*5.2.1 Video encoding method*

Unlike local surgical robots, remote surgery requires the transmission of endoscopic high-definition images through the Internet. Under certain network bandwidth conditions, in order to ensure the real time of image transmission, image compression means are needed to reduce the amount of data transmitted, and image compression and decompression processing will introduce new delays. Common video coding modes include H.264/MPEG-AVC coding, H.265/MPEG-HEVC coding, etc [11].

Compared with H.264, in order to improve the compression and coding efficiency of high-definition video, H.265 adopts the ultra-large quadtree coding architecture, and uses three basic units, namely, coding unit (CU), prediction unit (PU), and transformation unit (TU), to implement the whole coding process, which improves the coding efficiency and effectively reduces the decoding time [12].

*Application and Prospect of Telesurgery: The Role of Artificial Intelligence DOI: http://dx.doi.org/10.5772/intechopen.111494*

#### *5.2.2 Stereo image transmission mode*

Three-dimensional stereo images are composed of two cameras taking pictures of objects from different angles of view, and then interleaving the images with odd and even lines. The 3D stereo image synthesis process adopted by the remote surgery robot, At any time, the 3D stereo endoscope camera outputs two high-definition images (a) and (b) with a resolution of 1920 \* 1080, scales the two images to an image (c) with a resolution of 1920 \* 540, and then splices the two images to form a 1920 \* 1080 Top-Bottom format high-definition image, which is then input to the image encoder for compression and remote network transmission. After receiving the image at the main hand end, through parameter adjustment, the two images spliced up and down are displayed alternately in odd and even rows to form a three-dimensional stereo image (d), and finally, the stereo image under the endoscope field of vision is displayed on the display at the main hand operation end.

#### *5.2.3 Delay and optimization of remote surgery*

Low transparency and large network delay of remote minimally invasive surgical robot will prolong the response time of surgeons. According to the experiment, when the delay of remote surgery exceeds 500 ms, the operation risk will be significantly increased [13]; According to the statistics of the transatlantic remote "Lindbergh operation," the delay doctors can tolerate is 330 ms. For the developer of robot equipment, a detailed quantitative description of the system delay will help to find deficiencies and continuously optimize, so the delay test of surgical robot is very meaningful.

The delay of the remote robot system is mainly composed of two parts: ① the sample-communication-execution delay between the master and slave hands; ② capture-transmission-display delay between the endoscope and the display. Therefore, it is necessary to measure the delay of these two parts separately. After continuous measurement and optimization of the test results, the final test results completely test the system delay of the remote surgical robot, and theoretically ensure that its reliability meets the use requirements.

### *5.2.4 Master and slave configuration of remote surgical robot*

Based on the above test results, combined with the architecture of the minimally invasive surgical robot and the requirements for signal and video transmission, we designed a remote communication control system based on 5G/Internet dedicated line, which integrates the remote surgical robot.

The main terminal communication control box is the receiving and sending and control module of all kinds of information at the doctor's operating terminal under network conditions. It consists of a box, an image encoding and decoding unit, a power supply unit, a network communication unit, a motion control and signal processing unit, a status display unit, an interaction unit, an interface unit, etc. The functions of each unit are as follows:

Box: integrated with each component unit to facilitate overall transportation.

Image encoding and decoding unit: composed of image encoder, used for encoding and decoding stereo endoscope dual-channel images and transmitting them at both ends of remote surgery.

Power supply unit: It is a switch power supply conforming to medical specifications, which is used to supply power to all units inside the box.

Network communication unit: It is a special industrial computer used to transmit control signals at both ends of remote surgery and monitor the network status.

Motion control and signal processing unit: interacts with the network communication unit, can collect the motion information of the master hand, and can actively control the motion of the master hand.

Status display unit: used to display the working status of network communication unit and motion control and signal processing unit.

Interaction unit: human-computer interaction interface, which is used to set network connection, start/stop data transmission, etc., and can feedback the robot operation status to the operator through prompt tone, etc.

Interface unit: including power supply interface, network interface, video output interface, foot switch signal acquisition interface, robot main end operation data output interface, etc.

The main communication control workflow is to connect the interface of the main end of the robot itself and the main end medical monitor with the main end communication control box, and then connect the main end communication control box to the Internet through the RJ45 interface. At the same time, supply 220 V AC power through the interface unit, and start-up.

The slave communication control box is the receiving and sending and control module of all kinds of information at the slave end of the robot under network conditions. It is composed of box, image encoding and decoding unit, power supply unit, network communication unit, energy instrument control unit, status display unit, interaction unit, interface unit, etc. The functions of each unit are as follows.

Box, power supply unit, network communication unit and status display unit: the same as the main control box.

Image encoding and decoding unit: composed of image encoder, used for encoding and decoding stereo endoscope dual-channel images and transmitting them at both ends of remote surgery.

Energy instrument control unit: It is composed of PLC modules, which is used to simulate the control signal output by the main machine of the excitation energy tool.

Interaction unit: human-computer interaction interface, which is used to set network connection, start/stop data transmission, etc., and can feedback the robot operation status to the slave assistant through prompt tone.

Interface unit: including power supply interface, network interface, video input interface, robot slave operation data output interface, etc.

The work flow of the slave communication control box is as follows: connect the communication port of the slave robot to the slave communication box through the network cable, and then connect the slave communication control box to the Internet through the RJ45 interface. At the same time, supply 220 V AC power through the interface unit and start-up.

#### *5.2.5 Use of remote surgical robot*

After testing, in order to ensure the smoothness and security of remote operation, the average network delay should not exceed 30 ms, and two dedicated networks with a bandwidth of not less than 50 Mb should be provided to ensure network stability.

The remote surgical operation doctors should not only receive the operation training of local surgical robots, but also receive the operation training in the remote environment. The operating physician also needs to be familiar with the operation mode and operation specification of the robot, be able to know the meaning of
