Experimental Investigation of Operability in Six-DOF Gesture-Based Operation Using a Lower Limb and Comparison With That in an Upper Limb

To operate robots and machines intuitively, interfaces using body motion have recently been investigated. However, compared to the upper limbs, the lower limb operation has not been fully explored. In the present paper, we conducted an experiment involving the six-degree-of-freedom operation of an imaginary object with a lower or upper limb gesture using a virtual-space-based evaluation system. We analyzed the motions of the upper and lower limbs in the operation and discussed the difference between their characteristics. The experimental results showed that the operability of the lower limb was lower than that of the upper limb in terms of time by approximately 79%, accuracy by approximately 109%, subjective evaluation by approximately 39%, and frequency of ON/OFF switching by approximately 82%. We analyzed the results in detail by defining the operational ideality and roughness based on fuzzy estimation. The results clarified that the ideality of the lower limb operation was lower than that of the upper limb by approximately 20–25% and that the ideality was lower in the posture operation than in the position operation by approximately 7–13%. Evaluation of the macro-approaching motions using the roughness index showed that the moving distance, rotating angle, and rotating velocity for a single motion were all smaller in the lower limb operation than in the upper limb operation by approximately 18%, 44%, and 33%, respectively. Consequently, there was the main difference between the upper and lower limbs in the posture operation.