Abstract
The automation of the steering of a vehicle is an essential part of any kind of application that involves autonomous driving or navigation. This paper presents an apparatus and its control architecture able to control the steering of a road vehicle without the need for any intervention from human drivers. This device can be installed in any kind of vehicle regardless of the kind of assistance of the steering.
The aim of the mechanism of the steering automation system is to transmit torque from an electric motor to the steering column, through a gear or pulley. This system is similar to that already used in other automation solutions. However, in these solutions, switching from manual to automatic driving and vice versa is done manually and, in general, when the vehicle is stopped. This invention overcomes this limitation through an intermediate electromagnetic clutch. This apparatus has the following characteristics: 1) The device is independent of the type of vehicle and type of steering assistance; 2) The steering control does not require command transmission through the vehicle internal communication bus 3) The engagement or disengagement of the autonomous mode is automatically controlled; 4) The driver never loses complete control of the vehicle; 5) It does not interfere with the driving task.; 6) The mounting involves no permanent modifications to the vehicle
The system has been installed in a passenger car and has been tested on the University Institute for Automobile Research test track. The aim of these tests was to verify that the mechanism and the control system are suitable to be used for driver assistance and for autonomous driving. High demanding test scenarios have been examined in order to verify that the system meets certain minimum requirements for replicating high demanding manoeuvres. The system very faithfully reproduces human behaviour taken as reference, and is able to perform an aggressive manoeuvre of large amplitude turns in a fairly short time. According to this, the system described is able to reproduce the most aggressive evasive manoeuvre that has been taken as reference.
The main limitation of the device is its size, so implementation in some types of passenger cars could be difficult. However, in most vehicles there is room enough to mount the device without problems. More compact solutions are now under development. The device overcomes the limitations of previous solutions oriented to vehicles with hydraulic or electric assistance of the steering system and takes advantage of their strengths.
KEYWORDS – Automation; universal device; mechanical design; steering system