GNSS Guided Munitions

[Acronyms]

BTERM(Ballistic Trajectory Extended Munitions), BTERM II

PGMM M396: terminated due to overarching costs.

PGK M1156

APMI: mortar, 120mm, 7.4km, by IMI/Raytheon, 5m CEP

MGK: mortar guidance kit, by ATK, 10m CEP

Excalibur M982: 15mm, full production in 2016

GMLRS M30, M31: Lockheed Martin, 227mm, 85km

ATACMS: 300km

JDAM-PIP: 24km, 100s free fall, 3m CEP

JSOW

Paveway II GBU-12: 273mm, 15km, 1m CEP

Deadedy

ANSR

ERM

ERGM(Extended Range Guided Munition]

LRLAP(Long Range Land Attack Projectile): US Navy, Lockheed Martin

CCF

[APMI XM395]

• APM(Accelerated Precision Mortar Initiative), 6.3km, 120mm, 5m CEP, MGK(Mortar Guidance Kit) by ATK

• 120mm mortar fired, 5-40Hz spin, 130-330m/s speed, 8.5kg setback, 1-6.5km range

• Nose assembly: PGK modified, IEC GPS receiver

[ATACMS]

• 270/300-km range. Inertial/GPS aided.

[ECF(European Correcting Fuze), CCF(Course Correction Fuze)]

• BAE Systems

• 2 drag brakes = range correction, spin brakes = reduce spin to reduce the yaw of repose. → range and deflection control, 1D course correction

• M549A1

• GPS C/A receiver

• Antenna: revolution symmetric radiation pattern

[ERGM(Extended Range Guided Munition, XM171]

• US Navy, 5" gun-fired, 15-60nm range, 127mm dia. 1.55m length, 50kg, 10m CEP

• Roll-stabilized, fin-stabilized glide

• GPS antenna: 2 units on the skin.

• DCI(Digital Communication Interface): for initialization, two-way serial communication, dual coil design, provides power to GPS receiver

- Power: 20kHz 50% duty, 80W

- Data: 500kHz Manchester encoded data, CRC except crypto, 0.02% BER

• GPS receiver: L3 IEC TruTrack receiver.

[Excalibur]

• US Army, Raytheon, fielded in May 2007

• 155mm, 41km range, 6m CEP, 32kg, 0.987m, 4-axis canard actuation, spinning base, GPS/INS with anti-jam

• Excalibur Ia-1: 24km range

• Excalibur Ia-2: lot acceptance test, Oct. 2011. 6m CEP, 37.5km range, more than 500 rounds fired up to Oct. 2011

• Excalibur Ib: full-rate production in 2016.

• Near vertical top attack

[GMLRS]

• 70/80-km range. Inertial/GPS aided, 4 SMArt sensor fuzed submunitions (94GHz), 10m CEP, non-spinning,

• GPS antenna: one top, the other bottom, near the front of TM section.

• GPS receiver: by IEC, 6-ch, L1-C/A 1.023Mbps, L2-P/Y 10.23Mbps, single ant. Input, tracks 8 sat. by multiplexing two of ch., use measured velocity data to aid GPS signal acquisition.

• TM section: encoder(temp. at 16 places, flight data), radar transponder, TM transmitter, encoder = Lockheed Conic PCM 600 (encode raw data and combine); TM tx = Lockheed Martin CTS 905, 3 S-band antennas at the rear portion of TM section with each 120° apart.; radar transponder = to aid the radar tracking of the munition, 2 C-band antenna 180° apart, Herley-Vega Systems model 349C-6; Power = 24 Panasonic NiCd cells for all TM components.

[LRLAP]

US Navy, Lockheed Martin

74nmi range, INS/GPS-guided, 10 rounds/min, 104kg, 2.2mm long, 155mm dia., 0.45m wingspan

[Mk.84 GAM]

• Tail kit: tail GPS antenna = for good reception in terminal vertical dive.

[PGK, M1156]

• US Army, ATK

• Screw-on fuze replacement, $3000 low-rate initial production

• 50m CEP (initial), 30m CEP (final)

• 155mm howitzer fired, later applied to 105mm system also(2008), IOC at FY12

• 150-275Hz spin, 330-830m/s speed, 20kg setback, 6-27km range

• IEC (L-3 Comm. subsidiary) TruTrak Evolution (TTE) GPS receiver

- Size: 1.75"x2.45", 3.07"x0.93", 2.45"x2.45" for various projectile applications

- Low power consumption: 3W @ highest performance mode, 0.7W @ low power mode, 20mW @ standby mode

- Anti-jamming: 4s acquisition at 55dB J/S, track at 65dB J/S and at 90dB J/S with optional FaSTAP(with Deep Integration with IMU)

- Accuracy: 3m(1 sigma) pseudorange, 0.025m (1s) delta range

- TTFF: <6s (direct Y, hot start, no jamming), <5s (reacquisition)

- Navigation: unfiltered GPS-only least squares, deeply integrated Kalman filter, IMU-less attitude determination

- Hardware: 24-ch., L1 C/A, L1 & L2 P(Y), 4 embedded processors, synchronization on pulses, 0-100,000ft altitude, 20kg 16ms gun setback, 5kg 1ms lateral balloting, SAASM

- Dynamics: <1200m/s velocity, < 10g acceleration

- Used in Excalibur also.

[MGK(Mortar Guidance Kit)]

• US Army, ATK

• 120mm mortar:

[TopGun]

IAI, Eurosatory Symposium & Exhibition in Paris June 14th-18th 2010

GPS/INS 2D course correction, 4 fins

Compatible with 2" thread well 155mm artillery projectile

20m CEP for all ranges

[VAPP(Very Affordable Precision Projectile]

• US Army

• Lower the cost of guided munitions by 10 times. Use low-cost guidance solution. Use COTS(commercial-off-the-shelf) components.

• Retrofitting existing munitions: reduced cost but limited performance due to the narrowed design space.

• Conventional maneuver mechanisms (servomotor-driven fins = carnards) do not have the frequency response to actuate at high spin rates (hundreds of rps).

• Main development considerations: precision, range, angle-of-fall, cost

• System features: rolling and fin-stabilized airframe, single-axis maneuver mechanism, ballistic-based guidance and flight control

• System parameters:

1) Roll rate = 5-30Hz (fin-stabilized)(for simplified and cost-reduced maneuver mechanism, use slipping band obturator for disengagement from gun rifling, and tail fiins depolyed after launch and generating appropriate aerodynamic center of pressure location),

2) GNC(guidance, navigation and control) = GPS receiver and antenna (position, velocity, time, roll orientation with a discrete pulse generated when the GPS antenna is oriented toward the earth), guidance and flight control algorithm, maneuver system, axial accelerometer for initiation of GNC at launch, telemetry transmitter and antenna for obtaining data during flight.

4) Guidance and flight control: use GPS data, with reference to up pulse (=maneuver direction), canard amplitude and phase wrt up pulse, impact point calculation using a closed-form flight dynamic model of projectile airframe and GPS-supplied position and velocity, trajectory shaping in glide and endgame phases of the trajectory, rotate canards by desired positive and negative angles during one roll cycle. Active damping based on expensive IMU is not used.

5) Airframe: 105/120/155mm, interior ballistics(projectile weight, chamber volume, muzzle velocity, roll rate, propellant), sub-system packaging, aeroballistics (wind tunnel experiments, CFD predictions, free-flight experiments, aerodynamic behavior prediction, flight stability, six degree-of-freedom Monte Carlo flight simulations with such parameters as physical properties, aerodynamics, launch conditions, and atmospheric conditions), structural integrity, a classic multi-disciplinary design problem with competing requirements, compact GNC(size, weight, battery power) to provide more space for warhead or rocket motor.

6) Gun hardening: electrical and mechanical components' survival through gun launch environment, FEM modeling, extensive structural dynamics simulation, verified through state-of-the-art soft-catch and ground-truth data acquisition-based gun firings, ensured structural integrity

7) GPS: L3 IEC, SAASM-enabled, gun-hardened, direct acquisition of encrypted Y-code, RHCP patch antenna, integration of antenna with GPS receiver, have to cope with reduced signal level of Y-code, active beam-forming not applicable, use shielding for EMI effects on antenna and RF front-end, assess GPS performance for projectile trajectories, Monte Carlo simulation of the receiver with the GPS simulator gives GPS errors and the Kalman filter gains to be tuned for specific maneuverability. field test = to confirm navigation and up-finding (finding sky direction) + mounted to cantilevered roll drive to check the GPS estimate of roll angle.

8) Performance evaluation on rolling platform: check GPS performance and canards deflections throughout a roll cycle, use high-speed camera.

9) IMU: not used to reduce the cost.

10) Maneuver system: single-axis maneuver control, phasing of the canard deflections wrt roll orientation permits maneuvers in any direction, used DSP with feedback, 2-4 canards on projectile head, tail fins for maintaining roll rate, wind tunnel experiments, test firing, range can be adjusted ±30% by maneuvering.

11) Hardware-in-the-loop experiment: maneuver system, guidance and control algorithm, GPS and telemetry are fully integrated.

12) Test Firing: guide-to-hit flight experiments, 120mm mortar fired in Mar. 2010 at the Aberdeen Proving Ground. 155mm in July 2010.

-120mm mortar: 62-deg quadrant elevation with muzzle velocity 233m/s, target at 3.8km, downrange(X) and crossrange(Y) error converge to zero. max. trajectory height 1.5km, projectile landed with 10m from target.

-155mm artillery: 50-deg. quad. elevation with muzzle velocity 696ms/, target at 16.4km, projectile landed within 1m of target.