How to detect vertical and horizontal movement read description

Projects General Guidance
1

Hi! i want to know how this guy in the video below is detecting horizontal and vertical motion of his hands like what sensors he is using to detect the movement of hand going up and down left and right:

Thanks

2

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3

There might be a language barrier.

4

Two potentiometers in his elbow. The rod going from his right shoulder to his elbow has to twist in either end, when the arm moves horizontally. The pot is probably in the shoulder end, which gives space for the vertical pot in the lower end.

5

Johan_Ha:
Two potentiometers in his elbow. The rod going from his right shoulder to his elbow has to twist in either end, when the arm moves horizontally. The pot is probably in the shoulder end, which gives space for the vertical pot in the lower end.

Thank you very much this seems quite useful.