An Original Feedback Control with a Reversible Electromechanical Actuator Used as an Active Isolation System for a Seat Suspension. Part I: Theoretical Study

This paper provides an overview of a theoretical study of an active seat suspension. The principal objective of this study is to improve ride passenger comfort by reducing transmitted seat acceleration. The seat is represented by a non-linear two degree of freedom model. The system is linearized for small perturbations around the equilibrium. To control the dynamic of the seat suspension, an original feedback control command with a reversible electromechanical actuator is achieved. The synthesis of the regulator is realized on the linearized model of the seat suspension and the root locus method is employed. Stability and robustness characteristics have been studied. Numerical simulations in time and frequency domain show the interests of the regulator and its capability to isolate seat passenger.     

An Original Feedback Control with a Reversible Electromechanical Actuator Used as an Active Isolation System for a Seat Suspension. Part II: Experimental Study

From the theoretical study presented in [1], we investigate the experimental feasibility of the active seat suspension to improve ride comfort. The prototype of the reversible electromechanical actuator used in the active seat suspension is presented. First, the kinematic guide with a vertical auto-levelling system is described. Second, the electromechamical actuator and the power drive transmission are presented. It is noticed that the prototype design is achieved with a systemic approach taking into account the industrial constraints. Then, the laboratory experimental setup is described. Several tests are performed on the prototype for model validation and performance purposes. Correct force feedback control in the actuator is verified. The real performances of the active seat suspension on a prototype is investigated for different pertubation inputs. Experimental results clearly show the efficiency of the active seat suspension to improve passenger comfort and demonstrate its feasability.     

An Original Feedback Control with a Reversible Electromechanical Actuator Used as an Active Isolation System for a Seat Suspension. Part II: Experimental Study

From the theoretical study presented in [1], we investigate the experimental feasibility of the active seat suspension to improve ride comfort. The prototype of the reversible electromechanical actuator used in the active seat suspension is presented. First, the kinematic guide with a vertical auto-levelling system is described. Second, the electromechamical actuator and the power drive transmission are presented. It is noticed that the prototype design is achieved with a systemic approach taking into account the industrial constraints. Then, the laboratory experimental setup is described. Several tests are performed on the prototype for model validation and performance purposes. Correct force feedback control in the actuator is verified. The real performances of the active seat suspension on a prototype is investigated for different pertubation inputs. Experimental results clearly show the efficiency of the active seat suspension to improve passenger comfort and demonstrate its feasability.     

A study of locomotive driver's seat vertical suspension system with adjustable damper

This paper shows that laboratory measurements can be used for the identification of structure and parameters of commercial seat vertical suspension system model. A commonly used single-degree-of-freedom suspension model does not suffice. The system model presented is based on Zener's structure and clearly describes the dynamic properties of a vertical seat suspension with an adjustable damper. The model introduced, augmented with seat cushion dynamic model, predicts the seat vertical vibration mitigation properties under field conditions with a reasonable accuracy. Optimisation of the adjustable damper setting is performed using a two-objective function optimisation technique. This enables us to optimise not only the exerted vertical vibration acceleration but also the seat relative vertical displacement (stroke). Optimisation was facilitated for the particular suspended seat without the requirement of further field measurements. In addition, a two-parameter optimisation was performed showing possible further improvement in both objectives at the manufacturer's discretion. This study could be representative of driver's seats equipped with vertical seat suspension system using an air-spring and an adjustable damper.     

Semi-Active Suspension with Preview Using a Frequency-Shaped Performance Index

The objective of this study is to develop a control law for a semi-active suspension for the purpose of ride quality improvement. The semi-active control law is determined by reproducing the control force of an optimally controlled active suspension while suppressing its damping coefficient variation. The performance index of the optimal control for the active suspension is modified to include frequency-shaping by use of Parseval's theorem, which allows us to de-emphasize the effects of particular variables over specific frequency bands.

Through the numerical simulations, it was found that the semi-active suspension may reduce the vertical acceleration of the driver's seat and the sprung mass motions significantly. The road-holding and tire deflections were not affected much.     

A Pitch-Plane Model of a Vehicle with Controlled Suspension

A vehicle model incorporating front and rear wheel suspensions and seat suspension is presented. The suspension control includes algorithms to provide both dynamic and steady state (levelling) control. Vehicle response to (a) vertical inputs due to ground disturbances at the wheels and (b) longitudinal inputs due to the inertial forces during braking and accelerating, are investigated. It is shown that the static (self-levelling) control causes a slight deterioration in dynamic performance. The active ride control produces improvements of ride comfort under dynamic conditions compared to an equivalent passively suspended vehicle. In steady state the proposed control eliminates the error heave of the body caused by tilting of the vehicle with active suspension.     

汽车智能乘员约束系统效能的仿真研究

智能乘员约束系统的核心是控制系统，控制系统对输入的参量，包括安全带的应用情况、乘员位置以及乘员身体质量等进行判断，碰撞中按输入参量的级别确定约束值，调整气囊充气速度、进入气囊的气体体积、气囊泄气孔的面积和安全带的载荷限值。基于某微型客车乘员约束系统动力学仿真模型，以安全气囊低能量触发为例，研究了智能系统对乘员保护范围和约束效能的影响。     

Vibration Control of a Passenger Vehicle Utilizing a Semi-Active ER Engine Mount

This paper presents vibration control of a passenger vehicle using an electronically controllable electro-rheological (ER) engine mount. A mixed-mode ER engine mount operating under the flow and shear modes is devised and manufactured. After establishing the dynamic model of the proposed ER engine mount, both field-dependent displacement transmissibility and dynamic stiffness of the ER engine mount are empirically evaluated. The ER engine mount is then incorporated with a full-vehicle model in order to investigate vibration control performance at the driver's seat position. The governing equation of motion of the full-vehicle model is formulated by considering engine excitation force, followed by designing a skyhook controller to attenuate unwanted vibration. The controller is implemented through a hardware-in-the-loop simulation (HILS), and control responses such as acceleration level at idle speed are evaluated in the frequency and time domains.     

Vibration Control of a Passenger Vehicle Utilizing a Semi-Active ER Engine Mount

This paper presents vibration control of a passenger vehicle using an electronically controllable electro-rheological (ER) engine mount. A mixed-mode ER engine mount operating under the flow and shear modes is devised and manufactured. After establishing the dynamic model of the proposed ER engine mount, both field-dependent displacement transmissibility and dynamic stiffness of the ER engine mount are empirically evaluated. The ER engine mount is then incorporated with a full-vehicle model in order to investigate vibration control performance at the driver's seat position. The governing equation of motion of the full-vehicle model is formulated by considering engine excitation force, followed by designing a skyhook controller to attenuate unwanted vibration. The controller is implemented through a hardware-in-the-loop simulation (HILS), and control responses such as acceleration level at idle speed are evaluated in the frequency and time domains.     

Semi-Active Suspension with Preview Using a Frequency-Shaped Performance Index

SUMMARY

The objective of this study is to develop a control law for a semi-active suspension for the purpose of ride quality improvement. The semi-active control law is determined by reproducing the control force of an optimally controlled active suspension while suppressing its damping coefficient variation. The performance index of the optimal control for the active suspension is modified to include frequency-shaping by use of Parseval's theorem, which allows us to de-emphasize the effects of particular variables over specific frequency bands.

Through the numerical simulations, it was found that the semi-active suspension may reduce the vertical acceleration of the driver's seat and the sprung mass motions significantly. The road-holding and tire deflections were not affected much.     

Hierarchical optimisation on scissor seat suspension characteristic and structure

Scissor seat suspension has been applied widely to attenuate the cab vibrations of commercial vehicles, while its design generally needs a trade-off between the seat acceleration and suspension travel, which creates a typical optimisation issue. A complexity for this issue is that the optimal dynamics parameters are not easy to approach solutions fast and unequivocally. Hence, the hierarchical optimisation on scissor seat suspension characteristic and structure is proposed, providing a top-down methodology with the globally optimal and fast convergent solutions to compromise these design contradictions. In details, a characteristic-oriented non-parametric dynamics model of the scissor seat suspension is formulated firstly via databases, describing its vertical dynamics accurately. Then, the ideal vertical stiffness-damping characteristic is cascaded via the characteristic-oriented model, and the structure parameters are optimised in accordance with a structure-oriented multi-body dynamics model of the scissor seat suspension. Eventually, the seat effective amplitude transmissibility factor, suspension travel and the CPU time for solving are evaluated. The results show the seat suspension performance and convergent speed of the globally optimal solutions are improved well. Hence, the proposed hierarchical optimisation methodology regarding characteristic and structure of the scissor seat suspension is promising for its virtual development.     

A Full-Car Roll Model of a Vehicle with Controlled Suspension

SUMMARY

The full-car roll model of a vehicle suspension with static and dynamic control (using wheel, body and seat) is described by means of vertical and lateral input for both static and dynamic states. It is shown that the control deteriorates the static performance of the vertical response and improves the performance of the lateral response.     

基于坐席类型动态分配的旅客列车开行方案

为提高铁路部门服务质量和铁路旅客出行体验, 并制定可满足旅客需求多元化的旅客列车开行方案, 考虑坐席动态分配对旅客列车开行方案进行研究。从旅客和铁路运营部门2个角度出发, 分别以旅客动态乘车广义时间最短和铁路收益最大为目标, 以客流守恒、区间通过能力和满足客流需求等为约束建立多目标规划模型。通过Logit模型确定硬座、硬卧、软卧这3类坐席的分担率, 确定列车定员数, 并在求解过程中依据生成的开行方案不断更新3类坐席的分担率以实现3类坐席的动态分配, 直至结果趋于稳定。结合算例采用带精英策略的非支配排序遗传算法(NSGA-Ⅱ)求解, 并进行算例分析, 计算结果表明: 建立考虑坐席类型动态分配的旅客列车开行方案, 在实现旅客对坐席选择的同时, 铁路旅客服务率提高了3.5%, 铁路部门收益增大了1.5%。      

Fuzzy adaptive sliding mode controller for an air spring active suspension

A fuzzy adaptive sliding mode controller for an air spring active suspension system is developed. Due to nonlinearity, preload-dependent spring force and parameter uncertainty in the air spring, it is difficult to control the suspension system. To achieve the desired performance, a fuzzy adaptive sliding mode controller (FASMC) is designed to improve the passenger comfort and the manipulability of the vehicle. The fuzzy adaptive system handles the nonlinearity and uncertainty of the air suspension. A normal linear suspension model with an optimal state feedback control is designed as the reference model. The simulation results show that this control scheme more effectively and robustly isolates vibrations of the vehicle body than the conventional sliding mode controller (CSMC).     

Parameters optimisation of a vehicle suspension system using a particle swarm optimisation algorithm

The purpose of this paper is to determine the lumped suspension parameters that minimise a multi-objective function in a vehicle model under different standard PSD road profiles. This optimisation tries to meet the rms vertical acceleration weighted limits for human sensitivity curves from ISO 2631 [ISO-2631: guide for evaluation of human exposure to whole-body vibration. Europe; 1997] at the driver's seat, the road holding capability and the suspension working space. The vehicle is modelled in the frequency domain using eight degrees of freedom under a random road profile. The particle swarm optimisation and sequential quadratic programming algorithms are used to obtain the suspension optimal parameters in different road profile and vehicle velocity conditions. A sensitivity analysis is performed using the obtained results and, in Class G road profile, the seat damping has the major influence on the minimisation of the multi-objective function. The influence of vehicle parameters in vibration attenuation is analysed and it is concluded that the front suspension stiffness should be less stiff than the rear ones when the driver's seat relative position is located forward the centre of gravity of the car body. Graphs and tables for the behaviour of suspension parameters related to road classes, used algorithms and velocities are presented to illustrate the results. In Class A road profile it was possible to find optimal parameters within the boundaries of the design variables that resulted in acceptable values for the comfort, road holding and suspension working space.     

2车碰撞事故下5座乘用车乘员死亡风险分析

为探究5座乘用车乘员在2车碰撞事故下的死亡风险,研究了6种单一特征变量对乘员致死率的影响,进而基于二项Logistic回归模型分别对单一特征变量和组合特征变量进行显著性分析。通过9种常用的分类算法,结合网格搜索的调参方法,以F1为衡量指标选出相对较优的3种分类算法,即投票分类器、梯度提升及决策树,来构建多特征组合下的死亡风险预测模型。研究结果表明:①单一特征变量中行驶方向、路段类型、碰撞对象、乘坐位置对乘员死亡有显著影响。其中,异向行驶的车辆碰撞与同向行驶相比,乘员的死亡风险增加72%;非高速交叉路段与高速路段相比,乘员的死亡风险降低69%;碰撞对象为商用货车、商用客车的乘员死亡风险分别是乘用车的5倍和3倍,若在非高速非交叉路段发生碰撞则乘员死亡风险升至8倍左右,若在高速路段则高达15倍左右;相对于驾驶位乘员,副驾驶位乘员的死亡风险增加70%,且该位置乘员的死亡风险在高速路段会升高到驾驶位乘员的近4倍;②碰撞对象和路段类型是影响乘员死亡情况的主要特征变量;③由模型的预测结果可知:5座乘用车的正面或后面与商用货车在高速路段或非高速非交叉路段发生碰撞,乘员的死亡风险高于生存几率。      

Application of the Pareto-optimal approach for selecting dynamic characteristics of seat suspension systems

In this paper, a method for selecting the dynamic characteristics of seat suspension systems is presented. The basic principle of such a method consists in the shaping of nonlinear seat suspension dynamic behaviour for the different requirements defined by machine operators. A combined optimisation procedure has allowed to find the Pareto-optimal system configuration with simultaneous minimisation of conflicted optimisation criteria: the suspended body acceleration and suspension travel. As an example of the proposed method, the seat with a viscous-elastic passive suspension is investigated and its vibro-isolation properties are shaped by the air-spring and shock-absorber force characteristics.     

Nonlinear Backstepping Active Suspension Design Applied to a Half-Car Model

A fresh nonlinear backstepping design scheme, which is developed for the control of half-car active suspension systems to improve the inherent tradeoff between ride quality and suspension travel, is proposed in this paper. Since ride quality is dependent on a combination of vertical and angular displacements of a vehicle body, the design of active suspensions must have the potential to minimize heave and pitch movements in order to guarantee the ride comfort of passengers. The other important factor to be emphasized in the design of active suspensions is the suspension travel which means the space variation between the car body and the tires. In order to avoid damaging vehicle components and generating more passenger discomfort, the active suspension controllers must be capable of preventing the suspension from hitting its travel limits. Our design strategy, with two intentionally additional nonlinear filters, shows the potential to achieve these conflicting control objectives. The novelty of our active suspension design is in the use of two particular nonlinear filters at both the front and rear wheels. The effective bandwidths of these two nonlinear filters depend on the magnitudes of the front and rear suspension travels, individually. When suspension travel is small, the proposed controllers soften the suspension for enhancing passenger comfort. However, our control design shifts its attention to rattlespace utilization by stiffening the suspension when suspension travel approaches its limits. As a result, the improvement of tradeoff between ride quality and suspension travel can be guaranteed and is then demonstrated through comparative simulations.     

Power Requirement of Active Vibration Control Systems

The paper deals with the theoretical estimation of the minimal power requirement, necessary for the operation of the active vibration control system (AVCS), connected with a passive one. It is assumed this compound system is used for the vibration control purposes in the heavy vehicle driver's seats. The systems considered in the paper are of two kinds. In the first case the electro-hydraulic actuator of the AVCS is situated in series to the spring-damper combination of the seat suspension. The second system under consideration is formed by parallel connection of electro-pneumatic actuator and the spring-damper combination of the seat suspension, which is a mechanical model of a real air spring with controlled in-flow and out-flow of the air. The comparison of results for both compound systems shows markedly higher power consumption of the serial system. The theoretical results are in acceptable agreement with the experimental data.     

针对儿童座椅拉拽失效的车身结构改进

在乘用车前期设计阶段,为让儿童保护的安全性能得到控制和优化,以某乘用车根据国家安全法规要求进行儿童座椅拉拽台架试验时,ISOFIX固定装置出现焊点从车身上拉脱失效为例,基于焊点热影响区损伤的焊点失效准则和钣金断裂失效准则,运用有限元分析对其进行虚拟评估和结构改进,有限元分析与试验结果吻合良好.改进结构通过了儿童座椅拉拽...