MATLAB AND SIMULINK BASED IMPLEMENTATION OF

GUIDANCE AND CONTROL OF WEAPON SYSTEM

By,CH.PRAVALLIKAG.SAKETHG.SAMPREETH

MISSILE

SIMULATION BLOCK DIAGRAM

TRAJECTORY ELEVATOR

A Trajectory elevator modifies h as a function of time . At the start of the flight, it rises the weapon trajectory approximately 1.2m above the sighting axis . This value(ho) progressively drops, to reach 0.5m at the end of the flight.These signals are fed to the compensating network.

COMPENSATING NETWORK

A compensating network consists of two blocks: (a) A Phase Lag-Lead Network to ensure that trajectory settles to the one that is desired. (b) A High Frequency filter to filter out the voltage generated due to high frequency noise in the surroundingsSignificance: This block ensures that the weapon trajectory settles to one that is desired.

MULTIPLIERThe multiplier linearly amplifies the signal elaborated by the compensating networks, in order to compensate the stability of weapon.The stability increases with the flight time,due to the shifting of the centre of gravity and to the increasing speed during the flight.During the course of flight, fuel is burnt, thereby reducing the weight of the weapon and changing the position of centre of gravity. Significance: A multiplier, again a time dependent function (starts only after second reference pulse is received), supplies the required acceleration to counter this effect of stability, thereby, increasing the controllability.

GRAVITY COMPENSATOR

In order to compensate the attraction of the Earth,an additional weight compensating signal is injected into the elevation channel. A weapon is under the constant influence of gravity, i.e. it has a tendency to go down. Hence, a counter upward thrust is required to ensure that it does not fall down.However, as the weight of the weapon decreases during the course of flight, a lesser upward thrust is required.Significance: This block ensures that the required upward thrust decreases with respect to time.

COORDINATE CONVERTER

This assembly converts the Cartesian coordinates signal μy and μh into polar coordinates(Uα and Uρ).

PUSH PULL

AMPLIFIER

PHASEDETECT

OR

PHASEDETECT

OR

FILTER

FILTER

PULSE COMPUTERDue to the time lag between pulse transmission and jet deflector response,the control command is elaborated.As a result no accidental command pulses can be elaborated,due to the jamming during the launching phase.To this end,the computer is inhibited upto 2nd reference pulse(2nd weapon revolution) till then ,the weapon remains unguided.

INPUTS TO THE COMPENSATING NETWORKDELTA H VS TIME

DELTA H0 VS TIME

DELTA Y VS TIME

OUTPUT STAGEOutput stage consists of three blocks: (a) Elevation limiter to cancel any down commands to the weapon (b) Non-linearity Circuit to account for the time lag in the propagation of commands over the wire to the weapon (c) Co-ordinate Converter to convert the Voltage Levels of the commands to relevant angles, and subsequently, to time.

6 DEGREE OF FREEDOM SIMULATOR

It simulates the weapon dynamics, i.e., it is a mathematical model of the weapon when subjected to different forces and moments. When the commands from guidance electronics unit are received, they are translated to the relevant time dependent forces and moments in the weapon. This causes a change in position of the weapon, thereby, generating new values of Δh and Δy.These new values are again fed to the guidance electronics unit, and a loop is formed until the end of flight.

POWER SUPPLYThe firing unit is electrically supplied by the thermal battery contained in the junction unit,via the 12 pin weapon unit connector.From this supply,the guidance electronics elaborates the voltage is requires:±15v,for analog elements±10v,for reference voltages±22v,for the final stage±5v,for digital elements