Conditional contact y direction

Hi all,

At the moment I am designing a human body undergoing side to side whole body vibration. This involves a person standing on a platform and the platform lifting up either foot up alternatively over a fulcrum.

The issue I’m having is that I have designed the foot position with a driver to be fixed relative to the platform. This means that the foot would be connected to the platform which in reality is not the case.

While I don’t mind the foot being constrained in the x and z direction relative to the platform, the issue is that the platform will drive the foot in both the upwards and downwards direction when in reality it should only drive it upwards.

I’ve seen some models with conditional contact but don’t know how to apply this to my model.

Any help would be greatly appreciated.

Many thanks,