environment
Description
returns a structure that captures all the relevant environmental variables for the specified
UAV guidance model. Use this function to ensure you have the proper fields for your
environmental parameters. Use the environmental inputs as an input to the envStruct
= environment(uavGuidanceModel
)derivative
function to get the state time-derivative of the UAV.
Examples
Simulate A Multirotor Control Command
This example shows how to use the multirotor
guidance model to simulate the change in state of a UAV due to a command input.
Create the multirotor guidance model.
model = multirotor;
Create a state structure. Specify the location in world coordinates.
s = state(model); s(1:3) = [3;2;1];
Specify a control command, u
, that specified the roll and thrust of the multirotor.
u = control(model); u.Roll = pi/12; u.Thrust = 1;
Create a default environment without wind.
e = environment(model);
Compute the time derivative of the state given the current state, control command, and environment.
sdot = derivative(model,s,u,e);
Simulate the UAV state using ode45
integration. The y
field outputs the multirotor UAV states as a 13-by-n matrix.
simOut = ode45(@(~,x)derivative(model,x,u,e), [0 3], s); size(simOut.y)
ans = 1×2
13 3536
Plot the change in roll angle based on the simulation output. The roll angle (the X Euler angle) is the 9th row of the simOut.y
output.
plot(simOut.y(9,:))
Plot the change in the Y and Z positions. With the specified thrust and roll angle, the multirotor should fly over and lose some altitude. A positive value for Z is expected as positive Z is down.
figure plot(simOut.y(2,:)); hold on plot(simOut.y(3,:)); legend('Y-position','Z-position') hold off
You can also plot the multirotor trajectory using plotTransforms
. Create the translation and rotation vectors from the simulated state. Downsample (every 300th element) and transpose the simOut
elements, and convert the Euler angles to quaternions. Specify the mesh as the multirotor.stl
file and the positive Z-direction as "down"
. The displayed view shows the UAV translating in the Y-direction and losing altitude.
translations = simOut.y(1:3,1:300:end)'; % xyz position rotations = eul2quat(simOut.y(7:9,1:300:end)'); % ZYX Euler plotTransforms(translations,rotations,... 'MeshFilePath','multirotor.stl','InertialZDirection',"down") view([90.00 -0.60])
Simulate A Fixed-Wing Control Command
This example shows how to use the fixedwing
guidance model to simulate the change in state of a UAV due to a command input.
Create the fixed-wing guidance model.
model = fixedwing;
Set the air speed of the vehicle by modifying the structure from the state
function.
s = state(model);
s(4) = 5; % 5 m/s
Specify a control command, u
, that maintains the air speed and gives a roll angle of pi/12
.
u = control(model); u.RollAngle = pi/12; u.AirSpeed = 5;
Create a default environment without wind.
e = environment(model);
Compute the time derivative of the state given the current state, control command, and environment.
sdot = derivative(model,s,u,e);
Simulate the UAV state using ode45
integration. The y
field outputs the fixed-wing UAV states based on this simulation.
simOut = ode45(@(~,x)derivative(model,x,u,e), [0 50], s); size(simOut.y)
ans = 1×2
8 904
Plot the change in roll angle based on the simulation output. The roll angle is the 7th row of the simOut.y
output.
plot(simOut.y(7,:))
You can also plot the fixed-wing trajectory using plotTransforms
. Create the translation and rotation vectors from the simulated state. Downsample (every 30th element) and transpose the simOut
elements, and convert the Euler angles to quaternions. Specify the mesh as the fixedwing.stl
file and the positive Z-direction as "down"
. The displayed view shows the UAV making a constant turn based on the constant roll angle.
downsample = 1:30:size(simOut.y,2); translations = simOut.y(1:3,downsample)'; % xyz-position rotations = eul2quat([simOut.y(5,downsample)',simOut.y(6,downsample)',simOut.y(7,downsample)']); % ZYX Euler plotTransforms(translations,rotations,... 'MeshFilePath','fixedwing.stl','InertialZDirection',"down") hold on plot3(simOut.y(1,:),-simOut.y(2,:),simOut.y(3,:),'--b') % full path xlim([-10.0 10.0]) ylim([-20.0 5.0]) zlim([-0.5 4.00]) view([-45 90]) hold off
Input Arguments
uavGuidanceModel
— UAV guidance model
fixedwing
object | multirotor
object
UAV guidance model, specified as a fixedwing
or multirotor
object.
Output Arguments
envStruct
— Environmental input parameters
structure
Environmental input parameters, returned as a structure.
For fixed-wing UAVs, the fields of the structure are WindNorth
,
WindEast
,WindDown
, and
Gravity
. Wind speeds are in meters per second and negative speeds
point in the opposite direction. Gravity
is in meters per second
squared (default 9.81
).
For multirotor UAVs, the only element of the structure is Gravity
(default 9.81
) in meters per second.
Extended Capabilities
C/C++ Code Generation
Generate C and C++ code using MATLAB® Coder™.
Version History
Introduced in R2018b
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