Selection of Driving Mode in Autonomous Vehicles Based on Road Profile and Vehicle Speed

In this work, a switching mechanism is proposed using variation in Tire Spring Length (Ls (Tire)), Suspension Spring Length (Ls (Suspension)) together with changes in Sprung Mass Acceleration (SMA), all correlated as a function of speed and road profile to enable optimum driving mode selection and setting of Suspension Stiffness to Damping Ratio (r). To achieve the stated objective of this work, MATLAB simulation is performed using three main r ratios (1, 25, 0.25) and two main road elevation profiles (1, 6). It is shown through this work that each mode of driving has unique signals resulting from Sprung Mass Acceleration (SMA), Sprung Mass Position (SMP), and variation in both Tire Spring Length and Suspension Spring Length. All these signals are used to enable optimization and automatic selection of driving mode and strategy especially in autonomous vehicles. Optimization of driving mode is critical particularly when trajectory information is exchanged between vehicles using Basic Safety Messages (BSMs) and between vehicles and Road Side Units (RSUs).