基于滑移-黏滞摩擦机理的制动系统模型开发

研究了制动近零状态和制动抱死状态下制动力矩的求解理论,开发了一种新的制动系统模型。根据制动过程中制动盘与制动钳(制动鼓与制动蹄)之间的运动状态,基于滑移-黏滞摩擦机理,建立了动、静两种摩擦状态下的制动力矩求解算法。开发了独立的制动模型子程序,并在ADAMS软件中进行应用。仿真结果表明:建立的制动系统模型比原ADAMS中的模型可以更准确地仿真车辆平路制动停车工况和坡道制动停车工况,对于汽车的仿真分析具有应用价值。

A new semi-active suspension control strategy through mixed H_2/H_∞ robust technique

A new semi-active suspension control strategy through mixed H2/H∞ robust technique was developed due to its flexibility and robustness to model uncertainties.A full car model with seven degrees of freedom was established to demonstrate the effectiveness of the new control approach.Magneto-rheological(MR) dampers were designed,manufactured and characterized as available semi-active actuators in the developed semi-active suspension system.The four independent mixed H2/H∞ controllers were devised in order to perform a distributed semi-active control system in the vehicle by which the response velocity and reliability can be improved significantly.The performance of the proposed new approach was investigated in time and frequency domains.A good balance between vehicle's comfort and road holding was achieved.An effective and practical control strategy for semi-active suspension system was thus obtained.This new approach exhibits some advantages in implementation,performance flexibility and robustness compared to existing methods.

Automobile active suspension system with fuzzy control

A quarter-automobile active suspension model was proposed. High speed on/off solenoid valves were used as control valves and fuzzy control was chosen as control method . Based on force analyses of system parts, a mathematical model of the active suspension system was established and simplified by linearization method. Simulation study was conducted with Matlab and three scale coefficients of fuzzy controller (ke, kec, ku) were acquired. And an experimental device was designed and produced. The results indicate that the active suspension system can achieve better vibration isolation performance than passive suspension system, the displacement amplitude of automobile body can be reduced to 55%. Fuzzy control is an effective control method for active suspension system.

Dynamics Modeling and Simulation of Autonomous Underwater Vehicles with Appendages

To provide a simulation system platform for designing and debugging a small autonomous underwater vehicle＇s （AUV） motion controller, a six-degree of freedom （6-DOF） dynamic model for AUV controlled by thruster and fins with appendages is examined. Based on the dynamic model, a simulation system for the AUV＇s motion is established. The different kinds of typical motions are simulated to analyze the motion performance and the maneuverability of the AUV. In order to evaluate the influences of appendages on the motion performance of the AUV, simulations of the AUV with and without appendages are performed and compared. The results demonstrate the AUV has good maneuverability with and without appendages.

Dynamic Thermal Model and Temperature Control of Proton Exchange Membrane Fuel Cell Stack

A dynamic thermal transfer model of a proton exchange membrane fuel cell (PEMFC) stack is developed based on energy conservation in order to reach better temperature control of PEMFC stack. Considering its uncertain parameters and disturbance, we propose a robust adaptive controller based on backstepping algorithm of Lyaponov function. Numerical simulations indicate the validity of the proposed controller.

Design of increasing controllability of braking vehicle

The operating principle of an antilock braking system （ABS） is it compares current value of angular acceleration with the threshold value. The advantage of such system is that enough it has only the angular velocity sensors. The disadvantage is successive overshoot, i. e. successive transition from wheels locking mode to wheels rolling mode. So braking mechanism can’ t realize the maximum possible torque in the current road conditions. The idea of increasing the braking effectiveness is the intensity of rising pressure depends on the road conditions. The problem is the torque produced by braking mechanism, current road conditions and the value of traction coefficient is unknown For evaluation of these parameters built and training three neural networks. A simulator of random road condition＇s variation was built to test adequacy of the control unites operation in close to real conditions.

A Sliding Mode Control for Uncertain Time-delay Systems

By means of the feasibility of some linear matrix inequalities(LMIs),delay dependent sufficient condition is derived for the existence of a linear sliding surface,which guarantees quadratic stability of the reduced-order equivalent system restricted to the sliding surface.And a reaching motion controller is proposed.A numerical simulation shows the effectiveness of the approach.

Semi-active predictive control strategy for seismically excited structures using MRF-04K dampers

The theoretical study of a semi-active predictive control(SAPC) system with magnetorheological(MR) dampers to reduce the responses of seismically excited structures was presented.The SAPC scheme is based on a prediction model of the system response to obtain the control actions by minimizing an object function,which has a function of self-compensation for time delay occurring in real application.A double-ended shear mode combined with a valve mode MR damper,named MRF-04K damper,with the maximum force of 20 kN was designed and manufactured,and parameters of the Bouc-Wen hysteresis model were determined to portray the behavior of this damper.As an example,a 5-story building frame equipped with 2 MRF-04K dampers was presented to demonstrate the performance of the proposed SAPC scheme for addressing time delay and reducing the structural responses under different earthquakes.Comparison with the uncontrolled structure,the passive-off and passive-on cases indicates that both the peak and the norm values of structural responses are all clearly reduced,and the SAPC scheme has a better performance than the two passive cases.

Multi-objective Scheduling Using an Artificial Immune System

Production scheduling is one of the most important problems to be considered in the effective performance of the automatic manufacturing system.It is the typical kind of NP-complete problem. The methods commonly used are not suitable to solve complicated problems because the calculating time rises exponentially with the increase of the problem size. In this paper, a new algorithm - immune based scheduling algorithm (IBSA) is proposed. After the description of the mathematics model and the calculating procedure of immune based scheduling,some examples are tested in the software system called HM IM& C that is developed usingVC+ +6.0. The testing results show that IBSA has high efficiency to solve scheduling problem.

The Dynamic Model of Allocation Control in Venture Capital

The allocation of control and stock in venture capital is the key point of the venture capital project.This paper develops a dynamic model of control and stock and profoundly analyses how to allocate the control between the entrepreneur and the venture capitalist.The model reveals the relationship of control and stock's structure,the time and the degree of imparting the control to the entrepreneur or the venture capitalist,the condition of retracting the control and compensation accordingly.

An optimal filter based MPC for systems with arbitrary disturbances

In this study, a linear model predictive control(MPC) approach with optimal filters is proposed for handling unmeasured disturbances with arbitrary statistics. Two types of optimal filters are introduced into the framework of MPC to relax the assumption of integrated white noise model in existing approaches. The introduced filters are globally optimal for linear systems with unmeasured disturbances that have unknown statistics. This enables the proposed MPC to better handle disturbances without access to disturbance statistics. As a result, the effort required for disturbance modeling can be alleviated. The proposed MPC can achieve offset-free control in the presence of asymptotically constant unmeasured disturbances. Simulation results demonstrate that the proposed approach can provide an improved disturbance ?rejection performance over conventional approaches when applied to the control of systems with unmeasured disturbances that have arbitrary statistics.

Yaw stability control using the fuzzy PID controller for active front steering

In order to improve the yaw stability of the vehicle with active front steering system, an adaptive PID-type fuzzy control scheme is designed to make the yaw rate tracking the desired values as close as possible. A 2-DOF vehicle model with active front steering is built firstly, and then the fuzzy PID controller is designed in detail. The simulation investigations of the yaw stability with different steering ma- neuvers are performed. The simulation results show the effectiveness of the fuzzy PID controller for improving the vehicle＇s yaw stability.

Research on the evaluation and mechanism of socio-economic benefit of highway projects

Based on the theory of system dynamics, the paper analyzes the mechanism of socio-economic benefits of highway projects and establishes the system dynamics model of regional economic-highway development. Then taking Jinji（Tianjin--Jixian） Highway of Tianjin as an example, the errors of system simulation are tested, and the system dynamics model built is verified to be quite stable, which has a high performance. Through the comparison of simulation results with and without Jinji Highway, the paper simulates and predicts the socio-economie benefit of each year from 2003 to 2013. Thus the quantification evaluation of socio-economic benefit of highway project is realized and will provide the theory instructions for similar projects in the future.

Robust Intelligent Control Design for Marine Diesel Engine

This work deals with the nonlinear control of a marine diesel engine by use of a robust intelligent control strategy based on cerebellar model articulation controller （CMAC）. A mathematical model of diesel engine propulsion system is presented. In order to increase the accuracy of dynamical speed, the mathematical model of engagement process based on the law of energy conservation is proposed. Then, a robust cerebellar model articulation controller is proposed for uncertain nonlinear systems. The concept of active disturbance rejection control （ADRC） is adopted so that the proposed controller has more robustness against uncertainties. Finally, the proposed controller is applied to engine speed control system. Both the model of the diesel engine propulsion system and of the control law are validated by a virtual detailed simulation environment. The prediction capability of the model and the control efficiency are clearly shown.

Probing the constitutive behavior of microcrystals by analyzing the dynamics of the micromechanical testing system

The constitutive behavior of microcrystals remains mysterious since very little,or no information regarding plastic deformation in the measured stress-strain curve is available due to plastic instability.Furthermore,the measured stress-strain curves vary greatly under different control modes,while constitutive behavior should remain unaffected by test methods.Beyond these reasons,probing the real constitutive behavior of microcrystals has long been a challenge because the nonlinear dynamical behaviors of micromechanical testing systems are unclear.Here,we perform and carefully analyze the experiments on singlecrystal aluminum micropillars under displacement control and load control.To interpret these experimental results,a lumpedparameter physical model based on the principle of micromechanical testing is developed,which can directly relate nonlinear dynamics of the micromechanical testing system to the constitutive behavior of microcrystals.This reveals that some stages of the measured stress-strain curve attributed to the control algorithm are not related to constitutive behavior.By solving the nonlinear dynamics of the micromechanical testing system,intense plastic instability(large strain burst)starting from the equilibrium state is attributed to the strain-softening stage of microcrystals.Parametric studies are also performed to reduce the influence of plastic instability on the measured responses.This study provides critical insights for developing various constitutive models and designing a reliable micromechanical testing system.