods were used,where the surface perturbation was controlled by an external sinusoidal wave and a feedback pressure signal from a pressure transducer installed at the leading edge,respectively.It was observed that the closed-loop control was superior to the open-loop one;the closed-and open-loop controls achieve a maximum reduction in the pressure fluctuation at the dominant vortex frequency by 32% and 11%,respectively.The detailed physics behind the observations was discussed.

Gait fitting for snake robots with binary actuators

Thanks to the special physical architectures and various locomotion gaits,snake robots may offer significant benefits over traditional legged or wheeled locomotion designs in vast types of scenarios.This paper proposes an innovative snake robot with digitally-actuated Stewart platforms as its modules and mainly focuses on the simulations of various snake gaits.Three categories of fitting algorithms are elaborated in simulations of lateral undulation and Configuration-Fitting Algorithm of Four Modules is demonstrated as a universal gait fitting algorithm for all kinds of snake robots with binary actuators.Several typical snake gaits are simulated and the results demonstrate the excellent mobility of the snake robot.