Michael Hagan

A TEST FACILITY FOR THE MEASUREMENT OF HEAVY VEHICLE SUSPENSION PARAMETERS

The Highway Safety Research Institute (University of Michigan) Heavy Vehicle Suspension Testing Facility is described, a new installation for the measurement of compliance, kinematic, and coulomb friction properties of heavy-vehicle suspension and steering systems as they react to vertical force, roll moment, lateral force, brake force, and aligning moment. The facility was designed and constructed under the sponsorship of the Motor Vehicle Manufacturers Association, Ad Hoc Committee on Heavy Truck Braking and Handling. Single and tandem-axle suspensions (maximum tandem spread 180 cm. or 70 in.) of all common on-highway truck widths can be tested in their normal configuration or as mounted on an abbreviated frame section. All measurements are performed at steady-state or quasi-steady-state. The facility has three major mechanical systems: a static structure, a movable table, and four wheel pad assemblies. Various test procedures are described, and qualitative findings to date are reviewed. Detailed descriptions of machine elements and specific suspension data are appended.

An instrumentation system for gathering information pertinent to the performance of an adaptive cruise control system

The data acquisition system (DAS) installed in the ACC-equipped vehicles is designed to collect, process, and store both numerical and video data files using two on-board computers to quantify aspects of the driving process that are pertinent to the control of speed and clearance gap relative to the closest preceding vehicle. The data are collected and stored on a trip-per-trip basis. Once a trip is completed an on-board computer sends summary data via cellular phone to a server at the base station. These data are mainly in the form of histograms and trip summary numerics computed online to describe features of the trip. After 2 to 5 weeks in typical transportation service in the field operational test (FOT), the ACC vehicles are returned to the base station and time histories of pertinent variables such as range, range-rate, and velocity plus GPS and video data are downloaded. This paper describes how and why the DAS does what it does.

Site-Based Video System Design and Development

The goal of the Strategic Highway Research Program 2 (SHRP 2) Safety program is to prevent or reduce the severity of highway crashes through more accurate knowledge of driver behavior and other factors. The Safety program’s research is proceeding along two distinct but related tracks: (1) the in-vehicle, naturalistic driving study, which encompasses all types of driving, and (2) the site-based risk study, which focuses on vehicle trajectories at specific locations, such as intersections. This report describes the work that was done in the latter track to develop and test an on-site, video-based data collection system with the potential for widespread application by researchers and state and local authorities to examine intersection safety. This report documents the development of a prototype system capable of capturing vehicle movements through intersections by using a site-based video imaging system. By tracking individual vehicles through an intersection, the Site Observer provides a basis not only for viewing crashes and near crashes but also for developing objective measures of intersection conflicts and collecting before-and-after data when design or operational changes are made at intersections. It also yields detailed and searchable data on the normal driving population so that exposure measures can be determined. This research built on previous work on video-based systems to develop a system that is relatively inexpensive, portable, and flexible enough for installation at all types of intersections, as well as robust enough for use in locations with a wide range of environmental conditions. The system embraces modern machine vision cameras and draws from the large body of research on algorithms for extracting information from video streams, a key advantage where data must be collected continuously. It was tested at a location during fall and winter months and found to operate as designed. The Site Observer is a robust prototype system that is deployable as is but is also capable of further development and refinement for use in intersection safety assessment.

A New Facility for Testing Motorcycle Tires

Analysis of the dynamic modes of the single-track vehicle has been hampered by the general lack of facilities for gathering force and moment data on motorcycle tires under dynamic test conditions. The facility described was designed and constructed by UMTRI under the sponsorship of the HONDA Research and Development Company in order to alleviate this problem. Unlike conventional tire dynamometers, this new facility allows for testing under dynamic conditions and provides for non-zero path curvature. These particular capabilities hold promise for advancement in the state-of-the-art understanding of the dynamic operating modes of the single-track, pneumatic-tired vehicle. The facility is unique in its physical design in that it employs a small, light tire-mounting head which is controlled by a mechanically simple system of servo-controlled hydraulic cylinders. This mechanical simplicity is achieved, however, at the cost of a complex electronic control system involving substantial on-line digital calculation.

Lateral-acceleration experience of six commercial vehicles

Abstract This communication provides a detailed review of the lateral‐acceleration experience of six tractor‐semitrailer combinations in real commercial service for approximately one year. Lateral‐acceleration experience is described in histograms of travel time. Influences of speed, load, road geometry, driving style, and longitudinal position on the vehicle are examined. Distributions of both path curvature and lateral acceleration are presented. The six vehicles studied were all five‐axle, tractor‐semitrailer combinations. The semitrailers were cryogenic tankers for transporting liquid nitrogen. The fleet operated from La Porte, Indiana and serviced much of Illinois, Indiana, Michigan, and Wisconsin. Data from nearly 10,000 hours and more than 770,000 km of travel were collected and analyzed.