Nonlinear chaos identification of traffic flow parameters on expressway based on the C-C average method

Abstract

The transportation system is a complex giant system under a variety of internal and external factors restrict and influence, which makes traffic system showed a strong nonlinearity and uncertainty, and traffic flow is the most intuitive reflect these features. Phase space reconstruction based on the chaos is the necessary steps to analyze the nonlinear characteristics of complex systems. The C-C algorithm that using the correlation integral is an effective way to estimate the parameters of delay time τ and delay time window Tw of phase space reconstruction. Due to the length limited and noise of traffic flow time series, the τ and Tw estimated by C-C method is with volatility. To reduce value deviation, the C — C average algorithm is used in this paper to reconstruct the phase space, and to get the optimal delay time of short-term traffic flow parameters. Then the maximal Lyapunov exponent is calculated by the small-data method, to determine whether the traffic flow time series is chaotic system or not.