Toward Automated Vehicle Control Beyond the Stability Limits: Drifting Along a General Path

Abstract

Professional drivers in drifting competitions demonstrate accurate control over a car's position and sideslip while operating in an open-loop unstable region of state-space. Could similar approaches help autonomous cars contend with excursions past the stable handling limits, thereby improving overall safety outcomes? As a first step toward answering that question, this paper presents a novel controller framework for automated drifting along a path. The controller is derived for the general case, without reference to a nearby equilibrium point. This leads to the physically insightful result that one can use the rotation rate of the vehicle's velocity vector to track the path, while simultaneously using the yaw acceleration to stabilize sideslip. Nonlinear model inversion, in concert with low-level wheelspeed control, is then used to achieve these required state derivatives over a broad range of conditions. Experiments on MARTY, a modified 1981 DMC DeLorean, demonstrate excellent tracking of a path with varying curvature, speed, and sideslip. Comparisons to a test run without wheelspeed control highlight the importance of accounting for the rear saturated-tire wheelspeed dynamics.

Development of a New System for Attaching the Wheels of the Front Axle in the Cross-Country Vehicle

“…The aforementioned design shortages of the wheel suspension are removed by the design that attaches the wheels of the front axle in the cross-country vehicles according to the presented technical solution [22,23]. Its essence lies in the fact it consists of the upper (1) and bottom control arm (2). They are anchored in the basic shape of a square (SK 7960 Y1, Figure 3a) or a rhomb (SK 7945 Y1, Figure 3b) to a frame in an oscillating way and are inclined backwards by an inclination angle of α = 15° to 50° [22].…”

“…However, it must not be too soft for the stability at a higher speed to be kept. Therefore, the suspension adjustment is a compromise between the stability, safety and driving quality [1][2][3]. The wheel suspension has been improved and developed since the first vehicles appeared.…”

Autonomous Vehicle Maneuvering at the Limit of Friction

“…This can be taken advantage of to model the driving behavior when the tire forces are fully saturated, such as for drifting maneuvers [72]. In the friction-ellipse based model, this is assumed to also hold for any nominal lateral tire force [59]…”

A Methodological Review of fNIRS in Driving Research: Relevance to the Future of Autonomous Vehicles

“…While semi-autonomous cars or “SAE Level 2 Automation Systems” ( SAE, 2018 ) have become visible on our roads ( Martinho et al, 2021 ; Tan et al, 2021 ), higher order automated systems (i.e., SAE Level 3–5 Automation Systems) are being engineered and tested (see Figure 1 ). Among the many advantages automated vehicles could bring to our streets is an increase in safety by outperforming the human through manipulation in driving dynamics ( Goh et al, 2020 ), an increase in consumption efficiency ( Phan et al, 2020 ), or a reduction of overall travel time by stabilizing traffic flow ( Wu et al, 2018 ). However, until fully automated systems are engineered, approved, and legalized for the transport of (fully) passive passengers (i.e., SAE Level 4–5), the human driver will still manually drive the car, for at least segments of the drive, for many years to come.…”