This report describes an applied research program aimed at identifying those characteristics of the driver/vehicle system which influence the driver's ability to maintain control over the vehicle path in a variety of steering tasks. Program objective include comprehensive measurements of driver and vehicle responses and the quantification of optimum driver/vehicle system characteristics as functions of simplified vehicle dynamic properties and task durations. To accomplish this, a three-pronged approach of analysis, fixed-base simulation, and road test was used for compensatory steering tasks, while road test results were emphasized in discrete and transient maneuvers. The regulation task subjected the car to a random gust disturbance which had to be countered by driver control action. Driver describing functions were estimated (in the analytical treatment) and measured (in the fixed-base simulation and road test environments). A specially-designed variable stability vehicle was used to permit insertion of the simulated gust disturbances and for the driver/vehicle system measurement. Measures of system bandwidth, stability, and time delays were deduced, compared, and rationalized. The experimentally determined driver dynamics correlated well with the driver/vehicle system theory developed in the analytical phase. The full-scale tests were conducted in two phases: an initial phase covering 12 configurations of vehicle dynamics and sterring gain with an expert test driver; and a validation phase which covered six sets of vehicle dynamics and four unmodified production car configurations with 17 subjects. The steering tasks tested included regulation and a complete cross-section of steering maneuvers, such as emergency and double lane changes, which evoked a dual-mode behavior from the driver. Driver evasive action was also studied with the aid of an unexpected obstacle. Key performance measures (including system bandwidth and phase margin for regulation tasks and lane exceedances and driver steering reversals for discrete maneuvers) were shown to be descriptive, selective, and readily applicable to discriminate among the vehicle configurations. These were also correlated with driver ratings of attention and workload in the regulation task and of vehicle responsive in discrete tasks. A six-hour driving duration did not change relative orders among vehicles of driver ratings and response or system performance. Durations as short as one-quarter hour did produce order-of-presentation effects. The key vehicle parameters influencing the driver's response were the vehicle's overall yaw velocity to steering wheel gain and the yaw velocity numerator time constant. Directional undamped natural frequency and damping ratio were also influential but secondary. A tentative optimum range of vehicle dynamics for the directional properties was established, based on the total driver population of 18 and the tests with both laboratory and production vehicles. /Author/

  • Corporate Authors:

    Systems Technology, Incorporated

    13766 South Hawthorne Boulevard
    Hawthorne, CA  United States  90250
  • Authors:
    • McRuer, D T
    • Klein, R H
  • Publication Date: 1975-2

Media Info

  • Features: Figures; References; Tables;
  • Pagination: 269 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00097101
  • Record Type: Publication
  • Source Agency: National Safety Council Safety Research Info Serv
  • Report/Paper Numbers: TR-1040-1-I
  • Contract Numbers: DOT-HS-359-3-762
  • Files: TRIS
  • Created Date: Sep 30 1975 12:00AM