SHUYU Robot: an Automatic Rapid Temperature Screening System
The health of people around the world and the global economy are under substantial threat from the outbreak of pandemics. Controlling pandemics is extremely challenging, with preventing the spread of pathogens the most important and critical step. Of all preventative actions, body temperature screening is undoubtedly highly necessary and effective.
At all types of entrances, automobile passengers and pedestrians should be screened. Currently, screening tasks are conducted by security guards or other staff via infrared (IR) thermometers. In general, thermometers can be classified into contact and non-contact ones. Contact thermometers are usually time-consuming and increase the risk of cross infection between the humans being tested. In comparison, non-contact thermometers have obvious advantages. Among them, IR forehead thermometers and IR screening instruments are most widely used, with typical accuracy levels of 0.5 °C and a maximum accuracy of 0.3 °C.
In practice, the following problems are encountered when using forehead thermometers or screening instruments. 1) To achieve the expected accuracy, the ambient temperature is strictly limited (to approximately 20 ℃) and a wind-free environment is usually required, i.e., the default service environment is generally indoors. 2) Indoor use raises the possibility of bringing pathogens indoors, which increases the risk of cross infection. 3) When measuring facial temperature, facial coverings (cosmetics, dust, hair, etc.) easily lead to inaccurate results. To avoid these problems, the only reasonable approach is to measure body temperature outdoors on skin covered by clothes.
As there is no available and reliable equipment for outdoor temperature measurement, forehead thermometers must be used outdoors. As a result, large deviations in temperature measurements are inevitable. In addition, temperature measurements by hand-held forehead thermometers are inefficient and highly labor intensive. Furthermore, the procedure might cause personal discomfort, and the possibility of cross infection still exists even outdoors. Therefore, a method for performing automatic rapid and accurate temperature measurements in an outdoor environment is urgently required.
In this context, the Tsinghua Advanced Mechanism and Robotized Equipment Laboratory and the Yantai Tsingke+ Robot Joint Research Institute Co., Ltd. have jointly developed an automatic rapid temperature screening system that is particularly suitable for outdoor environments. The research and development of this system are mainly focused on the robotic design, temperature measurement model design, compensation algorithm development, visual semantic perception, and control strategy.
The automatic rapid temperature screening system has two different configurations. One is for drivers and passengers of mobile vehicles and the other is for pedestrians. The system has the following characteristics:
1. Semantic recognition and instance segmentation are achieved with a deep neural network. Using dual IR cameras, the number and position of passengers in the car are identified. The facial recognition rate exceeds 98% when the confidence is set to 92%.
2. A constant-temperature measurement model is designed and an intelligent temperature compensation algorithm is established. On these bases, the accuracy of temperature measurement reaches 0.2 ℃.
3. Multiple sensors are integrated with functions of visual recognition, ultrasonic detection or IR detection. Consequently, rapid positioning of vehicles, and automatic temperature screening of drivers, passengers, and pedestrians are realized. The detection time for a vehicle is less than 20 s and that for a passenger is less than 2 s.
4. Using big-data technology, maps of vehicle, passenger, and temperature data are generated and uploaded to the cloud for management.
A schematic of the automatic rapid temperature screening system for drivers and passengers in mobile vehicles is presented in Figure 1. The system consists of two robots (named SHUYU robots). As shown in Figure 2, the SHUYU robot is composed of a two-degrees-of-freedom translational parallel manipulator.
Figure 1 Schematic of the temperature screening system
Two high-accuracy thermometers developed for outdoor applications are installed at the end of the parallel manipulator. Two cameras (Figure 2) are also equipped to monitor the driver and passengers. Both SHUYU robots are equipped with ultrasonic sensors to detect the distance between the robot and the vehicle. In addition, the robot is equipped with a voice broadcast system for guiding the passengers through the temperature measurement step by step. A total of four high-accuracy thermometers are included in the screening system; therefore, four passengers (including the driver) can be measured simultaneously. When the number of people in a vehicle exceeds four, a nearby thermometer can subsequently be used to complete the additional measurements. If all temperatures are within normal ranges, the gate in Figure 1 will open, allowing the vehicle to pass through; otherwise, the gate will remain closed and the system will sound an alarm.
Figure 2 Structure of the SHUYU robot
To screen the temperatures of pedestrians at various entrances, the SHUYUmini robotic system presented in Figure 3 has been developed. The arm of SHUYUmini is a parallelogram mechanism with one degree of freedom. The high-accuracy thermometer is connected to the body of the robot through a damped spherical joint. The user can adjust the direction to find a comfortable measurement pose. Three laser-ranging sensors are arranged on the side of the robot to identify the position of pedestrians. Similarly, if the temperature is in a normal range, the arm will open; otherwise, the arm will remain closed and the system will sound an alarm.
Figure 3 Structure of the SHUYUmini robot
Currently, the SHUYU screening system has been used in parking lots in Yantai ETDA (Figure 4) and Tsinghua University (Figure 5). The SHUYUmini screening system has been used in Peking Union Medical College Hospital, the First Affiliated Hospital of Tsinghua University (Figure 6), and the LeeShauKee Building of Tsinghua University.
Figure 4 SHUYU robot used in Yantai ETDA Figure 5 SHUYU robot used in Tsinghua University
Figure 6 SHUYUmini robot used in the First Affiliated Hospital of Tsinghua University
The developed screening system can also be applied to highways, airports, bus stations, and checkpoints, as well as hospitals, schools, banks, conference venues, exhibition halls, office areas, hotels, residential quarters, supermarket parking lots, and any other channel requiring rapid automatic temperature screening.
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About the author
Prof. Xin-Jun Liu received the Ph.D. degree in Mechanical Design and Theory from Yanshan University, Qinhuangdao, China, in 1999, the M.S. and B.S. degrees in Machine Design and Manufacture and Mechanics from Northeast Heavy Machinery Institute in 1994 and 1995, respectively.
Currently, he is a full professor with tenure in Department of Mechanical Engineering at Tsinghua University, Beijing, China, the Winner of National Outstanding Youth Fund of China, the "Cheung Kong" Chair Professor, the Associate Editor of Mechanism and Machine Theory, and the Director of Tsinghua Uni.(DME)-Siemens Joint Research Center for Advanced Robotics (JCAR). From 2000 to 2001, he worked as a Postdoctoral Researcher at Tsinghua University. He was a Visiting Researcher at Seoul National University, Seoul, Korea in 2002-2003. He was the Alexander von Humboldt (AvH) Research Fellow at University of Stuttgart in Germany from 2004 to 2005. He was the Visiting Professor with Prof. Dr. Reimund Neugebauer at Fraunhofer Institute for Machine Tools and Forming Technology, Germany, in August of 2007. He has published over 160 papers in refereed journals and refereed conference proceedings. His research interests include parallel mechanisms and robotics, parallel kinematic machines, and advanced manufacturing equipments.
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