Robotic Devices for the Transit Environment (2003)

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2 OVERVIEW This document is organized into three sections that describe the process of selecting a robotic device for general and specific applications in the transit environment. The first section, “Environments,” identifies the expected conditions in which a device must operate and through which it must navigate. The second section, “Available Robotic Systems,” explains the features available for robot devices and provides a market survey of readily available systems that are appropriate for at least some transit applications. Finally, the section called “Selection Analysis” identifies the limitations in meeting the requirement specifications for transit applications. This section also reviews operator demands, training, and maintenance. This illustration is based on a review of several transit environments. When selecting a robotic device for transit applications, end users should strive to ensure that the physical and operational capabilities of the device meet the demands of the targeted transit environments. ENVIRONMENTS In this section, the transit environments in which a robotic device must be able to function are listed and illustrated. These environments are discussed in the subsections titled “Structures,” “Vehicles,” “Roadways and Terrain,” “Weather Conditions,” “Optical Navigation Environments,” “Radio Environments,” “Hazardous Environments,” and “Other Requirements.” Both normal conditions and hazardous situations are examined. At the end of the “Environments” section, a compilation of robotic device performance requirements is assigned values, and constraining specifications are tabulated. This requirements specification defines the goals for a robotic device in a generic transit application. Structures For the purpose of this report, structures are defined as buildings that are boarding/alighting points, equipment or vehicle storage garages, or permanent structures that in other ways provide a service to the transit system. This section does not include tunnels or bridges; these will be discussed later. Train and bus stations are structures of primary interest. They range in complexity of design and layout from small, one-room Quonsets to substantial buildings. Two environmental conditions will be considered here and throughout this report: standard obstacles under normal operating circumstances and random obstacles in disaster situations. Under normal conditions, the size of a robotic device should allow it to negotiate seating benches, fare collection equipment, ticketing counters, restrooms, offices, and so forth. Stairs and stairwell landing areas will define the robotic device climbing and turning requirements. The reach of the articulating arm that might carry a gripper, camera, or other sensor should be sufficient to access any elevated surfaces and recesses. In a disaster such as a building collapse, debris, rubble, and fallen structures will determine the robot height dimension and climbing requirement. Exemplary environments will be examined and a compilation of robotic device requirements relating to mobility and service capabilities in structures will be presented. Washington DC Union Station Photo by Mark M. Piotrowski, courtesy of Washington, D.C. Chapter NRHS

In general, for normal operating conditions, large and small stations and terminals present identical obstacles. Although a terrorist attack is more likely to occur at a large busy terminal, smaller stations tend to have slightly smaller spaces and therefore are more demanding environments for robot use. Thus, for this report, local commuter stations were studied because they represent worst-case examples. Smaller stations are also more numerous and may provide more opportunities for the investigation of false alarms than larger stations. Two stations were analyzed, a commuter train station and a bus station in southern California. The train station waiting Commuter train station, track level 3 Elevator outside clearance room presented no remarkable challenges to a robotic device as it was built for handicapped access. Handicapped access provides more than adequate mobility and reach clearances for almost all robot devices in the small-to-medium class. Access to the train, however, requires the use of a footbridge and an elevator. In the event of a disaster (assuming that conventional access would not be functional), access to the train would require a descent down a 60% grade or approximately a 1,000-foot drive on gravel. Further, in the event of structure collapse, in this station or in larger stations, access would be restricted in height to ground-based supporting structures such as counters or platforms. Although the bus station access was not as challenging, the structure makes identical demands on robotic devices. Other structures, such as storage and repair buildings, were also examined. Lack of handicapped access meant that for a robotic device to function in these structures, it would need to have stair- climbing capability. In general, a robotic device would not have size restrictions in order to function in these structures. Elevators Footbridge Grade Free access on gravel 1000 feet away Commuter train station, street level - footbridge connecting north- and south-bound boarding/alighting platforms

4 Courtesy of Center for Robot-Assisted Search and Rescue By permission of Amtrak Cascades Structure disasters produce several types of environments for robots, as seen in their use at the World Trade Center. These include small passageways (typically in the ducting between floors), highly variable passageways caused by random building members and material distributions, and impenetrable areas or tall drop-offs. Investigating these different environments requires an arsenal of specialized robotic devices. However, it is highly impractical for any one agency to own this number of devices. More typically, a single bomb of relatively low energy will demolish a portion of a building (as seen in some terrorism acts in the Middle East). This kind of destruction produces a more negotiable environment, consisting of passageways created by structure collapse onto desks, seats, and so forth, and produces 2- to 10-inch diameter rubble and steps. Vehicles Vehicle Access/Egress Vehicle entrance and egress present the most challenging mobility constraints on a robotic device. Although handicapped access allows good mobility to seating and restrooms, such access is not afforded to locations that are apt to have suspicious packages, perpetrator hiding places, or injured passengers. Further, the handicapped assist equipment may not be available in the event of a disaster or even a minor power outage. An analysis was performed on several vehicles, including commuter trains of pre- and post-1980s vintage, an intercity bus, and a trolley. Shown on the following page are the critical constraining dimensions of these vehicles for establishing robot requirements. Shown on the next page are data on vehicle parameters that will dictate the robotic device’s physical dimensions, stair-climbing ability, and power requirements. In “Vehicle Pathways, Overheads, and Transitions,” data on vehicle parameters that will dictate the device's turning radius, manipulator arm reach and dexterity requirements are provided. In the section, “Vehicle Special Obstacles,” data on vehicle parameters such as extreme stair pitch and passageways of unusually small width are provided. In “Vehicle Special Obstacles,” the vehicle parameters created by disaster situations are also discussed.

36" Width Train pre-1980s Intercity Bus Commuter Trolley 8" 11" 12" 8" Platform 14" 24" Width Ground 18" 8" 8" 24" Width 5 Platform Track bed 11" Landing 12" 8" 9" 8" 11" 3" 5"

Vehicle Pathways, Overheads, and Transitions Shown below are corridors, seating, and overhead baggage compartments for typical transit vehicles. The arrangement and dimensions of these items are the primary factors in determining the requirements for a robot arm—typically a device that has multiple links and joints, provides an extension for reaching, and terminates in a claw-like gripper. Looking into an overhead carrier and removing a package or deploying an X-ray camera to examine a package under a seat are just two examples of the demands on the arm and gripper. Shown below are examples of the kind of detailed drawings of vehicle floor plans that would be needed to determine robotic device requirements. Train post-1980s Train pre-1980s Intercity Bus Commuter Trolley 6 Luggage Carrier 24" 21" (64" high) Restroom 35" 40" 42" 16" 27"Stairs Seats Luggage Carrier 16" (32"up to 12") 30" (63" high) 24" (63" & 68" high at ramp extremes) Luggage Carrier 14" 39" Seats 36" Seats Ramp 10" 39" 24" Train post-1980s Train pre-1980s Bus

Bus 16” x 24” step to corridor transition 20 20” Compared with trains, buses have few unique mobility obstacles. With some exceptions, public transit buses are designed primarily for seated transport and do not have features such as diners, sleepers, or unique function areas. Because of this and the shorter commutes than trains, buses have comparatively smaller mobility areas and present the more stringent access requirements. On buses, the height of the first step, steepness of steps, transition from steps to corridor, and width of corridor all make access more difficult for a robotic device. Vehicle Special Obstacles Rail cars comprise a wide variety of designs for functions ranging from dining to sleeping. Although no special function cars were studied for this report, a commuter train provided many obstacles that would challenge a robotic device. Shown below are features of a dining area on an upper deck. These features include a steep and narrow stair climb, an extremely small turning landing, and a dining floor raised above a very narrow corridor. Also shown is a stairway transition to upper-level seating, which has a severe stair incline and a small transition landing. Narrow stairs ” wide, 50% pitch 36” wRaised eating deck wide x 13” high corridorStair-to-corridor transition landing 24” x 40” 7 Stair-to-corridor transition landing 36” x 36” Stairs ide, 50% pitch

8 By permission of North Bank Fred Personal items within vehicles can be as much of an obstacle for a robotic device as vehicle structure. Obstacles such as randomly placed luggage can present a formidable mobility impasse for a robotic device, even if it is not operating in a disaster situation. Such obstacles have a wide variety of shapes and sizes; no a priori standard can be used. Stair-climb and debris-diameter parameters should be used to estimate a robotic device's ability to negotiate random items. The effects of a disaster—debris, wreckage, and angle of floor and walls—also cannot be predicted, and any attempt at a specification must be tempered with a classification of the severity of the situation. Robots are primarily used in a disaster for search and observation in impenetrable locations. In the worst-case scenario, the vehicle height will be reduced to the height of other supporting structures such as seat bases, tables, and so forth. In such cases, attempts at conventional access are typically abandoned, and the robotic device is deployed through a window. In hazardous situations, the device is sometimes thrown through the window. Therefore, a critical requirement for the device, in addition to climbing and debris-traversing ability, is small physical size. Requirement specifications for incline climb, debris diameter, and physical size will all need to be considered in selecting a robotic device; however, it is important to remember that deployment of robotic devices in a disaster situation is a best-effort basis.

9Roadways and Terrain Roadways and terrain consist of paved streets and highways, railroad and subway tracks, bridges and tunnels, and all surrounding areas that a robotic device must traverse to access the vehicle thoroughfare. A robotic device can negotiate paved roads in good condition quite easily. Railroad tracks in open country are similarly unchallenging in the area along the track. Crossing the rail, however, will be difficult for a robotic device. Climbing the rail will be a challenge, and if the surrounding terrain is gravel or loose dirt, this will be a challenge too. To function in these conditions, a robotic device will have to meet certain wheel or continuous-tread requirements. Common rail sizes range from 132 to 136 lbs/yard, depending on whether they are 7 1/2- or 8-inches high. Gravel, dirt, sand, grass, and low brush get trapped in robotic device wheel and tread mechanisms; this requires that the device undercarriage and drive system design include either guards or a compliant drive train. Unusual terrain features such as potholes and low straddle holes and drive off ledges. With vehicles o becomes critical. Shown above is a typical reduc access is caused by the vehicle. It will be difficul dividers, median barriers, and other extremely impe to navigate around them. Disaster situations on roadways include bridge col subways, weather- or bomb-damaged roads, and fixtures might support a collapse and allow some structures will overload such supports. In roadway that determine the clearances, and, as seen in the ea (Oakland, CA) shown below, will be reduced to suggested for such occurrences. The robotic dev performs to all other requirements will fare best in a Damaged Cypress St 14” ledge 2” to pea gravel ered track bed n roadways or ed-access railw t to find a robo netrable roadw lapses, smoke- so forth. Un vertical clearan collapses, the v rthquake-dama an impenetrab ice with the s disaster. reet section of I-88 5” x 40” or 20” x 28” undercarriage clearances require that a device be able to tracks, a clearance dimension also ay situation in which the reduced tic device that can negotiate high ay obstacles. The device will have or chemical-agent-filled tunnels or like buildings, where floor-based ce, the extreme mass of roadway ehicles themselves are the supports ged Cypress Street section of I-880 le height. No set standard can be mallest physical dimensions that By permission of ABS Consulting 0

10 By permission of Larry McNaughton Weather Conditions Weather conditions can challenge robotic device functioning ability. For the device to be mobile in snow and water and operable and storable in certain temperature ranges, certain requirements have to be met in the traction and motor power of the device’s drive system; the robustness of electronic, electrical, and mechanical components with respect to temperature; and water-sealing capabilities. Military requirements are used in the sample requirements specification. Optical Navigation Environments Optical navigation refers to the robotic device operator's ability to operate the device remotely without seeing it or the terrain directly, relying only on the optical system on the robot. Optical navigation environments include lighting conditions, visibility (e.g., smoke or fog), and optical properties of targets (e.g., infrared, diffuse, or transparent). The demands of these environments must be met not only by a device's lighting and camera system, but also by other features. These include the use of multiple views, adequate picture quality in video presented to the operator, and the capability of commanding the optical system to simulate the operator actually being at the robot’s location with the ability to look around. This feature is called “situational awareness” and is the single most important feature for ease and safety in controlling the robotic device. Some minimum robotic device requirements for transit environments include path flood lighting, end-effector lighting, and a steerable spotlight. Camera requirements include a forward-looking path camera, an overhead- steerable camera, and an arm-mounted camera for monitoring the end effector or viewing areas only accessible by the extended arm. The device's video presentation must allow the operator to view all the images with minimal confusion. The ability to zoom in/out is also a requirement for at least one camera. The system should also have auto focus, auto iris (mechanical or electronic), and image stabilization. For disasters with a smoke-filled environment, an infrared lighting and camera system is required. Radio Environments How well a robotic device can be operated remotely depends on the radio environment in which it is used. Interfering radio transmission from other sources is of little concern for the use of robotic devices in transit environments. However, closed metal structures, such as bus and train bodies, impair radio transmission and will limit the range of tele-operation. A radio link range for open terrain is determined by accessibility to the target and a safe operating distance in hazardous situations. An alternative to a poor radio link is an optical-fiber tether from the operator station to the robotic device. Two considerations—vehicle or structure length and a safe operating distance—will dictate how long the tether will have to be. Tethered operation of robotic devices is generally less desirable because cable kinking during deployment can lead to potential entanglements and possible fiber breakage. Hazardous Environments Hazardous environments typically include nuclear, biological, or chemical (NBC) threats. These hazards present several electrical and mechanical challenges for the robotic device. The main concern is whether it will able to operate in the presence of high radiation and corrosive chemicals. Nuclear radiation primarily affects the electronics of the device, including the video system. Biological hazards do not affect the device, but require it to be decontaminated, usually with a bleach solution. Chemical hazards, such as an acid spill, present the threat of corrosion. Robotic devices used in these

11 kinds of hazardous environments need to meet requirement specifications for liquid-sealing ability and corrosion resistance of materials. Other Requirements The critical performance requirements for robotic device use in various parts of the transit environment have been reviewed above. There are, however, other requirements that must be met for robotic devices to operate successfully in the transit environment. These requirements are the following: • Weight—The human carrying weight of the entire robotic system and individual components. • Endurance—The length of the mission, usually a function of battery life. • Speed—Robotic device ground speed, which determines time to target. • Audio—The ability to listen and talk via the robotic device. • Load—Amount of payload weight the robotic device and manipulator arm can carry. • Set-up and turnaround times—Time to prepare to deploy and to refurbish for another mission. • Reliability—Mean time between failure (MTBF) for mission hours. • Maintainability—Mean time to repair (MTTR) and availability of spare parts and support. • Usability—Ease of use, intuitive operation, and training. • Industry compatibility—Conformance to industry standards, off-the-shelf components, common communication protocols, and ability to link to industry sensors and payloads. • Survivability—Robustness of the design for shock, vibration, impact, and watertight seals. • Cost—Within the typical budget of a law enforcement or civic agency.

12 Requirements Specification As seen in the section “Environments,” transit vehicles, structures, operating arena, and other related environmental conditions dictate requirement specifications for robotic devices used in transit applications. Table 1 presents a compilation of the requirements discussed in “Environments” with specifications determined by worst-case environmental demands. The source of the specification is given, and the objective of the requirement is listed for reference. This compilation, appropriately tailored, can serve as a requirements specification for a robotic device. Some requirements are not specific to the transit environment, so military standards or typical industrial-product specifications have been used to complete the specification. Two of these specifications are the Naval Sea System Command (NAVSEA) “Man Transportable Robotic System” (MTRS) solicitation and the National Institute of Justice (NIJ) “Bomb Disposal/Law Enforcement Robot Design Guidelines.” TRANSIT ENVIRONMENT ROBOT SYSTEM REQUIREMENTS Table 1 REQUIREMENT SPECIFICATION OBJECTIVE SOURCE Size Length Width Height Limited by Turn Circle, below 16 in. max. 12 in. max. Stair to corridor transition Corridor width Under seat, disaster debris Train corridor transition Bus corridor Bus seats Weight 150 lbs max. Carried by two people Typ. human factors spec. Speed 2 mph min. On scene in 15 min Typical access distance Stair Climb Solid Gap 8 in. x 8 in. 12 in. x 8 in. Building, vehicle stairway Curb to vehicle empty span Bus & train steps Train step Inscribed Turn Circle Severe Typical 16 in. 36 in Stair to corridor transition Bus entrance Train upper deck Slope Climb Traverse 60 deg. 45 deg. Embankments Train Station Snow 4 in. deep min. Roadside terrain MTRS spec. Hurtle 8 in. Railroad track Typical track Curb 14 in. Railroad platform curb Train station Rubble, Debris 4 in. diameter min. Concrete building collapse MTRS spec. Loose Sand 2 in. deep min. Roadside terrain MTRS spec. Gravel 2 in. diameter min. Railroad track Train station High Grass, Brush 6 in. high min. Roadside terrain MTRS spec. Shallow Water & Rain 2 in. deep min. Pooled rain MTRS spec. Range Wireless Wired ½ mi min. ⅛ mi min. Safe access Inside car, safe access Train station Vehicle & safety Endurance ½ mi driving, 1hr mission, ½ mi driving Drive to/from mission, all functions for 1 hr MTRS spec. & NIJ guidelines Payload Weight 50 lbs min. X-ray sensor payload Typical sensor Manipulator Reach Load Grip Dexterity 68 in. from ground 15 lbs 4 in. diameter min. 5 degrees of freedom Luggage carrier X-ray source Retrieve pipe bomb Reach into overhead Bus NIJ guidelines MTRS spec. Bus Set-up Time Deploy Refresh 10 min, no tools 2 min no tools Quick response time Quick battery change time MTRS spec. MTRS spec. Video Cameras Zoom Infrared Path, steerable, arm 20X Optional Full situational awareness Detailed viewing Night/smoke vision Typical & hazardous rail environments Lights Path, steerable, arm, infrared Same as video Same as video Audio Two way, recordable Survivor location Perpetrator statements MTRS spec. & NIJ guidelines Power Rechargeable battery, 110VAC Common battery charger MTRS spec. Data & Power Jacks RS232, USB, 12VDC Sensor & payload data MTRS spec. Usability 8 hrs training Minimize training/practice NIJ guidelines Survivability 10 ft drop & tumble on dirt Dropped, thrown, fall, etc. Rough deployment Reliability 100 mission hrs MTBF Maximize up time Typ. product standard Maintenance 30 min MTTR Minimize maintenance Typ. product standard