An Instrumentation System for Vehicle Stopping Distance Tests

An accurate, compact, and convenient instrumentation system for vehicle brake testing has been developed. The system comprises a counter assembly mounted inside the vehicle, a switch that closes at the onset of braking, and a specially modified “fifth wheel.” Stopping distance and initial vehicle speed are displayed in numerical form on the face of the counter assembly.

Data acquisition is accomplished almost entirely by digital techniques. Measurement accuracy is therefore enhanced (by eliminating the usual dependence on analog voltage scaling). Digital techniques also permit useful control (decision-making) functions to be included. Once such function is the unique feature of automatically eliminating erroneous distance pickup during vehicle “rock-back” at the end of a high deceleration stop.