英语翻译

问题描述:

英语翻译
We acquire pulse wave from PPG sensor placed on an earlobe because there is less variation in the relative vertical position of a head for the heart.

我觉得应该理解为...because there is less variation (for the heart) in the relative vertical position of a head.
我们从一个放在耳垂上的PPG传感器上获得脉搏波,因为在头部相对竖直的位置上心脏数据较稳定.