IJEEDC, ISSN (P): 2320-2084, (O) 2321–2950, COE, Bharti Vidyapeeth, Deemed University, Pune, Special Issue-1 April-2015
PYRO MEMS DESIGN FOR FUZE
1
POOJA SHARMA, 2VIRENDRA KUMAR, 3ARCHANA SINGH
1,3
E&Tc Dept., G.S. Moze COE, University of Pune, Pune– 411045
2
Armament Research and Development Establishment Pashan, Pune – 411 021
Abstract─ Electro explosive devices are extensively used in military and civil application for initiation of explosive
materials. The semiconductor bridge (SCB) detonator is one of the initiation means for explosive materials. Semiconductor
bridge (SCB) igniters are widely used as electro explosive device (EED) for the initiation of explosives and propellants in
advanced ammunitions due to its most excellent performance, low all-fire energy (requires small quantities of electrical
energy to function), fast function time, less weight, small volume, low cost, immunity to EMI (Electromagnetic
interference), ESD (Electrostatic discharge) and RF (Radio Frequency) hazards. SCB is integrated with MEMS based safe,
arm and fire (SAF) device. SAF Device is employed in military and defence applications particularly used in missiles for
fuzing. We are miniaturizing the system by using SCB[1] and 6-pin microcontroller rather than 20-pin microcontroller
previously used. To detonate explosive, detonators are used. An electrical detonator responds to predefined electrical signal
to activate an explosive. We are using SCB since it has reduced size, low input energy, fast functioning, digital compatibility
and improved safety against ESD and RF interference. ATtiny10 microcontroller is used because of its features like reduced
voltage and energy requirements. Here, we have a architecture of Safe, Arm and Fire device (SAF)[2] that constitute a real
breakthrough for safe miniature fuzing device. It takes conventional mechanical arm and fire system and integrates them in a
single 1cm3 package made of different parts. And on other hand, it combines mechanical arming unit[4][5] with electrical
safety functionality on the same silicon initiator’s chip. It respects the STANAG 4187[3] norm (1 A/W during 5 minute of
no fire) and requires 635 mW for ignition.
Keywords: Semiconductor Bridge (SCB), Electro explosive Device, SCB, MEMS, Safe arm and fire device, detonator,
igniter
I. INTRODUCTION An Arm fire (AF) device[2] is a safety device is a
safety device that provides electrical and mechanical
Initiation of explosive charge is normally carried interruption of an ignition train in order to prevent
with the help of electrically or mechanically the unintended functionality of a missile’s rocket
activated detonators. motor. These devices are used to prevent accidental
Today, most missiles and bombs use electronic or inadvertent ignition of rocket motors during flight
fuzes. Fuzing mechanisms are devices used to ‘safe’, or in any usage which could cause an extreme hazard
‘arm’ and detonate explosive military munitions to personnel or facilities. AF devices incoperate a
(such as missiles, mines, demolition charges, fail-safe mechanism that enables the device to remain
explosive shells, unguided bombs and various armed only while power is applied. When power is
submunitions). We have a three layer circuitry used removed from the device, they return to the safe
in missiles: first layer is power supply unit, second position.
layer is electronic circuitry and third layer is SAF Safe and Arm (S&A) device[2] which can be fail
unit. In military munitions, a fuze is the part of the safe or which can incoperate a launching mechanism
device that initiates function. The term fuze is used to which enables a device to remain armed after power
indicate a sophisticated ignition device incorporating is removed and can be typically be returned to safe
mechanical and/or electronic components. A Fuze is a position by applying power.Launching S&A devices
device used in munitions which is designed to are commonly used to initiate system destruct in the
detonate, or to set forces into action to ignite, event of a test failure. Fail-safe S&A devices are
detonate or deflagrate, the charge (or primer) under typically used for launch vehicle initiation and for
specified conditions. In contrast to a simple rocket motor stage separation during flight. S&A
pyrotechnic fuse, a munitions fuze always has some devices commonly use an Explosive Train (ET) to
form of safety/arming mechanism, designed to transfer energy to another device from the S&A.
protect the user from premature or accidental
detonation. II. SYSTEM DEVELOPMENT
The fuze is designed to initiate the warhead either
on hitting the target or at some distance from the In military munitions, a fuze is the part of the
target. Today, most missiles and bombs use electronic device that initiates function. The term fuze is used
fuzes. Fuzing mechanisms are devices used to ‘safe’, to indicate a ignition device incorporating
‘arm’ and detonate explosive military munitions mechanical and/or electronic components. A Fuze is
(such as missiles, mines, demolition charges, a device used in munitions which is designed to
explosive shells, unguided bombs and various detonate, or to set forces into action to ignite,
submunitions). The initiation may also be done after detonate or deflagrate, the charge (or primer) under
certain time delay, after the projectile has been fired. specified conditions. In contrast to a simple
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IJEEDC, ISSN (P): 2320-2084, (O) 2321–2950, COE, Bharti Vidyapeeth, Deemed University, Pune, Special Issue-1 April-2015
pyrotechnic fuse, a munitions fuze always has some IV. SIMULATION RESULTS & ANALYSIS
form of safety/arming mechanism, designed to
protect the user from premature or accidental We simulation the firing unit in Proteus7.7. LED here
detonation. shown is placed instead of SCB. In our firing circuit
we use two SCB’s, one for arming and another is for
The main components that make up a fuze are: firing.
1. Electronic circuitry to initiate warhead,
2. Power supply for the electronic circuit,
3. Safe & arm unit
Figure 2: Block diagram of MEMS SAF Device
1)Power supply unit: It consist of Li-ion battery
Fig: Simulated Firing Circuit
which gives constant 3V supply to inductor and
microcontroller. Through PWM we get a boosted
We booster our circuit from 3V to 30V at the output
voltage from 3V to 30V.
capacitor starts charging and when we get sensor
input from accelerometer then capacitor will
2) Electronic circuitry: We use 8-pin
discharge through SCB for performing arming
microcontroller rather than 20-pin microcontroller
function. The duty cycle for the PWM of the
which was previously been used. When power is
microcontroller used in the firing circuit is 92% to
given to microcontroller than it gives instructions to
obtain the boosted voltage of 30volts. PWM is used
do mechanical arming functions. Microcontroller will
for switching the MOSFET Q1 of the boost convertor
first give instruction to microactuator (SCB) for
circuit. Figure given shows the PWM waveform
arming and second firing instruction will given to
generation.
microinitiator (SCB) for exposion.
3) Accelerometer: It is used to detect force in x-axis
only of about 10g. When force s detected than sensor
input will be given to microcontroller to trigger OFF-
ON switch to discharge SCB.
4) Si-based safe initiator: It consists of two OFF-ON
switches with two SCB for arming and firing SCB.
We use electronic switches there.
III. FLOW CHART
Fig: PWM waveform
Capacitor continues to charge through PWM then
after a delay of 4 sec w give firing instruction to the
second SCB and explosion will be done. Figure
shown how the capacitor charging and discharging is
done.
Fig: simulation result of capacitor chargin
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IJEEDC, ISSN (P): 2320-2084, (O) 2321–2950, COE, Bharti Vidyapeeth, Deemed University, Pune, Special Issue-1 April-2015
CONCLUSION technology for making energetic microsystems: review
and prospective. Sensors and Actuators A Physical,
Elsevier, 2005, Volume120, (Issue 2), pp.Pages 297-310.
This paper describes the arming and disarming <hal-00150261>
function of safe, arm and fire device. The MEMS [2] Integration of MEMS based safe arm and fire device by
SAF device previously designed used 20-pin Helene Pezous, Carole Rossi, Marjorie Sanchez, Fabrice
Mathieu, Xavier Dollat, Samuel Charlot, Ludovic
microcontroller so it took more space. As, today is
Salvagnac, Veronique Conedera.
the age of miniaturization we obtain it by using a 6- [3] Fabrication of Fuze Micro-electro-mechanical System
pin microcontroller. Hence, it fulfills the requirement Safety Device by DU Liqun, JIA Shengfang, NIE
of compactness, reliability and speed. By using SCB Weirong, and WANG Qijia.
instead of resistances we get our system more [4] J. D. Kim, Modeling of the current density distribution in a
heavily doped semiconductor bridge, International Journal
compact, safe with fast ignition time. of Electronics, Vol. 80, No.5, 623-628 (1996).
[5] Virendra Kumar, Semiconductor Bridge (SCB) detonator and
Table I : Specifications its applications, 8th National Seminar & Exhibition on
Aerospace Related Mechanisms at ARDE during 06 -08
Dec 2012.
[6] Fabrication, assembly & tests of a MEMS based safe, Arm
& Fire device by Hélène Pezous, Marjorie Sanchez,
Fabrice Mathieu, Xavier Dollat, Samuel Charlot,
CaroleRossi.
[7] Materials, Fabrication and Assembly technologies for
advanced MEMS based safety and arming mechanism for
projectile munitions by C. H. Robinson*, T. Q. Hoang, M.
R. Gelak, G. L. Smith, R. H. Wood.
[8] Micropyrotechnics, a new technology for making energetic
ACKNOWLEDGEMENT microsystems: review and prospective by Carole Rossi,
Daniel Esteve.
The completion of this paper would not have been [9] Ultra miniature electro-mechanical safety and arming device
possible without support and guidance of Dr. by C. H. Robinson*, T. Q. Hoang, M. R. Gelak, G. L.
Smith, R. H. Wood.
Virendra Kumar, Scientist 'F', from ARDE DRDO [10] Semiconductor bridge (SCB) igniter, U.S.Patent by Robert
Pashan, Pune. This paper would not have been W. Bickes, Jr.; Alfred C.Schwarz.
possible without his guidance and support as he has [11] K. Hodge et al. 2002 MEMS arm fire and safe and arm
given his valuable time from his busy schedule. devices, US Patent number 6,431,071B1.
[12] C. Rossi 1997 Conception and realisation of a fluidic
microsystem suitable for transdermal drug delivery device
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[1] Carole Rossi, Daniel Esteve. Micropyrotechnics, a new
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