Active Model-Based Suppression of Secondary Ride for Electric Vehicles With In-Wheel Motors

In vehicle motion control, the objective is to improve both dynamic performance and ride comfort through vibration analysis and compensation. Conventional drivetrains (combustion engines or on-board eletric motors) can only suppress primary modes (0.1–3 Hz) due to their limited torque response though the transmission shaft. In the case of electric vehicles with in-wheel motors (IWM), the shaft-less drivetrain enables besides primary also the active suppression of secondary ride modes (3–25 Hz). These compact and light-weight drivetrains have a higher unsprung mass, and therefore, require advanced suppression control methods that encompass both vibration regimes (0.1–25 Hz). The approach presented in this article aims to suppress the secondary ride in IWM vehicles through experimental model analysis and model-based control. In this study, the frequency characteristics of a Toyota IWM vehicle are experimentally analyzed on vibration test rigs, and subsequently, in multiple driving conditions. Based on the identified frequency responses, a model-based longitudinal acceleration control method is then analytically derived to suppress the vibration over a wide frequency band. The proposed technique is validated through experiments on Toyota’s IWM prototype vehicles.