MATLAB: Advice on processing raw gait data

force plategaitraw data

Hi,

I collected gait data using a force plate several years ago as a part of an experiment. The data is raw data, a sample of which I am attaching in an excel file. As I have very limited experience in MAT LAB, (however I would really really like to learn) i would appreciate any insights into this data and on how to proceed with it so that I can extract parameters such as step length, stride length and cadence etc to come to some conclusive results and findings.

i hope i am not being too ambitious, but i would really appreciate any help on how to proceed further.

Thanks a lot! Jen

Best Answer

Getting the data and variable names is straightforward:

[d,s,r] = xlsread('jennifer aniston Gait Data.xls');
var_names = s(11,:);

What am I looking at? What experiment did you do?

What are the data? (Force is obvious.) What are x and y? They seem to be displacements, but how to they factor into all this?

Related Solutions

MATLAB: Separating left and right leg data given ground reaction force gait data

You need to use the Signal Processing Toolbox findpeaks function. It retuens the values of the peaks and their locations. I only had the indices to work with, but you can easily use the indices to convert to time if you need to.

The code:

[d,s,r] = xlsread('Anthony 1 Column Gait Data.xlsx');
[pks,locs] = findpeaks(d, 'MinPeakDistance',500, 'MinPeakHeight',1000);
figure(1)
plot(d)
hold on
plot(locs(1:2:end), pks(1:2:end), '^r', 'MarkerFaceColor','r')
plot(locs(2:2:end), pks(2:2:end), '^g', 'MarkerFaceColor','g')
hold off
grid
axis([0  5000    ylim])
legend('Force Plate Data', 'Right Foot', 'Left Foot', 'Location','E')
xlabel('Index')
ylabel('Force')

I plotted a portion of the data to show the details here. The code works for the entire data set.

The plot:

MATLAB: Plotting a graph for step length

This is a bit much for an introduction to MATLAB.

The code begins by using the find function to determine the indices where ‘SoundLeft’ and ‘SoundRight’ are equal to 1, in ‘LSteps’ and ‘RSteps’ respectively. It then uses the index vectors to determine the times (denoted by the ‘Time’ vector) that the respective steps occur, in ‘LStepT’ and ‘RStepT’ respectively. Since you wanted the time differences between heel-strike for the left and right foot separately, all I then needed to do was the calculate the time differences between the successive heel strikes, and for that I used the diff function for each foot, in ‘LStepL’ and ‘RStepL’. Those are one element shorter than the corresponding ‘LStepT’ and ‘RStepT’, necessitating the (1:end-1) subscripts in the plot call. [The EDIT is this explanation, since you mentioned this was your first time using MATLAB.]

See if this does what you want:

[Time,Avatar_On,Sound_On,Sequenceindex,Condition,Treadmillpos,Treadmilltime,Treadmillspeed,SoundLeft,SoundRight,Avatar1pos,Avatar2pos,Avatar3pos,Action,AvatarSpeed,time,timespeed] = ImportAvatar0007('Avatar0007.txt',2, 33118);
LSteps = find(SoundLeft == 1);
RSteps = find(SoundRight == 1); 
LStepT = Time(LSteps);
LStepL = diff(LStepT);
RStepT = Time(RSteps);
RStepL = diff(RStepT);
figure(1)
plot(LStepT(1:end-1), LStepL)
hold on
plot(RStepT(1:end-1), RStepL)
hold off
grid
xlabel('Time')
ylabel('Step Length (s)')
legend('Left', 'Right', 'Location','NE')

The code for the function MATLAB created to read your file (using textscan) is attached for you to use. My code requires it because I refer to the variables it creates.

Best Answer

Related Solutions

MATLAB: Separating left and right leg data given ground reaction force gait data

MATLAB: Plotting a graph for step length

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