Reproducibility and Repeatability of the SAE J4002 and J826 H-point Machines

A study of repeatability and reproducibility of the SAE J4002 and SAE J826 H-point machines (HPMs) was conducted using 15 operators, five of each type of HPM, and four different vehicle seats. Each operator performed 24 installations over two days. Across the 24 measurements, operators used 3-4 of each type of manikin in 2-4 of the seats. For each operator, some trials were repeated three times to generate measures of within-operator repeatability. Operators measured H-point x and z location, and torso angle. Variance decomposition showed that for H-point measurements, the J4002 manikin has better reproducibility (between-operator variance) but the J826 manikin has better repeatability (within-operator variance). For torso angle, both reproducibility and repeatability are better for the newer manikin. In addition, different manikins of one type produced negligible additional variability. Thus, different manikins of one type can be considered virtually identical, while the variance in measurements is attributed to operators.