How to store any sensor's last 1 second's values in workspace as a vector (Real Time mode)?

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JAI PRAKASH 2018-6-30

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https://ww2.mathworks.cn/matlabcentral/answers/408202-how-to-store-any-sensor-s-last-1-second-s-values-in-workspace-as-a-vector-real-time-mode

评论： Adam Danz 2018-7-3

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Hey

e.g.

joy = vrjoystick(1);
x = axis(joy, 1);     % This just gives me current value of x-axis of the joystick

But I need a vector which gives me values of 'x' in latest 1 second.

Why I need this? Because one of my matlabscript.m demands values of 'x' in latest 1 second. Not just the current value of x-axis of the joystick.

% So i think there should be something always running in background of Matlab, which can give me recent values of 'x'%.

Thanks

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Walter Roberson 2018-7-2

axis() is a method of the vrjoystick class

Adam Danz 2018-7-2

ah.... I see!

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Adam Danz 2018-7-2

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https://ww2.mathworks.cn/matlabcentral/answers/408202-how-to-store-any-sensor-s-last-1-second-s-values-in-workspace-as-a-vector-real-time-mode#answer_327198

编辑：Adam Danz 2018-7-2

在 MATLAB Online 中打开

What's the sampling rate? In your plot, I assume the y axis is angular velocity while the x axis is an index of samples such that x=60 is the 60th sample. If you're sampling at 200Hz that's a sample per 5ms so x=60 is 300ms; if you're sampling at 60Hz, x=60 is 1000ms.

I assume the variable 's' is a vector whose length continually grows. Say your sampling rate is 200Hz, all you need is the last 200 samples of 's' to isolate the last 1-second of data. Within your while loop, that would be ...

sampleRate = 200 %hz
while ...
   lastSecond = s(end-sampleRate+1 : end); 
end

Variable 'lastSecond' will always contain the most recent (hense last) second of data. However you'll likely run into memory problems if you allow s to grow to enormous lengths.

If you're interested in collecting only the last second of data continuously and tossing any data prior to 1 second,

sampleRate = 200 %hz
s = zeros(1, sampleRate); 
while ...
    d = 25*axis(joy, 1); 
    s(1) = [];             %get rid of oldest value
    s(sampleRate) = d;     %add newest value
end

Of course none of this is tested because I don't have a cool steering wheel interface.

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JAI PRAKASH 2018-7-2

@ Adam Danz Thanks for your effort & Time.

But my interest is doing all this in a parallel i.e. in background. Please read last two lines of my initial question.

please refer this ongoing question.. How can I run 2 tasks in parallel?

Adam Danz 2018-7-3

If you create a timer object, which was mentioned in this thread and the thread in your link, you'll still need code that continually collects the most recent 1-second of joystick data and the code offered here should help you with that.

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