Introduction (problem statement and relevance). Energy efficiency is one of the most important properties of present-day vehicles. Energy efficiency increasing allows reducing the costs for vehicle movement and for cargo and passenger transportation respectively, as well as decreasing harmful environmental impact. Vehicle energy efficiency increasing can be achieved in different ways, including by optimizing the law of control of the power supplied to the running gear in order to decrease energy consumption for motion caused by wheel slipping (spinning). The research objective is to increase the wheeled vehicle energy efficiency by means of optimal control of the power supplied to the running gear.Methodology and research methods. Vehicle driving inevitably consumes energy, part of which ensures tractive or propelling force generation in the driving wheels when overcoming resistance to motion, while other part is spent to transform energy supplied to the running gear and losses for wheel slipping. Thus, a vehicle energy efficiency increase can be reached by optimal control of the power supplied to the running gear. The loss power in the process of vehicle motion when interacting with the environment is used as a target function in solving this optimization problem. Besides decreasing the energy costs or consumption for the motion, the required vehicle traction level shall be ensured in order to ensure the driving speed mode set by the driver. In this regard, when solving the optimization problem the equality-type constraint describing the mentioned condition shall be taken into account. The method of Lagrange multipliers is used to solve the optimization task.Scientific novelty and results. When developing the control law for the power supplied to the running gear, one shall use additional information on interaction of the wheels with the supporting surface. An additional source of information here is the axial force on the wheel axis measured by installation of the force measuring (dynamometrical) wheels that are an integral part of the wheeled vehicle design. The developed control law for the power supplied to the running gear allows ensuring higher energy efficiency of a vehicle, thereby leveling the disadvantages of the known transmission types with a coupled and individual drive: locked, differential and individual distributing tractive effort torques between the wheels in proportion to the actual normal loads.Practical significance. Application of the developed control law for the power supplied to the running gear will allow, using a common transmission control approach, ensuring of high traction properties under various conditions as well as reduction of energy costs for vehicle motion without requiring additional differential lock control, in case of differential interconnections, and will also allow prevention of additional tyre wear or transmission element malfunction when power circulation occurs in case of a locked drive.
An increase in the slipping of a wheel propeller leads both to the energy loss and, up to a certain limit, the traction force increase. In this regard, in order to reduce energy losses for the movement of the vehicle, it is necessary to limit wheel slip at a level sufficient to create the required traction. Most of the existing algorithms aimed at implementing this constraint require information about the vehicle's linear speed. However, measuring the latter with a given accuracy outside laboratory conditions is difficult, which in some cases leads to a malfunction of the control algorithm. Therefore, it is relevant to develop a control method for the traction control system; in particular, for the case of acceleration, which will make it possible to estimate and limit wheel slip within specified limits with unknown characteristics of the supporting surface and the vehicle speed. The article is devoted to the development of a method for assessing and limiting slipping of a wheeled engine at a level sufficient to realize the required tractive forces without using data on the vehicle's linear speed and adhesion properties of the supporting surface. The article describes the mathematical model of the dynamics of the rectilinear movement of the quarter of the vehicle on a solid flat horizontal support surface. Through virtual experiments simulating the acceleration of a quarter of the vehicle with low slip, there was established a relationship between the traction force on the wheel axle and the kinematic parameters of the rotational motion, which are measurable and can be controlled during the movement of the vehicle, for example, using dynamometric wheels. On the basis of the obtained criterion, a regulator was developed to limit wheel slip during vehicle acceleration. The effectiveness of the developed regulator is proved by mathematical modeling of the acceleration of a quarter of the vehicle with different intensities on two types of supporting surfaces. It is also substantiated analytically provided that the wheel slip is constant within the measurement interval. The paper presents an approach to assessing and limiting the slip of the wheels of a vehicle during acceleration using a regulator based on fuzzy logic. A theoretical justification of the proposed method is given. It does not require information about the linear speed of the vehicle and the adhesion properties of a wheel with a supporting surface. An algorithm for the operation of the traction control system was developed. It allows to limit wheel slip at a given level while maintaining a sufficient margin of traction, which leads to a decrease in tire wear, a decrease in the likelihood of loss of mobility and an increase in the energy efficiency of the vehicle.
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