I will create a model of real planar joint defined by stiffness and damping matrices. The joint movements are in x and y axes and rotation around z-axis. For model of this, I have used block “Custom Joint” with same primitive joints (P1 and P2 for planar moving in x and y, and one Revolute for rotating around z). As actuator was used block “Joint Spring & Damper”. When stiffness matrix is diagonal, all is correct. Problem is when stiffness matrix is in the form (real planar joint):
K=[Kx 0 0; 0 KyF –KyM; 0 –KthetaF KthetaM]; the stiffnesses KyM and KthetaM are equal.
How can create model of this joint in SimMechanics because I can define only one stiffness for one primitive joint, but for one primitive, for instance y-direction, I have two stiffness, one main KyF, and one parasitic –KthetaF.