Abstract
RESEARCH OBJECTIVE
The Three-wheeled Urban Electric Vehicle is composed with two front in-wheel motors and a rear-wheel steering motor. This structure is tend to lose stability such as oversteering or spin-out at high-speed. The objective of this study was to improve vehicle stability of the three-wheeled urban electric vehicle by using torque vectoring and active rear-wheel steering control. Scale-down vehicle experiment has been conducted to verify its performance.
METHODOLOGY
Reference model following controller is designed for torque vectoring control. Ideal four-wheel steering (4WS) vehicle is selected as reference vehicle model which can maximize stability. By designing controller, three-wheeled vehicle model is used to calculate vehicle input to mimic reference vehicle’s states. Hardware and software limitations such as maximum motor torque are considered for real application. Scale-down vehicle is designed with two wheel speed encoders and 6-DOF IMU sensor. To estimate vehicle’s unknown parameters such as cornering stiffness, parameter estimating experiments are firstly performed. For main experiment, there are two different driving maneuvers which are steady-state cornering and lane change. For each maneuvers, different velocity and steering amplitude is applied to verify control performance. In order to ensure repeatability, each maneuver has conducted at least 5 times.
RESULTS
Control performance can be verified by simulation and scale-down vehicle experiment. From the experiment, following results are expected: minimized yaw and lateral acceleration delay, body side-slip angle, trajectory error, and improved stability.
LIMITATIONS OF THIS STUDY
This study is proceeded with scale-down vehicle which can show feasibility, but cannot fully represent the full-scale vehicle.
WHAT DOES THE PAPER OFFER THAT IS NEW IN THE FIELD INCLUDING IN COMPARISON TO OTHER WORK BY THE AUTHORS?
Hardware and software limitations are considered for real application. By choosing reference vehicle model, we can expect reference vehicle’s performance on Three-wheeled urban electric vehicle. Scale-down vehicle experiments are conducted with various maneuvers to verify control performance.
CONCLUSIONS
The reference following controller is implemented to the scale-down three-wheeled urban electric vehicle. By selecting ideal 4WS vehicle, the vehicle can improve stability within acceptable power consumption.
KEYWORDS : Three-wheeled Urban Electric Vehicle (TWUEV), In-wheel motor, Torque vectoring, Active rear-wheel steering, Scale-down vehicle experiment