Longitudinal Control of Autonomous Vehicles Consisting Power-Train With Non-Linear Characteristics

Abstract

The autonomous vehicle studiesrecently have been accelerated to ensure more secure, efficient, and comfortable transportation. Non-linearity in the power-train makes longitudinal control of autonomous vehicles difficult at low speeds. Additionally, rapid acceleration and deceleration (due to the behavior of the surrounding vehicles) increase complexity in control of such systems. In this study, we designed a novel longitudinal controller including the reverse plant model of the vehicle to overcome these problems. The complete controller is designed using parameters known to OEMs (Original Equipment Manufacturer) with vehicle CAN bus signals. The longitudinal controller consists of two parts: The outer controller which determines the target speed according to lead vehicle's speed and the inner controller which determines the accelerator pedal percentage and brake requests. The inner controller includes PI followed by the reverse plant model with a virtual load sensor. This model enables control of a vehicle with non-linear power-train. The designed controller performance was tested on a city bus with a diesel engine and automatic transmission. Vehicle test results proved, that the designed controller is capable of controlling an autonomous vehicle with nonlinear power-train dynamics with onboard computational capacity even at low speeds.