Safe Bilateral Teleoperation for a UAV Using Control Barrier Functions and Passivity

In this work, an optimization-based control scheme for a bilateral teleopered unmanned aerial vehicle (UAV) is proposed using control barrier functions (CBFs) and passivity. We consider a human operator moving the position of an end effector of a haptic device as the velocity command input to the UAV. The CBF is applied as a constraint to maintain the collision-free motion of the UAV for safety. On the other hand, to preserve the stability of the system, we consider passivity as another constraint together, but it leads to undesired behavior of an optimal solution for haptic feedback. To deal with the issue, the strategy called energy tank for passivity is included to replace the condition of strict output passivity. The aforementioned designs are formalized as a quadratically constrained quadratic program (QCQP) to solve numerically. Through numerical examples, we have a comprehensive discussion about the features of the proposed controller with better safety. The experimental results verify the effectiveness of our method in practice.