rt_ftrans - transform force/moment between coordinate frames[view code]

Calling Sequence

F2 = rt_ftrans(T, F)

Parameters

• T : 4-by-4 matrix. Homogeneous transform which relates two coordinate frames.
• F : 6-element vector. Generalized force vector which has to be expressed in the new coordinate frame.
• F2 : 6-element vector. Generalized force vector resulting from coordinate transformation.

Description

Transform the generalized force vector F, express in the current coordinate frame, to force vector F2 in the second coordinate frame. The second frame is related to the first by the homogeneous transform T.

Examples

   // The following example shows how rt_ftrans() can be used to rewrite a
   // given generalized force vector in terms of a wrench applied at a
   // different point (and with respect to a different coordinate frame)
   // by using a direct approach.

   // given the wrench F applied at the origin
   // of the World frame
   F = rand(6,1);

   // we wish to determine the equivalent wrench
   // (Fb) applied at the origin of frame B, whose
   // configuration with respect to the World frame
   // is
   Tb = rt_rotz(%pi/4)*rt_transl(0.25,-0.25,0.55),

   // by compounded transforms
   Rb = rt_tr2rot(Tb);
   pb = rt_transl(Tb);
   pb_hat = [0, -pb(3), pb(2); pb(3), 0, -pb(1); -pb(2), pb(1), 0];
   M = [Rb', zeros(3,3); -Rb'*pb_hat, Rb'];
   Fb = M*F,

   // by using rt_ftrans() (direct approach)
   Fb = rt_ftrans(Tb, F),

  

See Also

rt_diff2tr,  

Authors

original Matlab version by

Peter I. Corke CSIRO Manufacturing Science and Technology

Scilab implementation by

Matteo Morelli Interdepartmental Research Center "E. Piaggio", University of Pisa

Bibliography

Corke, P.I. "A Robotics Toolbox for MATLAB", IEEE Robotics and Automation Magazine, Volume 3(1), March 1996, pp. 24-32