Challenge

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

KKamlesh Sonawane15 Sept 2022

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

Answer :-

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 :-

Main.c :-

#include //PREPROCESSOR//
#include "State.h" //HEADER FILE INCLUDING//

static void (*state_table[])(void) = {gear_down, checking_before_takeoff, raising_gear,
gear_up, checking_before_landing, lowering_gear}; //DECLARING VARIABLES TO STATE TABLE//

int main() //MAIN FUNCTION//
{
init_state_machine(); //INITIALIZE STATE MACHINE//
while(1) //WHILE LOOP//
{
state_table[current_state](); //CALLING STATE TABLE//
}
}

State.h :-

#ifndef STATE_H_ //INCLUDING HEADER FILE//
#define STATE_H_

void init_state_machine(); //FUNCTION DECLARING INITIAL STATE MACHINE//
void gear_down(); //FUNCTION DECLARING GEAR DOWN//
void checking_before_takeoff(); //FUNCTION DECLARING CHECKING BEFORE TAKE OFF//
void raising_gear(); //FUNCTION DECLARING RISING GEAR//
void gear_up(); //FUNCTION DECLARING GEAR UP//
void checking_before_landing(); //FUNCTION DECLARING CHECKING BEFORE LANDING//
void lowering_gear(); //FUNCTION DECLARING LOWERING GEAR//

typedef enum state //TYPEDEF ENUM FUNCTION TO DEFINE STATE TYPE//
{

gr_dwn,
chk_bfr_tkof,
rsing_gr,
gr_up,
chk_bfr_lnd,
lwrng_gr

}state_type;

typedef enum Switch //TYPEDEF ENUM FUNCTION TO DEFINE SWITCH//
{

open,
close

}Switch_status;

typedef enum pilot_lever //TYPEDEF ENUM FUNCTION TO DEFINE PILOT LEVER STATUS//
{

rising,
falling,
up,
down

}pilot_lever_status;

typedef enum hydraulic_mechanism //TYPEDEF ENUM FUNCTION TO DEFINE HYDRAULIC MECHANISM STATUS//
{

working,
malfunctioning

}hydraulic_mechanism_status;

static volatile Switch_status squat_switch; //INPUT VARIABLE FOR CHANGING THE STATES//
static volatile Switch_status limit_switch; //INPUT VARIABLE FOR CHANGING THE STATES//
static volatile pilot_lever_status pilot_lever; //INPUT VARIABLE FOR CHANGING THE STATES//
static volatile hydraulic_mechanism_status hydraulic_mechanism; //INPUT VARIABLE FOR CHANGING THE STATES//

state_type current_state; //DEFINING CURRENT STATE AS STATE TYPE//

typedef struct //DEFINING STATE TABLE VARIABLES AS TYPEDEF STRUCTURE WITH CHARACTER DATATYPE//
{
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"}}
}; //STATE TABLE ARRAY DECLARATION//
#endif /* STATES_H_ */ //END OF HEADER FILE//

Init State Machine.c :-

#include "State.h" //INCLUDING HEADER FILE//

void init_state_machine() //FUNCTION INITIAL STATE MACHINE CALLED//
{

current_state = gr_dwn; //ASSIGNING CURRENT STATE TO LOWERING GEAR//
printf("\n state machine is initialized & program is in gear down state & light status:%s\n",state_machine[current_state].light_status); //DISPLAY LIGHT STATE//

}

Gear Down.c :-

#include "State.h" //INCLUDING HEADER FILE//
#include //PREPROCESSOR//

void gear_down(void) //FUNCTION GEAR DOWN CALLED//
{

current_state=gr_dwn; //ASSIGNING CURRENT STATE TO GEAR DOWN//
printf("\ncurrent state: %s\n",state_machine[current_state].current_state_indication); //DISPLAY CURRENT STATE//

printf("\nenter the pilot lever position & squat switch status:"); //PRINT THE MESSAGE//
fflush(stdout); //CLEAR CACHE MEMORY//
scanf("%d %d",&pilot_lever,&squat_switch); //READS AND STORES THE DATA//

if(pilot_lever==rising && squat_switch==open) //IF CONDITION TO CHECK THE CONDITIONS//
{

current_state = chk_bfr_tkof; //IF CONDITION IS TRUE ASSIGN CURRENT STATE TO CHECK BEFORE TAKEOFF//
printf("\ncurrent state: %s\n",state_machine[current_state].current_state_indication); //DISPLAY CURRENT STATE//
printf("\nlight status: %s\n",state_machine[current_state].light_status); //DISPLAY LIGHT STATE//

}

else //IF CONDITIONS ARE NOT SATISFIED GO TO GEAR DOWN FUNCTION//
{
gear_down(); //REPEAT//
}
}

Checking Before Takeoff.c :-

#include "State.h" //INCLUDING HEADER FILE//
#include //PREPROCESSOR//

void checking_before_takeoff() //FUNCTION CHECKING BEFORE LANDING CALLED//
{

current_state=chk_bfr_tkof; //ASSIGNING CURRENT STATE TO CHECK BEFORE TAKEOFF//
printf("\ncurrent state: %s\n",state_machine[current_state].current_state_indication); //DISPLAY CURRENT STATE//

printf("\nenter the pilot lever position,squat switch status & status of hydraulic mechanism:"); //PRINT THE MESSAGE//
fflush(stdout); //CLEAR CACHE MEMORY//
scanf("%d %d %d",&pilot_lever,&squat_switch,&hydraulic_mechanism); //READS AND STORES THE DATA//
printf("\nwait for 2 secs\n"); //PRINT THE MESSAGE//

if(pilot_lever==falling || squat_switch==close) //IF CONDITION TO CHECK THE CONDITIONS//
{
gear_down(); //IF CONDITION IS TRUE GO TO GEAR DOWN FUNCTION//
}

else if(pilot_lever==up && squat_switch==open && hydraulic_mechanism==working) //NESTED IF CONDITION TO CHECK OTHER CONDITION//
{

current_state = rsing_gr; //IF CONDITION IS TRUE ASSIGN CURRENT STATE TO RISING GEAR//
printf("\ncurrent state: %s\n",state_machine[current_state].current_state_indication); //DISPLAY CURRENT STATE//
printf("\nlight status: %s\n",state_machine[current_state].light_status); //DISPLAY LIGHT STATE//
printf("direction valve status:%s\n",state_machine[current_state].direction_valve_status); //DISPLAY DIRECTION VALVE STATUS//

}

else if(pilot_lever==up && squat_switch==open && hydraulic_mechanism==malfunctioning) //NESTED IF CONDITION TO CHECK OTHER CONDITION//
{

printf("\nlight status: %s\n",state_machine[current_state].light_status); //DISPLAY LIGHT STATE//
printf("direction valve status:%s\n",state_machine[current_state].direction_valve_status); //DISPLAY DIRECTION VALVE STATUS//
printf("gas pressurized spring status:%s\n",state_machine[current_state].gas_pressurized_spring_status[hydraulic_mechanism]); //DISPLAY GAS PRESSURIZED SPRING STATUS//

}
}

Rising Gear.c :-

#include "State.h" //INCLUDING HEADER FILE//
#include //PREPROCESSOR//

void raising_gear() //FUNCTION RAISING GEAR CALLED//
{

current_state=rsing_gr; //ASSIGNING CURRENT STATE TO RISING GEAR//
printf("\n current state: %s\n",state_machine[current_state].current_state_indication); //DISPLAY CURRENT STATE//

printf("\n enter the limit switch status,pilot lever position:"); //PRINT THE MESSAGE//
fflush(stdout); //CLEAR CACHE MEMORY//
scanf("%d %d",&pilot_lever,&limit_switch); //READS AND STORES THE DATA//
printf("\n wait for 1 sec\n"); //PRINT THE MESSAGE//

if(pilot_lever==falling && limit_switch==open) //IF CONDITION TO CHECK THE CONDITIONS//
{

current_state = chk_bfr_lnd; //IF CONDITION IS TRUE ASSIGN CURRENT STATE TO CHECK BEFORE LANDING//
printf("\ncurrent state: %s\n",state_machine[current_state].current_state_indication); //DISPLAY CURRENT STATE//
printf("\nlight status: %s\n",state_machine[current_state].light_status); //DISPLAY LIGHT STATE//
printf("hydraulic control for landing gear status:%s\n",state_machine[current_state].hydraulic_pump_control_status); //DISPLAY HYDRAULIC PUMP CONTROL STATUS//

}

else if(pilot_lever==up && limit_switch==close) //NESTED IF CONDITION TO CHECK OTHER CONDITION//
{

current_state=gr_up; //IF CONDITION IS TRUE ASSIGN CURRENT STATE TO GEAR UP//
printf("\ncurrent state: %s\n",state_machine[current_state].current_state_indication); //DISPLAY CURRENT STATE//
printf("\nlight status: %s\n",state_machine[current_state].light_status); //DISPLAY LIGHT STATE//
printf("hydraulic control for landing gear status:%s\n",state_machine[current_state].hydraulic_pump_control_status); //DISPLAY HYDRAULIC PUMP CONTROL STATUS//

}

else //IF CONDITIONS ARE NOT SATISFIED GO TO RAISING GEAR FUNCTION//
{
raising_gear(); //REPEAT//
}
}

Gear Up :-

#include "State.h" //INCLUDING HEADER FILE//
#include //PREPROCESSOR//

void gear_up() //FUNCTION GEAR UP CALLED//
{

current_state=gr_up; //ASSIGNING CURRENT STATE TO GEAR UP//
printf("\ncurrent state: %s\n",state_machine[current_state].current_state_indication); //DISPLAY CURRENT STATE//

printf("\nenter the pilot lever position:"); //PRINT THE MESSAGE//
fflush(stdout); //CLEAR CACHE MEMORY//
scanf("%d",&pilot_lever); //READS AND STORES THE DATA//

if(pilot_lever==falling) //IF CONDITION TO CHECK THE CONDITIONS//
{

}

else //IF CONDITIONS ARE NOT SATISFIED GO TO GEAR UP FUNCTION//
{
gear_up(); //REPEAT//
}
}

Checking Before Landing.c :-

#include "State.h" //INCLUDING HEADER FILE//
#include //PREPROCESSOR//

void checking_before_landing() //FUNCTION CHECKING BEFORE LANDING CALLED//
{

current_state=chk_bfr_lnd; //ASSIGNING CURRENT STATE TO CHECK BEFORE LANDING//
printf("\ncurrent state: %s\n",state_machine[current_state].current_state_indication); //DISPLAY CURRENT STATE//

printf("\nenter the pilot lever position & status of hydraulic mechanism:"); //PRINT THE MESSAGE//
fflush(stdout); //CLEAR CACHE MEMORY//
scanf("%d %d",&pilot_lever,&hydraulic_mechanism); //READS AND STORES THE DATA//

if(pilot_lever==down && hydraulic_mechanism==working) //IF CONDITION TO CHECK THE CONDITIONS//
{

current_state = lwrng_gr; //IF CONDITION IS TRUE ASSIGN CURRENT STATE TO LOWERING GEAR//
printf("\n current state: %s\n",state_machine[current_state].current_state_indication); //DISPLAY CURRENT STATE//
printf("\n light status: %s\n",state_machine[current_state].light_status); //DISPLAY LIGHT STATE//
printf("direction valve status:%s\n",state_machine[current_state].direction_valve_status); //DISPLAY DIRECTION VALVE STATUS//

}

else if(pilot_lever==down && hydraulic_mechanism==malfunctioning) //NESTED IF CONDITION TO CHECK OTHER CONDITION//
{

}

else if (pilot_lever == (up || rising || falling)) //NESTED IF CONDITION TO CHECK OTHER CONDITION//
{
checking_before_landing(); //REPEAT//
}
}

Lowering Gear.c :-

#include "State.h" //INCLUDING HEADER FILE//
#include //PREPROCESSOR//

void lowering_gear() //FUNCTION LOWERING GEAR CALLED//
{

current_state=lwrng_gr; //ASSIGNING CURRENT STATE TO LOWERING GEAR//
printf("\ncurrent state: %s\n",state_machine[current_state].current_state_indication); //DISPLAY CURRENT STATE//

printf("\nenter the limit switch status,pilot lever position:"); //PRINT THE MESSAGE//
fflush(stdout); //CLEAR CACHE MEMORY//
scanf("%d %d",&limit_switch,&pilot_lever); //READS AND STORES THE DATA//

if (limit_switch == close && pilot_lever==rising) //IF CONDITION TO CHECK THE CONDITIONS//
{
current_state = chk_bfr_tkof; //IF CONDITION IS TRUE ASSIGN CURRENT STATE TO CHECK BEFORE TAKEOFF//
printf("\ncurrent state: %s\n",state_machine[current_state].current_state_indication); //DISPLAY CURRENT STATE//
printf("\nlight state: %s\n",state_machine[current_state].light_status); //DISPLAY LIGHT STATE//
}

else if(limit_switch==open && pilot_lever==down) //NESTED IF CONDITION TO CHECK OTHER CONDITION//
{
current_state = gr_dwn; //IF CONDITION IS TRUE ASSIGN CURRENT STATE TO GEAR DOWN//
printf("\ncurrent state: %s\n",state_machine[current_state].current_state_indication); //DISPLAY CURRENT STATE//
printf("\nlight status: %s\n",state_machine[current_state].light_status); //DISPLAY LIGHT STATE//
printf("hydraulic control for landing gear status:%s\n",state_machine[current_state].hydraulic_pump_control_status); //DISPLAY HYDRAULIC PUMP CONTROL STATUS//
}

else //IF CONDITIONS ARE NOT SATISFIED GO TO LOWERING GEAR FUNCTION//
{
lowering_gear(); //REPEAT//
}
}

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

Init_State_machine.c :-

After inititializing the code ,current state is in Gear Down with green light.

state machine is initialized & program is in gear down state & light status:green

INITIAL CONDITION GEAR DOWN TO CHECK BEFORE TAKEOFF :-

state machine is initialized & program is in gear down state & light status:green

current state: geardown

enter the pilot lever position & squat switch status: 0 0

current state: checking before take off

light status: green

CHECK BEFORE TAKE OFF TO RAISING GEAR :-

current state: checking before take off

enter the pilot lever position,squat switch status & status of hydraulic mechanism:2 0 0

wait for 2 secs

current state: raising gear

light status: red
direction valve status:up

RAISING GEAR TO GEAR UP :-

current state: raising gear

enter the limit switch status,pilot lever position:2 1

wait for 1 sec

current state: gear up

light status: off
hydraulic control for landing gear status:disabled

GEAR UP TO CHECK BEFORE LANDING :-

current state: gear up

enter the pilot lever position:1

current state: checking before landing

light status: red
hydraulic control for landing gear status:enabled

current state: checking before landing

CHECK BEFORE LANDING TO LOWERING GEAR :-

current state: checking before landing

enter the pilot lever position & status of hydraulic mechanism:3 1

current state: lowering gear

light status: green
direction valve status:down
gas pressurized spring status:enabled

current state: lowering gear

LOWERING GEAR TO GEAR DOWN :-

current state: lowering gear

enter the limit switch status,pilot lever position:0 3

current state: geardown

light status: green
hydraulic control for landing gear status:enabled

current state: geardown

LOWERING GEAR TO TAKE OFF :-

current state: lowering gear

enter the limit switch status,pilot lever position:1 0

current state: checking before take off

light state: green

current state: checking before take off

RISING GEAR TO CHECK BEFORE LANDING :-

current state: raising gear

enter the limit switch status,pilot lever position:1 0

wait for 1 sec

current state: checking before landing

light status: red
hydraulic control for landing gear status:enabled

current state: checking before landing

OVERVIEW OF THE PROJECT:-

The project is to know the knowledge of retraction and extensions of landing gear using a code.
This can be achieved by using finite state machine which is used in the states header file.
FSM (Finite state machine) is a mathematical model of computation.
It is the most efficient algorithm which can be used.
The creation of source file helps us easy to understand the program.

GOALS:-

The main goals are to control the direction of valve and retraction and extension of landing gear.
The control of direction valve is controlled by pilot lever which we can see in the program (reference given in attachment provided).
The retraction and extension of landing gear is controlled by switch states in the program.
Hence, all the goals are achieved.

KEY HIGHLIGHTS OF PROJECT:-

We can observe that the direction valve helps us to raise or lower the landing gear.
The direction valve is controlled by the software.
With the help of this software we control the hydraulic mechanism.
The hydraulic pump controls the raising or lowering of the landing gear.
The hydraulic mechanism helps us to land and take off of the airplane.

DELIVERABLES OF THIS PROJECT:-

The retraction and extension of landing gears is controlled by various switch and gear.
The status of these switches and gears are shown below in various tables.

Table1:-

Switch State	State of Gears
Limit Switch CLOSED	Gear is UP
Limit Switch OPENED	Gear is DOWN
Switch State	State of Airplane
Squat Switch CLOSED	Airplane is grounded and Gears are locked
Squat Switch OPENED	Airplane is taking off / landing / airborne

A direction valve is controlled by the software to allow hydraulic pressure to either raise or lower the landing gear.

Table 2:-

Status of Direction Valve	States of landing gear
Direction valve = Down	(Gear Down)(Parked at bay or Landed)
Direction valve = Up	Raising Gear(Taking Off)
Control of hydraulic pump for the landing gear part is disabled	Gear Up(Airborne)
Direction valve = down	Lowering Gear(Landing)

INPUT FOR THE DIRECTION VALVE:-

Table 3:-

Pilot’s Lever State	Direction Valve State
Lever UP	Direction valve = Up
Lever Down	Direction valve = Down

Table 4:-

Pilot’s Lever State	Light Status
Lever Rising Edge	Red
Lever Falling Edge	Red

Table 5:-

Every gear has one light. According to the state of the gear,color of light is changing.

Landing Gear State	Light Status
Gear is up	OFF
Gear is down	Green
Gear in transit(Raising or Lowering)	Red

EXPECTED OUTCOMES:-

In this project we get a good knowledge about the finite state machine algorithm.
This algorithm helps us to achieve the control over the retraction and extension of airplane's landing gear.
The switch states and gear states of airplane plays a major role in control of retraction and extension.
The project has a easy logics which is shown in flowchart diagram which makes it easy and interesting.
All the .c files, .h file and screenshots of outputs are uploaded for the reference.

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

Ship work like this
in your own course.

Talk to a career counsellor

Ship work like thisin your own course.

Talk to a career counsellor

Ship work like this
in your own course.