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The road impact load and the vibration are the main factors for the commercial vehicle, especially on the van trailer. In this paper, a new method which puts the operating modal identification and power spectrum density (PSD) analysis together was presented. The analysis results coincided with the road test quite well. The power spectrum response was obtained and the fatigue life of the vehicle was also estimated. This method can be used for the vibration optimization design and a random fatigue design of other commercial vehicles.

The performance of Hydraulic Anti-lock Braking System (ABS) is important to vehicle brake safety. In this paper, finite element models and simulation models for studying dynamic response of solenoid valve, a critical part of ABS, are established. Based on the calculation results, which are proved in experiment, several effective methods for improving the performance of the solenoid valve are presented. Furthermore, an ABS-vehicle model is developed to study the influence of hydraulic ABS parameters on braking effect. The simulation results have good agreement with the data of in-vehicle driving experiments.

A Traction Control System (TCS) is developed for the Anti-lock Braking system (ABS). A Hardware-in-the-loop simulation (HILS) method is used to help debug the control strategy of a TCS for a passenger vehicle. The TCS HILS platform is extended from the ABS test rig by adding a throttle controller and two pressure control solenoid valves. First is established vehicle simulation model that includes a half vehicle dynamic submodel, an engine submodel, a manual transmission system submodel and the tyre submodel. Secondly, the control model of the TCS based on the logical threshold method is included in the same digital simulation software. The digital simulations of the passenger vehicle shows that the control model with different control thresholds as input is correct and it can be run in a real TCS's structure parameters and real electric control unit (ECU). An ECU of TCS with an Infineon's 16-bit microcontroller C167CS as the main central processor unit is designed.

A DSP-based (digital-signal-processing-based) measuring technique of jerk is proposed in this paper. By analyzing the frequency characteristics of jerk, we design a low pass digital differentiator suitable for jerk measuring. The digital differentiator is a linear-phase FIR system, and has the advantages of low order, favorable low frequency performance and good suppression of upper band frequencies. A measuring device has been developed based on this measuring technique, and has been used in practical applications. The accuracy and stability of the measuring device have been verified by experiments, which also approved the good performance of our DSP-based measuring technique of jerk.

Electronic Stability Program (ESP), also named Vehicle Dynamic Control (VDC), extends the capabilities of the Anti-lock Braking System and the Traction Control System. Firstly, a vehicle dynamic model with 16 DOF, including vehicle body submodel, wheel submodel, force submodel, tire submodel, engine submodel, transmission submodel, also containing braking submodel, and steering submodel is built under SIMULINK software. After completing the simulation under normal mode, A Real-Time Windows Target model under the external mode is produced. The Real-Time Windows Target model for ESP is upgraded to run under Matlab/Simulink/RTW software, to complete the ESP’s Hardware-in-the- Loop simulation (HILS) with the help of the I/O boards produced by the Advantech Co. and the I/O driver block library provided by the Real-Time Windows Target. In the end, an interface for controlling the simulation system is designed.

A thorough study on the physiological experience of jerk is made in this work. Referring the physiological feeling, we classified the jerks into two groups, which are transient jerks and durative jerks, and made a series of experiments for research. The experiment method is detailed in the literature. By reviewing the experiment results, we discussed the current quantifying methods of jerk and proposed a comprehensive method using magnitude of jerk and root mean square (rms) jerk for evaluating the shift quality and ride comfort. All the conclusions and proposals we made in this work are supported by experiment data.

Anti-lock Braking System (ABS) is an important control system that can improve the automotive performance, reliability and safety obviously. Hardware-in-the-loop Simulation (HILS) testing is a promising method to assistant design automotive electronics system. In the State Key Laboratory of Automotive Safety and Energy, a HILS system was established to assistant design ABS. The HILS system is composed of a hydraulic control unit of ABS, a normal brake system, a commercial personal computer, a data acquisition card, and several signal-conditioning modules. Powerful software was programmed to perform managing input and output signals, solving 7-freedom and 15-freedom vehicle models, and acquiring response signals of the brake system. Based on the simulations of HILS system, the road experiments with the same conditions of ABS are very necessary and important.

The cruise control as one of promising vehicle active control has been receiving a considerable attention in recent years, so the related problems are discussed in this paper. Mathematical model of the engine under the steady state and general dynamics equation of the Continuously Variable Transmission(CVT) are given, the regulating principle of the operating state of the engine is analyzed, and the conjugate gradient method employed to solve the optimal control problem of the vehicle in the cruise control is described, so the operating state of the engine could be controlled. At end of paper, some results are provided to verify the approach based on the vehicular powertrain with a hydromechanical CVT.

Although Hydrostatic Transmission System (HTS) had been used in many places, such as machine tools, agriculture machinery, construction machinery, and vehicles, it had not been used in good performance. Twenty years ago many people began to design new hydrostatic transmission with higher efficiency. Hydrostatic Energy Storage Transmission System (HESTS) is one of new hydrostatic transmission system with higher efficiency. HESTS is more fit for being used in vehicle that is always running in undulating ground or starting and braking frequently. Construction of vehicular HESTS was analyzed, mathematical model of vehicular HESTS was established. The needed control strategies of vehicular HESTS were analyzed because there are many variables would be controlled in the new transmission system.

In View of the performance of high output torque moment, good response and continuously variable transmission of hydrostatic transmission, a new concept of Hydraulic Energy Storage Transmission System (HESTS) of city bus was put forward, although the hydraulic-mechanical split power hybrid city bus had run effectively in some cities, such as Copenhagen, Stockholm and Berlin, etc.[1][2]. HESTS was comprised of a variable displacement pump, a variable displacement pump/motor unit, two accumulators and an Electrical Control Unit (ECU). The high pressure accumulator could be controlled to absorb braking energy in hydraulic energy and reuse the stored energy to restart the prime mover or accelerate the vehicle. HESTS could operate in seven modes while the ECU outputs different combined control signals to pump, pump/motor and directional valves. The mathematical model of a HESTS for a city bus was established.

A Hydrostatic Energy Storage Transmission System(HESTS) designed for vehicle is presented in this paper*. A bench-scale HESTS was built in the Fluid Power and Control Laboratory of Harbin Institute of Technology. The laboratory testing HESTS was powered by a DC. motor which was controlled by a Silicon-Controlled Rectifier(SCR). Loads adding to the HESTS were regulated by a proportional valve control system. The HESTS is more complex because there are not only continuous variables-the shaft speed of the hydraulic axial piston variable displacement pump/motor unit and the position of the displacement-varying cylinder, but also discrete variables-the on/off states of clutch, 2/2 solenoid valve and 2/4 solenoid valve in the HESTS to be controlled. So a fuzzy logic controller with a mode selector is designed to perform the role of control to the HESTS. A personal computer stored control rules executes the tasks of data acquisition, fuzzy logic inference and control.

A low cost, anti-pollution pump/motor displacement-varying mechanism was studied in this paper. In the hydrostatic energy storage transmission system(HESTS), a variable pump (motor) unit was used to transfer the energy. A new pump/motor displacement-varying mechanism was obtained based on low price manual manipulating variable pump with high-speed on-off solenoid valves supporting pressure oil. Simulation results showed that the position precision and the ability of following sinusoidal wave signal of the new mechanism met the requirement of the pump/motor unit. Experiment results proved that the new pump/motor displacement-varying mechanism operated precisely and reliably.

A novel hydraulic transmission system-Hydraulic Energystorage Transmission System(HESTS) which contains a Hydraulic Continuously Variable Transmission(HCVT) and a flow controllable accumulator is proposed. The power flows of the HESTS has been analyzed. Computer simulations show the potentialities of improving fuel economy of a vehicle with a HESTS. A fuzzy logic controller with two regulating factors is developed to improve the performance of the HESTS with variable loads.