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Control of the Clutch is a complex system with multi-infactor, multi-goal and nonlinear properties, the fast tracing capability should be needed at the same time, so the fuzzy control is suitable for it. The difficulty of the clutch fuzzy control is how to analyze its stability. In this paper, the theory of Lyapunov and linear approximation is applied to analyze and design the stability of the clutch fuzzy control, which is a practical method in analysis of the stability of nonlinear systems.

Based on analysis problems of vehicle with present automatic transmission, an Intelligent Shift Strategy(ITSS) is proposed for the first time. Three kinds of information, which are the driver intention, the vehicle dynamic characteristics and the outside environment, are included in it, and the humachine technology is applied to decide shift strategy.

Difficulty of the Automatic Transmission(AT) is to properly control its clutch while the vehicle starts. An intelligent hierarchical controller is proposed in this paper. The upper of it is an intelligent PID controller based on a driver's experience and an expert's knowledge. It gives real time signals to the lower controller and coordinates the control between engine and clutch. The lower Variable Structure Fuzzy Controller (VSFC) executes the upper controller's direction signal.

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.

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 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.

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.

The control of vehicle clutches is somehow different of non-linearity from others and needs consideration of control matching between the clutch and engine. For that reason, an expert fuzzy control is proposed in this paper, which is integrated with expert control, fuzzy control and hierarchical control. By real vehicle test results, the control function is verified.

For the fast tracing control problem of clutch actuator with non-linear characteristics, multi-factor and multi-target, a kind of VSFC is proposed in this paper which has a PD forward unit to improve its fast tracing capability. According to the characteristic status of system, the proper control strategy is applied in the VSFC.