Simulating friction on floor for a humanoid in simmechanics second generation

I am currently working on a humanoid simulation on simmechanics 2G and working on getting the friction on the floor working. For the normal force, we are using the overdamped spring model for the floor. I have tried out the following ways to simulate friction:

1) Put overdamped springs in the two horizontal axes.

2) I tried to adapt the same function as used in the simmechanics 1g stiction block for friction: F = -drag_coef*v - constant - k*exp(-trans_coef*v)

Both of them don't seem to work, as the humanoid still keeps slipping on the floor. Any other suggestions on how else it can be implemented?

[Stephen23]

Stop posting duplicates:

http://www.mathworks.com/matlabcentral/answers/254789-simulating-friction-on-floor-for-a-humanoid-in-simmechanics-second-generation