从手册上找到一段文字
Feedforward Control The conventional position control concept (P controller) always requires a deviation
(following error = FE) between position setpoint and actual position value. This
deviation can lead to unwanted axis behavior, e.g. contour errors, poor dynamics
(performance characteristics during rise time) etc.
The feedforward control's task is to compensate for these problems. The
feedforward control calculates the axis (setpoint) velocity directly from the position
setpoints by differentiation, multiplies it with the KPC factor, then passes it directly
to the position controller output. In the best of cases, the feedforward control
setpoint will cause the axis to move at the velocity calculated by the interpolator.
If the actual axis position were immediately returned to the position controller, the
following error would be 0. The position controller would then only have to deal with
the task of correcting disturbance-induced fluctuations of the real actual axis
position.

大体翻译一下

传统的P控制器，需要一个跟随误差（设定值-实际值）这样造成了轴的轮廓错误，动态响应性差，在执行轮廓上升期间。

前馈控制就是解决这些问题。前馈控制设定速度值来自位置设定值的微分，乘以KPC，直接传送到位置控制器的输出。这样可以减小在运行过程中的跟随误差。