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 .