The exterior trochoid ( hypocycloid ) demonstration instrument is made and the patterns are studied .

制做了圆外（内）旋轮线演示仪，并对其产生的图案进行了分析。

In the article , hypocycloid 's formation method , engagement theory , driving theory , and typical structure of the hypocycloidal drive are mainly discussed , and besides , a contrastive analysis of hypocycloid and epicycloid is made .

本文主要论述了内摆线的形成方法、啮合原理、传动原理、内摆线针轮行星传动的典型结构、并对内、外摆线作对比分析。