Active Pitch Control for Prevention of Passenger Falling Over in Autonomous Shuttle

Abstract

This study focuses on an autonomous shuttle (level 4 driving automation) with four-wheel-drive in-wheel motors. We propose an active pitch control, called APC, by a driving/braking force distribution of the front and rear wheels to prevent passengers from falling over inside the shuttle. This study applies a half-car model that considers the driving/braking force and a passenger model using a rigid body. A passenger system's zero-moment point (ZMP) is defined as an index to evaluate the possibility of passengers falling over. The present manuscript applies a 2DOF control system that consists of an optimum regulator as a state feedback controller and a feedforward controller derived from the inverse characteristic of the closed-loop system where the feedback component is substituted into the state equation. Moreover, we designed a motor output limiter and a limiter to avoid tire force saturation. Numerical simulations were performed to verify that the proposed APC can reduce the possibility of the passenger's falling over when the shuttle accelerates/decelerates.