Modern_Robotics/packages/MATLAB/mr/TransInv.m

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function invT = TransInv(T)
% *** CHAPTER 3: RIGID-BODY MOTIONS ***
% Takes a transformation matrix T.
% Returns its inverse.
% Uses the structure of transformation matrices to avoid taking a matrix
% inverse, for efficiency.
% Example Input:
%
% clear; clc;
% T = [[1, 0, 0, 0]; [0, 0, -1, 0]; [0, 1, 0, 3]; [0, 0, 0, 1]];
% invT = TransInv(T)
%
% Ouput:
% invT =
% 1 0 0 0
% 0 0 1 -3
% 0 -1 0 0
% 0 0 0 1
[R, p] = TransToRp(T);
invT = [R', -R' * p; 0, 0, 0, 1];
end