Fix a bad eigen vector cast.
Fix a bad eigen vector cast.

gergondet/RBDyn,gergondet/RBDyn,gergondet/RBDyn,jrl-umi3218/RBDyn,jrl-umi3218/RBDyn,gergondet/RBDyn,jrl-umi3218/RBDyn,jrl-umi3218/RBDyn,gergondet/RBDyn