GUN SIMULATOR

Abstract

The chain gun simulator provides a high-fidelity simulation of the electrical control system signals for any weapon platform using a variety of chain gun types. The simulator device is stand-alone, requiring no external equipment, and replicates the electrical states, levels, and timing of the real guns such that the weapon platform's fire control interface can function normally without the need for a real gun and live ammunition. In addition, the simulator provides user control for selecting gun type and mode, and provides visual indication of modes, feed selection, and simulated weapon bolt position. There may also be an audible indication every time the simulator has advanced through the normal shutdown portion of the gun cycle.

Description

RELATED APPLICATIONS

The present application claims priority to U.S. Provisional Application 61/070,233 filed May 16, 2008, entitled “Gun Simulator”, which is hereby incorporated by reference.

FIELD OF THE INVENTION

The invention generally relates to the field of providing high-fidelity simulation of weapon systems. More specifically, the invention relates to a high-fidelity simulation of the electrical control system signals for weapons platforms utilizing electrically powered chain guns.

BACKGROUND OF THE INVENTION

Weapons platforms are central in the protection from known and unknown threats. Advanced weapons platforms may provide an edge to systems and personnel in the field where assets and lives are at risk. Examples of weapon systems are present throughout history, for example chariots are described in various texts as early as 3000 BC. Other early weapons platforms included war-carts and various seafaring vessels exhibiting various armaments. As time has passed weapons platforms have matured in capabilities and complexity, developing from the early simple designs to the systems utilized in present day civil and military applications. Today's weapons platforms are highly precise and reliable pieces of machinery entrusted with some of the most important duties in modern-day warfare and peacekeeping. Due to their importance, billions of dollars have been spent world-wide in developing modern weapons platforms.

The weapons platforms often include highly integrated and complex weapons control systems or fire control systems. These systems often utilize sensors mated with computational devices to improve weapons performance, consistency and reliability. Fire control systems have been mounted in a variety of weapons platforms and recently in smaller user-manipulatable platforms such as rifles or tactical weapons such as the Fabrique Nationale F2000. The weapons platforms, with the integrated fire control systems are often able to accept a variety of loadouts or armaments. These include chain guns, missile systems, cannon or mortars and various active armor systems. Many of these weapons platforms are fitted with electrically powered chain guns such as the 25 mm M242 chain gun or increasingly, the 30 mm Mark 44 chain gun, which are precise and reliable chain guns. The M242, particularly, is a proven gun system with years of active duty.

The M242 chain gun has been in widespread use for some time and is the primary armament on the Bradley Fighting Vehicle (BFV). The M242 is electrically powered, chain driven and supports multiple rates of fire including single, low (125 rounds/min) and high (225 rounds/min). Further, the M242 is capable of handling several different types of ammunition. The Mark 44 is a related design that increases the caliber to 30 mm while maintaining many of the same features as the M242. The Mark 44 utilizes a similar set of logistics components when compared to the M242 and allows for varying rates of fire. The Mark 44, however, is capable of conversion to fire 40 mm rounds in situations where greater armor penetration and urban target neutralization require. The 35/50 mm or Bushmaster III is an additional variant that supports 35 mm and 50 mm rounds. The M242, Mark 44 and 35/50 mm are highly accurate in the hands of a trained operator and can destroy lightly armored vehicles and aerial targets such as helicopters and slow-flying aircraft. They can also suppress enemy positions such as troops in the open, dug-in positions, and built-up areas.

In order to reliably produce these capabilities in the field, the cannons rely on a complex firing mechanism and control electronics which controls and monitors multiple stages of fire. As opposed to conventional automatic weapons, which utilize gas-blowback for cycling, chain guns such as the M242 use an electric drive motor to operate. A small motor drives a gearbox, which in turn supplies torque to the feed mechanism as well an chain-driven bolt assembly. The gun also has a number of electrical sub-assemblies including various sensors, switches and solenoids that help maintain smooth operation. Due to the complexity and the extreme accuracy and reliability required of these weapons, they must be maintained and continually tested to ensure proper function. Moreover, training is essential to promote efficiency.

To fully operate or test the BFV's fire control systems certain signals must be exchanged between the weapon and other vehicle components. On a fully functional and armed vehicle, the weapon and the fire control system or Gun Control Unit (GCU), in the BFV, exchange electrical signals based off of weapon state. Without these signals the weapon system will enter a malfunction state; thus preventing full testing of the system. In the past, weapons platforms utilizing the M242 were tested using the M242 gun and live ammunition to ensure proper function and to provide validation and training of the fire control electronics. However, this method has fallen out of favor as expense and safety concerns have increased. Further, utilizing live ammunition in research and development cycles would increase the time and expense of developing new variations and improvements on the M242, Mark 44 and Bushmaster III chain guns.

Thus, several disparate devices have been developed to test various aspects of the M242. These testing devices include: (1) the Simplified Test Equipment for M1 and Bradley Fighting Vehicle gun simulator (STE-M1/FVS), (2) the Multiple Integrated Laser Engagement System/Simulated Area Weapon Effects 25 mm gun shorting plug (MILES), and (3) the Precision Gunnery System 25 mm shorting plug (PGS). However, each of these testing devices suffers from various shortcomings in design and implementation. For instance, the STE requires that the M242 is absent, i.e. it cannot be utilized to quickly recertify weapons platforms by maintaining installed systems. Other limitations are evident in the current simulators including inability to track gun timing, lack of fault avoidance and recovery, inability to provide training, specificity to one weapons platform and lack of adaptability to be installed without significant alterations to weapon platforms and systems. Some of the current simulators require a significant amount of re-tooling or retrofitting to be operable in the testing and validation on various weapons platforms. Thus, the current gun simulation systems are incapable of simulating the operating parameters of the M242 gun on various weapons platforms. Further, while these disparate gun simulators exist for the M242 on specific platforms, there is no known gun simulator for the Mark 44. Thus, the issues presented in testing and maintenance with the M242 are heightened in the case of the Mark 44. As the Mark 44 is seeing a greater use in both marine and terrestrial applications, lack of a simulation system is problematic. Further, as with the Mark 44, simulators are not available for the Bushmaster III.

As a result of the numerous limitations of existing systems, or lack of availability, a high-fidelity universal chain gun simulator compatible with all current and future electrically driven chain guns, weapons platforms, fire control systems, training systems and production and engineering systems is welcome.

SUMMARY OF THE INVENTION

Various embodiments of the invention reliably simulate the gun system electrical characteristics including gun sequences, gun operation states, gun timing, and gun operational electrical levels such that the fire control interface on various weapon platforms can function as if a real gun and live ammunition is used. Thus, the gun simulator is able to examine the fitness of the fire control interface and at the same time provide accurate training for operators of the weapon system. In various embodiments an operator may select the mode of operation. The modes of operation available may include, but are not limited to, misfire, gun malfunction, and feeder malfunction. Further, in various embodiments, the advancing states of gun operation are provided to the weapon platform as well as conveyed to the operator. In these embodiments, states of gun operation may be conveyed to the operator using audible or visible indicators or a combination thereof. Finally, various embodiments may allow the operator to select gun type. Examples of available gun types include, but are not limited to 25 mm and 30 mm. In this way the simulator reflects what control signals an actual gun firing live ammunition would produce under the same conditions.

Various embodiments handle multiple input data streams including inputs handling sear solenoid power, motor field, motor armature, motor brake, feeder power, armor piercing feed command and high explosive feed command. Further, various embodiments handle multiple output streams including output sear pin position, seared, breech lock, normal shutdown, feeder at armor piercing and feeder at high explosive information. By handling the inputs and outputs and regulating the voltages of the signals, the simulator simulates and regulates the various inputs and outputs to provide a high-fidelity simulation of the states and timing of chain gun operations.

In various embodiments the universal chain gun simulator provides: simulation of all of the real chain gun signals, conformance to the interface control specifications and timing of the real chain gun, the ability to simulate defective ammunition or misfires, the ability to simulate a gun malfunction, the ability to simulate a feeder malfunction, the ability to provide audible and visual representation of the gun cycle, the ability to work on multiple platforms with different control system power supplies and signal interfaces, and the ability to fit in the weapon platform while the real gun remains installed.

Various embodiments of the invention provide a method and apparatus for simulating the operation of a chain gun. In certain embodiments a programmable simulator is coupled to a firing control system of a weapons platform, the programmable simulator having programs capable of simulating: chain gun fire sequence initialization, chain gun fire sequence primer, chain gun firing sequence, chain gun extraction sequence; and chain gun end of fire sequence. In various embodiments chain gun simulator mode of operation is selectable as well as gun type and ammunition type.

In certain embodiments the chain gun simulation system includes; a fire sequence initialization; a feeder test sequence; a sear solenoid test sequence; a sear pin retraction sequence; an armature test sequence; a mechanical hangfire set sequence; an initial RAM sequence; a malfunction sequence; a normal sequence; a malfunctioning RAM sequence; gun malfunction sequence; a RAM sequence; a misfire test sequence; a misfire clearing sequence; a normal firing sequence; an extraction sequence; an initial shutdown sequence; a high rate of fire end of cycle sequence; a low rate of fire end sequence or any combination thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a flow chart depicting the initialization and gun type selection in an embodiment of the invention;

FIG. 2A is schematic depicting the organization of partial views 2B and 2C;

FIG. 2B is a partial view of a flow chart depicting the simulation of a 25 mm chain gun in an embodiment of the invention;

FIG. 2C is a partial view of a flow chart depicting the simulation of a 25 mm chain gun in an embodiment of the invention;

FIG. 3A is schematic depicting the organization of partial views 3B and 3C;

FIG. 3B is a partial view of a flow chart depicting the simulation of a 25 mm chain gun in an embodiment of the invention;

FIG. 3C is a partial view of a flow chart depicting the simulation of a 25 mm chain gun in an embodiment of the invention;

FIG. 4 is a schematic diagram depicting an implementation of a gun simulator in an embodiment of the invention;

FIG. 5 is a schematic diagram showing a detailed view of the feed select solenoid and feed position outputs of a gun simulator from FIG. 4 in an embodiment of the invention;

FIG. 6 is a schematic diagram showing a detailed view of the signal input circuit of a gun simulator from FIG. 4 in an embodiment of the invention;

FIG. 7 is a schematic diagram showing a detailed view of the signal output circuit of a gun simulator from FIG. 4 in an embodiment of the invention;

FIG. 8 is a diagram depicting a user display of a gun simulator in an embodiment of the invention;

FIG. 9A depicts the installation of a gun simulator in an embodiment of the invention; and positioned within the rotor under the chain gun; and

FIG. 9B depicts an alternate view of a gun simulator in an embodiment of the invention.

DETAILED DESCRIPTION OF THE DRAWINGS

Various embodiments of the invention simulate the electrical signals of the M242 and Mark 44 chain guns. The M242 and Mark 44 exhibit complex firing mechanisms in order to maintain highly accurate and reliable function. In order to better understand various embodiments of the invention, a brief review the firing operation M242 and Mark 44 chain guns is warranted. The firing operation of the M242 and Mark 44 chain guns is broken into several stages, each stage is important in maintaining proper function of the chain gun. The weapons system firing control monitors the stages through feedback signals. In the Sear or Charge Cycle, the 25 mm bolt is oriented forward of the rear position. A sear engages the master link to lock the position. During this stage the firing pin remains uncocked. In the Feed Cycle, ammunition enters the 25 mm or 30 mm gun feeder. The rounds are stripped from links if linked and are moved into the round positioner. The round positioner pushes the round into the ready position. During this cycle, the bolt is 25 mm to the rear of the sear position. The feeder rotor rotates, permitting the round positioner to place a round into the rotor. Subsequently, the hang-fire protection system activates. In the Chamber or Ram Cycle the rotor stops moving once the round is positioned on the bolt face. The bolt assembly and round move forward until the round seats fully in the chamber. The Lock Cycle locks the blot and the breech. The bolt is in the full forward position and the bolt carrier is still moving forward. The lugs on the bolt engage in the recesses of the breech, making a solid lock. In the Fire Cycle the firing pin springs to push the firing pin forward. The indicator arrow points to FIRE. If the breech fails to recoil, the gun stops cycling with the bolt still locked in the breech. The Unlock Cycle opens the bolt carrier and the Extract Cycle removes the cartridge case as the bolt moves to the rear. Further, the bolt continues to the rear until it locks in the sear position. The expended case remains in the bolt face until the gunner pulls the trigger to fire another round. When that happens, the bolt moves to the feed position. Finally, as the bolt moves forward to chamber the round, the eject arm on the bolt carrier pushes the expended case from the receiver cartridge eject port, finishing the Eject cycle. A full description of the M242 firing cycle is described in “Bradley Gunnery”, Department of the Army, 3-22.1 (2003). The Mark 44 is similar in basic fire cycling but the technical details of the Mark 44 are distinct from the M242. Armed with the basic knowledge of the firing cycles of the M242, various embodiments of the gun simulator can now be fully understood.

The basic modes of operation in various embodiments simulate modes including normal firing, misfire, gun malfunction, and feeder out of detent. These embodiments cover all existing uses of the gun simulator: engineering and production, unit level maintenance, and combat training. However, various embodiments of the gun simulator are flexible and reprogrammable to allow for reprogramming the simulator as new uses and new gun models are released. Further, various embodiments include bolt position indicators, software control of the feed signals, and a feeder test mode. Various embodiments of the modes of operation and supported gun types are listed in Table 1.

TABLE 1
Modes of Operation
Gun Type/Mode (mode is
common to all gun types)
25 mm
30 mm
Future Combat System (FCS)
Normal firing
Misfire
Malfunction
Feeder Test

Referring to FIG. 1, initialization and selection of gun type is depicted according to one embodiment of the invention. In various embodiments, the gun simulator, when powered on, enters an initialization 100 phase. The initialization phase 100 may include initialization and setup of various gun simulator components 102. In various embodiments the initialization phase includes interrupt setup 104, memory setup 106, input and output (I/O) port initialization 108, timer initialization 110, memory initialization 112, interrupt initialization 114 and watchdog timer (WDT) initialization 116. Once the initialization stage is complete the gun simulator is ready to simulate the operation of a live chain gun. In various embodiments, the gun simulator is able to simulate a variety of chain guns, including the M242 and Mark 44. In certain embodiments, gun selection is performed utilizing a gun jumper check 116. However, one having skill in the art will recognize that gun selection may be performed in other ways including software or by communicating with a weapons platform via wired or wireless communication to obtain weapons configuration information. Further, in various embodiments, additional models of chain gun are simulated by adding additional gun jumpers or implementing a software-controlled switch. After setup of gun simulator components 102, the gun jumper 116 will be analyzed to determine which chain gun the gun simulator is to simulate. In various embodiments, once gun selection is determined, a feeder test is performed and then the simulation sequence is begun. In certain embodiments the gun selection is limited to the 25 mm M242 and the 30 mm Mark 44. Thus, in various embodiments the initialization phase 100 ends with the 30 mm feeder test 118 and 30 mm sequence start 120 while in other embodiments the initialization phase 100 ends with the 25 mm feeder test 122 and 25 mm sequence start 124.

Now referring to FIGS. 2A-2C, a simulator simulating operation of a 25 mm chain gun 200 according to various embodiments is provided. During the 25 mm simulation 200 the gun simulator will check for feeder test mode 202. In various embodiments checking for feeder test mode 202 includes checking for the gun simulator operation mode. If the operator has selected feeder test mode 202, the weapon does not cycle. In various embodiments the feeder test mode 202 includes stroking the watchdog timer 204, simulating feeder output signal 206 and running a feeder mode test 208. If the feeder test mode is active then the feeder test mode 202 will continue by looping back and repeating the process. If feeder test mode 202 is not active then the feeder test outputs are set to default values and the feeder output signal 210 is simulated. The simulator 200 then detects sear solenoid activation 212. If the sear solenoid isn't activated, the simulator strokes the WDT 204 and repeats. The simulator 200 then delays 214 before simulating the sear pin retraction signal 216. In various embodiments the delay is based on the clock cycles of the implemented hardware. The clock cycle may be 4.096 ms, however the clock cycle may vary based on the microprocessor and timer used. Thus, in various embodiments the simulator 200 allows for the adjustment of wait or delay cycles based on multiples of clock cycles to ensure proper simulation of the chain gun. Thus, in the following embodiment delay may be two clock cycles, five clock cycles or seven clock cycles. One having skill in the art will recognize that the clock cycle delay can be adjusted based on the microprocessor and timer use in the simulator 200. Next the simulator 200 tests the armature status 218 of the weapons system. In certain embodiments, the weapons system communication and armament activation results in a 15 ms delay. If an armature is not active, the simulator will recheck the status. The simulator 200 will then delay 220 to simulate bolt carrier movement. Next, the simulator 200 will simulate the setting of the mechanical hangfire 222. The mechanical hangfire 222 simulation includes simulation of extending the sear pin signal 224 and rotating out of seared signal 226. The simulator 200 then simulates the initial RAM cycle 228. The initial RAM cycle 228 is simulated by a clock delay 230, simulated RAM signal 232 and an additional clock delay 234. The simulator 200 then checks for gun malfunction 236. In various embodiments checking for gun malfunction 236 includes checking for the gun simulator operation mode. If the operator has selected malfunction mode, then the simulator 200 will enter the MALF RAM 238 simulation. If gun malfunction mode is not selected, the simulator 200 will enter normal RAM mode 240.

MALF RAM 238 simulation includes simulating retraction of the sear pin signal 242 followed by a delay 244. The simulator 200 then simulates breech lock 246, clock delay 248, simulates a misfire signal 250 and delays the clock 252. The simulator 200 then checks to see if sear solenoid is off 254. If the sear solenoid is on the simulator enters Gun MALF mode 256. Gun MALF mode 256 includes simulating sear pin retract signal 258, and disabling the WDT 260. The end of Gun MALF 254 mode requires that the operator cycle the power to restart the simulation. If the solenoid is on, the simulator 200 enters the extract simulation 262.

Normal RAM mode 240 includes clock delay 264 and signal simulating breech lock 266. The simulator 200 will then test the sear solenoid for misfire 268. The misfire test 268 includes a clock delay 270, simulating a misfire signal 272 and an additional clock delay 274. At this point, the simulator 200 checks the operation mode 276. If the operation mode is misfire mode then the simulator 200 will enter the misfire clearing simulation. If the simulator 200 is not in misfire mode it will continue to the normal firing simulation, which generates a sear pin retraction simulation 278, and extraction simulation 280.

The misfire clearing simulation includes a clock delay 282, and a start restart loop 284 that checks the sear solenoid to make sure it is on. If the sear solenoid is on, the misfire is clear and the simulation 200 proceeds. If the sear solenoid is not on, the WDT 204 is stroked and the loop 284 continues. If the sear solenoid is on, the simulator 200 clock delays 286 before simulating the sear pin retraction 288 which indicates misfire clearing process is complete. After completion of the misfire clearing simulation 276 the simulator enters extraction simulation 280

Extraction simulation 280 of the simulator 200 includes a clock delay 290 a simulation of the signal for moving out of misfire position 292, a clock delay 294, an extraction signal simulation 296 and a clock delay 298. Once extraction simulation 280 is complete, the simulator moves on to the normal shutdown simulation 300. Normal shutdown simulation 300 includes a normal shutdown signal simulation 302 and a clock delay 304 to allow the weapons system to turn off sear solenoid if in single shot or low rate of fire shot modes. After the clock delay 304, the simulator checks to see if the sear solenoid is on 306. If the sear solenoid is on, the simulator moves to simulate the high rate of fire end of cycle simulation 308. If the sear solenoid check 306 indicates the sear solenoid is off, then this indicates a single or low rate of fire and the single/low rate of fire end of cycle begins 310.

The high rate of fire end of cycle simulation 308 includes a clock delay 312 followed by a simulation of normal shutdown signal 314, followed by a clock delay 316. The cycle simulation 306 then generates a seared signal simulation 318 and strokes the WDT 320. A delay is simulated 322 before the completion of the high rate of fire end of cycle simulation 308. The simulator 200 will then return to the mechanical hangfire simulation 222 portion to simulate the firing of the next round of ammunition.

The single/low rate of fire end of cycle 310 simulation will simulate the sear pin retraction 324, and then delay 326 before simulating a normal shutdown signal 328. The end of cycle simulation 308 then delays 330 and simulates the seared signal 332 indicating to the weapon system that the fire cycle is complete and ready for the next round of fire. If the weapons system operator initiates another firing sequence then the simulator 200 will return to feeder test mode 202 and the cycle repeats.

Now referring to FIGS. 3A-3C, a simulator simulating operation of a 30 mm chain gun 400 according to various embodiments is provided. During the 30 mm simulation 400 the gun simulator will check for feeder test mode 402. In various embodiments checking for feeder test mode 402 includes checking for the simulator 400 operation mode. If the operator has selected feeder test mode 402, the weapon does not cycle. In various embodiments the feeder test mode 402 includes stroking the watchdog timer 404, simulating feeder output signal 406 and running a feeder mode test 408. If the feeder test mode is active then the feeder test mode 402 will continue by looping back and repeating the process. If feeder test mode 402 is not active then the feeder test outputs are set to default values and the feeder output signal 410 is simulated. The simulator 400 then detects sear solenoid activation 412. If the sear solenoid isn't activated, the simulator strokes the WDT and repeats. The simulator 400 then delays 414 before providing the sear pin retraction simulation signal 416. In various embodiments the delay is based on the clock cycles of the implemented hardware. In certain embodiments the clock cycle is 4.096 ms, however in various other embodiments the clock cycle may vary based on the microprocessor and timer used. Thus, in various embodiments the simulator 400 allows for the adjustment of wait cycles based on multiples of clock cycles to ensure proper simulation of the chain gun. Thus, in the following embodiment delay may be two clock cycles, five clock cycles or seven clock cycles. One having skill in the art will recognize that the clock cycle delay can be adjusted based on the microprocessor and timer used in the simulator 400. Next the simulator 400 tests the armature status 418 of the weapons system. In certain embodiments, the weapons system communication and armament activation results in a 15 ms delay. If an armature is not active, the simulator will recheck the status. The simulator 400 will then delay 420 to simulate bolt carrier movement. Next, the simulator 400 will simulate the setting of the mechanical hangfire 422. The mechanical hangfire 422 simulation includes simulation of extending the sear pin signal 424 a delay 426 and rotating out of seared signal 428. The simulator 400 then simulates the initial RAM cycle 430. The initial RAM cycle 430 is simulated by a clock delay 432, simulated RAM signal 434 and an additional clock delay 436. The simulator 400 then checks for gun malfunction 438. In various embodiments checking for gun malfunction 438 includes checking for the gun simulator 400 operation mode. If the operator has selected malfunction mode, then the simulator 400 will enter the MALF RAM 440 simulation. If gun malfunction mode is not selected, the simulator 400 will enter normal 30 mm firing mode 442.

MALF RAM 440 simulation includes simulating retraction of the sear pin 444 followed by a clock delay 446. The simulator 400 then simulates breech lock 448, clock delay 450, simulates a misfire signal 452 and delays the clock 454. The simulator 400 then checks to see if sear solenoid is off 456. If the sear solenoid is on the simulator enters Gun MALF mode 458. Gun MALF mode 458 includes simulating sear pin retract 460, and disabling the WDT 462. The end of Gun MALF mode requires that the operator cycle the power to restart the simulation. If the solenoid is on, the simulator 400 enters the extract simulation 464.

Normal 30 mm firing mode 442 includes a clock delay 466 and a simulated breech lock signal 468. At this point, the simulator checks the operation mode of the gun simulator 470. If the gun simulator operation mode is misfire mode then the gun simulator will enter the 30 mm RAM cycle 472. If the simulator is not in misfire mode it will continue to the 30 mm firing simulation 474.

The 30 mm RAM cycle 472 includes a clock delay 476 a simulated breech lock signal 478, followed by a clock delay 480, a simulated misfire signal 482 and an additional delay 484. The simulator 400 then enters into a start restart 486 loop that checks to see if the sear solenoid is active. If the sear solenoid is not active the start restart loop stroked the WDT and rechecks the sear solenoid activity. If the sear solenoid is active then the simulator delays 488 before simulating a sear pin retraction signal 490. The simulator will then delay 492 before entering the extract simulation 464.

The 30 mm firing simulation includes a clock delay 494, a sear pin retraction simulation signal 496, a clock delay 498, a simulated breech lock signal 500, a clock delay 502 and a simulated misfire signal 504. The simulator will then delay 492 before entering the extract simulation 464.

The extract simulation 464 of the simulator 400 includes a simulated misfire signal 506, a clock delay 508, a simulated extraction signal 510 and a clock delay 512. The extraction simulation thus simulates the gun rotating our of misfire bolt position and then rotating out of the extract bolt position of the firing sequence for the 30 mm Mark 44.

Next the simulator 400 enters into the normal shutdown simulation 514. The normal shutdown simulation 514 includes a normal shutdown simulation signal 516 that simulates rotation to the normal shutdown mode, a clock delay 518 and another shutdown simulation signal 520 and simulates rotation out of normal shutdown in anticipation of next round cycle.

The simulator 400 then checks the sear solenoid 522. If the sear solenoid is on then the simulator enters hi rate of fire mode 524 and simulates a sear signal 526. The sear signal 526 simulates the firing mechanism rotating to seared position. The simulator then strokes the WDT 404 and delays 528 before returning to the mechanical hangfire simulation 422 to simulate the next round of fire. In the case that the sear solenoid check 522 indicates that the sear solenoid is off then the simulator 400 enters the 30 mm end of cycle 530. The 30 mm end of cycle includes a simulated sear pin retract signal 532 followed by a simulated seared signal 534. At this point the 30 mm simulation cycle is complete and ready for the next round of fire. If the weapons system operator initiates another firing sequence then the simulator 400 will return to feeder test mode 402 and the cycle repeats.

Now referring to FIGS. 4-7, schematics of a hardware implementation of the gun simulator 600 are presented. As mentioned above, the gun simulator interfaces with the weapons platform weapons system. In certain embodiments the weapon system is the BVFS and the associated GCU. The inputs and outputs of the gun simulator according to one embodiments are listed in Table 2.

TABLE 2
Gun Simulator Inputs and Outputs
INPUTS	OUTPUTS
N	Sear Solenoid	28 V/0	Sear Pin Position	28 V/0	D
E	Armature	28 V/0	Seared	0/5-28 V	K
F	Power	12-28 V	Breech Lock	0/5-28 V	L
M, P	Return	ground	Normal Shutdown	0/5-28 V	V
G	Feeder AP Command	28 V/0	Feeder AP Position	12-28 V/0	H
W	Feeder HE command	28 V/0	Feeder HE Position	12-28 V/0	S
C	Motor Field	28 V/0	RAM bolt position		—
J	Motor Brake	open/gnd	MISFIRE bolt position		—
			EXTRACT bolt position		—
—	Mode Selection		Normal firing mode ON		—
—	Gun Type Selection		Misfire mode ON		—
—	25 mm gun type in use		Malfunction mode ON		—
—	30 mm gun type in use		Feeder Test mode ON		—

In various embodiments the gun simulator includes software embedded into hardware such as the AVR 8515, ATMega48 processor from Atmel®. In these embodiments the gun simulator is able to utilize 8 Kbyte or 4 Kbyte program flash capacity and 40-pin or 28-pin counts respectively. In these embodiments, the gun simulator does not utilize any operating system to ensure fast operation and peak reliability while reducing part count, footprint and cost. One having skill in the art will recognize that the gun simulator may utilize variety of alternate programmable microcontrollers including, but not limited to, the Atmel® 8086. In certain embodiments the gun simulator utilizes AVR studio from Atmel® to develop the software programmed to the microprocessors. Further, microprocessor flashing may be performed utilizing Atmel STK 500 or Atmel AVR ISP mkII. However, one having skill in the art will recognize that the gun simulator may run on various gun simulator hardware platforms utilizing operating systems configured to run software coded in languages such as C, C++, C#, Java and the like. Further, one having skill in the art will recognize that the gun simulator may utilize any gun simulation hardware platform utilizing volatile or non-volatile memory to store program code. In this way, the gun simulator is able to run on any platform that is able to transform the physical electrical signals of chain gun operation into computational data.

In various embodiments the gun simulator is electronically connected to the fire control systems of the weapons platform. For example, in certain embodiments the gun simulator is connected to a BFV's GCU by utilizing a standard gun connection harness. One having skill in the art will recognize that a variety of standard and non-standard wiring harnesses as well as alternate communications technologies including 802.11x, Bluetooth, Infrared, radio and other wireless protocols may be utilized to communicate with the weapons platform's weapons systems. FIG. 4 shows one implementation of the gun simulator utilizing the AVR 8515 600. The inputs and outputs of the AVR 8515 in one embodiment are outlined in Table 3.

TABLE 3
AVR 8515 I/O
			Right
Left Ports	Signal	Signal	Ports
PB0	Gun type selection	25 mm gun type in use	PA0
PB1	Sear Solenoid	30 mm gun type in use	PA1
PB2	unused	Sear Pin Position	PA2
PB3	unused	unused	PA3
PB4	Motor Armature	unused	PA4
PB5	MOSI* (reserved for ISP)	unused	PA5
PB6	MISO* (reserved for ISP)	unused	PA6
PB7	SCK* (reserved for ISP)	unused	PA7
PD0	NORMAL mode ON	Seared bolt position	PC0
PD1	MISFIRE mode ON	Ram bolt position	PC1
PD2/INTO	Mode Select	Breech Lock bolt	PC2
		position
PD3	unused	Misfire bolt position	PC3
PD4	MALFUNCTION mode	Extract bolt position	PC4
	ON
PD5	FEEDER TEST mode ON	Normal Shutdn bolt	PC5
		position
PD6	FEEDER TEST	unused	PC6
PD7	FEEDER TEST	unused	PC7
Total I/O count 22 lines (reducible to 20)

In various embodiments, the feeder position switch excitation power is the only signal that is both on continuously and has appreciable current sourcing capability across all the platforms. Various embodiments draw input power from this source, pin F 602. While drawing from pin F 602, the simulator maintains operative capacity from 7 to 35 V and exhibit a current draw of 30 to 45 mA. A LM109K 5V regulator 604 may be used to regulate input across military-class temp ranges. Base requirements and actual voltage and current requirements of the gun simulator according to various embodiments are listed in Table 4.

TABLE 4
Input Power
	Requirement	Actual
	Input Voltage	10-30	V	7-35	V
	Input Current	<500	mA	<50	mA

In various embodiments, gun type selection is a single bit, selectable by a CCA jumper 606 and mode selection is accomplished by a single momentary pushbutton 608. These inputs may then be debounced. In these embodiments, the default power up state is normal mode and bitwise logic is used to determine the mode of operation. Each pushbutton 608 press advances the mode, and repeated presses roll mode selection back to the start. Further, in various embodiments each pushbutton press 608 stimulates an I/O interrupt bringing the system to a function where the mode counter increments or resets thus triggering output indicators and switching software modes. The signals may be debounced by a hardware debouncer 610 or implemented in software.

FIGS. 4 and 5 show the feeder signal circuit 612 of the gun simulator according to one embodiment. In this embodiment the feed select solenoids and feed position outputs are simulated with a 28 v dual coil latching relay with double pole, double throw contacts 614. Solid state relays (SSR) 616 controlled by software may interrupt each pole common. This embodiment allows for gun simulation operation over a voltage range of 12 v to 28 v. The electro-mechanical relay coils may be driven directly by the weapons control system such as the BVCS, and the contacts may switch the supplied voltage to indicate the chosen feed position. One pole of the solid state relay 616 may switch the control system feedback signals APP and HEP 618, and the second pole may turn on the AP/HE indicators of the simulator 620. In this embodiment the common of each pole is wired in series with a normally closed solid state relay (SSR) 616. The simulator 200 may control the SSR 616 to interrupt both sets of signals for the feeder test mode of operation. In various embodiments, for normal feed select operations, the SSR 616 remains un-driven and the normally closed contacts do not affect the signals. Additionally, in various embodiments the input circuits have 470 and 330 ohm resistors that form a voltage divider to scale the feeder signal circuit 612.

In various embodiments, the electro-mechanical relay is driven directly by the momentary HE 622 and AP 624 feed commands of the control system, just as the real gun feed select solenoids are driven. The solenoids were tested utilizing 12V and switched without problems. Thus, various embodiments will meet interface control drawings (ICD) requirements. The SSRs 616 may be driven directly by the AVR microcontroller 600. Further, the control circuit of the SSR 616 may utilize infrared light emitting diode (LED) which may be driven by the AVR microcontroller 600 ports, with a series current limiting resistor like a regular LED. In various embodiments, the feeder test circuits 612 must only provide contact signal closure back to the control system.

FIGS. 4 and 6 provide various embodiments of the sear solenoid 626 and motor armature 628 inputs. Various embodiments utilize relatively large load resistors in order to work with all fire control systems. These two 28V signals are also substantial loads on the operation of a chain gun. Further, in various embodiments, load resistors 630 provide a wiping current to clean contacts, or make the solid state switches behave more predictably. However, in some embodiments, a large sear solenoid load resistor would unduly burden the circuit card traces or small internal wiring harnesses. Thus, a small ribbon cable of 30 gauge wire to bring the box edge signals to the Circuit Card Assembly (CCA) may be utilized. In various embodiments, a 511Ω 5 Watt resistor 632 is sufficient on the sear solenoid 632 input. This embodiment consumes, at worst, 30/511=59 mA and V2/R=30*30/511=1.76 W. In addition, various embodiments utilize a 2.2K 0.5 W load resistor 634 on the motor armature 628 input Resulting in a worst case wattage of 30*30/2.2K=0.41 Watt and worst case current is 30/2.2 k=13.6 mA.

The sear solenoid 626 and armature signals 628 are the primary control system inputs that drive the states and timing of the gun simulator. Thus, in various embodiments, the 28V signals are conditioned for the AVR microcontroller 600 by attenuation down to the AVR thresholds and debounced, to eliminate sporadic triggering. In various embodiments FET drivers 636 such as Supertex TN0606N3 are utilized to further condition the signals. Further, 12K and (2.2+2.2)K voltage dividers 638 on each input may be utilized to provide a 0.2683 scale factor to the input voltage. The input voltages and corresponding gate voltages according to these embodiments are shown below in table 5, with key values of absolute max/min, nominal, and gate to source threshold values. The FETs may turn on at very low box-edge voltages but the load resistors will prevent spurious voltage triggering.

TABLE 5
Fet Input
	Box-edge input	FET VGS	Notes
	75 V	+20.0 V	Absolute max FET VGS
	30 V	8.0 V
	24 V	6.4 V
	18 V	4.8 V
	7.45 V	2.0 V	Max VGS(TH)
	2.24 V	0.6 V	Min VGS(TH)
	−75 V	−20.0 V	Absolute min FET VGS

To debounce the sear solenoid 626 and armature signals 628 a hardware debouncer 610 may be utilized. Several hardware debouncers have multiple debouncing circuits with provisions for setting the common time with a single external capacitor. In various embodiments, the initial debounce time was set by a 0.0047 μF capacitor, which yields a debounce time of C<in μF>/1.5=time in <ms> of 3.13. In other embodiments, common time may be set with 0.022 μF, 0.001 μF or 220 pF capacitors 640.

FIGS. 4 and 7 show the output signal circuit 700 of the gun simulator according to one embodiment. In various embodiments the seared 702, breech lock 704, and normal shutdown 706 gun microswitches needed to operate with either 5V or 28V depending upon the vehicle platform. Thus, in these embodiments N-channel enhancement mode TN0606N3 FETs 708 rated for 60V BV_DSS/BV_DGS are utilized. Further, 12 k pull-down resistors 710 are put on the gate to further ensure reliable operation, and an output filter 712 of a 2.2 k in series with 0.11 JF clean the output. In various embodiments, the FETs 708 can switch 3 A, which is in-line with control system and LED drive requirements. In these embodiments, the FETs may be driven directly by the AVR microprocessor 600 which may also drive the piezo-electric buzzer 714 of the normal shoutdown output 706.

In various embodiments, sear pin position signal output 716 utilizes solid state relays 718. The selected SSRs 718 have one normally open and one normally closed output driven by a separate IR LED 720, contacts rated for 170 mA, exceptional isolation characteristics, switch quickly and cleanly and can be driven by the AVR microprocessor 600 with nothing more than series current limiting resistors 722. In various embodiments the series current limiting resistors 722 are 680Ω resistors producing 1.21 Vf@5.08 mA. The SSRs 718 and LEDs 720 may all driven from their own AVR microprocessor 600 output pin. The combined current draw of these three outputs is low enough to be driven directly by a single AVR output pin. In various embodiments, discrete 820Ω series current limiting resistors may used for the gun type indicators. The remaining output LEDs 724 according to one embodiment are listed in Table 6. Finally, in various embodiments, Interrupt 0 utilizes negative edge trigger running at 4 MHz 726.

TABLE 6
Output LED Indicators
	Size	Res.	Green	Yellow	Red	Blue	White
Selected	5 mm	330 Ω	NORM,	MISF,	MALF	FDR	—
Mode,						(10 mm) no
Feed		330 Ω	AP	HE		blue 5 mm
Position						at Frys
Measured Current mA	8.9	9.2	9.6	4.7	—
Bolt	3 mm	1 kΩ,	SEAR,	BREECH	MISFIRE	EXTRACT	RAM,
position,				LOCK,			NS
Gun type*		820 Ω	25 MM*	30 MM*
Measured current mA	3.2	3.2	3.3	1.8	2.2

Now referring to FIGS. 8-9B, a gun simulator apparatus 800 according to various embodiments is presented. A pushbutton switch 802 may be used for main operator input and mode selection. The default power up state may normal mode which each press of the pushbutton switch 802 will advance through mode of operation indicators 804 that reflect simulator mode. The operation indicators 804 may be normal firing 806, misfire 808, malfunction (MALF) 810, and feeder test 812. In various embodiments the gun type selection jumper is an operator input is not accessible to the turret operator to prevent inadvertent manipulation. Further, embodiments provide a clear indication of the cycle progression via six LEDs were arranged in a circular pattern 814, and the lamps sweep as the cycle progresses. The six LEDs 814 may indicate simulated chain gun states, corresponding to the mechanical chain gun physical states: seared 816, ram 818, breech lock 820, misfire 822, extract 824, and normal shutdown 826. Thus the user obtains an indication the “gun” is working as desired. The illumination of the LEDs 814 corresponding to the simulated chain gun states is activated in the various stages as depicted in FIGS. 2A-2C and 3A-3B. For misfire and malfunction modes, the lamps 804 sweep, but stop on the appropriate bolt position where the “real” gun terminates. Further various embodiments include feed control indicators for AP 828 and HE 830 modes. Further, various embodiments utilize a standard gun harness connector 832 to enable the standard fire control system interconnect 834 to connect directly to the gun simulator.

In various embodiments, the gun simulator 800 is entered into operational status by first placing the gun simulator 800 within the turret's 860 shroud 862. In various embodiments, the gun simulator 800 is small enough to fit within the shroud of various weapon's plaform's turret 860 shroud 862 without disrupting normal operating procedure. Next, the fire control system's interconnect 834 is disconnected from the gun turret's gun harness connector 864. The fire control system interconnect 834 is then inserted into the gun simulator's 800 gun harness connector 832. In various embodiments, the operator will then power cycle the fire control system and ensure that the gun simulator 800 is active. The operator will then select the gun simulator 800 mode of operation using the pushbutton 802. In various embodiments, the gun simulator 800 will indicate to the operator what mode 804 and fire stage 814 and AP 828 or HE 830 feed modes the gun simulator 800 is currently on. Upon completion of testing, the fire control system is shut down and the gun simulator 800 is disconnected. The fire control system interconnect 834 will then be reconnected to the gun turret's gun harness connector 864.

As shown in FIGS. 9A and 9B, in various embodiments, the gun simulator 800 was designed to be small due to vehicle space constraints. For instance, the Bradley turret was designed to maximize lethality and protection and to minimize weight. The result is a constricting space with little room for additional equipment. In various embodiments the gun simulator 800 is placed within the BFV's gun rotor shroud 862. Further, in this embodiment, the gun simulator 800 may fit within the gas bag 866 surrounding the BFV gun rotor 860.

It should also be appreciated that the exemplary embodiment or exemplary embodiments are only examples, and are not intended to limit the scope, applicability, or configuration of the invention in any way. Rather, the foregoing detailed description will provide those skilled in the art with an enabling disclosure for implementing the exemplary embodiment or exemplary embodiments. It should be understood that various changes can be made in the function and arrangement of elements without departing from the scope of the invention as set forth in the appended claims and the legal equivalents thereof.

Claims

1. A chain gun simulator for simulating the operation of a chain gun, the chain gun simulator comprising:

a coupling member for coupling the chain gun simulator to a firing control system of a weapons platform;

a programmable microprocessor for simulating chain operation;

a mechanism for selecting ammunition type;

a mechanism for selecting gun type;

a mechanism for selecting operation modes;

a plurality of indicators indicating operation modes;

a plurality of indicators indicating stage of operation; and

a plurality of indicators indicting ammunition type; wherein the programmable microprocessor includes logic to:

simulate chain gun fire sequence initialization;

simulate chain gun fire sequence primer;

simulate chain gun firing sequence;

simulate chain gun extraction sequence; and

simulate chain gun end of fire sequence.

2. The apparatus of claim 1 wherein the mechanism for selecting ammunition type selects ammunition from the group consisting of anti-personnel and high-explosive.

3. The apparatus of claim 1 wherein the mechanism for selecting gun type selects guns selected from the group consisting of M242 and Mark 44 chain guns.

4. The apparatus of claim 1 wherein the mechanism for selecting modes of operation selects from the group consisting of normal firing, misfire, gun malfunction, and feeder test.

5. The apparatus of claim 1 wherein the plurality of indicators indicating operation indicates modes from the group consisting of normal firing, misfire, gun malfunction, and feeder test.

6. The apparatus of claim 1 wherein the plurality of indicators indicating stage of operation indicates stages of operation selected from the group consisting of breech lock, misfire, extract, normal shutdown, seared and RAM.

7. The apparatus of claim 1 wherein the plurality of indicators indicating ammunition type indicates ammunition selected from the group consisting of anti-personnel and high-explosive.

8. A method for simulating the operation of a chain gun, the method comprising:

coupling a programmable simulator to a firing control system of a weapons platform, the programmable simulator having programs comprising: simulating chain gun fire sequence initialization; simulating chain gun fire sequence primer; simulating chain gun firing sequence; simulating chain gun extraction sequence; and simulating chain gun end of fire sequence;

selecting chain gun simulator mode of operation;

selecting gun type; and

selecting an ammunition type.

9. The method of claim 8 wherein simulating the chain gun fire sequence initialization further comprises:

simulating a feeder test sequence;

simulating a sear solenoid test sequence;

simulating a sear pin retraction sequence; and

simulating an armature test sequence.

10. The method of claim 8 wherein simulating the chain gun fire sequence primer further comprises:

simulating a mechanical hangfire set sequence; and

simulating an initial RAM sequence;

11. The method of claim 8 wherein simulating the chain gun firing sequence further comprises:

simulating a malfunction sequence and a normal sequence wherein simulating the malfunction sequence is determined by the selected mode of operation.

12. The method of claim 11 wherein simulating the malfunction sequence further comprises:

simulating a malfunctioning RAM sequence; and

simulating a gun malfunction sequence determined by the fire control system.

13. The method of claim 11 wherein simulating the normal sequence further comprises:

simulating a RAM sequence;

simulating a misfire test sequence; and

simulating one of a misfire clearing sequence or a normal firing sequence determined by the selected mode of operation.

14. The method of claim 8 wherein simulating the chain gun extraction sequence further comprises:

simulating an extraction sequence; and

simulating an initial shutdown sequence.

15. The method of claim 8 wherein simulating the chain gun end of fire sequence further comprises:

either a high rate of fire end of cycle sequence or

a low rate of fire end sequence as determined by the firing control system.

16. The method of claim 8 wherein simulating a feeder test sequence simulates feeding ammunition selected from the group consisting of consisting of anti-personnel and high-explosive.

17. The method of claim 8 wherein selecting gun type includes a chain gun selected from the group consisting of M242 and Mark 44 chain guns.