Limitations of Torque Vectoring As a Backup Safety Strategy for Steer-by-Wire Vehicles due to Vehicle Stability Control

2017 ◽  
Author(s):  
Ahmet Kirli ◽  
Chinedum E. Okwudire ◽  
A. Galip Ulsoy
Keyword(s):  
Autonomous Vehicles ◽  
Stability Control ◽  
Vehicle Stability ◽  
Vehicle Stability Control ◽  
Torque Vectoring ◽  
Steer By Wire ◽  
Preliminary Study ◽  
Potential Strategy ◽  
First Time ◽  
Safety Strategy

There is growing interest in steer-by-wire (SBW) systems because they provide significant benefits to classical vehicles, and are indispensable to autonomous vehicles. However, an emergency backup strategy is needed to steer a vehicle to safety if its SBW actuators fail completely. Differential drive assisted steering (DDAS), which uses torque vectoring to steer a vehicle, has been proposed as a backup strategy for SBW systems. However, vehicle stability control (VSC) — a required feature in most modern vehicles — also relies on torque vectoring. This paper demonstrates, for the first time, through simulations, that conflicts may arise between VSC and DDAS, rendering DDAS ineffective as a SBW system backup strategy. This preliminary study motivates the need to pay attention to, and develop strategies for addressing these conflicts. As an example, the addition of speed control to DDAS is shown as a potential strategy for mitigating these conflicts.

Novel Vehicle Stability Control Using Steer-by-Wire and Independent Four Wheel Torque Distribution

2003 ◽  
Author(s):  
Stefan Kueperkoch ◽  
Jasim Ahmed ◽  
Aleksandar Kojic´ ◽  
Jean-Pierre Hathout
Keyword(s):  
Control Algorithm ◽  
Stability Control ◽  
Front Wheel ◽  
Vehicle Stability ◽  
Actuator Failure ◽  
Torque Distribution ◽  
Vehicle Stability Control ◽  
Steer By Wire ◽  
Wheel Torque ◽  
Electrical Connections

The introduction of X-By-Wire technology opens new possibilities for vehicle stability control. This technology replaces the mechanical links currently existing between the driver and different actuators with electrical connections so that the driver can be decoupled from the control system. In this paper, we consider a X-By-Wire vehicle powered by four independent wheel motors and front wheel steer-by-wire. For such a vehicle, a control algorithm is developed that employs steering and individual wheel acceleration in addition to braking to enhance stability and improve performance. Such a vehicle offers advantages in case of actuator failure where the remaining actuators can act to ensure stability and we illustrate this in simulation using our control algorithm. Finally, we describe our experimental setup and present preliminary experimental results.

An Analytical Transient Tire Model

2001 ◽  
Vol 29 (2) ◽  
pp. 108-132 ◽  
Author(s):  
A. Ghazi Zadeh ◽  
A. Fahim
Keyword(s):  
Transient Behavior ◽  
Stability Control ◽  
Vehicle Stability ◽  
Tire Model ◽  
Steering Angle ◽  
First Order ◽  
Vehicle Stability Control ◽  
Proposed Model ◽  
Depth Study ◽  
And Performance

Abstract The dynamics of a vehicle's tires is a major contributor to the vehicle stability, control, and performance. A better understanding of the handling performance and lateral stability of the vehicle can be achieved by an in-depth study of the transient behavior of the tire. In this article, the transient response of the tire to a steering angle input is examined and an analytical second order tire model is proposed. This model provides a means for a better understanding of the transient behavior of the tire. The proposed model is also applied to a vehicle model and its performance is compared with a first order tire model.

Vehicle Stability Control Through Predictive and Optimal Tire Saturation Management

2012 ◽  
Author(s):  
Justin Sill ◽  
Beshah Ayalew
Keyword(s):  
Stability Control ◽  
Vehicle Stability ◽  
Distribution Problem ◽  
Scale Separation ◽  
Torque Distribution ◽  
Hydraulic Hybrid ◽  
Time Scale Separation ◽  
Vehicle Stability Control ◽  
Natural Time ◽  
Set Up

This paper presents a predictive vehicle stability control (VSC) strategy that distributes the drive/braking torques to each wheel of the vehicle based on the optimal exploitation of the available traction capability for each tire. To this end, tire saturation levels are defined as the deficiency of a tire to generate a force that linearly increases with the relevant slip quantities. These saturation levels are then used to set up an optimization objective for a torque distribution problem within a novel cascade control structure that exploits the natural time scale separation of the slower lateral handling dynamics of the vehicle from the relatively faster rotational dynamics of the wheel/tire. The envisaged application of the proposed vehicle stability strategy is for vehicles with advanced and emerging pure electric, hybrid electric or hydraulic hybrid power trains featuring independent wheel drives. The developed predictive control strategy is evaluated for, a two-axle truck featuring such an independent drive system and subjected to a transient handling maneuver.

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