That's not true. All the points on this walker are the synthesis of two actions. One is upward movement. When your feet move forward, your body will move upward. If you don't believe me, you can look at the shadow and find it when you walk forward. If you dress up, you have to translate unless your feet stay on the ground. The other is to move forward, which is easier to understand. The combined trajectory of these two actions is like the upper part of a sine curve.

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