sampling frequency (Hz).
%   zupt_th: 1x1 ZUPT threshold (m/s).
%  zupt_win: 1x1 ZUPT time window (seconds).
%       eps: 1x1 time interval to compare current IMU time to current vor_dme time vector (s).
%
%  att_mode: attitude mode string.
%      'quaternion': attitude updated in quaternion format. Default value.
%             'dcm': attitude updated in Direct Cosine Matrix format.
%
% OUTPUT
%   nav_e, INS/vor_dme navigation estimates data structure.
%         t: Ix1 INS time vector (seconds).
%        tg