Handshake telephone system to communicate with voice and force

In this paper, we propose the handshake telephone system using robot hands, through which users can shake hands to each other while talking on the telephone. Robot hand has one degree of freedom and is made of silicone rubber in order to get the natural feeling like human's hand. Four fingers are loosely joined together and the elbow joint can be freely rotated by the user's arm motion. A force sensor, which is composed of a rubber tube and an air pressure sensor, is attached at the lower part of the hand. The air pressure sensor measures the air pressure in the tube which changes according to the user's grasping power. The robot hands are connected through ordinary telephone line in parallel with the voice line. In our experiments with the bit-rate of 9600 bps, the transmission delay was around 45 ms which is acceptable for handshake communication. Additionally, we tried a self handshake mode to handshake with a virtual partner.