Active handling system using both brake and drive torque modulation

Recent advances in active control of vehicle lateral dynamics have arisen out of extensions to anti-lock brake and anti-slip torque control systems. These systems selectively apply brake torque to individual wheels to counteract excessive lateral motions at the front or the rear of a vehicle. An incipient slide at the rear may lead to a spin and this is sometimes referred to as “oversteering” or a “loose” condition. An incipient slide at the front is referred to as “ understeering” or a “pushing” condition. The system detects such undesirable conditions by measuring the actual vehicle yaw rate, lateral acceleration and steering wheel angle and comparing these actual values with values which a computer model would predict. This “model reference” type of control attempts to match the vehicle with the model behavior by selectively applying brake torque at one side of the vehicle or the other and at the front or the back appropriately.; Since only the brakes are used in the existing systems, such active handling systems result in a general slowing of the vehicle even in the case when the driver desires to accelerate. Depending on the details of the control system, the system may make the vehicle safer under slippery conditions at the expense of producing a rather sluggish feeling.; This study will attempt to add modulated drive torque to the control when the driver indicates by his throttle position that he not only wants to achieve a certain turn but does not wish to slow down. The first part of the study will assume that all four wheels can have almost arbitrary drive torque (consistent with the total power available and with the throttle setting) as if four electric wheel motors could be controlled electrically. Later more practical 2-wheel drive systems will be combined with 4-wheel braking systems. The result of the study will be to arrive at control strategies which optimize the handling including longitudinal acceleration or deceleration as desired by the driver.; The project will be accomplished by using a realistic model of the vehicle using a comprehensive model of the tires. The control strategies developed will be tested by simulation of a variety of situations ranging from emergency situations to closed course racing situations.