  Networked teleoperation with haptic feedback is a prime example for the
emerging Tactile Internet, which requires a careful orchestration of haptic
communication and control. One major challenge in this context is how to
maximize the user's quality-of-experience (QoE) while ensuring at the same time
the stability of the global control loop in the presence of communication
delay. In this paper, we propose a dynamic control scheme switching strategy
for teleoperation systems, which maximizes the QoE for time-varying
communication delay. In order to validate the feasibility of the proposed
approach, we perform a dedicated case study for a virtual teleoperation
environment consisting of a one-dimensional spring-damper system, and conduct
extensive subjective tests under various delay conditions for two control
schemes: (1) teleoperation with the time-domain passivity approach (TDPA),
which is highly delay-sensitive but supports highly dynamic interaction between
the operator and a potentially quickly changing remote environment; (2)
model-mediated teleoperation (MMT), which is tolerable to relatively larger
communication delays, but unsuitable for quickly changing, highly dynamic
remote environments. For both schemes, we use recently proposed extensions,
which incorporate perceptual data reduction to reduce the required packet rate
between the operator and the teleoperator. One key contribution of this paper
lies in the exploration of the intrinsic relationship among QoE, communication
delay and the control schemes which provides a fundamental guidance, not only
to this research, but also to the future joint optimization of communication
and control for time-delayed teleoperation systems.
