Study of torque vectoring for all-wheel-drive vehicles

Abstract

This article presents a novel approach to the control of modern torque-vectoring differentials based on the concept of β-angle minimization. Three case studies include two variants of a base case model; with three open differentials, a 70/30-30/70 switchable centre differential with open front and rear and a fully left-to-right vectoring front and rear differential capable of any ratio of torque distribution (the centre differential is left open). All three are examined as they progress through an ISO double-lane change manoeuvre. β-angle control was chosen because one attribute of a nimble car is its ability to accelerate through a double-lane change manoeuvre without excessive magnitude or oscillation (so-called fish-tailing) in vehicle β-angle. Each increase in the complexity of torque vectoring demonstrated a significant reduction in the magnitude of β-angle witnessed during the manoeuvre. As torque vectoring can also be employed to enhance yaw dynamics, the simulations were performed in such a manner as to produce nearly identical paths between the three models; this allowed the direct affect on β-angle to be understood without the added complexity of considering active yaw control influences.

Keywords:

• Vehicle dynamics
• Slip angle
• Differentials
• Simulation
• Torque vectoring
• Agility
• Active control
• Attitude
• AWD