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Technical Paper

Basis for Logical Control of Circumferential Wheel Forces of Highway Trucks for Improved Traction and Fuel Effeciency

Distribution of traction forces among driving wheels is one of the main factors governing the performance of a highway truck during acceleration and braking on varying macro and micro road surface conditions. Comprehension of the interaction between wheels and road surface provides a profound systematic way to simulate a truck's motion and design required components for the optimal performance. The development of electronic technologies has created the pre-conditions necessary to develop systems with controlled parameters. However, to realize the pre-conditions, vehicle dynamics problems have to be formulated and solved for both optimization and control. Many different approaches emerged with the aid of electronics to control the circumferential wheel forces (wheel torque) by restricting wheel slip. A part of such systems has been named as Acceleration Slip Regulation (ASR) and Anti Slip Differentials (ASD).
Technical Paper

Terrain Truck: Control of Wheel Rotational Velocities and Tire Slippages

The dynamics of an AWD vehicle is determined by the interactions between the vehicle's wheels and the tire contact surface. Understanding and controlling these interactions drives the vehicle mobility and energy efficiency. In this paper new issues related to tire slippage control are addressed. The paper analytically demonstrates that two tires on the same axle with the same rotational speeds can have different slippages when the normal reaction and inflation pressure vary due to motion conditions. Hence, a new method is proposed to control the rotational velocity of the wheels in a way that provides the same slippages of the tires by accounting for changes in the normal load and tire inflation pressure. This approach is especially beneficial for vehicles with individual (electric) wheel drives which can be individually controlled by introducing the proposed algorithm for controlling both the vehicle linear velocity and the tire slippages.
Technical Paper

Optimal Mass and Geometric Parameters in Multi-Wheel Drive Trucks for Improved Transport and Fuel Efficiency

To develop better performing vehicles, for ground transportation, it is necessary to improve the theory in vehicle dynamics for choosing suitable mass and geometric parameters for highway as well as for off road trucks. A new approach is required for choosing such optimal mass and geometric parameters. The present paper is devoted to this problem. A new method for synthesis of mass and geometric parameters is introduced here. The method allows us to synthesize the parameters in such way as to provide a vehicle with the best transport efficiency under various road surface conditions. Constraints such as limitations on these parameters, vehicle running modes, mass and geometric parameters are included in the model. Furthermore other constraints for vehicle running abilities which are dependent on mass and geometric parameters, as well as an algorithm for synthesizing mass and geometric parameters are also included in the paper for pre-optimization process.
Journal Article

A Central Differential Gear Ratio Optimization of a 6×6 Articulated Dump Truck

This paper starts with an analysis of design configurations of the drivelines with different power-dividing units (PDUs) of main dump truck manufacturing companies. As it follows from the analysis, improvements of articulated truck energy efficiency and reduction of fuel consumption by optimizing the power distribution to the drive wheels are still open issues. The problem is that a variety of operating and terrain conditions of dump trucks requires different wheel power distributions that cannot be provided by one set of PDUs employed in a truck. The central PDU in the transfer case was identified as the most important PDU among the five PDUs, which plays a crucial role in the power distribution between the front axle and the rear tandem of a 6×6 articulated dump truck. The paper formulates a constraint optimization problem to minimize the tire slippage power losses by optimizing the power distribution between the drive wheels.
Journal Article

Mobility and Energy Efficiency Analysis of a Terrain Truck

While much research has focused on improving terrain mobility, energy and fuel efficiency of terrain trucks, only a limited amount of investigation has gone into analysis of power distribution between the driving wheels. Distribution of power among the driving wheels has been shown to have a significant effect on vehicle operating characteristics for a given set of operating conditions and total power supplied to the wheels. Wheel power distribution is largely a function of the design of the driveline power dividing units (PDUs). In this paper, 6×6/6×4 terrain truck models are analyzed with the focus on various combinations of PDUs and suspension systems. While these models were found to have some common features, they demonstrate several different approaches to driveline system design.
Journal Article

Axle Drive and Brake-Based Traction Control Interaction

Brake-based traction control systems (TC), which utilize the brake of a spinning wheel of the drive axle, are widely used in passenger cars and light trucks, and recently were applied to all-wheel drive construction equipment. Such machines employ various types of interwheel drive systems (i.e., axle drives such as open differentials, limited slip differentials, etc.) 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 performance. Lack of analytical work in this area motivated this study of the interaction and impact of the two systems on each other and the dynamics and performance of a drive axle.