how to get each path point for uavDubinsConnection?

I am trying to turn my 2d dubins path to 3d by using the uavDubinsConnection code. My old code was;

dubinsSpace = stateSpaceDubins([0 500000; -100000 100000;-pi pi]); %In this line I determined the limits of the map

dubinsSpace.MinTurningRadius = 200;

pathobj = navPath(dubinsSpace);

append(pathobj,wayPoints); %waypoints is a matrix which consists 20 waypoints and corresponding angles

interpolate(pathobj,max(size(wayPoints))*10000); %in this line the code divides the path between two waypoints as the number ı have written

When I run this code ı get a pathobj and it has 3 properties in it, which are StateSpace, States ad NumStates.

For uavDubinsConnection I ran the code below.

connectionObj = uavDubinsConnection;

connectionObj.MaxRollAngle = deg2rad(5);

connectionObj.AirSpeed = 300;

for i = 1:1:39

pathSegObj = uavDubinsPathSegment(connectionObj,wayPoints(i,:),wayPoints(i+1,:));

end

%waypoints include x y z and heading degree of each point

When ı run the code aboje ı get a pathSegObj which includes the properties StartPose, GoalPose, FlightPathAngle, AirSpeed, MinTurningRadius, HelixRadius, MotionTypes,MotionLengths and Length. But, I dont get the states as I need. How could I get it, and how could I use the interpolate function for uavDubinsConnection.

Answer 1

[Raag]

Hi Sinem,

From what I gather, you want to obtain all the interpolated states along a 3D Dubins path generated using ‘uavDubinsConnection’, like your previous 2D workflow.

In 3D, the path is constructed as a sequence of ‘uavDubinsPathSegment’ objects, each representing the path between two waypoints. The ‘interpolate method‘of each segment object allows you to sample points along it.

Here is how you can do this:

% Example waypoints 
wayPoints = [ 
    0   0   0   0; 
    100 0   10  pi/6; 
    200 50  20  pi/4 
]; 
 
connectionObj = uavDubinsConnection; 
connectionObj.MaxRollAngle = deg2rad(5); 
connectionObj.AirSpeed = 30; 
 
allStates = []; 
for i = 1:size(wayPoints,1)-1 
    pathSegObj = uavDubinsPathSegment(connectionObj, wayPoints(i,:), wayPoints(i+1,:)); 
    N = 20; % Number of samples per segment 
    lengths = linspace(0, pathSegObj.Length, N); 
    states = interpolate(pathSegObj, lengths);  
    if i == 1 
        allStates = [allStates; states]; 
    else 
        allStates = [allStates; states(2:end,:)];  
    end 
end

Output:

Here we are using the interpolate method for each ’uavDubinsPathSegment’ to obtain path points and then concatenate results for the full path, like your 2D workflow.

For a better understanding of the above solution, refer to the following MATLAB documentations:

1. uavdubinsconnection: https://www.mathworks.com/help/releases/R2021a/uav/ref/uavdubinsconnection.html

2. uavdubinspathsegment https://www.mathworks.com/help/releases/R2021a/uav/ref/uavdubinspathsegment.html