> For the complete documentation index, see [llms.txt](https://wiki.polymaker.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://wiki.polymaker.com/polymaker-wiki/polymaker-wiki-zh/ji-chu-zhi-shi/fun-3d-printing-facts/jerk-doesnt-mean-what-you-think.md).

# “Jerk”的含义并不是你以为的那样

在 3D 打印中，术语“jerk（跃度）”与其在工程和物理学中的经典定义相比，具有不同的实际含义。传统上，jerk 被定义为加速度变化率——即位置对时间的三阶导数，单位通常为 mm/s³。它描述的是加速度本身变化得有多快，这是一个高度动态、瞬时的量，对运动控制和机械系统非常重要。

然而，在 3D 打印固件和运动控制中，“jerk”通常被用作一个简化设置，用于表示 *打印头在改变方向时允许的瞬时速度变化* ，单位为 mm/s（速度单位，而非加速度单位）。它实际上设定了一个速度阈值——即打印机在不需要先减速到完全停止的情况下，能够改变方向的最大速度。例如，如果 jerk 设置为 20 mm/s，打印机就可以在该速度下立即反向或转向，而无需完全减速，从而实现更平滑、更快速的拐角运动。这种用法更多是在限制各轴在连接点或拐角处的突兀速度变化，而不是像物理学中的 jerk 那样描述加速度变化。因此，在 3D 打印中，jerk 控制的是打印头改变方向的速度，从而影响打印速度、质量和机械振动，而不是真正的物理学“jerk”。

{% embed url="<https://www.youtube.com/shorts/zXKHPeOyRV4>" %}


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