School Bus Restraints for Small Children in Canada

6. DATA RECORDING AND ANALYSIS

6.1. Data Recording Equipment
Each test was recorded and the data were analyzed using the following equipment:

  • Transducers on the sled were supplied with 3.33 volt DC from local sled-mounted power supplies. Outputs were fed to off-board active analog filters (via a low-noise multi-coaxial umbilical cable), which filtered the data according to the SAE J2111.
  • The signals were then digitized at a sampling rate of 10,000 samples per second using a series of four National Instruments MIO-6070E multifunction boards containing 12-bit A/D converters, which provided direct memory access to the RAM of a National Instruments PXI 8156 computer system where the data was initially stored, with final indefinite storage on CD-ROM. 
  • Digital post-filtering was carried out from the data in RAM using custom-designed National Instruments Labview software as specified for the filter class by SAE J2111. The Labview software was further used to perform scaling, processing and plotting functions.

6.2. Film Recording and Analysis
Video recordings were used to perform the kinematics analysis for each test. This information was recorded using:

  • a Kodak EM Ektapro Motion Analyzer system;
  • a Kodak high-gain imager (video camera);
  • a Kodak EM Processor (model 1012) producing black and white motion pictures with X-Y electronic crosshair calculation capability;
  • a frame rate of 500 frames per second; and
  • a shutter speed of 1/1000 sec.

6.3. Variables Explored in the Study
The variables explored in the present study are the following:

6.3.1. Dummy/Child Size 
CRABI 18-month old and Hybrid III 3-year old and 6-year old dummies were used to simulate child occupants. 

6.3.2. Configuration of Restraint System 
The compartmentalization tests provide a baseline for the measurements for the different dummies. Child restraints used in the testing all had the same shell and harness design. 

6.4. Data Screening 
The data were examined for errors in data entry and to identify any outliers in the test results. No such occurrences were identified. Every test was also subjected to extensive photographic analysis. 



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