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With the goal of improving drivability, this research aimed to clarify the mechanism of vehicle longitudinal acceleration, focusing on tip-in acceleration. Conventional typical analysis methods include experimental modal and model-based analysis. However, since the former requires the measurement of impulses and other input forces while the vehicle is stopped, measurement under actual driving conditions is difficult. The latter requires characteristic values such as the stiffness and damping coefficients to be identified in advance, which cannot be achieved either easily or precisely. Therefore, this paper proposes a new experiment-based analysis method. This method enables the acquisition of engine torque and transmission torque/force by measuring only the acceleration values of some components under driving conditions.

In order to increase the transfer efficiency in a metal V-belt type CVT (Continuously Variable Transmission), it is effective to lower belt clamping force from a current setting value. However, setting the clamping force too low will cause a macro slip (large belt slip). Thus, in order to set the clamping force to the proper level, the friction characteristics between the belt and the pulley (belt friction characteristics) must be understood in detail, and the macro slip threshold must be defined. In this paper, we shall propose a friction expression model for a metal V-belt type CVT and use this model to explain the speed reducing ratio dependence and speed dependence of the maximum friction coefficient (μmax). We shall also define the macro slip threshold in torque fluctuation environment.

This paper describes the development of a detection system of maximum force for a metal belt type CVT. By detecting the occurrence of a macro slip between a belt and pulleys in its early stage, the maximal point of the friction force can be detected while the belt is still running with sufficient clamping force. The ability of the detection system was examined using an experimental test rig of a continuously variable unit.

For the vehicle stability control system, which improves vehicle yaw stability for limit driving condition, accurate vehicle sideslip angle detection is one of key issues to confirm the system performance. In this paper, an estimation method of vehicle sideslip angle is described. It is necessary that the vehicle sideslip angle estimation must be robust against road surface condition change, road bank, sensor error, brake force effect, driver's operation and so on. We have developed the sideslip angle estimation method for compensating the driving condition changes which disturb the sideslip estimation. The vehicle sideslip angle estimation using a combination of vehicle model observer and pseudo integral is proposed. The vehicle model observer includes tire non-linear characteristics for fitting actual tire characteristics. Moreover, road-tire friction, road bank and vehicle spinout judgments are developed for increasing the estimation accuracy.

This paper presents a new method for estimating the ambiguous change in a 4WS control system using a failure detection filter. This filter is designed to discriminate ambiguous failure modes in the control system by processing output errors between sensors and an observer. The result of the experiments using a 4WS vehicle revealed that the filter can estimate the failures of the sensors and the actuator with high accuracy. The effects of a lateral wind and other disturbances on the filter were also clarified.

Recently, active control technology of vehicles has extensively been developed. An experimental vehicle with independent hydro-pneumatic suspensions was constructed in our laboratory for the improvements in vehicle dynamics and ride-comfort. The vehicle includes a controller, mainly consisting of a multi-processor system with 5 CPUs. By combining this new system with a common bus, all CPUs can immediately access peripherals impartially without particular software. The CPUs can also acquire the data of sensors from the memory in the A/D module at any time without special software. The CPUs are shared to synthetically control the attitude and vibration of each vehicle wheel. Therefore, high capacity is exhibited by a simple system at low cost. The performance of the controller was examined by actual running tests using the experimental vehicle, confirming the improvements in vehicle dynamics and ride-comfort, such as reduction in roll angle and vibration.