Controllability and loading conditions of tractor and semitrailer combinations in lane change

This paper presents a theoretical study on the controllability of tractor and semitrailer combinations in lane changes. The analysis is conducted by using a three DOF model incorporating the lateral deviation and yawing of vehicles. The steering sensitivity, settling time, and maximum deviation are defined as controllability features and are calculated together with the stability factor and critical speed, taking into consideration overloading conditions. The following conclusions are drawn. (1) The steering sensitivity in lane changes is a function of the stability factor of the tractor combined with a semitrailer, the steering duration in lane changing and the width between center lines of the lanes. (2) For uniform over-loading conditions, the steering sensitivity in lane changes to forward velocities increases with increased loading. For the front overloading conditions, the steering sensitivity is greater than that of uniform over-loading conditions. For the rear overloading conditions, the steering sensitivity is less than that of uniform over-loading conditions. (3) The settling time is similar to the steering sensitivity because of non-oscillatory behavior of vehicles in over-loading conditions. (4) The maximum deviation becomes small as the vehicle forward velocity approaches the critical speed in over-loading conditions.