i have a geom "foot"(condim=3), slide friction=0.7, i calculate the wrench from the contact force Code: F=sigma(Fi) M=sigma(cross(Fi, com - pi)) where com is the data.xipos of the body, pi is the contact point in data.contact.pos. for each contact point Fi is calculated from data.efc_force by multiply E 1) But the force is the same with data.cfrc_ext , while the torque is not.what is the problem? 2) i want to calculate the constraint jacobian according to the wrench of the body("foot"), while eq below Code: Jac(foot) .T* wrench(foot) = (data.efc_J).T * data.efc_force does not match, in which wrench(foot) reffer to the data.cfrc_ext of the foot body. Code: data.efc_force : [11.85146135 13.42744924 13.01199359 12.266917 ] contact point : [-0.12220128 0.02669812 0.00031927] data.efc_force : [36.21655201 37.8791954 37.596309 36.49943841] contact point : [0.13779852 0.02664688 0.00016388] data.efc_force : [15.67559638 17.2787631 16.96416511 15.99019437] contact point : [-0.12217669 0.15158412 0.00031007] data.efc_force : [42.36771452 44.06469799 43.93559766 42.49681485] contact point : [0.13782311 0.15153288 0.00015468] force from contact: [ -2.97829051 -4.57714703 437.52285994] force from data.cfrc_ext: [ -2.97829051 -4.57714703 437.52285994] torque from contact: [ 2.42543742 -35.73485602 -0.08754942] torque from data.cfrc_ext: [37.54898519 -2.28141429 0.50151569]