Figure 11 Lateral Acceleration Responses of the Models
Related Figures (21)
Table 1. Double track vehicle parameters In equation (1), 6 = dy is the steering angle, f is the vehicle side slip angle, 7 is the yaw rate, Cy, and C,, are the front and rear tire cornering stiffness values, l; and l, are distances from the front and rear axles to the vehicle center of gravity, m is the vehicle mass, J, is the yaw moment of inertia, V is the vehicle velocity and y is the tire road friction coefficient. Fig. 2. Illustration of the single track vehicle model. The geometry of the double track model is displayed in Fig. Fig. 3. Illustration of the double track vehicle model. The variables used in the double track model are defined in Table 1. The subscript ‘i’ defines the tire under consideration as FL,FR, RL, RR. CarSim is a commercial program and provides a highly realistic, high fidelity vehicle model. The Carsim model includes a driver model (if needed), longitudinal, lateral and vertical dynamics and is real time capable. The fully electric light commercial vehicle considered in this paper is modelled and its YSC algorithm is tested by using the CarSim vehicle model in offline and HiL tests before proceeding to road testing. Fig. 4 shows an animation screenshot of the Carsim vehicle model in a double lane change maneuver. Fig. 5. Longitudinal Dynamics and Powertrain Models (One Wheel Only) The wheel dynamics can be represented as Fig. 6. Electric Motor Speed-Torque Map Ta = Tmnrk Fig. 7. Experimental Vehicle Steering Angle In this section, the double track fully electric vehicle model is validated by using the experimental vehicle data provided by Tofas-Fiat in Turkey based on experiments run using their first generation research prototype fully electric vehicle. Fig. 9. Steering Angles and Vehicle Speeds for Models Fig. 8. Experimental Vehicle Yaw Rate Response The steering wheel angle input in the experiment under consideration is shown in Fig. 7. Fig.8 shows the corresponding actual and double track vehicle model yaw rate responses at about 85 km/h of vehicle speed. Fig. 10. Yaw Rate Responses of the Models For this purpose, an adaptation of these commands is carried out. ASR signals enter the algorithm as inputs and they are converted to torque increase and decrease signals for the electric motor. The electric motor torque is fed back to the algorithm and intervention status is sent back to the YSC ECU. Table 2. Vehicle cases for lower controller design Fig. 13. Controller Structure The required individual braking moment for each wheel (Tyi,i = FL, FR, RL, RR) can be calculated using (26) and (27) for the vehicle in Fig. 3 (Falcone, P., 2008) as The main differences of the equations for front and rear wheels arise from the existence of the front wheel steering angle. Fig. 14. Vehicle steering angle and Vehicle Speed This table is used in the simulation results of Fig. 14-15 which are based on the double track fully electric vehicle model. Fig. 15. Simulation Results The steering angle input and the resulting vehicle speed with and without YSC are shown in Fig. 14. In the simulation, the road is dry and the vehicle speed is about 80 km/h. from the ECU and all its hydraulic parts (solenoid activated valves, return pump, etc.) are modelled in Simulink. Other approaches like model regulation also called disturbance observer control (Oncu et al, 2007; Aksun- Guvenc and Guvenc , 2002; Guvenc and Srinivasan, 1995), speed scheduled LQR control (Emirler et al, 2015), intelligent control ( Boyali and Guvenc, 2010), parameter space based robust control (Guvenc et al, 2017; Emirler et al, 2014, Emirler et al, 2015; Wang et al, 2018) and repetitive control (Demirel and Guvenc, 2010; Necipoglu et al 2011; Orun et al, 2009) for periodic speed profiles can also be applied for yaw stal bility control and for electric vehicle traction control. The yaw stability controller designed can also be tested as part of an autonomous driving system in an autonomous vehicle et al, 2017). hardware-in-the-loop simulator (Gelbal Fig. 17. Hardware In The Loop Simulator Schematic
