Hierarchical control system for autonomous vehicles based on robotic formalism

摘要

In this paper a novel method is presented for hierarchical control of autonomous vehicles consisting of high-level (HLC) and low-level (LLC) control systems. The LLC system can be commanded to assure a prescribed velocity and steering profile using PID-type active suspension, velocity and steering control. The outputs of the LLC system are the generalized forces and moments required by the vehicle. Because of its nature, the LLC system cannot eliminate position and orientation errors caused by the unknown centre of gravity point, drifting and time-varying friction. These errors are compensated by the HLC which uses the kinematic model of the vehicle to generate the reference trajectory from the prescribed profiles and employs a linear quadratic optimal controller to compensate the tracking errors. The control algorithm minimizes the perturbations and the optimal solution is realized as a time-varying state-feedback control law. The efficiency of the hierarchical vehicle control system is validated for realistic motion maneuvers by simulation on the nonlinear vehicle model using multibody robotic formalism.