I need to learn how to use this code. I'm trying to implement it in MATLAB. I'm having trouble getting the plane to assume a higher altitude.

I'm having trouble getting the plane to assume a higher altitude. Can anyone please look for the comment in the top section that is associated with assigning a variable a value, remove the comment, and see what the software does? Thank you. I have never dealt with "handles" before, and I need a quick course on the subject.

pn=0;

pe=0;

pd=0;

phi=0;

theta=0;

psi=0;

handle=[];

%Simulation parameters

dpn=0.5; %Change in position.

dpsi=0.01; %Change in yaw angle.

simlength=150;%Number of Sim Steps

%Draw and update the plane's position.

for k = 1:simlength

pn = pn+dpn;

pe = pe+dpn;

%THE CODE THAT PRODUCES A PROBLEM IS BELOW

%pd = pd +.1;

psi = psi+dpsi;

%Draw or update the plane.

handle = drawPlaneBody(pn,pe,pd,phi,theta,psi,handle);

pause(0.1); %Pause to visualize the movement

end

function handle = drawPlaneBody(pn,pe,pd,phi,theta,psi,handle)

%define points on plane in local NED coordintates

NED = airplanepoints;

%rotate plane by (phi; theta; psi)

NED = rotate(NED, phi, theta, psi);

%translate plane to [pn; pe; pd]

NED = translate(NED, pn, pe, pd);

%transform vertices from NED to XYZ

R = [...

0, 1, 0;...

1, 0 , 0;...

0, 0, -1;...

];

XYZ = R* NED';

%plot plane

if isempty(handle)

handle = plot3(XYZ(1,:),XYZ(2,:),XYZ(3,:),'b');

xlim([-100 100]);

ylim([-100 100]);

zlim([0 100]);

grid on;%show grid

xlabel('X');ylabel('Y');zlabel('Z');%label axes

else

set(handle, 'XData', XYZ(1,:), 'YData',XYZ(2,:), 'ZData',XYZ(3,:));

drawnow

end

end

function XYZ = airplanepoints

%define points on the aircraft in local NED

XYZ = [...

0 0 0;%point1

-2 1 1;%point2

-2 1 -1;%point3

0 0 0;%point1

-2 -1 1;%point4

-2 -1 -1;%point5

0 0 0;%point1

-2 1 1;%point2

-2 -1 1;%point4

0 0 0;%point1

-2 1 -1;%point3

-2 -1 -1;%point5

0 0 0;%point1

-2 1 1;%point2

-18 0 0;%point6

-2 1 -1;%point3

-18 0 0;%point6

-2 -1 -1;%point5

-18 0 0;%point6

-2 -1 1;%point4

-18 0 0;%point6

-2 1 1;%point2

0 0 0;%point1

-5 0 0;%point7

-5 -10 0;%point8

-8 -10 0;%point9

-8 10 0;%point10

-5 10 0;%point11

-5 0 0;%point7

-15.5 0 0;%point12

-15.5 2 0;%point13

-17.5 2 0;%point14

-17.5 -2 0;%point15

-15.5 -2 0;%point16

-15.5 0 0;%point12

-18 0 0;%point6

-18 0 -3;%point17

-15.5 0 0;%point15

-18 0 0;%point16

];

end

function XYZ=rotate(XYZ,phi,theta,psi)

%define rotation matrix

R_roll = [

1, 0, 0;

0, cos(phi), -sin(phi);

0, sin(phi), cos(phi)];

R_pitch = [

cos(theta), 0, sin(theta);

0, 1, 0;

-sin(theta), 0, cos(theta)];

R_yaw = [

cos(psi), -sin(psi), 0;

sin(psi), cos(psi), 0;

0, 0, 1];

R = R_roll*R_pitch*R_yaw;

%rotate vertices

XYZ =R*XYZ';

XYZ = XYZ';

end

function XYZ = translate(XYZ, pn, pe, pd)

XYZ = XYZ' + repmat([pn;pe;pd],1,size(XYZ,1));

XYZ=XYZ';

end

Answer 1

[Manikanta Aditya]

Hi @DJ V

The issue you’re facing is due to the commented line of code that changes the altitude (pd) of the plane. If you uncomment the line pd = pd +.1;, the plane will start to change its altitude.

Here’s the code:

pn=0;
pe=0;
pd=0;
phi=0;
theta=0;
psi=0;
handle=[];
%Simulation parameters
dpn=0.5; %Change in position.
dpsi=0.01; %Change in yaw angle.
simlength=150;%Number of Sim Steps
%Draw and update the plane's position.
for k = 1:simlength
    pn = pn+dpn;
    pe = pe+dpn;
    pd = pd +.1; %Uncommented this line
    psi = psi+dpsi;
    %Draw or update the plane.
    handle = drawPlaneBody(pn,pe,pd,phi,theta,psi,handle);
    pause(0.1); %Pause to visualize the movement
end
% Rest of the code remains the same

As for the “handles”, in MATLAB, a handle is a variable that you can use to access graphics objects (like plots, lines, surfaces, etc.). In your code, handle is used to store the handle of the plot created by plot3 function.

This handle is then used to update the plot in subsequent iterations of the loop. If handle is empty (i.e., the plot has not been created yet), a new plot is created. Otherwise, the existing plot is updated with new data. This is done using the set function.

Hope this helps.

[DJ V]

Alright, I can get this to work using the line of code in the program. I have to subtract the incrementing value from the base value to get the plane to ascend into the sky It is the same problem I had when I drew the aircraft. I had to meke the peak of the tail negative to get it to show up in the logical place. Why is this? Why must I reverse the sign associated with the aircraft and its parts to get them to show up in the animation in the irght place? Why does the plane ascend if I increment the altitude (Y value) by subtracting the increment from the current value?

[DJ V]

The new code that works.

pn=0;

pe=0;

pd=0;

phi=0;

theta=0;

psi=0;

handle=[];

%Simulation parameters

dpn=0.5; %Change in position.

dpsi=0.01; %Change in yaw angle.

simlength=150;%Number of Sim Steps

%Draw and update the plane's position.

for k = 1:simlength

pn = pn+dpn;

pe = pe+dpn;

%THE CODE THAT PRODUCES A PROBLEM IS BELOW

pd = pd -1;

psi = psi+dpsi;

%Draw or update the plane.

handle = drawPlaneBody(pn,pe,pd,phi,theta,psi,handle);

pause(0.1); %Pause to visualize the movement

end

[Manikanta Aditya]

Thanks for sharing @DJ V!