There are three DOF in the contact joint. A generic constraint equation is written as
J v = c | (1) |
The first DOF is in the normal direction. The LHS of Eq. (1) is
where r1 = cp - p1 and r2 = cp - p2. The RHS of Eq. (1) is
But c is limited by maxvel, so
if (c > maxvel) c = maxvel
Since cfm is associated with the constraint DOF, a specific cfm can be entered here. There are 3 possible cfm, which are set up by soft_cfm, slip1, and slip2, respectively.
cfm(1) = soft_cfm
The impact has a direct effect on c
pick the larger value between contact and impact
if(c_i > c) c = c_i
The lower and upper bounds are
lo(1) = 0
hi(1) = infinity
The second DOF is the first tangent direction. Let t1 and t2 be the tangent directions to normal n
c = motion1 (so motion1 and motion2 are velocities)
lo(2) = -mu (if mu=0, the friction force is practically set to zero)
hi(2) = mu
cfm(2) = slip1
The LHS of the constraint equation in the second tangent direction is
The RHS of the constraint equation is
c = motion2
lo(3) = -mu2
hi(3) = mu2
cfm(3) = slip2
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