INTRODUCTION Compared with vehicles powered by an internal combustion engine, the layout of the power source of electric vehicles (i.e. the motor) can be designed with a relatively high degree of freedom. It is also feasible to install power sources inside the wheels as in-wheel motors [ 1,2,3]. Although this type of layout has the potential to help innovate vehicle packaging, another extremely interesting aspect of in- wheel motors is related to vehicle dynamics. Installing motors in each wheel allows the driving force to be distributed freely, thereby making it easier to apply vehicle dynamics control. The direct yaw moment control method of distributing driving force has been investigated in a number of previous studies. This method is known to improve yaw motion. Since conventional driving force distribution control has limitations in terms of the response and durability of the control devices used, the main form of control that has been adopted is yaw control close to the limits of the tires. In contrast, vehicles powered by in-wheel motors can be controlled in the normal range of operation, and the controllability of motors means that these vehicles have a strong potential for improved performance. In addition, considering that a suspension reaction force is generated independently at each wheel, there is the possibility that roll, pitch, and heave motions, as well as yaw motion can be controlled [ 4]. This paper focuses on vehicle dynamics in the linear range. The following sections describe the construction of a 3D moment control method and the verification of its effect.3D MOMENT CONTROL BY IN- WHEEL MOTOR In-wheel motors are structured such that the reaction force from the road due to driving acts on the tire contact point. For this reason, as the vehicle is driven, a large reaction force is also generated in the vertical direction of the vehicle through the suspension, thereby affecting the behavior of the sprung mass. As shown in Figure 1, the front and rear vertical forces generated by motor driving can be calculated by Equation (1), in which the front and rear angles formed between the lines connecting the suspension rotational centers and the ground at the tire contact points are shown as θf and θr, respectively [5]. Accordingly, these vertical forces can be used proactively to construct a method that controls the sprung mass motion simultaneously as well as simply yaw. (1) If in-wheel motors are installed in all four wheels, then four-degree of freedom control becomes possible in principle. The control targets can be selected from the six degrees of freedom of the vehicle. However, it must be noted that the elements not selected for control may be affected by the other controls. Consequently, longitudinal motion and yaw cannot be excluded from the control targets. In addition, it is considered sensible to eliminate the lateral control because the layout of the motors makes this an inefficient control target and because it is less susceptible to the effects of other 2013-01-0679 Published 04/08/2013 Copyright © 2013 SAE International doi:10.4271/2013-01-0679 saepcmech.saejournals.org Decoupled 3D Moment Control for Vehicle Motion Using In- Wheel Motors Etsuo Katsuyama Toyota Motor Corp. ABSTRACT Vehicles equipped with in-wheel motors are being studied and developed as a type of electric vehicle. Since these motors are attached to the suspension, a large vertical suspension reaction force is generated during driving. Based on this mechanism, this paper describes the development of a method for independently controlling roll and pitch as well as yaw using driving force distribution control at each wheel. It also details the theoretical calculation of a method for decoupling the dynamic motions. Finally, it describes the application of these 3D dynamic motion control methods to a test vehicle and the confirmation of the performance improvement. CITATION: Katsuyama, E., "Decoupled 3D Moment Control for Vehicle Motio