Abstract:
A system for selectively disabling a vehicle. In the illustrative embodiment, the system adapted to prevent high-speed automotive chases. The system includes a first mechanism for locating vehicle to be disabled. A second mechanism launches a disabling projectile toward the vehicle. A third mechanism employs the projectile to disable the vehicle by suffocating an engine of the vehicle or otherwise compromising the fuel/air mixture. In a specific embodiment, and an infrared guidance system guides the projectile toward a muffler of the vehicle, and a muffler-plugging agent incorporated within the projectile plugs a muffler.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of Invention 
   This invention relates to suspect apprehension. Specifically, the present invention relates to systems and methods for remotely disabling and/or tracking vehicles employed by fleeing suspects or other persons of interest. 
   2. Description of the Related Art 
   Systems for facilitating suspect apprehension are employed in various applications including law enforcement and military operations. Such applications demand efficient mechanisms to facilitate apprehending suspects without undue danger to bystanders, pursuers, or the suspect(s). 
   Systems for facilitating suspect apprehension are particularly important during high-speed chases, where fleeing suspects create an extreme safety hazard. Conventionally, pursuing agents, such as law enforcement officers, simply chase the suspect via one or more police vehicles, attempting to corner the suspect or force the suspect to run out of gas. Unfortunately, these methods are undesirably dangerous. Accordingly, more local governments are opting to outlaw high-speed chases and instead, let the suspects escape. 
   To reduce the duration of high-speed chases and thereby reduce accompanying risks, road spikes are sometimes employed. However, pursuers must either guess where the suspect will flee and then place spikes accordingly, or they must divert the suspect to the desired road equipped with the spikes. Unfortunately, suspect movement is often unpredictable, and innocent persons may be killed before the fleeing suspect reaches the road spikes. Furthermore, even after hitting road spikes, suspects often continue the chase with flat tires, which may increase danger to innocents, since vehicles becomes less controllable without tires. 
   To reduce pressure on pursuing agents to closely trail fleeing suspects, systems for tracking the suspects&#39; locations may be employed. Such systems, such as those disclosed in U.S. Pat. No. 6,246,323, entitled METHOD AND SYSTEM FOR TRACKING A VEHICLE, employ a transmitter embedded in a carrier that sticks on the vehicle when launched at the vehicle. The transmitter broadcasts a signal that enables pursuing agents to track the fleeing vehicle. However, law enforcement agents relying on these systems may be less likely to maintain visual contact with the suspects. Consequently, suspects may more readily escape by parking their vehicles and fleeing. This is particularly true in urban environments, where a fleeing suspect can blend with a crowd and where high-speed chases are more dangerous. This is especially problematic when the fleeing suspect is wanted for a serious crime. 
   Furthermore, use of such tagging trackers may not end the chase. If the suspect is a murder or other dangerous criminal that must be apprehended, pursuing agents may still attempt to maintain visual contact with the fleeing suspect. Consequently, the pursuits may remain undesirably dangerous despite the use of the trackers. 
   Alternatively, systems for remotely controlling vehicles, as described in U.S. Pat. No. 6,411,887, entitled METHOD AND APPARATUS FOR REMOTELY CONTROLLING MOTOR VEHICLES, and U.S. Pat. No. 6,470,260, of the same title, may sometimes be employed. These systems include a device for sending control signals to control modules contained in the pursued vehicle. Unfortunately, pursued vehicles rarely have such control modules installed, and a clever suspect could conceivably disable such modules before or during the chase. 
   The art is crowded with systems that attempt to disable fleeing vehicles. One such system is disclosed in U.S. Pat. No. 5,503,059, entitled VEHICLE DISABLING DEVICE AND METHOD. Unfortunately, such systems often require equipment, such as remote-controlled vehicle-disabling devices, which often do not exist on fleeing suspect vehicles. Accordingly, these devices are not widely used by law enforcement. 
   Hence, a long-felt unsolved need remains for an efficient system and method for facilitating apprehending persons fleeing by vehicle while minimizing danger to innocent bystanders and maximizing chances that the suspects are caught. 
   SUMMARY OF THE INVENTION 
   The need in the art is addressed by the system for selectively disabling a vehicle of the present invention. In the illustrative embodiment, the system adapted to prevent high-speed automotive chases. The device includes first mechanism for locating the fleeing vehicle. A second mechanism launches a disabling projectile toward the fleeing vehicle. A third mechanism employs the projectile to disable the vehicle by suffocating an engine of the vehicle or otherwise compromising the fuel/air mixture. 
   In a specific embodiment, a fourth mechanism plugs a muffler of the vehicle and includes a muffler-plugging agent incorporated within the projectile. A fifth mechanism guides the projectile toward the muffler and includes an infrared guidance system. 
   In a more specific embodiment, the third mechanism includes a gas incorporated within the projectile. The gas is sufficient to stall the vehicle upon or after entering an engine of the vehicle. A sixth mechanism selectively disperses the gas upon or after impact of the projectile with the vehicle. The projectile includes a sticky substance for adhering the projectile to the vehicle. A seventh mechanism directs the projectile into an aperture of the muffler, thereby at least partially plugging the muffler. 
   The novel design of the present invention is facilitated by the second and third mechanisms, which employ a projectile to plug a vehicle muffler or air intake and/or to introduce an engine-stalling gas into the engine of the vehicle. Hence, the system may be readily employed to stop most existing automobiles without relying on pre-installed equipment. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a diagram of a system for selectively disabling a vehicle via a muffler-clogging projectile according to an embodiment of the present invention. 
       FIG. 2  is a diagram of an alternative embodiment of a system for selectively disabling a vehicle. 
       FIG. 3  is a diagram illustrating a muffler-clogging agent suitable for use with the projectiles of  FIGS. 1 and 2 . 
       FIG. 4  is a diagram illustrating an alternative muffler-clogging agent suitable for use with the projectiles of  FIGS. 1 and 2 . 
   

   DESCRIPTION OF THE INVENTION 
   While the present invention is described herein with reference to illustrative embodiments for particular applications, it should be understood that the invention is not limited thereto. Those having ordinary skill in the art and access to the teachings provided herein will recognize additional modifications, applications, and embodiments within the scope thereof and additional fields in which the present invention would be of significant utility. 
     FIG. 1  is a diagram of a system  10  for selectively disabling a vehicle  18  via a muffler-clogging projectile  12  according to an embodiment of the present invention. For clarity, various components, such as power supplies, amplifiers, integrated circuit chips, and so on, have been omitted from the figures. However, those skilled in he art with access to the present teachings will know which components to implement and how to implement them to meet the needs of a given application. 
   The system  10  includes a projectile launch/guidance system  14  in communication with the projectile  12 . The projectile launch/guidance system  14  is adapted to launch and guide the muffler-clogging projectile  12  toward the muffler  16  of the vehicle  18 . 
   The projectile launch/guidance system  14  includes an infrared aperture  20  and a laser radar (ladar) system aperture  22 . An Infrared (IR) Focal Plane Array (FPA)  24  of infrared energy detectors is positioned adjacent to the infrared aperture  20  through which infrared energy is received from a scene containing the vehicle  18 . The IR FPA  24  provides input to an IR system  26 , which performs IR image processing of the scene. The IR system  26  provides input to a tracking system  28 . The tracking system  28  also receives input from a ladar system  32 , which receives input from a ladar FPA  30 , which is positioned to receive laser energy via the ladar system aperture  22 . The ladar system  32  also communicates with a laser  40 , which selectively illuminates the scene containing the vehicle  18  via laser pulses  44 . Laser pulses  44  reflecting from the scene containing the vehicle  18  are called laser returns  46 . The laser returns  46  pass through the ladar aperture  22  to the ladar FPA  30 . 
   The tracking system  28  provides input to a launch/guidance controller (controller  2 )  34 , which also receives range input directly from the ladar system  32 . The launch/guidance controller  34  communicates with a launch/guidance transceiver (transceiver  2 )  36 , which has an antenna  38  for communicating with the projectile  12  via a radio signal  50 . The launch/guidance controller  34  also provides control input to a launcher  42 , which is capable of launching the muffler-clogging projectile  12 . 
   In the present specific embodiment, the muffler-clogging projectile  12  includes an IR seeker  56 , which provides input to a projectile controller (controller  1 )  58  and a projectile transceiver (transceiver  1 )  54  having an accompanying projectile antenna  52 . The projectile controller  58  provides input to a fuze  62  and projectile-steering actuators  66 , which control projectile steering fins  68 . 
   The fuze  62  provides a charge-activation signal to an explosive charge  64 , which is surrounded by a muffler-clogging agent  60 . The fuze  62  may be embedded within the muffler-clogging agent  60  and positioned adjacent to the charge  64 . The charge-activation signal may be a pressure wave or heat generated by an initiating charge (not shown) positioned within the fuze  62 . 
   In operation, the projectile launch/guidance system  14  views the scene containing the vehicle  18  through the apertures  20 ,  22  via the FPA&#39;s  24 ,  30 , which detect electromagnetic energy  46 ,  48  received from the scene. The construction details of suitable FPA&#39;s are known in the art, and one skilled in the art may readily select an appropriate FPA to meet the needs of a given application. 
   The FPA&#39;s  24 ,  30  detect electromagnetic energy and provide electrical signals in response thereto to the IR system  26  and the ladar system  32 , respectively. In the present embodiment, the systems  26 ,  32  are imaging systems. The IR system  26  constructs an infrared image of the scene containing the vehicle  18  and muffler  16  based on the infrared energy  48  emanating from the scene. Typically, the muffler  16  will provide a distinct heat signature, which may be readily illustrated by the IR system  26 . Tracking heat emanating from the muffler  16  facilitates targeting at night, where passive visual systems may be compromised. 
   The ladar system  32  also constructs an image of the scene containing the vehicle  18 . The ladar system  32  selectively causes the laser  40  to fire the laser pulses  44  toward the vehicle  18 , thereby illuminating the vehicle  18 . The return pulses  46  contain image information about the scene containing the vehicle  18 . Furthermore, by computing the time difference of arrival between when the pulses  44  are fired and the corresponding pulses  46  are received, the distance between the projectile launch/guidance system  14  and the muffler  16  may readily be computed based on the speed of light. Accordingly, the ladar system  32  provides both imaging information and range information. 
   Imaging information from the IR system  26  and from the ladar system  32  is provided to the tracking system  28 , which more precisely determines the position of an aperture  82  of the muffler  16  therefrom. The tracking system  28  may include matched filters, velocity filters, and/or other modules (not shown) to facilitate target detection, i.e., muffler-aperture location detection. Precise target location information or a prediction thereof is forwarded to the launch/guidance controller  34  in real time. Muffler aperture range information is also forwarded from the ladar system  32  to the launch/guidance controller  34 . 
   The launch/guidance controller  34  may receive additional input from a user-interface (not shown), which may be employed by operators to selectively enable and/or control the operation of the projectile launch/guidance system  14 . When the projectile launch/guidance system  14  is enabled, the launch/guidance controller  34  determines when the muffler aperture  82  (target) is within range of the projectile launch/guidance system  14  based on range information from the ladar system  32 . 
   When the target  82  is within adequate range of the projectile launch/guidance system  14 , the launch/guidance controller  34  activates the launcher  42 , which launches the muffler-clogging projectile  12  toward the muffler  16 . The projectile launch/guidance system  14  may be mounted on a gimbal (not shown) to facilitate properly orienting the launcher  42  so that the projectile  12  may be more effectively aimed at the muffler  16 . Furthermore, the projectile launch/guidance system  14  may be mounted on a pursuing vehicle, such as a helicopter, police car, or military vehicle. Those skilled in the art with access to the present teachings will know how to design and implement or otherwise obtain user-interfaces and gimbals to meet the needs of a given application and without undue experimentation. 
   In an alternative implementation, the launcher  42  is mounted separately from the projectile launch/guidance system  14 , such as on a helicopter or along the side of a road. Such a remotely positioned launcher may be wirelessly controlled. 
   When the projectile  12  is flying toward the muffler  16 , the IR seeker  56  on the projectile  12  zeros in on the location of the muffler  16 . The projectile controller  58  selectively controls the steering fins  68  via the steering actuators  66  based on information received from the IR seeker  56  and based on information received by the projectile transceiver  54  from the projectile launch/guidance system  14 . The transceiver  52  may also forward information from the IR seeker  56  to the launch/guidance controller  34  on the launch/guidance system  14  to enhance guidance controls forwarded to the projectile controller  58  from the launch/guidance controller  34  via the transceivers  36 ,  54 . 
   In the present illustrative embodiment, the projectile controller  58  employs an algorithm to optimally combine information from the IR seeker  56  and the transceiver  54  to accurately steer the projectile  12 . Those skilled in the art may readily implement customized algorithms to combine the information from the transceiver  54  and the IR seeker  56  as required for a given application. In some implementations, the transceivers  54  and  36  are omitted, and projectile steering after the projectile  12  is launched is performed solely based on information received by the projectile controller  58  from the IR seeker  56 . Furthermore, those skilled in the art will appreciate that the IR seeker  56  may be implemented as another type of seeker, such as a hybrid infrared, sonar, microwave, radar, and/or ladar seeker. 
   The transceiver  54  may act as a vehicle-locating device upon sticking to or lodging within the muffler  16 . The transceiver  54  may incorporate Global Positioning System (GPS) functionality so that the location of the vehicle  18  may be readily tracked via location signals transmitted from the projectile transceiver  54 . 
   Those skilled in the art will appreciate that other types of targeting technologies, such as sonar techniques, may be employed without departing from the scope of the present invention. For example, the ladar equipment  30 ,  32 ,  40  on the projectile launch/guidance system  14  may be replaced with radar equipment without departing from the scope of the present invention. Furthermore, the IR seeker  56  may be replaced with another type of seeker, or the seeker  56  may be omitted. 
   In the present embodiment, the projectile controller  58  receives timing information from the projectile launch/guidance system  14  via the projectile transceiver  54 . The timing information is based on the initial measured distance between the projectile launch/guidance system  14  and the muffler  16  as measured by the ladar system  32  and is based on the kinematic properties of the projectile flight, which are approximately governed by the following well-known equation: 
                   P   =         1   2     ⁢   a   ⁢           ⁢     t   2       +       v   o     ⁢   t     +     P   o         ,           [   1   ]               
where t is time; P is the current position; a represents projectile acceleration; v o  is the initial velocity; and P o  is the initial position of the projectile  12 . The timing information is employed by the projectile controller  58  to selectively trigger activation of the fuze  62 , which detonates the charge  64 , thereby dispersing the muffler-clogging agent  60  on, over, or within the muffler  16 .
 
   The projectile controller  58  may employ equation (1) in combination with initial range information from the launch/guidance system  14  to compute the distance between the projectile  12  and the muffler  16  to facilitate timing of activation of the fuze  62 . Other timing methods may be employed without departing from the scope of the present invention. 
   In some implementations, the muffler-clogging agent  60  is designed to disperse over the muffler  16 , thereby covering the muffler aperture, as discussed more fully below. In other applications, the muffler-clogging agent  60  lodges within the muffler  16  or aperture thereof. 
   In an alternative implementation, the fuze  62  does not receive input from the controller  58 , and instead is a microelectromechanical (MEMS) or nanosystems fuze that arms upon launch setback acceleration and triggers upon impact with the muffler  16 . An exemplary MEMS safe-and-arm device is disclosed in U.S. Pat. No. 6,167,809, entitled ULTRA-MINATURE, MONOLITHIC MECHANICAL SAFETY-AND-ARMING DEVICE FOR PROJECTED MUNITIONS, by Charles H. Robinson et al, the teachings of which are herein incorporated by reference. Those skilled in the art with access to the present teachings may readily implement a suitable fuze without undue experimentation. 
   Furthermore, in some implementations, the muffler-clogging projectile  12  is fitted with wings that may have accompanying control surfaces (not shown) on the projectile  12  to enable relatively slow projectile flight toward the muffler  16  before the muffler-clogging agent  60  is dispersed on or within the muffler  16 . Relatively slow projectile flight in combination with winged control surfaces may provide more time for the projectile  12  to seek and steer toward the muffler  16  and may enhance safety, especially when hard-surfaced projectiles are employed. Implementation of slow-flying projectiles or fast-flying projectiles is application-specific and may be determined by those skilled in the art to meet the needs of a given application. 
   The steering fins  68  may be replaced by another type of actuator, such as micro thrusters or charges that are selectively detonated to create desired directional changes in the motion of the projectile  12 . An exemplary micro-actuator is disclosed in U.S. Pat. No. 6,105,503, by Baginski, issued Aug. 22, 2000, entitled ELECTRO-EXPLOSIVE DEVICE WITH SHAPED PRIMARY CHARGE, the teachings of which are herein incorporated by reference. 
   The projectile  12  may be constructed in a gelatinous housing so that in the unlikely event that the projectile misses the muffler  16 , it will not result in injury or other collateral damage. 
   Hence, the system  10  is an effective system for disabling a vehicle, such as the truck  18 , during pursuit or a high-speed chase. This system  10  improves upon the current state of the art by not requiring special equipment to be installed on the fleeing vehicle and by not allowing the criminal to park and escape before the police converge on the scene. By firing the heat-seeking projectile  12  toward the tailpipe  16  of the automobile  18  and thereby plugging the tailpipe and suffocating the engine, the engine of the vehicle  18  stalls. The projectile  12  may be contained in a glue or other sticky gelatinous material that disposes around the tailpipe  16 . 
   Alternatively, a detonator  62 ,  64  within the projectile  12  activates in response to the projectile travel time with reference to range information determined by the launch/guidance system  14  to determine just the right time to detonate, releasing a wall of clogging-agent from within the projectile  12 , which is sufficient to coat the muffler  16 , sealing the muffler aperture  82 . Various other projectiles may be employed without departing from the scope of the invention. Side firing of the projectile  12  is enabled to account for horizontally mounted tail pipes (not shown). However, the clogging-agent  60  may still wrap around the side of such tailpipes when fired from the rear of the associated vehicles and may be sufficient to stop or at least slow the suspect vehicle  18 . 
     FIG. 2  is a diagram of an alternative embodiment of a system  10 ′ for selectively disabling the vehicle  18 . The alternative muffler-clogging projectile  12 ′ is similar to the muffler-clogging projectile  12  of  FIG. 1 , with the exception that the IR seeker  56  of  FIG. 1  is omitted, and the projectile transceiver  54  and accompanying antenna  52  of  FIG. 1  are replaced with a receiver  54 ′ and antenna  52 ′ in  FIG. 2 . The infrared and ladar components  20 - 32 ,  40  of the launch/guidance system  14  of  FIG. 1  are omitted in the system  10 ′  FIG. 2 . 
   The alternative launch/guidance system  14 ′ employs an optical aperture  22 ′ for receiving optical energy  74  from the scene containing the muffler  16 . An optical FPA  70  converts the received optical energy  74  into an electrical signal, which is forwarded to an optical imaging system  72 . The optical imaging system  72  constructs an image of the vehicle  18  and muffler  16  based on the received optical energy  74 . The resulting image information is forwarded to a boresighting system  72 . 
   The boresighting system  72  includes a user-interface (not shown) that enables a user to guide the projectile  12 ′ toward the muffler  16  by aligning a boresight (crosshairs) with the muffler  16 . The boresight location of the image information received from the optical imaging system  72  is employed by an accompanying launch and guidance controller  34 ′ to generate control signals  50 ′ effective to guide the muffler-clogging projectile  12 ′ toward the muffler  16  when the location of the muffler  16  is aligned with the boresight. The control signals are transmitted via a launch/guidance transmitter  36 ′ and accompanying antenna  38 ′. The projectile receiver  54 ′ then forwards the control signals to the projectile controller  58 ′, which controls activation of the fuze  62  and fin steering actuators  66  accordingly in response thereto. 
   The launcher  42  may be manually activated via the user-interface of the boresighting system  72 . The projectile launch/guidance system  14 ′ may be mounted on a manually controlled gimbal and/or an automatically controlled gimbal (not shown) to facilitate initial projectile aiming. 
   Those skilled in the art may employ other types of guidance systems and techniques, such as Tube-launched Optically-tracked, Wire-guided (TOW) methods, which may employ beacons placed on the projectile  12 ′. Furthermore, guidance systems employing Inertial Reference Units (IRU&#39;s) or Inertial Measurement Units (IMU&#39;s) may be employed without departing from the scope of the present invention. In addition, the optical components  22 ′,  70 ,  72  may be replaced with other types of components, such as infrared components. Those skilled in the art will know which components to implement to meet the needs (such as budget requirements) of a given application. 
   Alternative projectiles may be guided in accordance with various other well-known guidance techniques, such as those disclosed in U.S. Pat. No. 6,565,036, entitled TECHNIQUE FOR IMPROVING ACCURACY OF HIGH SPEED PROJECTILES, the teachings of which are herein incorporated by reference, without departing from the scope of the present invention. 
     FIG. 3  is a diagram illustrating a muffler-clogging agent  60  suitable for use with the projectiles  12 ,  12 ′ of  FIGS. 1 and 2 . With reference to  FIGS. 1 and 3 , the muffler-clogging agent  60  is selectively dispersed from the projectile  12  in response to activation of the charge  64  when the projectile  12  is sufficiently close to the muffler  16 . 
   In the present specific embodiment, the muffler-clogging agent  60  includes plural beads  80 , which can readily enter an aperture  82  of the muffler  16 . The beads  80  enter a main body  84  of the muffler  16  via the muffler aperture  82  and begin to expand. The beads  80  each include a small gas cartridge  90  in communication with a micro-fuze  62 ′, which are surrounded by a durable balloon, foam, or other material that expands upon activation of the small gas cartridge  90  in response to an activation signal from the fuze  62 ′. The fuze  62 ′ may be a temperature-sensitive fuze that triggers in response to heat from the muffler  16 . Alternatively, the fuze  62 ′ arms in response to setback acceleration from the launch of the projectile  12  and/or from activation of the dispersing charge  64  and then activates upon sensing impact with the muffler  16 . Alternatively, the fuze  62 ′ incorporates a receiver (not shown) and is remotely activated via the launch/guidance system  10 . When the fuze  62 ′ activates, it causes the small gas cartridge  90  to release pressurized gas, which expands the surrounding coating  92 , thereby expanding the beads  80 . The beads lodged within the muffler body  84  are designed to sufficiently expand to block the muffler aperture  82 . 
   In the present embodiment, some of the beads  80  are designed to rupture once inside the muffler body  84 . These beads contain a special gas within the small gas cartridge  90 . This special gas is sufficient to trigger engine stall when it diffuses back through the muffler system to the engine cylinders (not shown) of the vehicle  18 . A suitable gas may include a trifluoroidomethane mixture with an inert atmospheric buoyant gas such as helium as disclosed in U.S. Pat. No. 5,848,650, VEHICULAR ENGINE COMBUSTION SUPPRESSION METHOD, by Brian B. Brady, the teachings of which are herein incorporated by reference. 
   Any diffusion of such gas back to the cylinders will promote engine stall. Furthermore, the projectile  12  may be fired at the front of the vehicle  18  being pursued. Impact with the cars front grill will trigger the fuze to release the gas, which will pass into the engine air intake, thereby stalling the engine. 
   In some implementations, the beads  80  are designed to penetrate the walls of the muffler body  84  rather than entering through the aperture  82 . When the beads  80  expand upon penetrating the muffler body  84 , they plug the holes created therein. In other implementations, the projectile  12  passes to the side or underneath the muffler and ejects the beads  80  sideways or upward to facilitate plugging side-facing or downward-facing tailpipes. 
   In an alternative implementation, the projectile  12  is launched toward a front of the vehicle  18 . The clogging agent  60  then disperses within the air intake of the vehicle  18  or attaches to the front grill, which triggers release of the engine-stalling gas from the gas cartridge  90 . The engine-stalling gas will then suffocate the engine of the vehicle  18 . Alternatively, expansion of the beads  80  may sufficiently plug the air intake to cause the vehicle  18  to stall. 
   Hence, embodiments of the present invention often cause the engine of a fleeing vehicle, such as the vehicle  18 , to stall by controlling the fuel/air mixture in the combustion chambers of the accompanying engine via direct suffocation by plugging the muffler  16  or air intake (not shown) and/or by gas that suffocates the engine or otherwise compromises the fuel/air mixture. 
   In an alternative embodiment, the muffler-clogging agent  60  may be built into the muffler  16  or air intake and remotely activated by law-enforcement other pursuing agents. Pre-positioning the disabling mechanism  60  within the muffler  16  or air intake decreases tampering likelihood, as it cannot be seen unless the muffler  16  is destroyed. Activation may be implemented via a directional signal transmitted by authorities and received by a receiver (not shown) included in the fuze  62 ′. By aiming the directional signal at the muffler  16 , authorities may selectively disable the desired automobiles even when they are positioned among several other automobiles. Various directional signals that may be employed include laser beams, microwave beams, and so on. In implementations employing laser beams, the fuze receiver (not shown) will likely include a photodetector (not shown) responsive to a particular beam signature. The photodetector will be positioned within the muffler  16  so that laser light can reach the detector. This may require use of reflective surfaces interior to the muffler  16 . 
     FIG. 4  is a diagram illustrating an alternative muffler-clogging agent  60 ′ suitable for use with the projectiles of  FIGS. 1 and 2 . With reference to  FIGS. 2 and 4 , the clogging agent  60 ′ includes paddies  80 ′ of a sticky/pliable substance sufficient to stick to the muffler  16  and seal the muffler aperture  82 . The paddies  80 ′ may be constructed from hardening glue that hardens quickly when heated by the muffler  16 . 
   In some applications, the paddies  80 ′ may be made sufficiently large to coat the entire rear end of a fleeing vehicle, such as the vehicle  18  of  FIGS. 1 and 2 , including the muffler  16 . In systems employing such large paddies, projectile guidance and launch control mechanisms may be less stringent, due to a larger margin for error. By selectively detonating the charge  64  to release the muffler-clogging agent  60 ′ from an accompanying alternative projectile  12 ″ within a predetermined range of the muffler  16 , the effective surface area of the clogging agent  60 ′ expands to ensure that the muffler  16  is properly coated to block exhaust gases from exiting the muffler  16 . 
   Thus, the present invention has been described herein with reference to particular embodiments for particular applications. Those having ordinary skill in the art and access to the present teachings will recognize additional modifications, applications, and embodiments within the scope thereof. 
   It is therefore intended by the appended claims to cover any and all such applications, modifications and embodiments within the scope of the present invention. 
   Accordingly,