FUNDAMENTALS OF DRIVELINE AND TRACTION CONTROL SYSTEMS FUSION FOR IMPROVING TRACTION OF A 4X4 SINGLE BUCKET LOADER

摘要

Brake-based traction control systems, which utilize the brake of a spinning wheel, are widely used in various types of vehicles, Recently, those traction control systems (TC) were applied to all-wheel drive construction equipment. Such machines employ various types of driveline systems (i.e., inter-axle power-dividing units and axle differentials) to control torque split between the drive wheels and thus improve vehicle traction performance. As experimental research showed, the interaction between the traction control system and the axle drive can lead to unpredictable changes in vehicle traction. Lack of analytical work motivated a study of the interaction and impact of the two systems on each other and then traction a 4×4 single bucket loader. This paper presents an analytical and computer model of the loader's driveline system, which includes a positive engagement of the inter-axle drive (i.e., the transfer case is fully locked) and two inter-wheel limited slip differentials (LSD) with different torque biases. The operation of this driveline system is mathematically integrated with the brake mechanisms, which apply braking moments to spinning wheels. Mechanical power flows/distributions between the four driving wheels are analyzed when a brake mechanism of a spinning wheel is on. The developed math and computer model of the fused driveline and traction control systems was integrated in a computer model of the 4×4 loader, which is beyond the scope of the paper. Computer simulations were conducted on surfaces with different grip conditions of the left/right and front/rear wheels, with longitudinal and lateral inclination of the loader when scooping the material in the bucket. The paper discusses results of computer simulations and presents fundamentals for the fusion of the driveline and traction control systems to improve the loader's traction.