Using Matlab Runge Kutta Routine

9 次查看（过去 30 天）
DJ V
DJ V 2024-8-9
评论： James Tursa 2024-8-11
I'm having trouble with the following code. I'm trying to test it to get it to produce the final value as it proceeds through the count and increments the count, but it isn't working. It won't go past the first increment. I'm new to Matlab (once again). Can anyone assist me?
handle=[];
%Initial Conditions
pn0 = 0.0; %Initial north position
pe0 = 0.0; %initial east position
pd0 = -100.0; %initial east position
u0 =25.0; %initial velocity along body x-axis
v0 = 0.0; %initial velocity along body y-axis
w0 = 0.0; %initial velocity along body z-axis
phi0 = 0.0; %initial roll angle
theta0 = 0.0; %initial pitch angle
psi0 = 0.0; %initial yaw rate
l0 = 0; %initial moment about ib axis
m0 = 0; %initial moment about jb axis
n0 = 0; %initial moment about kb axis
p0 = 0; %initial roll rate along ib in Fb
q0 = 0; %initial pitch rate along jb in Fb
r0 = 0; %initial yaw rate along kb in Fb
Va0 = (u0^2 + v0^2 + w0^2)^0.5; %initial velocity
%Initial forces producing acceleration - fx, fy, fz
fx = 0; %Force in the ib direction.
fy = 0; %Force in the jb direciton.
fz = 0; %Force in the kb direction.
%Plane is initially aligned so that ib,jb, and kb
%correspond to x, y, z.
%Physical Parameters
mass = 11; % kg
Jx = 0.8244; %kg m^2
Jy = 1.135;
Jz = 1.759;
Jxz = 0.1204;
S_wing = 0.55;
b = 2.8956;
c = 0.18994;
Sprop = 0.2027;
rho = 1.2682;
e = 0.9;
AR = (b^2)/S_wing;
gravity = 9.81;
%Gamma Values
G = Jx * Jz - (Jxz^2);
G1 = (Jxz * (Jx - Jy + Jz))/ G ;
G2 = (Jz * (Jz - Jy) + (Jxz^2))/ G;
G3 = Jz / G;
G4 = Jxz / G;
G5 = (Jz - Jx) / Jy;
G6 = Jxz / Jy;
G7 = ((Jx - Jy) * Jx + (Jxz ^ 2)) / G;
G8 = Jx / G;
%Establish the parameters to pass to the subroutines
p = p0;
q = q0;
r = r0;
l = l0;
m = m0;
n = n0;
u = u0;
v = v0;
w = w0;
phi = phi0;
theta = theta0;
psi = psi0;
dt = 0.1;
fxone = fx;
fyone = fy;
fzone = fz;
fxtwo = 0;
fytwo = 0;
fztwo = 0;
n=0;
numsteps=100;
total_time = 100; % total simulation time in seconds
time_step = 0.1; % time step in seconds
num_steps = total_time / time_step; % number of steps
for count = 1:numsteps
clc;
clear all;
%Runge Kutta 4 attempt;
%fx = 5*t/mass
r=0
v=0;
q=0;
w=0;
mass = 10;
tstart = (count-1)*time_step;
tstop = tstart + 0.01;
tspan = [tstart,0.01,tstop];
y0=0.0;
[t,y]=ode45(@(t,y) (r*v-q*w)+5*t/mass, tspan, y0);
plot(t,y,'-o')
formatSpec = 'The next element of the Y array is equal to %6.4f at %6.4.';
fprintf (formatSpec,y(end,:),t(end,:));
pause;
end
  1 个评论
James Tursa
James Tursa 2024-8-11
You really intend to loop through 100 plots, pausing between each one?

请先登录，再进行评论。

请先登录，再回答此问题。

回答（1 个）

John D'Errico
John D'Errico 2024-8-9
编辑：John D'Errico 2024-8-9
"IT WON'T GO PAST THE FIRST INCREMENT".
Lol. Exactly what do you think this does in the very beginning of the loop?
for count = 1:numsteps
clc;
clear all;
...
You spent all that time setting up all of those constants and parameters. Then the very first thing you do is delete them all.
Any guesses why it won't go any further? Whether your code is correct besides that, I have not looked. But deleting everything you did is unlikely to be a good idea. It could have been worse I suppose. You could have put an exit command in your loop. ;-)
  3 个评论
显示 1更早的评论
John D'Errico
John D'Errico 2024-8-9
编辑：John D'Errico 2024-8-9
Ran in:
In case it is? What do you think "clear all" does?
CLEAR ALL removes all variables, globals, functions and MEX links.
How can your code proceed past that point?
help clear
CLEAR Clear variables and functions from memory. CLEAR removes all variables from the workspace. CLEAR VARIABLES does the same thing. CLEAR GLOBAL removes all global variables. CLEAR FUNCTIONS removes all compiled MATLAB and MEX-functions. Calling CLEAR FUNCTIONS decreases code performance and is usually unnecessary. For more information, see the clear Reference page. CLEAR ALL removes all variables, globals, functions and MEX links. CLEAR ALL at the command prompt also clears the base import list. Calling CLEAR ALL decreases code performance and is usually unnecessary. For more information, see the clear Reference page. CLEAR IMPORT clears the base import list. It can only be issued at the command prompt. It cannot be used in a function or a script. CLEAR CLASSES is the same as CLEAR ALL except that class definitions are also cleared. If any objects exist outside the workspace (say in userdata or persistent in a locked program file) a warning will be issued and the class definition will not be cleared. Calling CLEAR CLASSES decreases code performance and is usually unnecessary. If you modify a class definition, MATLAB automatically updates it. For more information, see the CLEAR Reference page. CLEAR JAVA is the same as CLEAR ALL except that java classes on the dynamic java path (defined using JAVACLASSPATH) are also cleared. CLEAR VAR1 VAR2 ... clears the variables specified. The wildcard character '*' can be used to clear variables that match a pattern. For instance, CLEAR X* clears all the variables in the current workspace that start with X. CLEAR -REGEXP PAT1 PAT2 can be used to match all patterns using regular expressions. This option only clears variables. For more information on using regular expressions, type "doc regexp" at the command prompt. If X is global, CLEAR X removes X from the current workspace, but leaves it accessible to any functions declaring it global. CLEAR GLOBAL -REGEXP PAT removes global variables that match regular expression patterns. Note that to clear specific global variables, the GLOBAL option must come first. Otherwise, all global variables will be cleared. CLEAR FUN clears the function specified. If FUN has been locked by MLOCK it will remain in memory. If FUN is a script or function that is currently executing, then it is not cleared. Use a partial path (see PARTIALPATH) to distinguish between different overloaded versions of FUN. For instance, 'clear inline/display' clears only the INLINE method for DISPLAY, leaving any other implementations in memory. Examples for pattern matching: clear a* % Clear variables starting with "a" clear -regexp ^b\d{3}$ % Clear variables starting with "b" and % followed by 3 digits clear -regexp \d % Clear variables containing any digits See also CLEARVARS, WHO, WHOS, MLOCK, MUNLOCK, PERSISTENT, IMPORT. Documentation for clear doc clear Other uses of clear beagleboneio/clear compiler_sdk/clear imaq/clear instrument/clear matlab.io.internal.functions.UsesWorksheet/clear matlab.io.spreadsheet.internal.Sheet/clear parallel-computing/clear Simulink.data.adapters.AdapterDataTester/clear Simulink.data.DataConnection/clear Simulink.history/clear Simulink.LibraryDictionary/clear Simulink.ModelWorkspace/clear Simulink.sdi/clear slreq.modeling.RequirementRow/clear slreq/clear sltest.testmanager/clear target/clear trackingGlobeViewer/clear
Walter Roberson
Walter Roberson 2024-8-9
Ran in:
Oddly enough, if you are within a for loop, "clear all" erases the loop control variable for the rest of the duration of that iteration, but the for loop recreates the variable the next iteration.
for k = 1 : 3; if k == 1; clear all; else; disp(k); end; end
2 3
for k = 1 : 3; if k == 1; clear all; end; disp(k); end
Unrecognized function or variable 'k'.
so the variable was recreated for iterations 2 and 3.

请先登录，再进行评论。

类别

在 Help Center 和 File Exchange 中查找有关 Introduction to Installation and Licensing 的更多信息

标签

产品


版本

R2019b

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by