Gait cycle: start periodic function

I have an array with values that are periodic. I have to plot one period of all this data. The problem that I have is that my period starts at knee_angle_r = 8 and there are multiple knee_angle_r = 8 in the same period. In my data there is a high peak that I can find with the code below. With this code it is easy to calculate the period length for any chosen period.

    [pks,locs] = findpeaks(knee_angle_r, 'MinPeakHeight',55)
    locs=locs.';
    a = 2;                       %Chosen period 
    b = locs(a + 1)-locs(a);     %Calculation of the period

Then I plot all the data by using plot(knee_angle_r) and trim it by using xlim(temp) where temp should be a matrix [StartPeriod StopPeriod]. I know that the peak that I have from earlier is arround 70% but because this isn't so for every person I can't use the following code.

    temp = [locs(a)-0.7b locs(a)+0.3b];
    plot(knee_angle_r)  
    xlim(temp)

Can anyone help me how to find StartPeriod (= +/-8 on plot (also have the array))? I was searching if it were possible by using 'MinPeakDistance' but didn't find the right answers. To make it more understandable I add a picture of the graph that I have obtained. It is important to me to find this because then other things can be seen on the graph (stance phase, swing phase etc.)

Thanks in advance!

Answer 1

[Elkyn Belalcazar]

Hi, I think you have to find gait temporal parameters. I've worked with the angular velocity, in order to find this start period. If you want to talk about it: [e-mail]