Objective assessment of vehicle controllability in straight-line motion

Introduction (statement of the problem and relevance). The problem of vehicle handling and stability during rectilinear motion was raised in the first half of the 20th century, and today this issue is still relevant. The requirements for handling, including during rectilinear movement of modern cars, are getting tougher. Straight-line stability and long-distance directional stability affect driver's fatigue, his driving safety and pleasure, as well as car fuel efficiency. Besides it, to provide modern driver assistance system, the car should possess good straight-line stability. At the same time, the design mustn't be affected by unbalanced forces and torques that could cause the trajectory deviation of the vehicle. There comes a need for an objective controllability and stability assessment of the car in a straight line.
The purpose of the research was to analyze the existing methods for studying rectilinear motion controllability, to develop objective parameters for evaluating such motion, and to apply the worked out solutions when analyzing vehicle tests results.
Methodology and research methods. Mathematical analysis, comparison, experiments, measurements were applied as research methods.
Scientific novelty and results. The results have been presented in the form of a developed straight motion evaluation parameters list and were processed by calculating objective evaluation parameters. The scientific novelty is presented by the parameters of the driver's work objective assessment, and the first step has been made to correlate the objective and subjective assessment of the test driver.
Practical significance. The developed method of the objective assessment can be applicable to all vehicles with traditional steering control.

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