Project 2 - Implement the Code for controlling the retraction and extension of Airplane’s landing gear
For this Project, the Chosen Algorithm is the Finite State Machine ( Mealy type).
Since, the implementation of the Control Mechanism of Retraction and extension of Airplane's landing gear is consisting varios state writing a code using the Finite State Machine is the best Algorithm that can be chosen
//Project2-Abinaya Inbamani
#include<stdio.h>
#include<stdlib.h>
//All the States related to the state machine are initialized here
void Initial_state_machine();
void Gear_down();
void Checking_before_takeoff();
void Raising_gear();
void Gear_up();
void Checking_before_landing();
void Lowering_gear();
//These are the parametric values assigned to each state
typedef enum states
{
GEAR_DOWN,
CHECK_BEFORE_TAKEOFF,
RAISING_GEAR,
GEAR_UP,
CHECK_BEFORE_LANDING,
LOWERING_GEAR
}state_type;
//The respected enum values
typedef enum Switch
{
open, close
}switch_status;
typedef enum pilot_lever
{
raising, falling, up, down
}pilot_lever_status;
typedef enum hydraulic_mechanism
{
working, malfunctioning
}hydraulic_mechanism_status;
//The enum values are getting linked here for the state machine operation
static volatile switch_status squat_switch;
static volatile switch_status limit_switch;
static volatile pilot_lever_status pilot_lever;
static volatile pilot_lever_status hydraulic_mechanism;
state_type current_state;
//The definition for the state table
typedef struct
{
char* current_state_status;
char* light_status;
char* direction_valve_status;
char* hydraulic_pump_ctrl_status;
char* gas_pressurized_status[2];
}state_table;
static state_table state_machine[6]={
{"gear down","green","down", "enables",{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}}
};
static void(*State_Table[])(void)={Gear_down,Checking_before_takeoff,Raising_gear, Gear_up,Checking_before_landing, Lowering_gear};
//All the respective states are being defined with necessary conditions here
void Initial_state_machine()
{
current_state = GEAR_DOWN;
printf("\n state machine is initials and at first program is in gear down and its light status is:%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:\n");
fflush(stdout);
scanf("%d %d", &pilot_lever,&squat_switch);
if(pilot_lever == raising && squat_switch == open)
{
current_state = CHECK_BEFORE_TAKEOFF;
printf("\n The current state of the machine is: %s\n",state_machine[current_state].current_state_status);
printf("\n Light status of the current machine state is :%s\n",state_machine[current_state].light_status);
}
}
void Checking_before_takeoff()
{
current_state = CHECK_BEFORE_TAKEOFF;
printf("\n Enter the pilot lever position, squat switch and hydraulic mechanism:\n");
fflush(stdout);
scanf("%d %d %d",&pilot_lever, &squat_switch,&hydraulic_mechanism);
printf("\n just wait 2 secs\n");
if (pilot_lever == up && squat_switch ==close )
{
Gear_down();
}
else if (pilot_lever == up && squat_switch == open && hydraulic_mechanism == working)
{
current_state = RAISING_GEAR;
printf("\n Current state: %s\n", state_machine[current_state].current_state_status);
printf("\n light status: %s\n",state_machine[current_state].light_status);
printf("\n direction status:%s\n\n", state_machine[current_state].direction_valve_status);
printf("\n Gas pressurized status:%s\n", state_machine[current_state].gas_pressurized_status[hydraulic_mechanism]);
}
}
void Raising_gear()
{
current_state =RAISING_GEAR;
printf("\n Enter the switch status and pilot lever status:\n");
fflush(stdout);
scanf("%d %d",&limit_switch,&pilot_lever);
printf("\n wait for 1 sec\n");
if(pilot_lever == falling && limit_switch == open)
{
current_state = CHECK_BEFORE_LANDING;
printf("\n current state is:%s\n",state_machine[current_state].current_state_status);
printf("\n Light Status: %s\n",state_machine[current_state].light_status);
printf("\n hydraulic condition for landing gear status is%s\n",state_machine[current_state].hydraulic_pump_ctrl_status);
}
else if(limit_switch == close && pilot_lever == up)
{
current_state = GEAR_UP;
printf("\n current state is:%s\n",state_machine[current_state].current_state_status);
printf("\n Light status:%s\n", state_machine[current_state].light_status);
printf("\n Hydraulic condition for landing gear status is %s\n ",state_machine[current_state].hydraulic_pump_ctrl_status);
}
else
{
Raising_gear();
}
}
void Gear_up()
{
current_state = GEAR_UP;
printf("\n Enter the pilot lever position :\n");
fflush(stdout);
printf("%d",&pilot_lever);
if(pilot_lever == falling)
{
current_state = CHECK_BEFORE_LANDING;
printf("\n Current state :%s\n", state_machine[current_state].current_state_status);
printf("\n light status: %s\n", state_machine[current_state].light_status);
printf("\n Hydraulic condition for landing gear status is %s\n ", state_machine[current_state].hydraulic_pump_ctrl_status);
}
else
{
Gear_up();
}
}
void Checking_before_landing()
{
current_state = CHECK_BEFORE_LANDING;
printf("\n Enter the pilot lower position, status of hydraulic mechanism:\n");
fflush(stdout);
scanf("%d %d", &pilot_lever,&hydraulic_mechanism);
if(pilot_lever == down && hydraulic_mechanism == working)
{
current_state = LOWERING_GEAR;
printf("\n CURRENt state: %s\n", state_machine[current_state].current_state_status);
printf("\nlight status: %s\n", state_machine[current_state].light_status);
printf("\n direction status: %s \n\n",state_machine[current_state].direction_valve_status);
}
else if(pilot_lever == down && hydraulic_mechanism == malfunctioning)
{
current_state = LOWERING_GEAR;
printf("\n Current state: %s\n",state_machine[current_state].current_state_status);
printf("\nlight status :%s\n", state_machine[current_state].light_status);
}
}
void Lowering_gear()
{
current_state= LOWERING_GEAR;
printf("\n Enter the pilot lower position, limit switch:");
fflush(stdout);
scanf("%d %d",&pilot_lever,&limit_switch);
if(pilot_lever == raising && limit_switch == close)
{
current_state = CHECK_BEFORE_TAKEOFF;
printf("\n Current state: %s\n",state_machine[current_state].current_state_status);
printf("\nlight status :%s\n", state_machine[current_state].light_status);
}
}
//This is the main function in which the state machine is operated from
int main()
{
Initial_state_machine();
while(1)
{
State_Table[current_state]();
}
}