Abstract: | The natural measure of a certain area in phase space is defined firstly. On the basis of natural measure, the expression of Lyapunov exponent based on unstable periodic orbits (UPOs) of chaotic systems is deduced from theoretical aspect. Then, by means of the inherent relation between UPOs and systematic Lyapunov exponent, the transitional mechanism and route of chaotic systems from low-dimensional chaos to high-dimensional chaos are explained. In the end,a novel method for computing systematic Lyapunov exponents based on UPOs is proposed. Its computing procedure is also summarized. The chaotic system described by Henon map is taken as example. Through calculating the Lypunov exponents of this system, validity of the suggested method is verified. |