his paper presents a model based control strategy aimed to reduce noise and wear during gearshifts in conventional and hybrid Dual Clutch Transmissions (DCT and DCTH) and Automated Manual Transmissions (AMT). The control strategy is based on a newly developed dog teeth position sensor layout at China Euro Vehicle Technology AB (CEVT), a detailed simulation model for gear engagement and already existing speed sensors in the transmission. The details of dog teeth position sensor and simulation model are also presented in this paper. During gear shifting, noise is generated because of impacts between the sleeve teeth and the idler gear dog teeth after speed synchronization. Besides noise, these impacts are also responsible for delaying the completion of shift and contribute to wear in the dog teeth, hence reducing the lifespan of the transmission. The simulation model for gear engagement can simulate these impacts. Based on the simulation model and optimal control theory, an ideal dog teeth position trajectory is formulated that avoids the impact between sleeve and idler gear dog teeth, before the start of torque ramp up. The open loop strategy then controls the synchronization torque in the beginning of speed synchronization in such a way that the dog teeth position during shift follows the ideal dog teeth position trajectory. Since the control strategy is based on optimal control theory, its effect on speed synchronization time is minimal. The control strategy is designed in such a way that it can easily be applied in the existing transmission control software. By applying the control strategy on the simulation model, it is shown that the impacts during gear engagement are reduced. * (). FIGURE 13 Selected Batch simulation results

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The most important characteristics of the behavior of viscoelastic materials are the time and temperature dependence of their properties. Viscoelastic models based on Prony series are usually used due to easy implementation in finite element analysis (FEA) codes. The experimental data are fitted to a Prony series using a user-convenience number of terms represented by two coefficients. The time coefficients 𝜏 𝑖 are previously fixed in the time scale in order to determine the second parameters of the model.Usually, an homogeneous distribution in logarithmic-time scale is used for τ i , which produces accurate fittings when a large number of terms in the Prony series are used as well as when the material presents a uniform sigmoidal viscoelastic curve along several decades of time. When short-time curves must be fitted or the relaxation curve shape is not so uniform distributed along time, the homogeneous distribution of time coefficients could be a significant drawback since a large number of coefficients could be needed or even a reasonable fitting with a Prony series model is not possible.In this study, an optimized 𝜏 𝑖 distributed method for fitting master curves of viscoelastic materials based on Prony series model is proposed. The method is based on an optimization algorithm strategy to allocate the time coefficients along the time scale in order to obtain the best fit. The method is validated by using experimental data of temporomandibular joint (TMJ) disc, which is a biological material that presents a shorttime and high relaxation rate viscoelastic curve. The results show that the method improves significantly the fitting of the viscoelastic curves when compared with uniform distributed time fittings. Furthermore, the optimized coefficients are also used to obtain the complex moduli of the material using an analytical conversion, which is compared with the experimental complex moduli curves of the material.

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