A novel gait phase detection method that can extract the timing of foot contact conditions (Heel Strike and Toe Off) by a single piezo film sensor attached on each leg is proposed. We focused on the occurrence of high-frequency vibrations (> 100 Hz) in the beginning and the end of stance phases during gait. After the features of vibration waveforms during gait were confirmed, we proposed the phase detection method. The optimal parameters were investigated to detect the phases robustly despite the walking speed and the shoe types. Experimental results showed that the detected ground contact events had high accuracy of timing. Finally, we confirmed the feasibility with the prototype wearable device in usual environments.

This paper presents an initial data that could show a possible contribution of mechanoreceptor activity to the perception of forces applied on grasped objects. Here, we obtained detailed psychophysical characteristics of perceived force-magnitude in multiple degrees of freedom (MDOF) using multi-point suction pressure stimuli. To obtain such data, we developed a multi-point stimulation method that can represent MDOF perceived force on a tool. We characterized the perceived force response of human subjects to suction pressure stimuli through psychophysical experiments. Moreover, we analyzed the strain energy density (SED) on the finger pads considering the force applied through finite element simulation. The results of the psychophysical experiments showed that multi-point stimulation method is effective for evoking MDOF perceived force on a tool. Interestingly, we found that the results of the finite element analysis agree with those of the psychophysical data. Therefore, we have verified that it is possible to use multi-point suction pressure stimulation for representing perceived force on objects held in a hand. In addition, a preliminary insight into the role of SED for perceiving force on tools is provided.