Exploring Active Camber for Path Following and Yaw Stability of Autonomous Vehicles

Author(s):  
Wenliang Zhang ◽  
Lars Drugge ◽  
Mikael Nybacka ◽  
Zhenpo Wang
Author(s):  
Yixiao Liang ◽  
Yinong Li ◽  
Ling Zheng ◽  
Yinghong Yu ◽  
Yue Ren

The path-following problem for four-wheel independent driving and four-wheel independent steering electric autonomous vehicles is investigated in this paper. Owing to the over-actuated characters of four-wheel independent driving and four-wheel independent steering autonomous vehicles, a novel yaw rate tracking-based path-following controller is proposed. First, according to the kinematic relationships between vehicle and the reference path, the yaw rate generator is designed by linear matrix inequality theory, with the ability to minimize the disturbances caused by vehicle side slip and varying curvature of path. Considering that the path-following objective and dynamics stability are in conflict with each other in some extreme path-following conditions, a coordinating mechanism based on yaw rate prediction is proposed to satisfy the two conflicting objectives. Then, according to the desired yaw rate and longitudinal velocity, a hierarchical structure is introduced for motion control. The upper-level controller calculates the generalized tracking forces while the allocation layer optimally distributes the generalized forces to tires considering tire vertical load and adhesive utilization. Finally, simulation results indicate that the proposed method can achieve excellent path-following performances in different driving conditions, while both path-following objective and dynamics stability can be satisfied.


Author(s):  
Srivatsan Srinivasan ◽  
Matthias J. Schmid ◽  
Venkat N. Krovi

Abstract Incorporation of electronic yaw stabilization in on-road vehicles can take many forms. Although the most popular ones are differential braking and torque distribution, a potentially better alternative would be the inclusion of a controller into the steering process. However, this is not often pursued in mechanically-coupled steering systems since the controller could work against the driver’s intentions creating potential challenges to safety. The growing adoption of steer-by-wire (SbW) systems now in autonomous/semi-autonomous vehicles offers an opportunity to simplify the incorporation of such steering-controller based assistance. Most current steering-assistance systems focus either on adaptive steering control (adaptive power steering and gear ratios) or on total steering control in autopilot functions (lane keeping control). Such steering-controllers (incorporated via SbW modality) can improve driving performance and maneuverability and contribute to the overall suite of active-safety vehicle systems. In this study, we introduce a new pure-feedforward (open loop) controller for the steer-by-wire system based on the concept of reference shaping control aimed at reducing the vibration/oscillation caused in vehicles during fast (evasive) maneuvers.


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