Stability investigation of car-trailer combinations (CTCs) based on time-frequency analysis (TFA) is the focus of this thesis. A state-of-the-art survey shows that very few research activities were performed to study the influence of the coupling between the vertical dynamics and horizontal dynamics, particularly for the system stability analysis. Based on the theoretical foundation of the stability analysis for CTCs, a time-frequency analysis based parameter identification method (TFA-based PIM) is proposed, in which a linear single-track model (STM), a Moving-Time-Windowed-Fast Fourier transform (MTWFFT) analysis method and an evaluation algorithm for the instantaneous cornering stiffness and the instantaneous effective axle load are integrated. It aims to study the time varying vehicle dynamics characteristics under harmonic conditions. With this PIM, vehicle dynamics parameters can be estimated continuously in time domain with a high accuracy in case a suitable model representing the system (here is a linear STM) is available. Also, they can be cross-checked by the phases of the obtained complex values of the general parameters involved here. For the analysis of the impact of the nonlinearity-induced harmonic dynamic axle load on the dynamic stability of CTCs, a complex driving dynamics simulation model of a CTC validated in the horizontal plane is utilized. With the PIM, the system characteristics of the simulation model are adjusted aiming for those delivered from the CTC applied in the road tests. To simulate the influence of the harmonic wheel load oscillations, a synthetic force generator is applied, which is synchronized to the phase of the yaw rate with a defined phase shift. Hence, the sensitivity analysis of the influence of the harmonic amplitude or phase of this force on the system dynamic stability is performed with a simulation model validated in the horizontal plane. Through this variation, the change of the system dynamic critical speed is actually determined and so is the reason why the temporal changes of the system dynamic stability can be explained by the fluctuations in the amplitude and/or the phase of the superimposed harmonic dynamic axle load.
Stability Investigation of Car-trailer Combinations based on Time-Frequency Analysis
2015-08-10
Theses
Electronic Resource
English
DDC: | 629 |
Stability Criteria for Automobile-Trailer Combinations
Taylor & Francis Verlag | 1980
|Stability Criteria for Automobil-Trailer Combinations
Automotive engineering | 1980
|NTIS | 1972
|