Decelerometer for goods vehicle seat-belt sleds

Status:

completed 11/2006

Aims:

The BG responsible for the vehicle operating trades (BGF) uses two seat-belt sleds in order to demonstrate the safety action of seat belts worn by goods vehicle drivers under realistic collision conditions. Some 10,000 braking tests are conducted each year at various locations and events. In the course of the braking tests which have been conducted over many years, it has been found that on their own, verbal descriptions following the braking test do not adequately explain the physical action of a braking shock upon the driver. Two decelerometers were to be developed and fabricated for precise measurement of the braking deceleration and for visual output of the brake shock signals and data relevant to the goods vehicle driver. The decelerometers were to be fitted as integral components within the goods vehicle seat-belt sleds. Following the braking test and processing of the data, the driver is to receive a personal printed report of the results.

Activities/Methods:

Two decelerometers were developed and fabricated for the BGF seat-belt sleds: types I and II. The compact decelerometers contain a deceleration sensor with electronic amplifier, a digital recorder for the measured data, an LCD monitor for display of the key signals and data, and a printer for output of a test report. The decelerometers were integrated into the front ends of the seat-belt sleds. An integral overall concept was developed for the decelerometer arrangement and for installation of the instruments into the seat-belt sleds in accordance with the particular requirements of the BGF. The mechanical excitation generated in the entire seat-belt sled structure by the deceleration shock necessitates the use of shockproof components. Special mechanical damping must also be employed between the frames of the decelerometers and the chassis of the seat-belt sleds. Software for measurement and analysis of the deceleration signal was developed, and includes functions for rapid calibration and long-term monitoring of the measurement system.

Results:

The instruments were developed, fabricated and installed permanently in the BGF's two seat-belt sleds according to the specifications. Presentation of the main signals and data enables the exposure levels which have arisen and the consequences of not wearing a seat belt to be demonstrated more effectively to the driver. The measurement protocol provides the driver with a better understanding of the hazards incurred not wearing a seat belt, and maintains this awareness over the longer term. These instruments provide the BGF with an extremely effective facility for demonstrating to goods vehicle drivers the consequences of an accident and the safety offered by the seat belt, and consequently for raising the safety level. During the large number of brake tests conducted each year at various locations and events, the instruments can be used for better presentation and documentation of the exposure and protection mechanisms. The decelerometers are subject to extremely high stresses, and are therefore of very robust construction. Practical experience can be exploited in order to optimize the modalities for screen display and logging over the longer term.

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