Sampled and continuous time passivity and stability of virtual environments

We propose new time domain passivity observer (PO) and passivity controller (PC) which removes the constant velocity assumption during one sample time, which was used in our previous PO/PC approach. A new sampled time definition of passivity is introduced, and this new definition is compared with the previous sampled time definition of passivity. Through this comparison, we propose the more accurate PO/PC approach. The proposed new PO/PC approach is applied to "Excalibur" haptic interface system with very high stiffness (K = 120 KN/m) virtual environment (VE), and stable contact is demonstrated.