Reducing the conservatism of the time domain passivity approach through consideration of energy reflection in delayed coupled network systems

The Time Domain Passivity Approach (TDPA), a method to inject adaptive damping to satisfy the passivity condition in real-time, has emerged as a powerful tool to stabilize coupled network systems with/without communication delay, such as haptic and teleoperation systems, due to its simplicity and effectiveness. However, we found that the conventional TDPA has unnecessary conservatism especially in delayed coupled network systems due to direction dependent energy calculation and dissipation. In this paper, we propose a new time domain passivity approach with reduced conservatism by considering the energy reflection from an energy storage element in the network. The method is generally formulated with a delayed 2-port network system including an energy storage element and implemented to a teleoperation system. The proposed method is experimentally tested and a comparison with the conventional TDPA reveals improved kinesthetic coupling and transparency in terms of position tracking and force reflection.