Systems and methods for improving efficiency of firefighting robots

A system and method suitable for improving the efficiency of a firefighting robot by managing a water supply in a hose coupled thereto is provided. The system includes a robot capable of self-propulsion. The robot is coupled to at least a first hose and is capable of receiving water through the first hose from a water source and discharging the water towards a fire to extinguish the fire. The system includes at least a first valve unit fluidically coupling the first hose to the water source, and means for controlling the robot and the first valve unit such that the first valve unit prevents the robot from receiving water from the water source and drains water from within the first hose when the robot maneuvers and provides water to the robot through the first hose from the water source when the robot is extinguishing the fire.

BACKGROUND OF THE INVENTION

This disclosure generally relates to systems and methods and for improving the efficiency of firefighting robots. The disclosure particularly relates to systems and methods for managing a water supply to a firefighting robot to improve its operating efficiency.

Every year, fires cause numerous deaths and significant property damage. For example,FIG. 1shows estimated property damages in the United States of America for the years of 2003 to 2012, andFIG. 2shows a number of firefighter deaths while on-duty in the United States of America for the years of 2005 to 2014. According to the United States Fire Administration, current estimates state that an average of 82.9 firefighters die in fires each year. Various solutions have been proposed in attempts to reduce casualties and property damage caused by fire. One solution currently available is the use of firefighting robots that substitute for firefighters on a fire scene, for example, a building that is on fire. Use of these robots may not only decrease the risk of life-threatening situations for firefighters but also can potentially extinguish a fire faster in an area that may be inaccessible to a firefighter. Such robots have the potential to significantly reduce the need for firefighters to work in hazardous areas and may improve firefighting capabilities.

Although firefighting robots have certain advantages, their effectiveness can be reduced by various limitations. As an example, these robots are generally powered with onboard energy storage devices, such as batteries, which have a limited amount of energy that may be used to power the robots. Current firefighting robots are in general relatively heavy devices and, even with an advertised eight-hour battery life, may only last around two hours in the field under normal operating conditions, including moving from location to location to extinguish fires. These robots are often not very agile and waste energy by having to maneuver around the fire scene while carrying a pressurized hose that couples the robot to a source of water for use in extinguishing the fire. This unwieldiness and inefficiency often diminish the advantages of the robots.

Thus there is an ongoing desire for systems and methods capable of improving the efficiency of firefighting robots by increasing the duration of operation for a given set of conditions while operating on a limited power source.

BRIEF DESCRIPTION OF THE INVENTION

The present invention provides systems and methods capable of improving the efficiency of a firefighting robot by managing water supplied to the robot.

According to one aspect of the invention, a system is provided that includes a robot capable of self propulsion. The robot is coupled to at least a first hose and is capable of receiving water through the first hose from a water source and discharging the water towards a fire to extinguish the fire. The system includes at least a first valve unit fluidically coupling the first hose to the water source, and means for controlling the robot and the first valve unit such that the first valve unit prevents the robot from receiving water from the water source and drains water from within the first hose when the robot maneuvers and provides water to the robot through the first hose from the water source when the robot is extinguishing the fire.

According to another aspect of the invention, a method is provided that includes deploying a robot to fight a fire with water from a water source, the water passing to the robot through a first hose coupled to the robot, the first hose being fluidically coupled via at least a first valve unit to the water source, providing the water to the robot through the first valve unit and the first hose when the robot is discharging the water from the water source toward a fire, and preventing the robot from receiving the water from the water source and draining the water from the first hose through the first valve unit when the robot is maneuvering.

Technical effects of the method and system described above preferably include the ability to operate a firefighting robot for longer periods of time between recharging a power supply of the robot by reducing the weight on the robot when it is moving between locations under its own power.

Other aspects and advantages of this invention will be further appreciated from the following detailed description.

DETAILED DESCRIPTION OF THE INVENTION

In this disclosure, firefighting systems and methods are provided that are intended to improve the energy efficiency and operating time of a firefighting robot by managing the water in a fire hose coupled to the robot. The firefighting system may include a controller for remotely operating the robot and at least one valve unit coupled to the fire hose. The valve unit is preferably a wireless valve unit that may include, but is not limited to, a valve, a wireless receiver, and a motor to control the operation of the valve unit. The valve unit is preferably capable of selectively providing water from a water source to the firefighting robot through a fire hose or draining water from the hose. The system preferably improves the traction efficiency of a firefighting robot by decreasing the weight of the fire hose during movement of the robot. In particular, whenever the robot is ready to be maneuvered to another location, the system can assist in removing some if not substantially all of the water within the fire hose, thereby reducing the weight that must be towed by the robot during movement. As a result, the system enables the robot and a fire hose coupled thereto to efficiently reach a desired destination with reduced energy cost, and in so doing is able to extend the operating time of the robot if powered by an onboard power source, such as a battery.

The following discussion will make reference to investigations based on a nonlimiting example of a firefighting robot12schematically represented inFIG. 3. The robot12includes an inlet16for receiving water through a fire hose (not shown) from an external and remote water source (not shown), and an outlet (nozzle)14for discharging the water toward a fire in order to extinguish a fire. The robot12is configured for self-propulsion, for example, with wheels or tracks18driven by a suitable motor or other prime mover (not shown). For the purpose of performing calculations during the investigations, the robot12weighed 210 kg (about 463 pounds) and was powered by a 24V/40 Ah battery based on a known commercial configuration. During use, a firefighting robot is usually required to move between various locations within a fire scene to extinguish fires. With the aforementioned 24V/40 Ah battery, the robot12depicted inFIG. 3would be capable of operating for a maximum of eight hours if allowed to maneuver without being coupled to a fire hose. However, when connected to a water-filled fire hose having an internal diameter of 2.5 inch (6.35 cm) and a length of 200 feet (about 61 m), the robot12would be able to maneuver for only about 1.5 hours due to the additional weight of the water within the hose. Consequently, during use under operating conditions at a fire scene, the robot12represented inFIG. 3could not operate for an extended period of time because a significant amount of battery power would be consumed to tow the heavy fire hose each time the robot12moved to another location.

FIG. 4schematically represents a valve unit20as a spherical automatic T-valve device (ATD) of a type suitable for use in a firefighting system according to nonlimiting embodiments of the invention. The valve unit20includes a housing22comprising at least first, second, and third ports28,30, and32, around which flanges or other means are provided for fluidically coupling a fire hose to at least the first and second ports28and30. As a matter of convenience, the first and second ports28and30will be respectively referred to as the inlet and outlet ports28and30of the valve unit20, though these designations could be reversed. A rotating T-valve ball24is located within the housing22and is adapted to be rotated to operate the valve unit20by selectively aligning a passage26within the valve unit20to connect the inlet port28to either the outlet port30or the third port32, hereinafter referred to as the discharge port32. During operation, the inlet port28may be coupled to a water source through at least a first fire hose and the outlet port30may be coupled to the robot12through at least a second fire hose.

FIG. 5schematically represents the valve unit20ofFIG. 4in an open mode or orientation wherein the passage26within the valve unit20is oriented to provide a flowpath between the inlet and outlet ports28and30that allows water to pass through the valve unit20and travel from a water source to the robot12. Simultaneously, the discharge port32is blocked so that the water cannot exit the valve unit20through the discharge port32.FIG. 6schematically represents the valve unit20ofFIGS. 4 and 5in a discharge mode wherein the passage26is oriented to provide a path between the outlet and discharge ports30and32and block the inlet port28. As a result, water within the fire hose between the robot12and valve unit20is able to enter the valve unit20, pass through the passage26, and exit the valve unit20through the discharge port32, while water from the water source is prevented from entering the valve unit20. As such, water located within the hose between the valve unit20and robot12is able to be drained from the hose under gravity via the discharge port32. In the embodiment represented, the valve unit20transitions from the open mode to the discharge mode by rotating the T-valve ball24counterclockwise within the housing22relative to the view represented. As a result of setting the valve unit20to the discharge mode, the hose between the robot12and the valve unit20will be at least partially empty of water and therefore will weight less during movement of the robot12. Other aspects of the valve unit20inFIGS. 4, 5, and 6will be readily understood by those of ordinary skill in the art.

FIGS. 7 and 8represent another nonlimiting embodiment of a system that includes the robot12and valve unit20ofFIGS. 3 through 6, in combination with two fire hoses40A and B, a wireless controller50, and a water source (fire truck)60. The direction of water flow within the hoses40A and B is represented with dashed arrows. Wireless connections between the controller50and the valve unit20, for example, through a wireless receiver52and motor54represented inFIG. 13as connected to the valve unit20, are represented with dashed lines inFIGS. 7 and 8. Although the system is described as including multiple hoses40A and40B connected by the valve unit20, it is within the scope of the invention that the water source60may be coupled to the robot12with a single hose40comprising the valve unit20as an integral component.FIG. 7represents the valve unit20as set to the open mode with water traveling from the water source60through the hose40A to the valve unit20, and then through the valve unit20and hose40B to the robot12.FIG. 8represents the valve unit20as set to the discharge mode, such that water supplied by the water source60through the hose40A is unable to enter the valve unit20. The hose40B coupling the robot12to the valve unit20is represented as empty of water as a result of the water within the hose40B being drained from the hose40B via the discharge port32of the valve unit20. Such draining occurs at least in part by gravity due to the hose40B being coupled to the elevated inlet16of the robot12. Although not shown, draining of the hose40B through the valve unit20may be promoted by other means, including but not limited to a pump coupled to the valve unit20. As will be discussed in more detailed hereinafter, water flow within the hoses40A and B can be controlled by an operator or automated through the use of sensors and/or preset directions.

FIG. 9is a flow chart schematically representing steps for the operation of the system ofFIGS. 7 and 8according to a nonlimiting method. The robot12may be operated to continuously or periodically sense the locations of fires within a fire scene. During its operation, the robot12will typically be commanded to maneuver from one location to another within the fire scene, during which time the attached hoses40A and B must be dragged. The system described in reference toFIGS. 7 and 8enable the hose40B connecting the valve unit20to the robot12to be drained of water to reduce the drag on the robot12attributable to the weight of the water within the hose40B. If the robot12detects a fire, the robot12may stop maneuvering and the valve unit20may be automatically or manually set to the open mode such that water can flow from the water source60through the valve unit20to the robot12. In addition, the robot12may be automatically or manually set to an extinguishing mode wherein the robot12preferably remains in a fixed, stationary location and sprays water from the water source60onto the fire to extinguish the fire. The robot12may continuously or periodically sense to determine if the fire has been extinguished.

Once the fire has been extinguished, the valve unit20may be automatically or manually set in the discharge mode such that water may drain from the hose40B coupling the valve unit20to the robot12. Preferably, the discharge port32of the valve unit20is located near or below a lowermost portion of the hose40B such that substantially all of the water within the hose40B drains therefrom. After the hose40B has been drained, the robot12may again be set to the maneuver mode and move about the fire scene until it detects another fire, repeating the method as desired until all fires have been extinguished or the robot12is otherwise deactivated. Consequently, whenever the robot12changes from the maneuver mode to the extinguishing mode, the valve unit20is preferably changed from discharge mode to open mode. On the other hand, whenever the robot12changes from the extinguishing mode to the maneuver mode, the valve unit20is preferably changed from open mode to discharge mode. It is foreseeable that, as the robot12maneuvers between locations dragging the hoses40A and B, the valve unit20will also be inherently towed by the robot12.

The method ofFIG. 9may be implemented in various ways. For example, an operator may manually operate the robot12and the valve unit20separately. Alternatively, an operator may manually operate the robot12, and the valve unit20may automatically change between the open and discharge modes upon, for example, receiving a signal or otherwise sensing that the robot12has been changed between maneuver and extinguishing modes. It is also within the scope of the invention that the robot12and/or the valve unit20may be controlled via a computer through the use of sensors and/or preset directions, for example, computer operating software. Regardless of the means, both the robot12and the valve unit20are preferably configured to be operated wirelessly, since during use they may be located in areas that could be dangerous to access, such as within a building that is on fire.

To predict improvements in traction efficiencies when the robot12is moving on a surface, frictional forces were calculated on the basis of an empty fire hose and a fire hose that is full of water. Because most sheaths of fire hoses are made of rubber polymers, a frictional coefficient of rubber was applied for the frictional force calculation. Information regarding frictional coefficients of various materials that were used in the calculations are shown in Table 1 below:

As a nonlimiting example, the static frictional coefficient (μs) of rubber on dry asphalt is 0.85 and the kinetic frictional coefficient (μk) is 0.67. At four degrees centigrade, one liter of water has a mass approximately equal to one kilogram as represented in Table 2 below.

TABLE 2Density and Volume of WaterTempDensityVolume(° C.)(kg/l)(l)−70.998921.00108−40.999451.00055−10.999791.0002141.000001.0000070.999931.00007100.999731.00027150.999131.00087200.998231.00177250.997081.00293300.995681.00434500.988071.011921000.958381.41623

The weight of a fire hose having an internal diameter of 2.5 inch (6.35 cm) and a length of 200 feet (about 61 m) is about 56 kilograms and the volume of water in such a hose is input 198.9975 liters, resulting in a combined weight of approximately 255 kilograms. The frictional force was calculated by a formula as follows:
F=μmg(1)
W=Fs(2)
where F is the frictional force between the hose and the surface on which it moves, μ is the frictional coefficient, m is the mass (of water and fire hose), and g is the acceleration due to gravity. W is work done in moving the robot12a distance s.

Thus, assuming that the system completely drains the water from the hose, the robot12would use just 24V/5.841 Ah power and thereby economize the power demand by up to about 78%. This means the robot12can constantly move up to 6.84 hours with an empty fire hose. This comparison is further shown in Table 3 below. Due to the longer operating time, the firefighting robot12may not need to be replaced with another robot or have its battery recharged during the fire, as may otherwise be the case.

Total Pressure Loss (TPL) is the sum of friction loss (FL), appliance loss (AL), and elevation loss/gain (EL/EG).
TPL=FL+AL+/−(EL/EG)  (11)

Friction loss (FL) is the pressure used to overcome resistance while forcing water through, for example, fire hoses, pipes, and appliances. To calculate the friction loss, it is necessary to know the size and length of the hose and the volume or quantity of water flowing through the hose. Friction loss is independent of pressure when the flow rate remains constant in the same size hose. In other words, if 200 gpm (757 lpm) is flowing through a 2.5 inch (6.35 cm) hose at 50 psi (about 345 kpa), the friction loss will remain the same if the pressure is increased to 100 psi (about 690 kpa). Thus,
FL=C×(Q/100)2L/100  (12)
where FL is the friction loss, C is the friction loss coefficient (See Table 4 below), Q is the flow rate, and L is the length of the hose.

Assuming a friction loss coefficient (C) for a 2.5 inch (6.35 cm) hose is two, the hose length (L) is 200 feet (about 61 meters), and the flow rate (Q) as 300 gpm (1,136 lpm), the friction loss may be calculated as:
FL=2×(300/100)2×200/100=36 psi  (13)

Therefore, it was calculated that there is 36.0 psi (about 248.2 kpa) of friction loss for a 200 feet (about 61 meters) section of 2.5 inch (6.35 cm) hose with 300 gpm (1136 lpm) of water passing through it.

Appliance loss: Every water appliance used in the fire service, from a simple wye to a ladder pipe, has friction loss, which is commonly called appliance loss. Friction loss in small appliances is negligible and therefore will not be calculated herein. In general, 25 psi for friction loss should to be added for a deck gun when mounted on a fire engine and 15 psi when used as a ground monitor.

Elevation Gain or Loss: When hoses are at an elevation that is higher or lower than the pump an additional factor known as “Elevation Pressure” (EP) should be considered. A column of water one foot (about 0.3 m) high exerts a downward pressure of 0.434 psi (about 3 kpa). This gain or loss is estimated to be about 10 to 12 feet (3 to 3.65 m) high. The downward pressure of a liquid is directly proportional to its depth up to about 12 feet (3.65 m) high. Therefore, a one-inch by one-inch (2.54×2.54 cm) column of water standing one foot (about 30 cm) tall will have a pressure at its base of about 0.434 pounds (0.197 kg). The pressure will increase by 0.434 pound for every foot added to the height.
EL for the firefighting robot=3 (ft)×0.434=1.302 psi  (14)
Thus, there is 1.302 psi (8.977 kPa) of elevation loss for 3 feet (0.91 m) height of a firefighting robot that will occur in the fire hose. Therefore, a volume of 300 gpm (1136 lpm) at a pressure of 400 psi (2758 kPa) of water is calculated as passing through a 200 foot (about 61 meters) section of 2.5 inch (6.35 cm) hose. Consequently, 36.0 psi (about 248.2 kpa) of friction loss and 1.302 psi (8.977 kPa) of elevation loss will occur from 400 psi (2758 kPa) internal pressure. Therefore, the output of the firefighting robot will be about 362.7 psi (2501 kPa).

To calculate the total pressure loss, it was again assumed that a volume of 300 gpm (1136 lpm) at a pressure of 400 psi (2758 kPa) of water was within the hose. Equation 15 describes the free flow in a fire hose, where Q is the amount of water discharged from an inclined part of the fire hose.
Q=0.61A{2(g*cos θ)(hu−hd)}1/2(15)
where 0.61 is the discharge coefficient, A is the area of the hole (m2), g is the acceleration due to gravity, huis the upstream water height (m), and hdis the downstream water height (m).

Due to the gap between the height of the firefighting robot and ground, the water in the first several feet of a fire hose (for example, measured from the inlet16of the robot12) will likely be easily discharged. However, if only one valve unit is used for 200 feet fire hose, it is likely that a majority of the hose that lays on flat ground will not drain much water due to the closing of the flexible fire hose by forces such as gravity, the frictional force in the fire hose, etc. For example,FIG. 10shows a plot of the amount of water in a 200 foot long fire hose and power demand for the firefighting robot12, as a function of time during the water discharge process utilizing a single valve unit20in the discharge mode. As represented, a single valve unit20could not overcome the forces to discharge all of the water in 200 feet of hose.

Consequently, to ensure more complete drainage of a fire hose will occur, additional valve units20may be added to the system to decrease the length of hoses between valve units20and thereby decrease the frictional force and the probabilities of the fire hose closing.FIG. 11represents a nonlimiting system comprising multiple valve units20interconnecting multiple hoses40A-E, each of which is shorter in length than the hoses40A and B ofFIGS. 7 and 8. Such an arrangement decreases the forces that inhibit drainage of the hoses40B-E, and leads to an increase in an amount of water drained from each hose40B-E located between at least one valve unit20and the robot12. Although the system is described as including multiple individual hoses40A-E connected by multiple valve units20, it is within the scope of the invention that the water source60may be coupled to the robot12with a single hose comprising multiple valve units20as integral components of the hose. As represented inFIG. 12, the use of multiple valve units20over a given total length of hoses40A-E greatly increased the predicted amount of water discharged from the hoses40B-E and reduced power demand on the robot12.

In view of the above calculations, it was determined that an increase in length of a hose causes an increase in the frictional force acting on the water within the hose. Therefore, if drainage of the hoses40B-E inFIG. 11are primarily accomplished by gravity, it is preferred that individual sections of the hoses40BA-E between the robot12and the valve units20are short enough such that substantially all of the water within the hoses40B-E can drainage in order to provide the largest reduction in weight being towed by the robot12during movement. It is foreseeable that during use of the robot12, as the robot12maneuvers to locations progressively farther from the water source60, additional hoses and valve units20may be added in series to the system in order to increase the operational area of the robot12while only using individual hoses have a desired maximum length. It should be understood that preferred dimensions of the hoses may vary depending on various parameters, including but not limited to the specific robot12, the height of its inlet16above ground, the slope, if any, of the ground, whether a pump or other device is used to assist in drainage of the hoses, etc.

Systems and methods as disclosed herein are intended to enable a firefighting robot to increase operating time and to effectively extinguish a fire while managing the amount of water in a fire hose coupled to the robot. By reducing the weight of the fire hose during movement of the robot, such systems and methods are believed to be capable of increasing battery life and therefore operating time of the robot, increase mobility of the robot, and reduce the likelihood of firefighters being placed in dangerous situations.

While the invention has been described in terms of specific or particular embodiments, it should be apparent that alternatives could be adopted by one skilled in the art. For example, the system, robot12, valve unit(s)20, and their components could differ in appearance and construction from the embodiments described herein and shown in the drawings, functions of certain components of the system could be performed by components of different construction but capable of a similar (though not necessarily equivalent) function, and various materials could be used in the fabrication of the components of the system. Accordingly, it should be understood that the invention is not necessarily limited to any embodiment described herein or illustrated in the drawings. It should also be understood that the phraseology and terminology employed above are for the purpose of describing the disclosed embodiments, and do not necessarily serve as limitations to the scope of the invention. Therefore, the scope of the invention is to be limited only by the following claims.