Autonomous Robots in SWAT Applications : Research , Design , and Operations Challenges

This paper describes the efforts of Stanford University’s Aerospace Robotics Laboratory (ARL), the Palo Alto – Mountain View (California) Regional Special Weapons and Tactics (SWAT) team, and the MLB Company to bridge the gap between the perception of potential uses of autonomous robots in police SWAT environments and the reality of their application. The ARL researchers were given freedom of movement throughout live SWAT field training exercises so that they could simultaneously monitor the command post actions, SWAT team movements, and suspects’ activities. This perspective highlighted five significant challenges that should influence future work. First, the considerable difficulty in building a consistent centralized world model indicates the necessity of relying on local sensing for robot tactical maneuvers. Second, the SWAT team referred to objects in the environment throughout their communications, yet the recognition and manipulation of previously unknown objects is a difficult task for robots. Third, the time available for tactical planning was observed to be one of two extremes: nearly infinite or infinitesimally small. Fourth, the SWAT environment has much uncertainty, and SWAT team members are reluctant to introduce any additional uncertainty, friendly or otherwise, via a robot. Finally, the operator plays important roles that must be supported by the robot and the user interface. This paper describes in detail the SWAT exercises that were observed, the challenges indicated by these observations, and a demonstration of an autonomous robot – the MLB Bat unmanned aerial vehicle – in a SWAT environment. Introduction This paper describes the efforts of Stanford University’s Aerospace Robotics Laboratory (ARL), the Palo Alto – Mountain View (California) County Special Weapons and Tactics (SWAT) team, and the MLB Company to bridge the gap between the perception of potential uses of autonomous robots in police SWAT environments and the reality of their application. The robot builders (the ARL researchers and MLB designers) and the SWAT leaders felt that such an effort would address an area of limited current understanding. Robotics motivation Many field robot and autonomous vehicles builders envision their work as assisting humans in positive ways – particularly by replacing them in dangerous, dirty, or dull missions. However, the experience of these robot creators in such hazardous situations is usually limited. Thus, there is some uncertainty regarding what characteristics a robot needs to have to truly be effective in these missions. Some research topics are more on the critical path to deployment than others, and some design criteria should be weighted differently. This research sought to identify these important areas for future work. SWAT motivation SWAT team members recognize that they hold one of the most dangerous civilian occupations. They want to take all possible steps to minimize that danger while accomplishing their mission. From exposure to robotics through the popular media, they envision the possibilities that robots may have to make their jobs safer. However, they do not have a true picture of the actual strengths, weaknesses, or operations requirements of modern robots. SWAT leaders do not know how soon they might be able to involve robots in their operations and are unsure of robots’ potential cost. They also have concerns about autonomous robot use in an environment that often leaves little margin for error. Through the research efforts described in this paper, SWAT team leaders were educated in the realistic capabilities of current autonomous robots through discussions with the ARL and demonstrations by MLB. The SWAT members were shown the operations realities of autonomous robots and the ramifications of their deployment. At the same time, the Aerospace Robotics Laboratory and the MLB Company learned about working in a SWAT environment. In particular, some important qualities for a SWAT robot were identified. The broader purpose of this research was to produce this paper and educate the robotics community about SWAT applications as discovered through this unique partnership. Outline This paper will give a brief description of the SWAT environment and the methods of observation available to the ARL researchers. The observations themselves are then discussed and are followed by the research and design challenges that were identified. Next, the use of the MLB Bat autonomous airplane in a SWAT exercise is discussed as well as the operations challenges that were highlighted through this preliminary test. Background and Terminology The audience for this paper is expected to be primarily from the robotics and automated vehicle fields and inexperienced in SWAT operations and terminology. Consequently, a description of SWAT teams and the SWAT incident environment will be given. The reader is assumed to have a basic understanding of robotics. Police Special Weapons and Tactics teams Police SWAT teams are responsible for handling high-risk tactical situations involving barricaded suspects, hostage situations, and the serving of warrants. The primary goal of the team is the successful conclusion of high-risk situations through the use of specially equipped and highly trained personnel without injury or loss of life to citizens, suspects, or police officers. Officers assigned to the SWAT team are required to pass a physical agility and strength test and a psychological examination, and to participate in monthly SWAT-specific training sessions. Components of a SWAT team deployed at a site vary from incident to incident, but typically include a command structure, tactical teams, a Hostage Negotiation Team (HNT), and a sniper component. The command structure consists of an incident commander, the tactical commander, and the Hostage Negotiator Team leader. These individuals establish an incident command post at some distance from the suspect. The location containing the suspects, hostages, and focus of the action is known as the objective site. The command post is located at a distance close enough to enable speedy travel by foot to the objective site, but far enough away to provide a safe and secure location for the command structure to function. A generic incident site map is shown in Figure 1. The incident commander ultimately makes the critical decisions and is responsible for the incident as a whole, including interactions with the press, coordination of action between the various team components, and handling logistics. The Hostage Negotiator Team works to achieve peaceful resolution of the incident through a dialogue with the suspects, and its leader is responsible for communicating the status and progress of the HNT to the other commanders and guiding HNT activities to complement the tactical squads. The tactical commander’s role is to coordinate the activities of the tactical teams – assault group, rescue element, sniper component, and perimeter control – throughout the incident. Typically, there is significant physical distance between the tactical commander (at the incident command post) and the tactical teams (at the action), and the commander does not have direct sight of the squads or the incident site. The tactical commander thus relies on radio (voice only) technology to gather information from and convey commands to the tactical teams. In some cases, members of the tactical squads will return to the command post for face-to-face meetings with the tactical commander. Figure 1 Generic SWAT incident site layout Also at the command post are tactical dispatchers, who handle most of the communications to the external world and from the commanders to the deployed squads. The dispatchers also maintain logs of all activities, descriptions of suspects and hostages, and maps of the objective site. This information is posted for display to the command structure and is used for tactical decisions. Hardcopy city planning maps are kept in each patrol car, so a detailed map of the neighborhood – street locations and widths, buildings, open lots, and routes of access – is immediately available to the SWAT team. Other information derived from intelligence sources (e.g. government records, neighbors, building supervisors), such as auxiliary maps and building layout descriptions, may be photocopied and distributed to the appropriate team members. SWAT conduct at the incident site The tactical commander provides instruction to the tactical squad leaders within minutes of arrival. One squad is the Emergency Response Team, which is immediately given contingency plans and sent to the objective site. A team of scouts is then sent to create an assessment of the situation and provide prospects for entry methods, methods of safe approach, and descriptions of other salient features. Snipers are also put in place to gather intelligence and report to the command post. These units would normally be outfitted with advanced optics, such as scoped rifles or high-powered binoculars. Then, while the team waits for the Hostage Negotiator Team to achieve a peaceful resolution of the situation, the tactical commander and the tactical squads devise an assault plan. When the scouts return, they are integrated back into the tactical squads. The team draws maps on paper and in chalk on the street, and practices the movements and timing that will be used in the assault. This is an unrushed process, and the tactical team will make the rest of the team wait, if possible, until they are satisfied with their plans. After the plan is set, the tactical squads deploy as appropriate. The pace of operations is typically unhurried and deliberate. Position reports are initially provided about once every two or three minutes, then slow down as squads settle into their positions. Twenty minutes might pass between orders, although this depends significantly on the pace of the incident. Intentions of tactical squads are reported more frequen