Controlling Human Perception and Interaction in a Safe Large-Scale Brake Actuate Haptic Environment. Assistive robots require intimate physical human robot interaction. With this intimate contact comes the need for a redefinition of safety. The chance that such devices can physically strike, overpower, or otherwise injure a human during interaction is unacceptable. One solution to this problem is passive actuation. Passive actuation enables safe large workspaces with low effective inertia, stable stiff virtual constraints, low power requirements, and robust wear characteristics.