Converting Accelerometer Data to Displacement

Hello,

We are trying to get displacement data in the time domain from our 3-axis accelerometer data. Is there a way to do this using the inverse fourier transform? This is what we have so far:

num = xlsread(filename);
num = num(1:2:end,:);                                           % Eliminate ?NaN? Values
num(:,1) = num(:,1)*1E-3;                                       % Convert Milliseconds To Seconds
Fs = 1/mean(diff(num(:,1)));                                    % Sampling Frequency (Convert Milliseconds To Seconds)
Fn = Fs/2;                                                      % Nyquist Frequency
Tr = linspace(num(1,1), num(1,end), size(num,1));               % Time Vector (Regular Samples)
Dr = resample(num(:,2:end), Tr);                                % Resample To Constant Sampling Interval
Dr_mc  = Dr - mean(Dr,1);                                       % Subtract Mean
FDr_mc = fft(Dr_mc, [], 1);

N1 = size(num,1);
N = 2^(nextpow2(N1)+3);
FDr_mc = fft(Dr_mc, N);                                         % Fourier Transform

% Fourier Transform
Fv = linspace(0, 1, fix(size(FDr_mc,1)/2)+1)*Fn;                % Frequency Vector
Iv = 1:numel(Fv);                                               % Index Vector