Seminar #11
10 November 2017 Friday, 14:00–15:00 YTÜ Beşiktaş Campus - A 310
Title: Analysis and Design of Torque-vectoring-based Backup Steering Strategy for Steer-by-wire Systems Considering the Influence of Vehicle Stability Control
Speaker: Dr. Ahmet KIRLI
Summary: Fully autonomous vehicles i.e. vehicles with level 5 autonomy use a form of steer-by-wire (SBW) system in which an electric motor performs the steering due to the control input provided by the electric control unit (ECU). Differential drive assisted steering (DDAS), which uses torque vectoring (TV) to steer a vehicle in the absence of actual steering, has been proposed as an emergency backup strategy for SBW systems where TV is the ability to control the longitudinal forces at each wheel, independently. Vehicle stability control (VSC), which also uses TV, is a required feature in most modern vehicles and it is designated to maintain stability. This study demonstrates for the first time that, instead of enhancing the stability, VSC deteriorates stability when combined with DDAS, through stability analyses on a linearized vehicle model. An integrated controller design that considers the interaction of DDAS with VSC is proposed to prevent undesirable loss of stability unlike current practice where VSC and steering control are designed separately. Five case studies with full nonlinear vehicle models have been constructed to cover all possible vehicle configurations, and simulations have been performed for ISO standard double lane change test. Simulation results support and demonstrate that the proposed MPC based integrated design, with speed and stability control, is effective in following the desired trajectory while preventing undesirable loss of stability whether the steering system is intact or not.
Short Bio: Ahmet KIRLI is a research assistant in the department of mechatronics engineering at Yıldız Technical University, where he has been a member since 2009. Dr. KIRLI received his B.S., M.Sc., and Ph.D. from Mechanical Engineering at Dumlupınar University in 2008, at Istanbul Technical University in 2010 and at Yıldız Technical University in 2015, respectively. He was with University of Michigan for post-doctoral studies in 2016. His research topics include but not limited to mechatronic systems, UAVs, tactile sensor, vehicle dynamics and control.