Vol. 3, No. 3 (2014): Regular Issue

This paper is the first part of a study related to modeling drivers dynamics in the overall driving loop in the context of disturbance rejection and trajectory tracking. The final objective is to dispose of a library of drivers models usable in a simulation context for Global Chassis Control (GCC) of automotive vehicles. Small angle variations are applied on the steering wheel and hence the use of a linear model is fully justified. The driver’s dynamics is first of all modeled by using a rational transfer function and then a fractional one. More specifically, the first part of the study presents the experimental set-up, named instrumented chair, and describes the experimental protocol. Then different models parts of the experimental set-up are established. Next, passive feedback and steering wheel/hand link is modeled. It is shown that a fractional model, as compared to a rational one, allows to enhance by a factor of 2.7 the criterion in modeling dissipative phenomena. The second part of the study treats both driver steering feel and visual feedback modeling, using a set-membership approach.

This paper is the second part of a study related to modeling drivers dynamics in the overall driving loop in the context of disturbance rejection and trajectory tracking. After a brief description of the experimental set-up, a fractional model for steering feel and visual feedback cases are proposed, and their parameters estimated. As expected in human reaction, data recorded from different experiments present a considerable dispersion, due to varying human reactions from one experiment to another. Such time-variant systems can be modeled using set membership methods which allow identifying a set of feasible models for healthy persons.

An elastic cantilever beam pressed against a rigid rotating disk is explored for studying the mitigation of self-excited friction-induced vibrations that are inherently unstable due to alternating friction conditions and decreasing dynamic friction characteristics. Because no linearization or approximation scheme is followed, the genuine characteristics of the system including stick-slip and inherent discontinuities are fully disclosed without any distortion. It is shown that the system dynamics is stable only within certain ranges of the relative velocity. With increasing relative velocity, the response loses its stability with diverging amplitude and broadening spectrum. A novel time-frequency controller is subsequently applied to negate the chaotic vibration at high relative velocity by adjusting the applied normal force. The controller design requires no closed-form solution or transfer function, hence allowing the underlying features of the discontinuous system to be fully established and properly controlled. The inception of chaotic response at high relative velocity is effectively denied to result in the restoration of the system back to a relatively stable state of limit-cycle.

We apply the method of variable feedback to obtain complete synchronization in a coupled map lattice. The conditions under which such a synchronization is possible are obtained analytically. We show that synchronization is robust against noise and parameter mismatches. This method leads to synchronized state quite rapidly and we discuss its applications for near-real-time multi-channel communications.

Articulated pipes conveying fluids are widely used in industries especially petroleum industries. The nonlinear oscillations of an articulated pipe jointed with an oil conveying system is studies and characterized in this research. The responses of the articulated pipe without external excitation are analyzed. The oscillations of the pipe corresponding to the fluid flow and joint stiffness are investigated in detail. The nonlinear oscillations of the pipe subjected to external excitation are also studied in this research. The periodic, quasi-periodic and chaotic oscillations of the pipe are found in the study. The nonlinear behaviors of the pipe’s responses are diagnosed and characterized with employment of the Periodicity Ratio (P-R) method. A regularirregular region diagram is developed corresponding to wide ranges of system parametric values, reflecting those used in engineering practices. The results of the research provide practically sound guidance for industrial application and research in this field.

Analytical and numerical methods are applied to a pair of coupled nonidentical phase-only oscillators, where each is driven by the same independent third oscillator. The presence of numerous bifurcation curves defines parameter regions with 2, 4, or 6 solutions corresponding to phase locking. In all cases, only one solution is stable. Elsewhere, phase locking to the driver does not occur, but the average frequencies of the drifting oscillators are in the ratio of m:n.These behaviors are shown analytically to exist in the case of no coupling, and are identified using numerical integration when coupling is included.

This paper investigates the dynamic response of a gear pair under random excitation from the view point of spectral density. Two methods are used to calculate the response spectral density function (SDF). The first method uses the statistical linearization (SL) technique to find an equivalent linear system to the original nonlinear one, then the response SDF is calculated with the equivalent linear system. While the second method regards the natural frequency of the system as a function of the response amplitude which is a random variable and its probability density function (PDF) is computed through stochastic averaging (SA). Then the response SDF is computed as a probabilistic averaging over the whole range of amplitude. Simulation result shows that both methods can predictthe resonant frequency very well and consistently in the case of weaknonlinearity. But with increasing of nonlinearity, the SDF predicted from the SL technique tends to be narrower than that from method II.