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 ) ;

}