Rollover Preventive Force Synthesis at Active Suspensions in a Vehicle Performing a Severe Maneuver with Wheels Lifted off

TL;DR

This paper develops an algorithm for synthesizing and allocating active suspension forces to prevent vehicle rollover during severe maneuvers, even when wheels lift off, by solving an optimal control problem with disjunctive constraints.

Contribution

It introduces a novel method to handle disjunctive constraints in active suspension control, enabling force synthesis during wheel lift-off scenarios.

Findings

Numerical simulations confirm effective stabilization of vehicle roll with lifted wheels.

The proposed convex combination approach satisfies disjunctive constraints accurately.

Control forces derived from sensor data successfully prevent rollover during severe maneuvers.

Abstract

Among the intelligent safety technologies for road vehicles, active suspensions controlled by embedded computing elements for preventing rollover have received a lot of attention. The existing models for synthesizing and allocating forces in such suspensions are conservatively based on the constraint that no wheels lift off the ground. However, in practice, smart/active suspensions are more necessary in the situation where the wheels have just lifted off the ground. The difficulty in computing control in the last situation is that the problem requires satisfying disjunctive constraints on the dynamics. To the authors',knowledge, no efficient solution method is available for the simulation of dynamics with disjunctive constraints and thus hardware realizable and accurate force allocation in an active suspension tends to be a difficulty. In this work we give an algorithm for and simulate numerical solutions of the force allocation problem as an optimal control problem constrained by dynamics with disjunctive constraints. In particular we study the allocation and synthesis of time-dependent active suspension forces in terms of sensor output data in order to stabilize the roll motion of the road vehicle. An equivalent constraint in the form of a convex combination (hull) is proposed to satisfy the disjunctive constraints. The validated numerical simulations show that it is possible to allocate and synthesize control forces at the active suspensions from sensor output data such that the forces stabilize the roll moment of the vehicle with its wheels just lifted off the ground during arbitrary fish-hook maneuvers.