Quality of Control Assessment for Tactile Cyber-Physical Systems

Abstract

We evolve a methodology and define a metric to evaluate Tactile Internet based Cyber-Physical Systems or Tactile Cyber-Physical Systems (TCPS). Towards this goal, we adopt the step response analysis, a well-known control-theoretic method. The adoption includes replacing the human operator (or master) with a controller with known characteristics and analyzing its response to slave side step disturbances. The resulting step response curves demonstrate that the Quality of Control (QoC) metric is sensitive to control loop instabilities and serves as a good indicator of cybersickness experienced by human operators. We demonstrate the efficacy of the proposed methodology and metric through experiments on a TCPS testbed. The experiments include assessing the suitability of several access technologies, intercontinental links, network topologies, network traffic conditions and testbed configurations. Further, we validate our claim of using QoC to predict and quantify cybersickness through experiments on a teleoperation setup built using Mininet and VREP.Index Terms-quality of control, tactile internet, tactile cyberphysical systems.

TCPSbed: A Modular Testbed for Tactile Internet-Based Cyber-Physical Systems

“…Recently, after publication of our initial work [1], we have extended the step response characterization of TCPS further. In [5] and [50], we standardize step response characterization of TCPS. We also use step response characterization to formulate a metric called Quality of Control (QoC).…”

“…The futuristic network will enable these real-time CPS to run with utmost stability and provide enhanced quality of experience to the human operators involved. We refer to these real-time human-in-the-loop cyber-physical systems as Tactile Cyber-Physical Systems (TCPS) [5], [6].…”

A review on tactile IoT: Architecture, requirements, prospects, and future directions

“…Cyber physical system: Tactile cyber physical system (TCPS) is proposed to enhance sensitivity of quality of control (QoC) metrics in TI-based test-bed. 48 The test-bed shows assessment of QoC elements while incorporating WAN connectivity to analyze the tactile slave's behavior. 49 3.…”

Dynamic Network Slicing for the Tactile Internet

“…E. Network Switching Overhead 1) Delay Overhead: The contribution to the "switching overhead" by the network is represented by the additional transmission delay from all the switches due to the increase in packet size of the first packet processed by the new slice. In the case of a slice setup message, this overhead is equal to (4). Here S hdr is the size of the Slice Configuration Protocol header (except the Ports Array field), n is the total number of switches in the path, R x is the speed of the output link of switch x and S port is the size in bits used to represent one port (usually 8bits).…”

“…For critical applications, like telesurgery, control loop instability can cause the remote-side robot to go out of control from the surgeon's hand resulting in injuries to patients. Similarly, cybersickness, which occurs when feedback delays are significant and noticeable to the human operator, can result in physical and physiological effects in human operators preventing them from extended use of the teleoperation system [3], [4]. To prevent the aforementioned problems, networks characterized by very low end-to-end latency (ideally 1ms), and very high packet reliability (approx 99.999%), termed tactile internet [2], are needed.…”