1991-09-01

Video-Based Measurement of Dynamic Tire Envelopes 911923

ABSTRACT

The three-dimensional motions of the front and rear wheels of a passenger car have been obtained from “Over-the-Road” tests, with great accuracy (1a RMSE ≊ 0.6mm) using raw data recovered from synchronized video cameras. Data from a variety of tests have been combined and treated to produce maximal tire envelopes. This effort has demonstrated the potential of image-based motion measurement as a product design and development tool.

Traditional techniques for recovering tire envelopes are described, and their limitations discussed. Image-based motion measurement is offered as an more accurate alternative. The task-specific constraints which limit the selection of imaging hardware are discussed, and a scientific foundation for the new technique is provided.

A series of tests has been conducted to demonstrate the viability of the proposed approach. The procedures used to instrument the vehicle and collect raw video images at highway speeds are described. The numerical methods used to reconstruct the histories of the required kinematic parameters are also described. Plots and typical results are included. The three-dimensional motions of the two wheels have been reconstructed using interactive computer graphics and a synthesized solid model. The increased ability to understand and interpret the data in this form has been illustrated by down-loading a sequence of computer-generated images to a VHS cassette for general display.

A time-dependent ‘voxel’ representation of the volume occupied by the tire and wheel is being developed to generate tire clearance envelopes.

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