6. How are we going to build a more stable Loiter program? - The Idea.

Whenever we wish our drone/U.A.V. to loiter we load a waypoint (x,y,z where z is height) and call the Loiter flag (F_LOITER) along with it. On the remote of our U.A.V. its in the auto mode. The Loiter flag has a program which guides the U.A.V. We are going to bring changes in this program.

The basic idea is that whenever a waypoint is loaded for loiter, 8 more waypoints are calculated around it and loaded one after another. to calculate the waypoints we use Switch case in C language with the following logic:

1. We know - Sin of any angle = Perpendicular/Hypotenuse and Cos of any angle = Base/Hypotenuse
2. Therefore, Sin45 = 1/1.414 and Cos45 = 1/1.414 (root of 2 = 1.414)
3. Hence if we load a waypoint for eg (0,0) with waypoint/loiter radius 1000 meters then our code will look like this -

void loiter_routine()

{

struct relative3D myltrpnt;

loitercount++; //set_goal(GPSlocation, wp_to_relative(currentWaypointSet[waypointIndex]).loc)

switch(loitercount)

{

case 1:

myltrpnt.x= currentWaypointSet[waypointIndex].loc.x;

myltrpnt.y= currentWaypointSet[waypointIndex].loc.y + LOITER_RADIUS;

myltrpnt.z= currentWaypointSet[waypointIndex].loc.z;

break;

case 2:

myltrpnt.x= (currentWaypointSet[waypointIndex].loc.x)-(LOITER_RADIUS/(1.414));

myltrpnt.y= (currentWaypointSet[waypointIndex].loc.y)+(LOITER_RADIUS/(1.414));

myltrpnt.z= currentWaypointSet[waypointIndex].loc.z;

break;

case 3:

myltrpnt.x= currentWaypointSet[waypointIndex].loc.x - LOITER_RADIUS;

myltrpnt.y= (currentWaypointSet[waypointIndex].loc.y);

myltrpnt.z= currentWaypointSet[waypointIndex].loc.z;

break;

case 4:

myltrpnt.x= (currentWaypointSet[waypointIndex].loc.x)-(LOITER_RADIUS/(1.414));

myltrpnt.y= (currentWaypointSet[waypointIndex].loc.y)-(LOITER_RADIUS/(1.414));

myltrpnt.z= currentWaypointSet[waypointIndex].loc.z;

break;

case 5:

myltrpnt.x= (currentWaypointSet[waypointIndex].loc.x);

myltrpnt.y= currentWaypointSet[waypointIndex].loc.y - LOITER_RADIUS;

myltrpnt.z= currentWaypointSet[waypointIndex].loc.z;

break;

case 6:

myltrpnt.x= (currentWaypointSet[waypointIndex].loc.x)+(LOITER_RADIUS/(1.414));

myltrpnt.y= (currentWaypointSet[waypointIndex].loc.y)-(LOITER_RADIUS/(1.414));

myltrpnt.z= currentWaypointSet[waypointIndex].loc.z;

break;

case 7:

myltrpnt.x= (currentWaypointSet[waypointIndex].loc.x)+(LOITER_RADIUS/(1.414));

myltrpnt.y= currentWaypointSet[waypointIndex].loc.y;

myltrpnt.z= currentWaypointSet[waypointIndex].loc.z;

break;

case 8:

myltrpnt.x= (currentWaypointSet[waypointIndex].loc.x)+(LOITER_RADIUS/(1.414));

myltrpnt.y= (currentWaypointSet[waypointIndex].loc.y)+(LOITER_RADIUS/(1.414));

myltrpnt.z= currentWaypointSet[waypointIndex].loc.z;

loitercount =0;

break;

default:

break;

}

set_goal( GPSlocation, myltrpnt ) ;

}

5. First Test Flight of the U.A.V.

This was the first test flight of our U.A.V. it was done near the Temple of Saaketri (few minutes ahead of Sukhna Lake).

The fuselage of the bird is made of EPP foam. It has a wingspan of 1500 mm, we will use a 1200 MAH LIPO Battery (11.1 Volts and 120 grams) which will give us 15 minutes of flight (approx.). Attached to it is an Electronic Speed Controller (PWM) which controls the brush-less DC motor in the fuselage. The bird or the fuselage runs on four controls - 

1. Aileron
2. Elevator
3. Rudder and
4. Throttle

Check out the catch by our RC instructor (Daaman Joyia) in the end !!! Enjoy the flight !!!!