Project 2 - Implement the Code for controlling the retraction and extension of Airplane’s landing gear

/*
Project 2 - Implement the Code for controlling the retraction and extension of the Airplane’s landing gear
*/

/*

To implement the Code for controlling the retraction and extension of an Airplane’s landing gear we will be using the Finite State Machine concept to make State Diagram and then State Table to make our algorithm and then implement that using c code.

Actually, an airplane has 3 gears for landing :
• Nose Gear
• Left Gear
• Right Gear
There is a hydraulic pump which is exerting pressure on the gears to bring them down or pull them up and that pump is electrically driven.

Here I am considering the following scenario:

6 Output States of the Machine( GearDown, DelayBeforeTakeOff, RaisingGear, GearUp, CheckBeforeLanding, LoweringGear).

3 status of indicator Light (Red, Green, OFF)

4 states of control input lever (Raising, Up, Falling, Down)

2 states of the limit switch (On, Off):- Every leg of the gear has one limit switch.

2 states of the squat switch (On, Off):- Nose gear has one Squat Switch to determine whether the airplane
is in the ground or not.

4 states of direction valve (Up, Down, Enable, Disable):- A direction valve is controlled by the software to allow the hydraulic pressure to either raise or lower the landing gear

*/

State Diagram

State Table

Current State	Lever Control Input	Next State	Light	Limit Switch	Squat Switch	Direction Valve
Gear Down	Raising	Delay 4 sec before Take Off	Green	Open	Open	Down
Delay 4 sec before Take Off	Up	Raising Gear	Red	Open	Open	Up
Delay 4 sec before Take Off	Falling	Gear Down	Red	Open	Close	Down
Raising Gear	Up	Gear Up (Airborne)	Off	Closed	Open	disable
Raising Gear	Falling	Check before Landing	Red	Open	Open	Down
Gear Up (Airborne	Falling	Check before Landing	Red	closed	Open	enable
Check before Landing	Down	Lowering Gear	Red	open	open	Down
Lowering Gear	Down	Gear Down	Green	open	close	Down
Lowering Gear	Raising	Delay 4 sec before Take Off	Red	open	open	down

CODE:

#include<stdio.h>

typedef enum
{
Raising, Up, Falling, Down
}Lever;

typedef enum
{
GearDown, DelayBeforeTakeOff, RaisingGear,
GearUp, CheckBeforeLanding, LoweringGear
}State;

int main()
{
int input;
State Current_state = GearDown; // by default

printf("\n Different Lever control inputs for landing gear are as follows:");
printf("\n Enter '0' for Raising");
printf("\n Enter '1' for Up");
printf("\n Enter '2' for Falling");
printf("\n Enter '3' for Down");

while(1)
{
//for taking lever input
printf("\n Enter Lever Control Input: ");
fflush(stdout);
scanf("%d",&input);
fflush(stdin);

if((Current_state == GearDown)&&(input==Raising))
{
printf("\n Current State = waiting for 4 second before Take Off");
printf("\n Light = Green");
printf("\n Limit Switch => Open");
printf("\n Squat Switch => Open");
printf("\n Valve Direction => Down");
Current_state = DelayBeforeTakeOff;
printf("\n \n \n");
}

else if((Current_state == DelayBeforeTakeOff)&&(input==Up))
{
printf("\n Current State = Raising Landing Gear");
printf("\n Light = Red");
printf("\n Limit Switch => Open");
printf("\n Squat Switch => Open");
printf("\n Valve Direction => Up");
Current_state = RaisingGear;
printf("\n \n \n");
}

else if((Current_state == DelayBeforeTakeOff)&&(input==Falling))
{
printf("\n Current State = Gear Down");
printf("\n Light = Red");
printf("\n Limit Switch => Open");
printf("\n Squat Switch => Close");
printf("\n Valve Direction => Down");
Current_state = GearDown;
printf("\n \n \n");
}

else if((Current_state == RaisingGear)&&(input==Up))
{
printf("\n Current State = Gear Up (Airborne)");
printf("\n Light = OFF");
printf("\n Limit Switch => Closed");
printf("\n Squat Switch => Open");
printf("\n Valve Direction => Disabled");
Current_state = GearUp;
printf("\n \n \n");
}

else if((Current_state == RaisingGear)&&(input==Falling))
{
printf("\n Current State = Checking Before Landing");
printf("\n Light = Red");
printf("\n Limit Switch => Open");
printf("\n Squat Switch => Open");
printf("\n Valve Direction => Down");
Current_state = CheckBeforeLanding;
printf("\n \n \n");
}

else if((Current_state == GearUp)&&(input==Falling))
{
printf("\n Current State = Checking Before Landing");
printf("\n Light = Red");
printf("\n Limit Switch => Closed");
printf("\n Squat Switch => Open");
printf("\n Valve Direction => Enabled");
Current_state = CheckBeforeLanding;
printf("\n \n \n");
}

else if((Current_state == CheckBeforeLanding)&&(input==Down))
{
printf("\n Current State = Lowering Landing Gear");
printf("\n Light = Red");
printf("\n Limit Switch => Open");
printf("\n Squat Switch => Open");
printf("\n Valve Direction => Down");
Current_state = LoweringGear;
printf("\n \n \n");
}

else if((Current_state == LoweringGear)&&(input==Down))
{
printf("\n Current State = Landing Gear Down");
printf("\n Light = Green");
printf("\n Limit Switch => Open");
printf("\n Squat Switch => Close");
printf("\n Valve Direction => Down");
Current_state = GearDown;
printf("\n \n \n");
}

else if((Current_state == LoweringGear)&&(input==Raising))
{
printf("\n Current State = Waiting for 4 seconds before Take Off");
printf("\n Light = Red");
printf("\n Limit Switch => Open");
printf("\n Squat Switch => Open");
printf("\n Valve Direction => Down");
Current_state = DelayBeforeTakeOff;
printf("\n \n \n");
}

else
{
printf("\n Wrong input Command Retry \n \n \n ");
}
}

return (0);
}

OUTPUT: