A. Introduction
There is a growing body of literature that recognises the importance of robotics devices, and with the recent improvements in robotic technologies, the trend has become that replacing human resources with robotic devices. Robotic devices have become widely used in a variety of different applications such as industrial applications, medical applications, search and rescue, and security applications as well.
Although passive security robots are used for many years, active security robots have been used only for a couple of decades. Active mobile robots could be used for both home patrols and public area patrols such as in shopping centres, hospitals, and schools. The main aim of using a robotic system for security services is to accomplish some important task which a human cannot achieve or which is not preferable to do by humans because of some reasons such as cost and safety. There are many benefits to using mobile robotic devices for security services. For instance, with mobile security robots, it could be decreased that the number of security personnel and the tasks of security organisations could be propelled [1]. On the other hand, there are also some challenges associated with the current devices such as reliability of control systems of devices and inadequate environmental factors for robots [2].
In the dissertation, it will be presented that the state of the art mobile security robotic devices with different examples. In addition, the advantages and disadvantages will be outlined. Finally, it will be interpreted that are they reliable or they only spy on people’s life.
B. State of The Art Mobile Security Robotic Devices
1. ROBART Series
ROBART I [3] (see Figure 1) could be named the first autonomous security robot in the world. ROBART I was designed by the United States Naval Post-Graduate School in Monterey between 1980 and 1982 years. It was designed to check for any unwanted conditions indoor environments such as smoke and fire. It contains two different operation modes: alert mode and passive mode. The robot was able to follow a reflective patrol path in the passive mode. However, it had no absolute location sense. When it detects any unusual condition, it turns the alert mode on. The lifespan of ROBART I was continuously six hours, and then it needed to be charged for twelve hours. However, the good thing was that it automatically recharges itself at a recharging station.
Figure 1 ROBART I [3].
The robot has a passive infrared motion detector which is mounted on the head of the robot, three optical motion sensors, collision and hearing sensors, cameras, single-board computer, and speech synthesis.
The second generation of the ROBART series is ROBART II [3] (see Figure 2) which was designed between 1982 and 1986 years in the US. ROBART II was able to detect and also assess any potential intruder through its assessment algorithm while ROBART I was only able to detect any possible intruder.
Figure 2 ROBART II [3].
ROBART II contains a precise map which allows the robot to determine the absolute location, seven different kinds of sensors including vibration monitor sensor and sound sensors, cameras, optical, ultrasonic, IR and microwave detectors. It was also able to monitor both room temperature and system temperature, humidity, light, and barometric pressure such an advance smart robot.
Although with ROBART II some big progress was shown, both ROBART I and ROBART II are not efficiently used indoor environment because of wheeled locomotion design and the algorithms of navigation.
As a final version of ROBART mobile robot series, ROBART III [3] (see Figure 3) was designed with an improved control algorithm compared to previous versions. The main purpose for designing the third generation of ROBART series was to demonstrate the feasibility of automated response through a pneumatically powered barrel. However, ROBART III is only a laboratory prototype and never used in the real-time field.
Figure 3 ROBART III [3].
2. The Guard Robot
An autonomous guard robot was designed by Shimosasa et al. [4] (see Figure 4) in 1999. The main purpose of this design is to provide an early detection of any abnormal issue and prevent the accident such as fire, theft and flood. The system of the robot could be divided two main parts: guard robot and the ground station.
The guard robot consists two wheels and moves on the pre-planned path. Some of the main features of the guard robot are a smoke detect sensor, a human detect sensor, a flame detect sensor, a leak sensor, an ultrasonic sensor, a radio wave antenna, five CCD cameras, and a speaker. On the other hand, the ground station comprises the monitoring station, the transmission equipment, the battery recharging station, and the elevator controller.
Figure 4 The guard robot [4].
The guard robot works in collaboration with guard people, and it is programmed to patrol the area in every two hours automatically or manually operated by guard people. During the patrolling process, robot sends all collected data to the monitoring station, and guard people could evaluate these data remotely. When it finishes the patrol, it automatically comes back to a charging station. The guard robot could also provide guidance for people. When someone stands in the front of the robot, the robot send the image of the person to the monitoring station, and if any guidance is needed, guard people could contact with the person through microphone and speaker which are mounted on the guard robot and in the monitoring station as well. However, the biggest challenge associated with the robot is that it is needed to replace the battery every month which makes the system unpractical.
3. Surveillance Robot
The surveillance robot [5] (see Figure 5) is a bio-inspired home security hybrid robot with hopping ability which is designed in 2009. The surveillance robot has two wheels and one hopping leg. The height of the robot is 9 cm, and the weight is 250 grams. It could jump over up to 40 cm in height, that is approximately 4 times higher than its height, and 24 cm to 84 cm in length. Thus, it could easily go up and down from stairs and jump over any obstacles in this range. In Figure 6, the hopping mechanism could be seen clearly. Song et al. [5] was inspired from frogs and kangaroos to design this hopping mechanism.
Figure 5 The prototype of the surveillance robot [5].
The surveillance robot comprises infrared sensors, accelerometers, shaft encoder, and video camera. The power system of the robot relies on two 3.7 V lithium-ion rechargeable batteries. The wireless communication is provided by ZigBee protocol, and sensor network is created in the house where patrolling is needed.
Figure 6 2D schematic view of the surveillance robot and the hopping mechanism [5].
The surveillance robot has three different working modes depended on the request of user which are patrolling mode, first responder mode and remote control mode. In the patrolling mode, the surveillance robot patrols the environment autonomously by following defined path. As mentioned previously, there is a sensor networks and the surveillance robot works in collaboration with this network. In the first responder mode, the surveillance robot acts according to the data comes from these sensors or monitoring systems. So, when the robot gets any security evet report from the network, it will do the inspection in that area.
The surveillance robot could be controlled remotely by the user through either computers or smartphones. In the remote control mode, the user guides the surveillance robot to check the area where the user wants to be checked.
The surveillance robot is experimentally validated. The results show that the best take-off angle is 60 in terms of vertical and horizontal displacements. However, as a future work, it is needed to be stabilized the control of landing which involves numerous practical challenges.
4. Avatar III Security Robot
One of the currently available mobile security robot is the Avatar III security robot [6] (see Figure 7) which is designed by Robotex company in 2012. This robot is suitable for indoor application and able to climb stair with its unique wheel design. Additionally, it also works on wet floors, slick concrete and rugged outdoor terrain.
Figure 7 Avatar III security robot [6].
The Avatar III security robot has the specification of 360-degree Pan-Tilt-Zoom (PTZ) and IR cameras. It could be controlled hundreds of miles away from an operation centre through Wi-Fi radio networks which has 2.4 GHz spectrum. Physical dimensions are 62 cm x 40 cm x 16 cm, and the weight is 11 kg that makes the robot portable. The Avatar III security robot has rechargeable lithium-ion battery.
The Avatar III security robot performs any given patrol routes and if it is needed, it could alarm. On the other hand, as mentioned previously, it could also be controlled remotely by a human. However, the biggest challenge associated with this robot is that it needs to be charged regularly because it cannot do that automatically.
5. Knightscope Autonomous Data Machines
Knightscope robotics company [7] is an advanced security company in the USA which produces autonomous security solutions with combination of software, hardware and humans. Knightscope robotics company provides two autonomous mobile security robots which are K3 and K5 (see Figure 8).
The Knightscope K3 and K5 robots are both fully autonomous, but they also could be controlled by an authorized person. The Knightscope K3 is mainly used for indoor applications such as shopping centres and sport centres. On the other hand, the Knightscope K5 is used for large outdoor applications such as parking lots and corporate campuses. The Knightscope K5 autonomous data machine has 1.5 metres height while the Knightscope K3 autonomous data machine is shorter.
Figure 7 Knightscope K3 on the left, Knightscope K5 on the right [7].
These autonomous data machines are equipped with GPS, laser range finders, 360-degree video recording, thermal imaging sensors, radar, air quality sensors, speaker, microphone, and smell detectors. The Knightscope K3 and K5 could autonomously recharge themselves, and their usual speed is between 1 to 3 mph while the maximum speed is 18 mph.
The working principle of both autonomous data machines is that they collect the data using sensors, then analyse the data through the provided analytics engines. When they finish the analysis, they could determine whether to alert the community or not. Both the K3 and K5 autonomous data machines incorporate the 90 terabytes data generated each year. In addition, the data is available to access through the Knightscope Security Operations Centre (KSOC).
Although the Knightscope autonomous machines could be classified as the best mobile security robots up to date, there are some challenges to achieve with these devices. First of all, the dimensions are quite big, and this makes the robot bulky. Secondly, these robots are only able to move on a plain surface and with a limited speed. However, the Knightscope robotics company is planning to improve these robots to become more convenient devices in terms of making decision and movements in other type of grounds.
C. Discussion and Conclusion
In the light of recent improvements in robotics, mobile security robots have become widely used devices. However, there are some doubts such as their reliability and effectiveness although they supply convenient security services. For instance, as mentioned previously, Knightscope K5 autonomous data machine [7] is used in public areas, and it is able to record videos and take pictures without any notification while people concern their daily life. It could also record people’s conversations, and this makes people to be afraid about their privacy. On the other hand, it will be never possible to completely replace all security people with mobile security robots. This is because the decision of the mobile security robots always needs to be evaluated by a human.
In conclusion, considered to the state of the art mentioned above, there are three main aspects need to be improved which are physical abilities of mobile security robots, control and decision making mechanisms and respecting the privacy of people in public areas. Mobile security robots need to have much more capabilities to participate in law enforcement and to cope with any obstacles either in outdoor environment or in indoor environment. In addition, there must be found a way to respect people privacy while using mobile security robots in public areas.