Feasibility Evaluation of Mobile Internet based Robot-assisted Tele-echography System

In this paper, we introduce a robot-assisted remote ultrasound imaging system connected to 4G LTE mobile internet. Unlike the wired internet connection with the static IP addresses, mobile internet connection makes it easy to move the slave system and allows a remote connection to wherever mobile communication is available, thus enabling tele-echography even in poorly equipped internet facilities. In order to connect the slave system with the master system through 4G LTE mobile internet, SIP and STUN server were included in the network part of the robot-assisted tele-echography system. In the experiment, the developed system was tested for the network performance between the urban hospital and the remote location separated about 250 km away. In addition, RTT test was performed to measure the speed of data transmission for remote robot control under 4G LTE mobile Internet. Based on the experimental results, the average RTT in the mobile Internet was 45.67 ms and the standard deviation is 7.17 ms, which shows that the communication speed is lower than the wired Internet connections and is also somewhat unstable. In addition, we examined that the tracking error between the slave robot and the master device with respect to different types of network configuration. The average RMSE by mobile internet was increased to 3.8 mm from 3.1 mm by the wired Internet. However, 30Hz of remote ultrasound imaging could be performed, and unidirectional remote control was available at the communication speed of up to 44 Hz. Therefore, there is no problem in utilizing the mobile Internet in the current robot-assisted tele-echography system.