Dynamics and parameter identification of a tractor semitrailer-driver closed-loop system using the simulated annealing optimization approach

摘要

Identifying the dynamics and parameters for an articulated heavy vehicle/driver (tractor semi-trailer/driver) system was the main objective of this thesis. The dynamic behaviour of the vehicle system was studied by setting up a closed-loop control model of a tractor semi-trailer/driver system that included a three-degree-of-freedom (3-DOF) tractor semi-trailer lateral dynamic model and a driver steering model. The tractor semi-trailer's lateral displacement, lateral velocity, yaw velocity and yaw angle were viewed as the state vector of the 3-DOF tractor semi-trailer lateral dynamic model. It was assumed that the driver-steering control model would respond to the state vector following a time delay. The inherent driver-steering parameters to be identified were the state vector's coefficients, here defined as an optimal control vector. The Simulated Annealing (SA) method was used to search this control vector, because the problem of searching optimal control vectors does not fall under classical control theory. When step lateral displacement was introduced, optimal control simulations were performed on the tractor semi-trailer vehicle using its own optimal control vector; this was searched using the SA method. The responses of the tractor semi-trailer vehicle illustrate its dynamic characteristics: these can be used to enhance the driver's steering performance. Other simulations were also conducted in order to discover optimal steering methods and the tractor semi-trailer's dynamic responses to various velocities, various loads and various human-reaction time delays. Somne crucial control parameters were obtained by comparing the responses made by two different types of tractor semi-trailer vehicles. Lastly, a preview driver model derived from the complex driver model was used to search safe preview distance.