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

Implementation of the code for controlling the retraction and extension of airplane’s landing gear

Aim:

• To implement the code for control retraction and extension of airplanes landing gear implementation using Finite State Machine (FSM).

Objective:

• Controlling the direction of valve.
• Controlling the retraction and extension of airplane’s landing gear.

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.

Process:

• Gear down
• Checking before take off
• Raising gear
• Gear up
• Checking before landing
• Lowering gear

State Type	Switch Status	Pilot Lever Status	Hydraulic Mechanics Status
GR_DWN	Open	Rising	Working
CHK_BFR_TKFF	Close	Falling	Malfunctioning
RSING_GR		Up
GR_UP		Down
CHK_BFR_LND
LWRNG_GR

Code:

Main1.c:

#include
#include "States.h"

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]();
 }
}



States.h:

#ifndef STATES_H_
#define STATES_H_

void Init_State_Machine();
void Gear_Down();
void Checking_Before_Takeoff();
void Raising_Gear();
void Gear_Up();
void Checking_Before_Landing();
void Lowering_Gear();

typedef enum State
{
 GR_DWN,
 CHK_BFR_TKFF,
 RSING_GR,
 GR_UP,
 CHK_BFR_LND,
 LWRNG_GR

}State_Type;

typedef enum Switch
{
 Open,
 Close

}Switch_Status;

typedef enum Pilot_Lever
{

 Rising,
 Falling,
 UP,
 DOWN

}Pilot_Lever_Status;

typedef enum Hydraulic_Mechanism
{
 Working,
 Malfunctioning

}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
{
 char* current_state_indication;
 char* light_status;
 char* direction_valve_status;
 char* hydraulic_pump_control_status;
 char* gas_pressurized_spring_status[2];
}State_Table;

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"}}

};

#endif




Init_State_Machine.c:

#include"States.h"

void Init_State_Machine()
{
 current_state = GR_DWN;
 printf("\nState Machine is initialized & Program is in Gear_Down State & Light Status: %s\n"
   ,State_Machine[current_state].light_status);
}




Gear _Down.c:

#include"States.h"
#include

void Gear_Down(void)
{
 current_state = GR_DWN;
 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 = CHK_BFR_TKFF;
  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();
 }
}




Checking_Before_Takeoff:

#include "States.h"
#include

void Checking_Before_Takeoff()
{
 current_state = CHK_BFR_TKFF;
 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("\nWait 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 = RSING_GR;
  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 = RSING_GR;
  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]);
 }
}




Rising_Gear.c:


#include"States.h"
#include

void Raising_Gear()
{
 current_state = RSING_GR;
 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 = CHK_BFR_LND;
  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 = GR_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();

 }

}



Gear_Up.c:

#include"States.h"
#include

void Gear_Up()
{
 current_state = GR_UP;
 printf("\nEnter the Pilot's Lever Position:");
 fflush(stdout);
 scanf("%d",&pilot_lever);
 if(pilot_lever == Falling)
 {
  current_state = CHK_BFR_LND;
  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();

 }
}


Check_Before_Landing:

#include "States.h"
#include
void Checking_Before_Landing()
{
 current_state = CHK_BFR_LND;
 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 = LWRNG_GR;
  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 = LWRNG_GR;
  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();
  }
}



Lowering_Gear.c:

#include "States.h"
#include
void Lowering_Gear()
{
 current_state = LWRNG_GR;
 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 = CHK_BFR_TKFF;
  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 = GR_DWN;
  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();
 }

}

Program:

Main1.c:

States.h:

Initial State Machine.c:

Gear Down.c:

Checking Before Taking Off:

Rising Gear:

Checking Before Landing:

Lowering Gear:

Output:

Main1.c:

• State table conditions are declared in main1.c.

States.h:

• Static table functions are defined in this header file of states.
• It consists of the various states of  retraction and extension of airplanes landing gear modes.

States:

GR_DWN
CHK_BFR_TKFF
RSING_GR
GR_UP
CHK_BFR_LND
LWRNG_GR

Switch state:

Open
Close

Pilot lever state:

Rising
Falling
UP
DOWN

Hydraulic mechanism:

Working
Malfunctioning