|Suri ashi means the walk on the tatami, the feet are not lifted as in normal walking but "shuffle" over the tatami. Suri ashi causes a much more stable posture and it is more difficult to the sweeping the feet away.|
Ayumi ashi is always executed as Suri ashi. It referred to the normal walking with one foot overtakes the other. Ayumi ashi can be performed forwards or backwards, or in all other directions.
Tsugi ashi is also performed basically as Suri ashi. Unlike Ayumi ashi the feet while walking are not overtaking them self. They approach each other and then detach again. Tsugi ashi can be performed forwards or backwards, or in all other directions. Tsugi ashi is e.g. applied at the complete Nage no kata.