AMT工作分哪5个阶段呢??急!!!

我翻译一篇文章,其中一句是:
The controller is designed through a hierarchical approach by discriminating among five different AMT operating phases: engaged, slipping-opening, synchronization, go-to-slipping, and slipping closing.

这五个阶段怎么翻译呢?是什么意思呢?
它贯穿全文,但我还是说不准它的意思!