This paper intends to lay the groundwork for detection of backlash nonlinearity in a two-mass rotational system representing a vehicle driveline. It involves experiments and practical considerations prior to carrying out a system identification of the plant. Four possible system configurations are elaborated. Parameter estimation is then carried out in Dymola. Practical factors that affect the quality of parameter estimation such as the type of input signal is discussed. It is established that it is more suitable to use Pseudorandom Multilevel Sequence (PRMLS) excitation for the detection of backlash because the multilevel magnitudes of the signal can invoke the nonlinearity of the system when the it is amplitude dependent. The preliminary identification results will be used in later work for active vibration control.

Experimental design for backlash detection in a two-mass rotational system

In this paper, a discretization-oriented describing function is derived for nonlinear devices combining backlash and quantization (resolution) while being subject to discretization through a sampler and zeroorder hold. Such a describing function is frequency-dependent so that the overall nonlinearity, which includes both resolution and backlash, is interpreted as possessing nonlinear inertia. That nonlinear inertia is generated by the sampling process, since it does not appear if the system is continuous. The presence of nonlinear sustained oscillations (limit cycles) is investigated through simulations.

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A. Pena J. Esnaola

Papers

Analysis of Nonlinear Sustained Oscillations in Discrete Systems with Backlash and Resolution by Using a Discretization-Oriented Describing Function