Two-phase optimal path planning of autonomous ground vehicles using pseudo-spectral method

Abstract

In this paper, an optimal path-planning method is proposed for autonomous ground vehicles in case of overtaking a moving obstacle by the application of a two-phase optimal-control problem. When the autonomous vehicle detects a moving vehicle in a proper speed and distance ahead, it decides to overtake the obstacle by executing a double-lane change manoeuvre. The path for the overtaking manoeuvre is generated by a two-phase optimal path-planning problem. The cost function of the first phase is defined in such a way that the vehicle approaches the obstacle as close as possible.In the second phase, the cost function is defined as sum of the vehicle lateral deviation from the reference path and the rate of steering angle. At the same time, the lateral acceleration of the vehicle must not exceed a specified limit. The radio pseudo-spectral method, which is a method for direct trajectory optimization using global collocation at Legendre-Gauss-Radau points, is applied for solving the two-phase nonlinear optimal-control problem. A full nonlinear vehicle model in CarSim software is used for path-tracking simulation by importing path data from a MATLAB code. The simulation results show that the generated path for the autonomous vehicle satisfies all vehicle-dynamics constraints and hence is applicable for a real autonomous vehicle.

Development of a neuromuscular driver model with an estimation of steering torque feedback in vehicle steer-by-wire systems

“…In this linear vehicle model, it is assumed that the lateral forces are regarded as linear functions of the tyre slip angle. Governing equations of the bicycle model can be derived as follows 19 where m is the vehicle mass, v is the lateral velocity, u is the vehicle longitudinal velocity, and I z is the yaw moment of inertia. Fyf and Fyr are the transient lateral tyre forces on the front and rear axles, respectively, which are generated by the interaction between the tyres and the road surface.…”

“…In this linear vehicle model, it is assumed that the lateral forces are regarded as linear functions of the tyre slip angle. Governing equations of the bicycle model can be derived as follows 19 m…”

Study on the optimal lane changing steering input under different road adhesion coefficients

“…14,15 With the development of the application of pseudospectral methods, pseudospectral methods have gradually become the most active branch of the numerical solution method for optimal control problem. 16 Mashadi and Majidi 17 used global Radau pseudospectral method (RPM) to study the two-phase optimal path planning problem; the optimal path required in different stages of overtaking process was obtained by setting different performance indexes. Liu and Jiang 18 presented a global Gauss Pseudospectral Method (GPM)-based inverse dynamics model to achieve the path tracking of vehicles; the results indicate that GPM has lower initial sensitivity and better convergence speed compared with the traditional methods.…”

Bond graph analysis and optimal control of the hybrid dual clutch transmission shift process

“…The shift control trajectories of different configurations of the HDCT-based powertrain system are optimised by using a pseudospectral collocation method, which is widely used for solving direct trajectory optimisation problems. 11,12 The methodology has been originally developed for optimal shift control of a 10-speed torque converter AT, as presented in Č oric´et al 13 It can readily be adjusted to other automatic transmission types and configurations, and to a more general problem of multibody system optimal control. The main contributions of the presented work include: (i) analysing the HDCT shift transient effects by using a systematic and illustrative graphical approach based on the bond graph methodology (similarly as it is done for ATs shifts in Ranogajec et al 7 ); and (ii) gaining quantitative insights into optimal control action and performance gains for different HDCT configurations and shift tasks.…”