Project 2 - Implement the Code for controlling the retraction and extension of Airplane’s landing gear
Aim:
To implement the code for control retraction and extension of Airplane’s landing gear can be implemented using Finite State Machine (FSM).
Principle:
The airplane has three gears for landing such as nose gear, left gear and right gear.
There is a hydraulic pump which is exerting pressure tothe gears to bring it down or pull it up using electrical driven pump.
When the direction of the valve is down then it is landed or gear down position.
Similarly when the direction of valve is up then it is in rising gear or taking off.
When gear is up then light status is off.
Gear is down then the light status is green.
Gear is raising or lowering then the colour of light is red.
State diagram:
| state type | switch status | Plot lever status | Hydraulic mechanics status |
|
GEAR_DOWN |
OPEN | RISING | WORKING |
|
CHECK_BEFORE_TAKEOFF |
CLOSE | FSLLING | NOTWORKING |
| RAISING_GEAR | UP | ||
| GEAR_UP | DOWN | ||
| CHECK_BEFORE_LANDING | |||
| LOWERING_GEAR |
Code:
#include
#include
/*Function used in this project*/
void Init_State_Machine(); //function declartion
void Gear_Down();
void Checking_Before_Takeoff();
void Raising_Gear();
void Gear_Up();
void Checking_Before_Landing();
void Lowering_Gear();
typedef enum State //enum used to give subsequent value for each state
{
GEAR_DOWN,//GEAR_DOWN= 0
CHECK_BEFORE_TAKEOFF,//CHECK_BEFORE_TAKEOFF= 1
RAISING_GEAR,//RAISING_GEAR= 2
GEAR_UP,//GEAR_UP= 3
CHECK_BEFORE_LAND,//CHECK_BEFORE_LAND= 4
LOWERING_GEAR//LOWERING_GEAR= 5
}State_Type;
typedef enum Switch//enum switch is used for sebsequent value of switch
{
Open, //Open=0
Close //Close=1
}Switch_Status;
typedef enum Pilot_Lever
{
Rising, //Rising=0
Falling, //Falling=1
UP, //UP=2
DOWN //DOWN=3
}Pilot_Lever_Status;
typedef enum Hydraulic_Mechanism
{
Working, //Working=o
Malfunctioning//Malfunctioning=1
}Hydraulic_Mechanism_Status;
static volatile Switch_Status squat_switch;
static volatile Switch_Status limit_switch;
static volatile Pilot_Lever_Status pilot_lever;
static volatile Hydraulic_Mechanism_Status hydraulic_mechanism;
State_Type current_state;
typedef struct //structre is used to have different types of datatype
{
char* current_state_indication; //output which we want to visualize aregiven under structure as structure member
char* light_status;
char* direction_valve_status;
char* hydraulic_pump_control_status;
char* gas_pressurized_spring_status[2];
}State_Table;
/*State table of the requried system*/
static State_Table State_Machine[6] = {
{"GearDown","Green","Down","Enabled",{0,0}},
{"Checking Before Take Off","Green","Down","Enabled",{0,0}},
{"Raising Gear","Red","Up","Enabled",{"Disabled","Enabled"}},
{"Gear Up","Off","Null","Disabled",{0,0}},
{"Checking Before Landing","Red","Down","Enabled",{0,0}},
{"Lowering Gear","Green","Down","Enabled",{"Disabled","Enabled"}}
};
static void(*state_table[])(void) = {Gear_Down, Checking_Before_Takeoff,Raising_Gear,
Gear_Up, Checking_Before_Landing, Lowering_Gear};
int main()
{
Init_State_Machine();
while(1)
{
state_table[current_state]();
}
}
void Init_State_Machine()
{
current_state = GEAR_DOWN;
printf("\nState Machine is initialized & Program is in Gear_Down State & Light Status: %s\n"
,State_Machine[current_state].light_status);
}
void Gear_Down(void)
{
current_state = GEAR_DOWN;
printf("\n Enter the Pilot's Lever Position and Squat Switch Status:");
fflush(stdout);
scanf("%d %d",&pilot_lever,&squat_switch);
if(pilot_lever == Rising && squat_switch == Open)
{
current_state = CHECK_BEFORE_TAKEOFF;
printf("\nCurrent State: %s\n",State_Machine[current_state].current_state_indication);
printf("Light Status:%s\n", State_Machine[current_state].light_status);
}
else
{
Gear_Down();
}
}
void Checking_Before_Takeoff()
{
current_state = CHECK_BEFORE_TAKEOFF;
printf("\nEnter the Pilot's Lever Position,Squat Switch Status and Hydraulic Mechanism Status:");
fflush(stdout);
scanf("%d %d %d",&pilot_lever,&squat_switch,&hydraulic_mechanism);
printf("\n Wait for 2 secs\n");
if(pilot_lever == Falling || squat_switch == Close)
{
Gear_Down();
}
else if(pilot_lever == UP && squat_switch == Open && hydraulic_mechanism == Working)
{
current_state = RAISING_GEAR;
printf("\nCurrent State :%s\n",State_Machine[current_state].current_state_indication);
printf("Light Status: %s\n", State_Machine[current_state].light_status);
printf("Direction Valve Status:%s\n\n", State_Machine[current_state].direction_valve_status);
}
else if(pilot_lever == UP && squat_switch == Open && hydraulic_mechanism == Malfunctioning)
{
current_state = RAISING_GEAR;
printf("\nCurrent State :%s\n",State_Machine[current_state].current_state_indication);
printf("Light Status: %s\n", State_Machine[current_state].light_status);
printf("Direction Valve Status:%s\n", State_Machine[current_state].direction_valve_status);
printf("Gas Pressurized Spring System Status:%s\n",State_Machine[current_state].gas_pressurized_spring_status[hydraulic_mechanism]);
}
}
void Raising_Gear()
{
current_state = RAISING_GEAR;
printf("\nEnter the Limit Switch Status,Pilots Leaver Status:");
fflush(stdout);
scanf("%d %d",&limit_switch,&pilot_lever);
printf("\nWait for 1 sec\n");
if(pilot_lever == Falling && limit_switch == Open)
{
current_state = CHECK_BEFORE_LAND;
printf("\nCurrent State: %s\n",State_Machine[current_state].current_state_indication);
printf("Light Status:%s\n",State_Machine[current_state].light_status);
printf("Hydraulic Control for Landing Gear Status:%s\n",State_Machine[current_state].hydraulic_pump_control_status);
}
else if(limit_switch == Close && pilot_lever == UP)
{
current_state = GEAR_UP;
printf("\nCurrent State: %s\n",State_Machine[current_state].current_state_indication);
printf("Light Status: %s\n", State_Machine[current_state].light_status);
printf("Hydraulic Control for Landing Gear Status:%s\n", State_Machine[current_state].hydraulic_pump_control_status);
}
else
{
Raising_Gear();
}
}
void Gear_Up()
{
current_state = GEAR_UP;
printf("\nEnter the Pilot's Lever Position:");
fflush(stdout);
scanf("%d",&pilot_lever);
if(pilot_lever == Falling)
{
current_state = CHECK_BEFORE_LAND;
printf("\nCurrent State: %s\n",State_Machine[current_state].current_state_indication);
printf("Light Status:%s\n", State_Machine[current_state].light_status);
printf("Hydraulic Control for Landing Gear Status:%s\n",State_Machine[current_state].hydraulic_pump_control_status);
}
else
{
Gear_Up();
}
}
void Checking_Before_Landing()
{
current_state = CHECK_BEFORE_LAND;
printf("\nEnter the Pilot's Lever Position and Status of Hydraulic Mechanism:");
fflush(stdout);
scanf("%d %d",&pilot_lever,&hydraulic_mechanism);
if(pilot_lever == DOWN && hydraulic_mechanism == Working)
{
current_state = LOWERING_GEAR;
printf("\nCurrent State:%s\n", State_Machine[current_state].current_state_indication);
printf("Light Status:%s\n", State_Machine[current_state].light_status);
printf("Direction Valve Status:%s\n", State_Machine[current_state].direction_valve_status);
}
else if(pilot_lever == DOWN && hydraulic_mechanism == Malfunctioning)
{
current_state = LOWERING_GEAR;
printf("\nCurrent State:%s\n",State_Machine[current_state].current_state_indication);
printf("Light Status:%s\n", State_Machine[current_state].light_status);
printf("Direction Valve Status:%s\n", State_Machine[current_state].direction_valve_status);
printf("Gas Pressurized Spring System Status:%s\n",State_Machine[current_state].gas_pressurized_spring_status[hydraulic_mechanism]);
}
else if(pilot_lever == (UP || Rising || Falling))
{
Checking_Before_Landing();
}
}
void Lowering_Gear()
{
current_state = LOWERING_GEAR;
printf("\nEnter the Limit Switch Status,Pilots Leaver Status:");
fflush(stdout);
scanf("%d %d",&limit_switch,&pilot_lever);
if(limit_switch == Close && pilot_lever == Rising )
{
current_state = CHECK_BEFORE_TAKEOFF;
printf("\nCurrent State:%s\n",State_Machine[current_state].current_state_indication);
printf("Light Status:%s\n",State_Machine[current_state].light_status);
}
if(limit_switch == Open && pilot_lever == DOWN)
{
current_state = GEAR_DOWN;
printf("\nCurrent State:%s\n",State_Machine[current_state].current_state_indication);
printf("Light Status:%s\n",State_Machine[current_state].light_status);
printf("Hydraulic Controlfor Landing Gear Status:%s\n",State_Machine[current_state].hydraulic_pump_control_status);
}
else
{
Lowering_Gear();
}
}
Result:
This a program code is created to control retraction and extension of airplanes landing gear implementation using Finite State Machine (FSM).