Polytopic LPV-LQR Lateral Controller for Varying Speeds AGVs Exploiting Uncertainty

The variation in road conditions and vehicle speeds poses significant challenges in maintaining the desired stability and tracking accuracy of Autonomous Ground Vehicles (AGVs). Uneven, wet, or slippery road surfaces reduce frictional properties, while larger speed variations generate multidirectional motions within the vehicle, ultimately degrading its stability and tracking performance. Additionally, parametric uncertainties, such as cornering stiffness, affect the lateral dynamics and further compromise the tracking performance and stability of the vehicle. To address these challenges, this paper presents a polytopic Linear Parameter Varying (LPV)-based Linear Quadratic Regulator (LQR) controller. The polytopic LPV framework is introduced to handle variations and uncertainties in AGV parameters and assisting the LQR in minimising errors and ensuring yaw stability effectively. The performance of the polytopic LPV-LQR controller is analysed during single-lane and double-lane change manoeuvres considering varying AGV speeds and road conditions with uncertainty. Additionally, the proposed controller's performance is compared with a Robust Controller to provide further insights based on different metrics such as lateral position error, heading angle error, slip angle, and yaw rate. The results show that the proposed LPV-LQR controller is more capable of managing varying and uncertain parameters than the robust controller, facilitating satisfactory AGV tracking performance and stability at higher AGVs speed.