Merge pull request #2063 from deslaughter/b/BeamDynRotStates

Fix bug in BD linearization resulting from reference rotation change

modules/beamdyn/src/BeamDyn.f90

@@ -932,6 +932,7 @@ subroutine SetParameters(InitInp, InputFileData, p, OtherState, ErrStat, ErrMsg)
 
 
    p%RotStates      = InputFileData%RotStates      ! Rotate states in linearization?
+   if (ChangeRefFrame) p%RotStates = .true.
    p%RelStates      = InputFileData%RelStates      ! Define states relative to root motion in linearization?
 
    p%rhoinf         = InputFileData%rhoinf         ! Numerical damping coefficient: [0,1].  No numerical damping if rhoinf = 1; maximum numerical damping if rhoinf = 0.
@@ -6025,7 +6026,8 @@ SUBROUTINE BD_JacobianPInput( t, u, p, x, xd, z, OtherState, y, m, ErrStat, ErrM
       end if
 
       if (p%RotStates) then
-         RotateStates = matmul( u%RootMotion%Orientation(:,:,1), transpose( u%RootMotion%RefOrientation(:,:,1) ) )
+         ! Calculate difference between input root orientation and root reference orientation
+         RotateStates = matmul( u%RootMotion%Orientation(:,:,1), OtherState%GlbRot )
          do i=1,size(dXdu,1),3
             dXdu(i:i+2, :) = matmul( RotateStates, dXdu(i:i+2, :) )
          end do
@@ -6121,7 +6123,8 @@ SUBROUTINE BD_JacobianPContState( t, u, p, x, xd, z, OtherState, y, m, ErrStat,
    call SetErrStat(ErrStat2,ErrMsg2,ErrStat,ErrMsg,RoutineName)
 
    if (p%RotStates) then
-      RotateStates          = matmul( u%RootMotion%Orientation(:,:,1), transpose( u%RootMotion%RefOrientation(:,:,1) ) )
+      ! Calculate difference between input root orientation and root reference orientation
+      RotateStates          = matmul( u%RootMotion%Orientation(:,:,1), OtherState%GlbRot )
       RotateStatesTranspose = transpose( RotateStates )
 
       if ( present(StateRotation) ) then