Robots can fold clothes but struggle to twirl a pen, revealing a fundamental shortfall in data capture technology. Peking University Assistant Professor Yixin Zhu points out that the industry has yet to answer the basic question of 'what is dexterity': resembling a human hand and being able to bend does not equate to dexterity; the speed of response to external stimuli is equally a core dimension.
Existing wearable devices rarely exceed 200 samples per second (200Hz), with most ranging from tens of hertz to 200Hz. Even at the 200Hz upper limit, according to the Nyquist-Shannon sampling theorem, they can theoretically only reproduce motion details below 100Hz, failing to capture higher-frequency motion information. Skilled actions like pen twirling can be completed in half a second, and spectral analysis shows that angular velocity signals carry significant energy in the frequency band above 100Hz.
To verify that high-frequency motions indeed exist in human hands, the team designed pen twirling and ball catching experiments. In one-directional pen twirling, the thumb, index, and middle fingers show clear energy bursts above 100Hz; in bidirectional twirling, high-frequency energy is stronger due to sudden stops and reverse accelerations. A four-finger twirling experiment (with the thumb not participating) shows active high-frequency signals in the four fingers and palm, while the thumb and forearm show no such signals, ruling out sensor noise or structural resonance. In ball catching, the entire hand exhibits synchronized high-frequency responses at the moment of impact, reflecting shock absorption effects.