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

Aim:

In this project, controlling the retraction and extension of Airplane’s landing gear can be implemented using Finite State Machine (FSM). FSM is the most efficient algorithm which is mathematical model of computation.

Goals:

• Controlling the direction of Valve.
• Controlling the retraction and extension of Airplane’s landing gear.

Highlights of the Project:

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

Deliverables of this project:

Implementing the control for the retraction and extension of Airplane’s landing gear using the Finite state machine with the knowledge of various states of switch and gear.

Expected Outcomes:

The student will be getting the Knowledge of Finite State Machine algorithm which is used to achieve the control over the retraction and extension of Airplane’s landing gear using the switch and gear states of Airplane.

Steps to Design the Control of the Airplane by using FSM:

Step 1: We need to create a project and source file in the STM cube IDE.

Step 2: We need to declare required header files and the required function prototypes like "Gear_Down", "Checking_Before_Take_Off", "Raising_Gear", "Gear_Up", "Checking_Before_Landing" and "Lowering_Gear".

Step 3: Using user defined datatypes like typedef and enum we are declaring 4 enumerated datatypes named as "State_type", "Switch", "Pilot_lever" and "Hydraulic_mechanism".

Step 4: The enumerated variable "State_type" has predefined states like "GEAR_DOWN", "CHECKING_BEFORE_TAKE_OFF", "RAISING_GEAR", "GEAR_UP", "CHECKING_BEFORE_LANDING", "LOWERING_GEAR" and the enumerated variable "Hydraulic_mechanism" has predefined states like "WORKING" and "NOT_WORKING".

Step 5: The enumerated variable "Switch" has predefined states like "OFF", "ON" and the enumerated variable "Pilot_lever" has predefined states like "RAISING", "FALLING", "UP" and "DOWN".

Step 6: In this step we are creating two variables of enumerated datatype "Switch" with type qualifier as "volatile" and storage class as "static" and the variables are named as "Squat_Switch" and "Limit_Switch".

Step 7: Similar to Step 6 we are creating two variables of enumerated datatype "Pilot_lever" with type qualifier as "volatile" and storage class as "static" and the variables are named as "PL".

Step 8: Similar to Step 6 we are creating two variables of enumerated datatype "Hydraulic_mechanism" with type qualifier as "volatile" and storage class as "static" and the variables are named as "HM".

Step 9: A structure is created with alias name of "State" and inside structure we are creating 4 string variables like "Currentstate", "Light", "Direction_valve" and "Hydraulic_control".

Step 10: We are creating array of function pointers in order to store the 6 different functions and it is created with the storage class of "static", return type and arguments as "void".

Step 11: Now we are creating an array of structure with storge class as "static" and it is named as "State_Machine" with the array size of 6 and each index of array will be storing current state, light status, Direction valve and Hydraulic control status as outputs.

Step 12: In main function we are assigning the "GEAR_DOWN" state as the current state and Using infinite while loop we are calling the array of function pointers(State_Table[Current_state]()).

Step 13: In function definition of Gear_Down() we are assigning the "GEAR_DOWN" state as the current state and using scanf() function we are getting the values of Pilot lever and Squat_Switch.

Step 14: Using If condition we are checking the Pilot lever is equal to "RAISING" and Squat_Switch is equal to "ON" and if the condition is true then we are assigning the "CHECKING_BEFORE_TAKE_OFF" as the current state.

Step 15: Using printf() function we are printing the values of Currentstate, Light, Direction_valve and Hydraulic_control values. When the IF condition fails we are calling the same function "Gear_Down()".

Step 16: In function definition of Checking_Before_Take_Off() we are assigning the "CHECKING_BEFORE_TAKE_OFF" state as the current state and using scanf() function we are getting the values of Pilot lever, Squat_Switch and Hydraulic_mechanism.

Step 17: Using If condition we are checking the Pilot lever is equal to "FALLING" and Squat_Switch is equal to "OFF" and if the condition is true then we are assigning the "GEAR_DOWN" as the current state and printing the required outputs as mentioned in Step 15.

Step 18: In Else If part we are checking the Pilot lever is equal to "UP" and Hydraulic_mechanism is equal to "WORKING" and if the condition is true then we are assigning the "RAISING_GEAR" as the current state and printing the required outputs as mentioned in Step 15 and in else part we are calling the same function "Checking_Before_Take_Off()".

Step 19: In function definition of Raising_Gear() we are assigning the "RAISING_GEAR" state as the current state and using scanf() function we are getting the values of Pilot lever,Limit_Switch.

Step 20: Using If condition we are checking the Pilot lever is equal to "FALLING" and if the condition is true then we are assigning the "CHECKING_BEFORE_LANDING" as the current state and printing the required outputs as mentioned in Step 15.

Step 21: In Else If part we are checking the Limit_Switch is equal to "OFF" and if the condition is true then we are assigning the "GEAR_UP" as the current state and printing the required outputs as mentioned in Step 15 and in else part we are calling the same function "Raising_Gear()".

Step 22: In function definition of Gear_Up() we are assigning the "GEAR_UP" state as the current state and using scanf() function we are getting the values of Pilot lever.

Step 23: Using If condition we are checking the Pilot lever is equal to "FALLING" and if the condition is true then we are assigning the "CHECKING_BEFORE_LANDING" as the current state and printing the required outputs as mentioned in Step 15 and in else part we are calling the same function "Gear_Up()".

Step 24: In function definition of Checking_Before_Landing() we are assigning the "CHECKING_BEFORE_LANDING" state as the current state and using scanf() function we are getting the values of the pilot lever and Hydraulic_mechanism.

Step 25: Using If condition we are checking the Pilot lever is equal to "DOWN" OR Hydraulic_mechanism is equal to NOT_WORKING if the condition is true then we are assigning the "LOWERING_GEAR" as the current state and printing the required outputs as mentioned in Step 15 and in else part we are calling the same function "Checking_Before_Landing()".

Step 26: In function definition of Lowering_Gear() we are assigning the "LOWERING_GEAR" state as the current state and using scanf() function we are getting the values of the Pilot lever and Limit Switch.

Step 27: Using If condition we are checking the Limit_Switch is equal to "ON" and if the condition is true then we are assigning the "GEAR_DOWN" as the current state and printing the required outputs as mentioned in Step 15.

Step 28: In Else If part we are checking the Pilot lever is equal to "RAISING" and if the condition is true then we are assigning the "CHECKING_BEFORE_TAKE_OFF" as the current state and printing the required outputs as mentioned in Step 15 and in else part we are calling the same function "Lowering_Gear()".

Code:

/*

* Proj_2.c

*

* Created on: Aug 1, 2023

* Author: MD.Ansar

*/

#include <stdio.h>

#include <stdlib.h>

void Gear_Down(void);

void Checking_Before_Take_Off(void);

void Raising_Gear(void);

void Gear_Up(void);

void Checking_Before_Landing(void);

void Lowering_Gear(void);

typedef enum

{

GEAR_DOWN,

CHECKING_BEFORE_TAKE_OFF,

RAISING_GEAR,

GEAR_UP,

CHECKING_BEFORE_LANDING,

LOWERING_GEAR

}State_type;

typedef enum

{

OFF,

ON

}Switch;

typedef enum

{

RAISING,

FALLING,

UP,

DOWN

}Pilot_lever;

typedef enum

{

WORKING,

NOT_WORKING

}Hydraulic_mechanism;

static volatile Switch Squat_Switch;

static volatile Switch Limit_Switch;

static volatile Pilot_lever PL;

static volatile Hydraulic_mechanism HM;

State_type Current_state;

typedef struct

{

char* Currentstate;

char* Light;

char* Direction_valve;

char* Hydraulic_control;

}State;

static void(*State_Table[])(void)={Gear_Down,Checking_Before_Take_Off,Raising_Gear,Gear_Up,Checking_Before_Landing,Lowering_Gear};

static State State_Machine[6]={

{"Gear Down","Green","Down","Enabled"},{"Checking Before Take Off","Green","Down","Enabled"},

{"Raising Gear","Red","Up","Enabled"},{"Gear Up","off","Null","Disabled"},

{"Checking Before Landing","Red","Down","Enabled"},{"Lowering Gear","Green","Down","Enabled"}

};

int main()

{

Current_state = GEAR_DOWN;

while(1)

{

State_Table[Current_state]();

}

return 0;

}

Gear_Down()

{

Current_state = GEAR_DOWN;

printf("\nEnter the Pilot lever and Squat_Switch Values:");

fflush(stdout);

scanf("%d %d",&PL,&Squat_Switch);

if((PL==RAISING)&&(Squat_Switch==ON))

{

Current_state = CHECKING_BEFORE_TAKE_OFF;

printf("\nCurrent state: %s",State_Machine[Current_state].Currentstate);

printf("\nLight Status: %s",State_Machine[Current_state].Light);

printf("\nDirection_valve Status: %s",State_Machine[Current_state].Direction_valve);

printf("\nHydraulic_control Status: %s",State_Machine[Current_state].Hydraulic_control);

}

else

{

Gear_Down();

}

}

Checking_Before_Take_Off()

{

Current_state = CHECKING_BEFORE_TAKE_OFF;

printf("\nEnter the Pilot lever, Squat_Switch and Hydraulic_mechanism Values:");

fflush(stdout);

scanf("%d %d %d",&PL,&Squat_Switch,&HM);

if((PL==FALLING)&&(Squat_Switch==OFF))

{

Current_state = GEAR_DOWN;

printf("\nCurrent state: %s",State_Machine[Current_state].Currentstate);

printf("\nLight Status: %s",State_Machine[Current_state].Light);

printf("\nDirection_valve Status: %s",State_Machine[Current_state].Direction_valve);

printf("\nHydraulic_control Status: %s",State_Machine[Current_state].Hydraulic_control);

}

else if((PL==UP)&&(HM==WORKING))

{

Current_state = RAISING_GEAR;

printf("\nCurrent state: %s",State_Machine[Current_state].Currentstate);

printf("\nLight Status: %s",State_Machine[Current_state].Light);

printf("\nDirection_valve Status: %s",State_Machine[Current_state].Direction_valve);

printf("\nHydraulic_control Status: %s",State_Machine[Current_state].Hydraulic_control);

}

else

{

Checking_Before_Take_Off();

}

}

Raising_Gear()

{

Current_state = RAISING_GEAR;

printf("\nEnter the Pilot lever,Limit_Switch Values:");

fflush(stdout);

scanf("%d %d",&PL,&Limit_Switch);

if(PL==FALLING)

{

Current_state = CHECKING_BEFORE_LANDING;

printf("\nCurrent state: %s",State_Machine[Current_state].Currentstate);

printf("\nLight Status: %s",State_Machine[Current_state].Light);

printf("\nDirection_valve Status: %s",State_Machine[Current_state].Direction_valve);

printf("\nHydraulic_control Status: %s",State_Machine[Current_state].Hydraulic_control);

}

else if(Limit_Switch==OFF)

{

Current_state = GEAR_UP;

printf("\nCurrent state: %s",State_Machine[Current_state].Currentstate);

printf("\nLight Status: %s",State_Machine[Current_state].Light);

printf("\nDirection_valve Status: %s",State_Machine[Current_state].Direction_valve);

printf("\nHydraulic_control Status: %s",State_Machine[Current_state].Hydraulic_control);

}

else

{

Raising_Gear();

}

}

Gear_Up()

{

Current_state = GEAR_UP;

printf("\nEnter the Pilot lever Values:");

fflush(stdout);

scanf("%d",&PL);

if(PL==FALLING)

{

Current_state = CHECKING_BEFORE_LANDING;

printf("\nCurrent state: %s",State_Machine[Current_state].Currentstate);

printf("\nLight Status: %s",State_Machine[Current_state].Light);

printf("\nDirection_valve Status: %s",State_Machine[Current_state].Direction_valve);

printf("\nHydraulic_control Status: %s",State_Machine[Current_state].Hydraulic_control);

}

else

{

Gear_Up();

}

}

Checking_Before_Landing()

{

Current_state = CHECKING_BEFORE_LANDING;

printf("\nEnter the Pilot lever and Hydraulic_mechanism Values:");

fflush(stdout);

scanf("%d%d",&PL,&HM);

if((PL==DOWN)||(HM==NOT_WORKING))

{

Current_state = LOWERING_GEAR;

printf("\nCurrent state: %s",State_Machine[Current_state].Currentstate);

printf("\nLight Status: %s",State_Machine[Current_state].Light);

printf("\nDirection_valve Status: %s",State_Machine[Current_state].Direction_valve);

printf("\nHydraulic_control Status: %s",State_Machine[Current_state].Hydraulic_control);

}

else

{

Checking_Before_Landing();

}

}

Lowering_Gear()

{

Current_state = LOWERING_GEAR;

printf("\nEnter the Pilot lever and Limit Switch Values:");

fflush(stdout);

scanf("%d %d",&PL,&Limit_Switch);

if((Limit_Switch==ON))

{

Current_state = GEAR_DOWN;

printf("\nCurrent state: %s",State_Machine[Current_state].Currentstate);

printf("\nLight Status: %s",State_Machine[Current_state].Light);

printf("\nDirection_valve Status: %s",State_Machine[Current_state].Direction_valve);

printf("\nHydraulic_control Status: %s",State_Machine[Current_state].Hydraulic_control);

}

else if(PL==RAISING)

{

Current_state = CHECKING_BEFORE_TAKE_OFF;

printf("\nCurrent state: %s",State_Machine[Current_state].Currentstate);

printf("\nLight Status: %s",State_Machine[Current_state].Light);

printf("\nDirection_valve Status: %s",State_Machine[Current_state].Direction_valve);

printf("\nHydraulic_control Status: %s",State_Machine[Current_state].Hydraulic_control);

}

else

{

Lowering_Gear();

}

}

Output:

Enter the Pilot lever and Squat_Switch Values:0 1

Current state: Checking Before Take Off

Light Status: Green

Direction_valve Status: Down

Hydraulic_control Status: Enabled

Enter the Pilot lever, Squat_Switch and Hydraulic_mechanism Values:1 0 0

Current state: Gear Down

Light Status: Green

Direction_valve Status: Down

Hydraulic_control Status: Enabled

Enter the Pilot lever and Squat_Switch Values: 0 1

Current state: Checking Before Take Off

Light Status: Green

Direction_valve Status: Down

Hydraulic_control Status: Enabled

Enter the Pilot lever, Squat_Switch and Hydraulic_mechanism Values: 2 1 0

Current state: Raising Gear

Light Status: Red

Direction_valve Status: Up

Hydraulic_control Status: Enabled

Enter the Pilot lever,Limit_Switch Values: 1 1

Current state: Checking Before Landing

Light Status: Red

Direction_valve Status: Down

Hydraulic_control Status: Enabled

Enter the Pilot lever and Hydraulic_mechanism Values: 3 1

Current state: Lowering Gear

Light Status: Green

Direction_valve Status: Down

Hydraulic_control Status: Enabled

Enter the Pilot lever and Limit Switch Values: 0 1

Current state: Gear Down

Light Status: Green

Direction_valve Status: Down

Hydraulic_control Status: Enabled

Enter the Pilot lever and Squat_Switch Values: 1 0 0

Note: Project Related all the files had attached as per the discussion with Raju M I had got all the States, it has show in result as well in above screen shot also.