Question

我试图通过将它与已记录的LVDT位移进行比较来验证我收集的一些加速器数据。为此，我试图区分LVDT数据两次以获得加速。但是，当我运行我的代码时，它有错误

Undefined function or variable 'DiffDiffLVDT'.

研究这个我发现Matlab没有处理第二个for循环，因此永远不会生成变量DiffDiffLVDT。

为什么跳过第二个for循环？

enter code here
clear all

clc

test2 = csvread('HZ1.csv'); %raw data from excel
time = test2(:,1);
%% Filtering 
f=250;%  sampling frequency
f_cutoff = 2; % cutoff frequency
f_cutoff2 = 5;

fnorm =f_cutoff/(f/2); % normalized cut off freq, you can change it to any value depending on your requirements
fnorm2 =f_cutoff2/(f/2);

[b1,a1] = butter(4,fnorm,'low'); % Low pass Butterworth filter of order 4
[b2,a2] = butter(4,fnorm2,'low'); % Low pass Butterworth filter of order 4

filtaccZ = filtfilt(b2,a2,test2(:,6));
filtLVDTZ = filtfilt(b1,a1,test2(:,7));

%% Remove Offset

Accz = filtaccZ -mean(filtaccZ);
LVDTz = filtLVDTZ - mean(filtLVDTZ);

%% Unit Conversion

LVDTm = LVDTz/1000; % mm to m

%% LVDT Displacement to Acc

% Displacement to Velocity
for d = 2:1:(size(LVDTm)-1)

    x = LVDTm(d+1);

    y = LVDTm(d-1);

    z = x-y; %differnce in y

    a = time (d+1);

    b = time (d-1);

    c = a-b; %differnce in x

    DiffLVDT(d)= (z/c); % Displacement to velocity

end

velocity = DiffLVDT;

% Velocity to Acceleration
for e=1:1:(size(velocity)-1)
    x2 = velocity(e+1); 

    y2 = velocity(e-1);

    z2 = x2-y2; %differnce in y

    a2 = time (e+1);

    b2 = time (e-1);

    c2 = a2-b2; %differnce in x

    DiffDiffLVDT(e)= (z2/c2) %velocity to acc.

end

Acc= DiffDiffLVDT
%% Plotting
close all 
figure
hold on
plot(time(1:5000),Acc(1:5000),'b')
plot(time(1:5000),Accz(1:5000),'r')

grid on;box on
legend('DiffDiffLVDTFilter','Accz')

    enter code here

Answer 1

由于

1:1:(size(velocity)-1)

没有按你的意愿行事。

velocity是1xN数组，size(velocity)因此返回[1 N]。冒号运算符只关心数组中的第一个值，而你想要循环的数组最终为空，因为

1:1:[1 N]-1 == 1:1:1-1 == 1:1:0 == Empty matrix

由于这些问题，在构造循环时应始终使用以下任一项而不是size(var)：

size(var, n) % Returns the size of the nth dimension of var
length(var) % Returns the size of the largest dimension of var
numel(var) % Returns the number of elements in var

Matlab没有处理第二个for循环

1 个答案: