A method of monitoring the level of course-keeping controllability in heavy-duty and urban passenger vehicles and evaluating its influence on traffic safety

The paper addresses an issue of substantiating the method of monitoring and digital evaluation of the influence of the technical state of automated combined steering systems in heavy-duty and urban passenger vehicles, that use channels of hydraulic booster (HB) steering installed in parallel with a mechanical channel, on traffic safety (TS) and efficiency of vehicle operation in the mileage interval between scheduled technical inspections. It is demonstrated that the maximum value of discrepancy in the HB set by the driver (within the limits of mandatory, functionally set artificial "gap" in a "spool–sleeve" pair, controlling the energy of the external source, i.e. a hydraulic pump) reduced to an angle of steering wheel rotation is negligibly small as compared to the size of the gap in the steering system as a whole; the latter is used to evaluate the compliance of this system with the traffic safety requirements. The specified value of the artificial gap does not exceed one degree in rotation of the steering wheel having an HB of a rotary type; it has a significantly smaller value for axial HBs (where the displacement axis of the spool coincides with the sleeve axis). Given that the value of the gap in the steering system is regulated by state standards and lies within the range of 15–20°, which considerably (more than one order of magnitude) exceeds the artificial HB gap, the contribution of the HB channel into the total gap value in the steering system is negligible, and accountably lies outside the area of operators’ attention. Therefore, a conclusion can be made that the evaluation of the above-mentioned gap, taking into account the physics of the operating HB, should be carried out according to other criteria that are not related to gauging the gap. It is shown that the feedback from drivers complaining on growing labor intensity of driving cars having HBs and long mileage, complying with the effective state Standard requirements under the current manufacturing technology can be used to substantiate the limit state indicator for steering systems using the criterion of vehicle controllability reflecting the level of the psychophysiological load. The paper demonstrates that the current practice of monitoring (preventing) the onset of reaching the limit technical state by the HB, assessed by the value of allowable drop of fluid pressure in the hydraulic system (relative to the pressure set by the limiting controller) detects the defect with delay exceeding a 100,000 km mileage with respect to the moment of evaluating the admissible controllability level determined by the driver according to his/her individual psychophysiological load. The paper reports results of bench tests of HBs having various mileage and results of road tests carried out using large capacity buses having HBs differing in mileage on an actual urban route. A mechanism of correspondence between HB parameters and the bus mileage with the level of the driver’s psychophysiological load and the energy spent by a driver to drive a vehicle, which allows estimating limit states against the criterion of vehicle controllability, as well as estimating financial losses of a company operating urban bus routes when the level of the actual driver’s load exceeds the allowable level, is presented.

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  • English

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  • Accession Number: 01695243
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Jan 3 2019 3:20PM