High reliability wireless communications for mission-critical applications often necessitates path diversity through redundant channels. In this context, we explore the combination of the IEC 62439 High-availability Seamless Redundancy (HSR) architecture with IEEE 802.1CB Frame Replication and Elimination for Reliability (FRER) features. While HSR is well-established for wired networks, both HSR and FRER aim to enhance network reliability through redundancy. However, the HSR algorithm assumes frame ordering, which is impractical in wireless networks due to packet ordering and time-based elimination challenges. To address this, we propose integrating the IEEE 802.1CB vector recovery algorithm within the HSR framework. We focus on Wireless Local Area Networks (WLANs), where we modify an existing HSR implementation in Linux to operate over wireless channels. Our experimental analysis demonstrates significant improvements in latency metrics compared to non-redundant communications subject to interfering traffic. The proposed implementation targets industrial applications, such as robotic feedback control with stringent two-millisecond latency deadlines. By considering latency and out-of-order delivery—features not well-supported by the current HSR standard, we demonstrate improved reliability and latency characteristics required for demanding real-time control applications utilizing wireless as a principal communications medium.

Time-sensitive networking (TSN) is emerging as a viable means to achieving deterministic quality of service (QoS) communications within mission critical industrial applications such as feedback control systems, robotics, and precision sensing and actuation. Originally developed for Ethernet-based audio-video applications using the User Datagram Protocol (UDP). TSN assume unidirectional flows from source (talked) to destination(listener) and it is most easily implemented using UDP in which packets are transmitted without an acknowledgment from the recipient. However, most existing industrial protocols are implemented using the reliable Transport Control Protocol (TCP) in which each transmission is explicitly acknowledged. In this work, a bandwidth efficient TSN schedule is developed to accommodate the TCP traffic flow between two synchronized robots collaboratively moving an object. We then demonstrate an IEEE 802.1Qbv TSN schedule over an IEEE 802.11 wireless medium that guarantees robot performance requirements are maintained while accommodating concurrent best-effort traffic flows. The process for schedule selection and experimental data collection is discussed, and TSN configuration parameter tuning and experimental results are provided.

Time-sensitive networking (TSN) is an emerging topic for the advancement of wireless networking for industrial applications. TSN, as defined under the umbrella of IEEE 802.1 working group standards, addresses issues related to providing deterministic communications over IEEE 802-based Local Area Networks (LANs). TSN was originally designed to support real-time audio/video applications over Ethernet providing better reliability and lower, more deterministic latency with traffic shaping capabilities. TSN has since expanded its scope and applicability to other applications such as those in industrial environments and automotive applications. Industrial examples include machine-machine communications for robot control, end-effector actuation, real-time sensing, and safety integrated systems. Applications utilizing a wireless local area network (WLAN) can also benefit from scheduling and traffic shaping as defined in the 802.1Qbv standard; however, factors such as clock stability, synchronization, resource requirements and protocol options come into play when selecting a schedule to support multiple application types on the same network. In this article, we present a scenario for a collaborative robot heavy lift operation, in which, two robots communicate over an IEEE 802.11 WLAN with TSN capabilities to lift a rigid body in three dimensions. Scheduling is performed using 802.1Qbv over WLAN with the robot operating system (ROS) used as the software middleware utilizing the transport control protocol (TCP). As a part of the research, we describe our process for schedule selection to accommodate the time-sensitive traffic of the robotic scenario while allowing an industrial internet of things (IIoT) high data rate traffic to coexist. We then provide an analysis of the impacts of TSN schedule selection on the operational performance of the collaborative robot application.

In this article, we describe a methodology and associated models to evaluate a time sensitive collaborative robotics application enabled by wireless time sensitive networking (WTSN) capabilities. We also present a method to configure WTSN scheduling to meet the application time budget and validate it in a realistic industrial use case. We detail the methodologies for implementing and characterizing the performance of key WTSN capabilities, namely time synchronization and time-aware scheduling, over an IEEE 802.11 based network. We deploy the WTSN capabilities with a collaborative robotic workcell consisting of two robotic arms, which emulate a material handling application, known as machine tending. We further explore configurations and measurement methodologies to characterize application performance of this use case and correlate it to the performance of the wireless network.

For accurate characterization and evaluation of wireless mechatronic systems, effective modeling of wireless communication channels is of paramount importance, especially to simulation-oriented methods. Conventional simulation methods employ mathematical models to abstract details of prototype channels. Although such mathematical models often have rigorous theoretical underpinnings, they can be weak in capturing complex environmental characteristics and complex forms of diversity that are exhibited in industrial communication environments. To address this problem, we develop, in this paper, a new approach to deriving effective simulation models for industrial communication channels. Our approach involves field measurements from actual wireless mechatronic environments together with feature extraction from the measurements, and data-driven classification based on the extracted features. Our approach leads to a general framework for simulating wireless mechatronic systems in a way that realistically incorporates the complex channel characteristics of these systems.

In this paper, we describe a collaborative robotic workcell testbed enabled by Wireless Time Sensitive Networking (WTSN) technologies and discuss deployment, performance measurement and management guidelines challenges. We detail the methodologies for implementing and characterizing the performance of key WTSN capabilities (time synchronization and time-aware scheduling) over IEEE 802.11/Wi-Fi. We deployed WTSN capabilities on the National Institute of Standards and Technology (NIST) collaborative robotic workcell testbed consisting of two robotic arms that emulates a material handling application, known as machine tending. We further explore configurations and measurement methodologies to characterize Quality of Experience (QoE) of this use case and correlate it to the performance of the wireless network.