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IEEE TRANSACTIONS ON INDUSTRIAL INFORMATICS, VOL. 19, NO. 9, SEPTEMBER 2023 9255 Impacts of Wireless on Robot Control: The Network Hardware-in-the-Loop Simulation Framework and Real-Life Comparisons Honghao Lv , Student Member, IEEE , Zhibo Pang , Senior Member, IEEE , Koushik Bhimavarapu , Member, IEEE , and Geng Yang , Member, IEEE Abstract As many robot applications become more re- liant on wireless communications, wireless network latency and reliability have a growing impact on robot control. This article proposes a network hardware-in-the-loop (N- HiL) simulation framework to evaluate the impacts of wire- less on robot control more efficiently and accurately, and then improve the design by employing correlation analysis between communication and control performances. The N- HiL method provides communication and robot developers with more trustworthy network conditions, while the huge efforts and costs of building and testing the entire physical robot system in real life are eliminated. These benefits are showcased in two representative latency-sensitive applica- tions: 1) safe multirobot coordination for mobile robots, and 2) human-motion-based teleoperation for manipula- tors. Moreover, we deliver a preliminary assessment of two new-generation wireless technologies, the Wi-Fi6 and 5G, for those applications, which has demonstrated the effec- tiveness of the N-HiL method as well as the attractiveness of the wireless technologies. Index Terms 5G, hardware-in-the-loop, multirobot coor- dination, teleoperation, Wi-Fi 6, wireless control. Manuscript received 18 October 2022; accepted 25 November 2022. Date of publication 8 December 2022; date of current version 24 July 2023. This work was supported in part by the Swedish Foundation for Strategic Research under Grant APR20-0023; in part by the National Natural Science Foundation of China under Grant 51975513; in part by the Natural Science Foundation of Zhejiang Province, China under Grant LR20E050003; in part by the Major Research Plan of National Natural Science Foundation of China under Grant 51890884; and in part by the Major Research Plan of Ningbo Innovation 2025 under Grant 2020Z022. The work of Honghao Lv was supported by the China Scholarship Council. Paper no. TII-22-4339. (Corresponding author: Zhibo Pang.) Honghao Lv is with the State Key Laboratory of Fluid Power and Mechatronic Systems, School of Mechanical Engineering, Zhejiang Uni- versity, Hangzhou 310027, China, and also with the Department of Intelligent Systems, Royal Institute of Technology, 114 28 Stockholm, Sweden (e-mail: lvhonghao@zju.edu.cn). Zhibo Pang is with the Department of Automation Technology, ABB Corporate Research, 722 26 Vasteras, Sweden, and also with the De- partment of Intelligent Systems, Royal Institute of Technology, 114 28 Stockholm, Sweden (e-mail: zhibo@kth.se). Koushik Bhimavarapu is with the Department of Automation Tech- nology, ABB Corporate Research, 722 26 Vasteras, Sweden (e-mail: koushik.bhimavarapu@se.abb.com). Geng Yang is with the State Key Laboratory of Fluid Power and Mechatronic Systems, School of Mechanical Engineering, Zhejiang Uni- versity, Hangzhou 310027, China (e-mail: yanggeng@zju.edu.cn). Color versions of one or more figures in this article are available at https://doi.org/10.1109/TII.2022.3227639. Digital Object Identifier 10.1109/TII.2022.3227639 I. I NTRODUCTION T HE growing wireless network technologies and the cloud and edge computing toward Industrial 4.0 enable various wireless-network-controlled robot platforms that are practically applied to industrial production [1], [2]. Intuitively, wireless networks enable higher flexibility of the robotic system and simplify design and installation processes, and diminish mainte- nance needs, especially for mobile robots [3], [4]. And wireless networks make it possible to implement a remote operation, because the controllers and actuators are deployed over a wire- less link, such as the teleoperation of the manipulators [5], [6]. However, wireless communication imposes challenges in time-critical robot control scenarios, where wireless networks involved extra latency compared to wired connection [7]. To ensure the robustness and reliability of the robotic system, simulation and testing for the communication are required dur- ing the design stage and deployment process of an industrial robotic platform [8]. Introducing latency or other communi- cation characteristics into the controller codes to imitate the profiles of the real network is a common solution for the sim- ulation [9]. However, the practical communication condition, particularly the long-term stable performance of a wireless network, is extremely difficult to be modeled and simulated [10]. Li and Savkin [11] simulated unmanned aerial vehicle (UAV) navigation based on the wireless sensor network using the professional simulation software V-REP in the industrial in- ternet of things applications. However, a stable and invulnerable network condition is assumed in the simulation environments. Despite the simulation method of [11] is able to do long-term stability tests but has no generalized capabilities to evaluate different network conditions and communication uncertainty. The model-based simulation methods are commonly used for validating the auto guide vehicles (AGVs) coordination, such as in [12] and [13], while both cannot be used to evaluate the communication uncertainty. Hardware-in-loop (HiL) simulation refers to the simulation technology, which simulates one part of the whole system with computer modeling while using physical modeling or an actual system for the other part [14]. In the past few years, research efforts have been made in HiL simulation for robot system design and optimization [15], [16]. Zhou et al. [14] proposed an HiL simulation method for underwater acoustic This work is licensed under a Creative Commons Attribution 4.0 License. For more information, see http://creativecommons.org/licenses/by/4.0/
9256 IEEE TRANSACTIONS ON INDUSTRIAL INFORMATICS, VOL. 19, NO. 9, SEPTEMBER 2023 TABLE I C OMPARISONS B ETWEEN THE P ROPOSED A PPROACH AND O THER R ELATED S IMULATION W ORKS FOR R OBOT C ONTROL Fig. 1. Diagram of the proposed network hardware-in-the-loop framework. communication, but without applying it to robots or other devices. Marco et al. proposed an on-ground HiL simulation method for prevalidation and optimization of on-orbit robotic missions. However, the technical requirements of the proposed approach are the real-time computations and the negligible latency given by Assumption 1 in [16]. An HiL simulation system for manipulator control in [17] was built to improve the system stability by deploying the self-designed PID controller. Lamping et al. [18] worked on a multiagent UAV system based on robot operation system (ROS), and they experimented with control and supervision algorithms on multiple UAVs using HiL simulation. The majority of these HiL simulation studies for robotic applications aimed to provide a flexible and easy-to-use interface for a controller design [19]. Markus et al. [20] from ABB and NOKIA investigated the capabilities of 5G and LTE for supporting industrial robotic applications using the traffic- model-based communication simulation methods. However, the simulation results are constrained to the specific scenario de- fined in this article and do not have the ability to evaluate the impact of network uncertainty. One common constraint of HiL simulation for robotics, mechatronics, and control is the limited modeling of the communication condition, especially for the growing wireless network controlled robots [21]. Lv et al. [22] presented an HiL simulation framework and conducted a preliminary study on wireless robot control using Wi-Fi 6. But it lacks the systematic evaluation of the network performance, and the simultaneous correlation between communication and controlisnotelaborated.Thesummarizedcomparisonsarelisted in Table I . To cover the gap in the literature, a network hardware-in-the- loop(N-HiL)simulationframeworkshowninFig. 1 isdeveloped in this article for evaluating the impacts of the wireless network on robot control systems, considering the scalability of the net- work interface, and the friendliness to both the communication and robot developers in the field. The major contributions can be summarized as follows: 1) A novel N-HiL simulation framework is proposed to evaluate the impacts of wireless on robot control, which provides more trustworthy results, while the huge efforts and costs of testing the entire physical robot system in real life are eliminated. 2) Two typical latency-sensitive robot control cases, safe multirobot coordination and human-motion-based tele- operation, are investigated, and the performance compar- isons of Wi-Fi 6 and 5G wireless networks are conducted. 3) The correlation between the communication and control is investigated using the proposed N-HiL method, and a selection rule is given for choosing the wireless networks
LV et al.: IMPACTS OF WIRELESS ON ROBOT CONTROL 9257 Fig. 2. Diagram of the overall methodology compared with previous methods: (a) traditional methodology and (b) N-HiL methodology pro- posed in this article. with different profiles for robot control applications in the design stage. The rest of this article is organized as follows. In Section II, the N-HiLframeworkisproposedandthemethodologyisdescribed. Two case studies are presented in Section III. Sections IV and V provide the experiments and validations of the coordination case and teleoperation case using the N-HiL framework. Finally, Section VI concludes this article. II. N ETWORK H ARDWARE - IN - THE -L OOP F RAMEWORK A. Overall Methodology The proposed N-HiL framework aims to provide a reliable and trustworthy methodology to evaluate the impacts of wireless on robot systems. The controller design is the essential part for designing a robot control system, where the simulation in the de- sign stage could provide a controller tuning according to the con- trol performance assessment. For most robotic simulation cases using the traditional methodologies, assumptions under ideal communication conditions or stable networks are considered, as shown in Fig. 2(a) , which provides an over-optimistic network model and an interpretable tracking behavior between the output and command by ignoring the network-communication uncer- tainty. Compared to the previous methods which integrate the network modeling in the controller for simulation, the proposed N-HiL framework injects the realistic network hardware into the simulation as shown in Fig. 2(b) . In addition, the control adjust- ment is associated with the communication adjustment based on the performance assessment both for the network and control in the N-HiL simulation framework. Driven by the system design from two representative use cases, the statistical evaluation met- rics for the control and communication are proposed. The results from the N-HiL simulation are coanalyzed to adjust the control strategies and network strategies collaboratively, investigating the impacts of wireless on robot control. The proposed N-HiL framework has the following expected benefits: 1) exposing the issues of the real wireless network condition that cannot be mimicked by statistical modeling; 2) eliminating the efforts and costs of building the entire physical robot system for assessment; 3) providing an effective approach for studying the interplay between the wireless and control strategy; and 4) enabling the long-term stability test of the communication for a robot system. B. System Architecture The system architecture of the proposed N-HiL framework includes four parts, as shown in Fig. 1 : simulated controller, simulatedrobot platform, networksniffer hardware, andthereal- life network environment. The essential element of the N-HiL framework is the unob- trusive network sniffer hardware interface deployed based on an Ethernet multichannel probe. The sniffer interface is deployed to connect the simulated controller and the simulated robot plat- form. The controller includes the robot kinematic forward model or the dynamic model, which is used to compute the discrete high-frequency control command in real time. The simulated robot is driven by the command transferred by the network hardware interface. The sniffer program keeps on sniffing the raw packet from the sniffer port continuously in real time to capture the packets and calculate the latency of the packets as the unobtrusive latency tester (ULT). The downstream latency of the packets that are transmitted from source to destination is calculated using the time stamping of destination output DOWN_OUT minus the time stamping of source input UP_IN. The upstream latency of the packets that are transmitted from destination to source is calculated using the time stamping of source output UP_OUT minus the time stamping of destination input DOWN_IN. The wired Ethernet and the wireless network, Wi-Fi6 and 5G, are implemented as shown in the floor plan of Fig. 1 . In particular, three test conditions of Wi-Fi 6, short-range, medium-range, and long-range, are set for the distance be- tween two access point (AP) nodes (hereafter represented as Wi-Fi 6 @ short/medium/long). The 5G station used here is an internal industrial solution provided by Ericsson AB. For the wired Ethernet network, the interface is con- nected using an Ethernet cable between port DOWN_OUT and port UP_OUT. For the wireless network framework, the master AP of Wi-Fi 6 and the user plane function of the 5G station are connected to port DOWN_OUT, while the slave AP and the 5G user equipment are connected to port UP_OUT. III. I MPLEMENTATION OF THE N-H I L F RAMEWORK A. Case Study Overview To investigate the impacts of wireless on robot control, the corresponding case studies are conducted by deploying the proposed N-HiL simulation framework. Two of the key concerns for wireless robot systems in practical application are safety and accuracy. Multirobot coordination is chosen as the first case study, which is a representative core problem in mobile robot fleets. Most multirobot coordination solutions assume good communication conditions [23], [24]. The unreliable commu- nication will lead to the delay of the real-time status update or control command loss of each robot, which final causes collision and unsafety [25]. The multirobot coordination does need to
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9258 IEEE TRANSACTIONS ON INDUSTRIAL INFORMATICS, VOL. 19, NO. 9, SEPTEMBER 2023 Fig. 3. N-HiL simulation framework for safe multirobot coordination. deploy the test on the proposed N-HiL framework since it is a key to pretest for avoiding collision and ensuring safety [26]. Moreover, the manipulator teleoperation is chosen as the sec- ond test case, which is another typical communication-sensitive robot application [27]. In order to achieve accurate and smooth control of a multijoint manipulator remotely, the high-frequency discrete joint commands need to be accurately transferred from the remote side to the robot controller [28]. The packet loss and latency introduced by the communication will change the motion status suddenly, which will greatly affect the control performance. B. Case Study 1: Safe Multirobot Coordination In this case, a centralized multirobot coordination platform from Orebro University is deployed, in which robots are driven by generic second-order dynamics and coordinated by heuristic robot ordering policies [12]. As shown in Fig. 3 , the motion planner is used to calculate the path and trajectory of each robot. The modeling method for the coordination avoids the need for a priority discretization of the environment and allows robots to “follow each other” through CSs (overlap of multirobot trajectory envelops). The coordinator decides the robot order in the CS to avoid collisions and ensure safety. The simulated robot forward model is driven by the motion command from the con- troller, and the real-time multirobot motion status is displayed in a graphical user interface. The modeling method we used in this article has been validated formally and experimentally in simulation and with real robots [29]. The robot trajectory tracker tracks the robot trajectories and sends the real-time robot status to the controller. The controller and the robot forward model, as the simulated robot system, are achieved by Java, running on Ubuntu 20.04 PC. Here, two agents are designed to forward the robot command and update the real-time robot status, as illustrated in Fig. 3 . Agent 1 is responsible to forward the robot motion command from the controller to the simulated robot model, which is done over two independent UDP sockets. Agent 2 is responsible to forward the current robot status from the driven robot model to the controller. These two agents are programmed by Java and deployed on a Windows 10 PC. The network hardware interface Fig. 4. N-HiL simulation framework for human-motion-based teleoper- ation. is deployed between the simulated robot and the agents. To more closely match the real AGVs, the proposed N-HiL framework has the feasibility to add more simulated agents with more APs connections and add more sniffer channels to measure the wireless network performance. C. Case Study 2: Human-Motion-Based Teleoperation In this case, a human–robot motion transfer teleoperation system is deployed to evaluate the impacts of wireless using the N-HiL framework. Here, the captured motion data from the operator are used to control the YuMi robot. The external guide motion (EGM) interface from ABB provides a motion control interface with high frequency (up to 250 Hz), which enables real-time human–robot motion mapping. As shown in Fig. 4 , the software Axis Neuron captures human motion and sends the data to the robot controller via ROS serial protocol from Windows 10 to Ubuntu 20.04. The controller is responsible for processing and converting the human motion data to robot tool center point data using the designed mapping strategy [30]. The robot tool center point data are used to calculate the real-time joint configuration by the inverse kinematic solver. The motion controller program is connected to the motion server running on the simulated robot model via TCP protocol. The motion server is responsible to control normal motion like linear motion and joint motion using the given robot target. The UDP User Communication device is defined for the task of each arm, which receives the joint values at a high rate. The EGM motion is activated/deactivated by the motion server. When the EGM motion is activated, the generated joint value queue will be sent using Google Protocol Buffers (Protobuf) based on the UDP protocol. In this case, the communication between the human motion capture part on the Windows 10 system and the ubuntu 20.04 is connected by Ethernet. The network hardware interface is injected between the controller running on a ubuntu 20.04 PC and the simulated YuMi robot in RobotStudio on a Windows 10 PC. RobotStudio is a mature commercial simulation software provided by ABB and has been used for many years in the industry. It is used in this article for simulating the YuMi robot provides the same configuration of
LV et al.: IMPACTS OF WIRELESS ON ROBOT CONTROL 9259 Fig. 5. Hardware setup for the experiments of the above two case studies. The different hardware settings in the red dotted box are the options for the two case studies, respectively. Case1: safe multirobot coordination, Case2: human-motion-based teleoperation. the EGM interface and the IRC5 controller behavior compared to the real robot. IV. W IRELESS FOR S AFE M ULTIROBOT C OORDINATION To validate the reliability of the proposed N-HiL framework compared to the previous methods, comparative experiments be- tween the statistical modeling method and the proposed N-HiL method are conducted. The statistical modeling model used and compared to the N-HiL simulation results in the experimental Section IV is following the simulation methods from [29]. And the experiments and evaluations under the wireless network condition are carried out, choosing the Ethernet wired network performance as the baseline. The hardware setup for the safe multirobot coordination case is demonstrated in Fig. 5 with the case1 option. One NUC10 PC running the Open JDK with Intel(R) Core(TM) i5-10210U CPU @ 1.60 GHz × 4 processor is set as the simulated agent. An HP Laptop PC running the Ubuntu OS with Intel(R) Core(TM) i7-7500U CPU @ 2.70 GHz × 4 processor is set to simulate the safe multirobot coordination platform. The ULT PC is another HP Laptop PC to sniff the network latency from the ET2000 probe. During the simulation for the safe multirobot coordination case, the maximum CPU usage case is 5.6%. A. Experiment Design and Environment Two practical AGV use cases from the real industry appli- cations, harbor, and warehouse are chosen for the reliability validations of the proposed N-HiL framework. Harbor AGV is with a bigger size and higher moving speed, while the warehouse is with a smaller size and lower moving speed [31]. Seven robots are simulated for each case and the map with several obstacles is set for each case. The collision counts are logged corresponding to the timestamp for each test. And the collision rate P collision is calculated based on the total number of critical sections (CS) in the test. Fig. 6 shows the collision occurrences under 5G network conditions for the harbor AGV and warehouse AGV multirobot coordination cases. For the simulation using the statistical mod- eling that used a Bernoulli distribution, the packet loss rate (PLR) of 0, 0.1, and the packet latency of 0, 10, 50, and 100 ms Fig. 6. Collision occurrences under 5G network conditions for the harbor AGV and warehouse AGV multirobot coordination. Fig. 7. N-HiL simulation results compared with the statistical modeling for the harbor AGV safe coordination case. are set as the condition variables, respectively, to conduct the simulation for both habor AGV and warehouse AGV cases. For the simulation used in the proposed N-HiL framework, the wired network Ethernet, the wireless network Wi-Fi 6, and 5G are tested to evaluate the impacts of wireless on the safe multirobot coordination. Furthermore, the experiments under the Wi-Fi 6 network condition for safe multirobot coordination are tested in both Wi-Fi 6 @short and Wi-Fi 6 @long conditions. We clarified that the N-HiL simulation experiments were conducted in our laboratories with multiple functional areas for daily tests and experiments. Most of the laboratories are related to the industrial field with various industrial devices and equipment, such as metal control cabinets, motors, programmable logical controller automation equipment, heavy-duty autonomous mobile robots, manipulators, etc., where the environment is similar to the industrial field. B. Results and Analysis The experiment results of the harbor AGV case and the warehouse AGV case are listed in Figs. 7 and 8 . From the results of the experiment, using the statistical modeling methodology,
9260 IEEE TRANSACTIONS ON INDUSTRIAL INFORMATICS, VOL. 19, NO. 9, SEPTEMBER 2023 Fig. 8. N-HiL simulation results compared with the statistical modeling for the warehouse AGV safe coordination case. there was no collision in the 10 000 CSs test under the 50 ms latency set for any case. For the bigger and faster harbor AGV case, some collisions were raised when the latency is set to 100 ms. The probability of collision P collision is 0.499 for zero PLR and 100 ms latency. The P collision is 1.789 for 0.1 PLR and 100 ms latency. Then the simulation results using the N-HiL framework for the harbor AGV case are listed in Fig. 7 . No col- lision occurred for the harbor AGV case when communicating via the Ethernet network. The P collision is 0.904 under the Wi-Fi6@shortand2.299 undertheWi-Fi6@longconditions. The P collision is 0.809 under the 5G network condition, which shows a better performance than Wi-Fi 6. As shown in Fig. 8 , for the smaller and slower warehouse AGV case, no collision happened when using the statistical modeling method. When using the N-HiL simulation method, the P collision is 0.099 , 1.477 , and 2.300 , respectively, under the Ethernet, Wi-Fi 6 @short, and Wi-Fi 6 @long conditions. And the P collision under the 5G network connection is 0.540 , which shows a better performance than Wi-Fi 6 for the warehouse AGV case same as the experiment results of the harbor AGV case. For the common wireless network condition, including Wi-Fi 6 and 5G, only the latency under 50 ms is considered meaningful. When we model the communication network using the experi- ence parameters, even with the probability distribution model, some uncommon factors for the network, such as congestion or the sync problem special for certain long-term control cases cannot be reproduced. The N-HiL simulation framework pro- vides a more realistic network condition for evaluating the robot control performance. Compared to the experiment results using statistical modeling, the N-HiL framework got higher results of P collision . V. W IRELESS FOR H UMAN -M OTION -B ASED T ELEOPERATION The experiments in the case study of human-motion-based teleoperation aim to evaluate the impacts of wireless on robot control performance. Meanwhile, the correlation analysis from the control perspective with the communication is investigated. In this case, the human motion data are recorded and repeated play at least 60 min for each test, where the human swings his right arm from one side to the other side. The motion data from the human side are sent under 125 Hz, and each test continues for 4 h to get reliable results. Meanwhile, the comparative exper- iments of using the raw data and the filtered data under various network conditions are conducted to investigate the effect of the control strategy on the network depletion from the local controller side. The hardware setup for the human-motion-based teleoperation case is demonstrated in Fig. 5 with the case2 option. One special HP Laptop PC running the motion capture software Neuron Axis is used to produce the human motion data. OneNUC10PCrunningtheROSissettosimulatethelocalrobot controller. Another HP Laptop PC running the Robot Studio is set to simulate the remote YuMi Robot platform. The ULT PC is another HP Laptop PC to sniff the network latency from the ET2000 probe. During the simulation for the teleoperation simulation case in Robot Studio, the maximum CPU usage is 18.3%. To guarantee the time synchronization among the multiple computers, we set up a network time protocol (NTP) server between the ULT PC and the other PCs (including the simulated controller PC and the simulated robot platform PC). All the network setup in this work is the local area network, and the NTP server can provide better than 1-ms accuracy to synchronize the time, which satisfies the time synchronization requirements in this article. A. Comparisons of Wireless Networks Compared to the wired network Ethernet, four wireless net- work conditions are implemented in this case to evaluate the impacts of the wireless on robot motion control performance, including Wi-Fi 6 with three range-level coupled APs and 5G. To evaluate the performance of the networks, the latency L is logged using the unobtrusive network sniffer. Moreover, the nor- malized probability density function (PDF) and complementary cumulative distribution function (CCDF) of L for each test are calculated and compared from a statistical perspective. Fig. 9 displays the wireless network conditions of Wi-Fi 6 and 5G using the PDF and CCDF. It shows an obvious different profile between Wi-Fi 6 and 5G, where the CCDF curves of Wi-Fi6 show “short-head-long-tail” (SHLT) and CCDF curves of 5G show “long-head-short-tail” (LHST). In 5G, radio transmissions are carefully scheduled into specified resource blocks within given time frames by base station, thus the latency is more bounded. In Wi-Fi 6, however, the transmissions are based on carrier-sense multiple access with collision avoidance, thus there are more chances that the device needs to wait for some time before the packet can be transmitted, which results in a shorter head and longer tail in the latency distribution. B. Intuitive Comparison of Control Performance To analyze the correlation between robot motion and the com- munication of the network, some key metrics are selected and defined for the human-motion-based teleoperation case study.
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LV et al.: IMPACTS OF WIRELESS ON ROBOT CONTROL 9261 Fig. 9. Network performance analysis of Wi-Fi 6 and 5G network conditions recorded in the experiments. (a)–(d) are the PDF and CCDF curves of the network downstream latency; (e)–(h) are the PDF and CCDF of the network upstream latency. The desired joint position (the commands sent from the re- mote side) values are defined as J d , while the measured joint values (feedback of the real joint states) are defined as J r . J d and J r are time-series signals, which are logged corresponding to the system timestamp with a sample rate of 500 Hz. The timestamps between the peaks of J d and J r are compared and subtracted as the motion delay τ by (1), and the motion delay sequence τ of all periods in one test is given by (2) ˆ τ i = arg max t N i J r ( t ) arg max t N i J d ( t ) (1) ˆ T = ˆ τ 1 ˆ τ 2 · · · ˆ τ P (2) where i = { 1 , 2 , 3 , . . . , P , } and N i denotes the i th period of the repeated motion. The cross-correlation between J d and J r is calculated follow- ing (3) and the average motion delay ¯ T is given by (4) ˆ R J d J r ( m ) = N m 1 n = 0 J d n + mJ r n , m 0 , ˆ R JrJd ( m ) , m < 0 . (3) ¯ T = arg max m [ T 2 , T 2 ] ˆ R JdJr ( m ) . (4) Fig. 10. Intuitive comparison for motion delay τ and peak amplitude error ε peak under Ethernet, Wi-Fi 6, and 5G network conditions, using raw data and the filtered data. In order to evaluate the remote-control performance of the teleoperation, the absolute errors between the peaks of desired joint values J d and the measure joint values J r are calculated as the peak amplitude error ε peak by (5), and the peak amplitude error sequence E peak is defined by (6) ˆ ε peak i = max t N i J r ( t ) max t N i J d ( t ) (5) ˆ E peak = ˆ ε peak 1 ˆ ε peak 2 · · · ˆ ε peak P . (6) Further, the average peak amplitude error E peak are calculated as E peak = mean ˆ E peak = P 1 ˆ ε peak p P . (7) Corresponding to the network analysis, the above evaluation metrics of robot motion, the robot motion delay τ , and peak amplitude error ε peak , are also statistically analyzed toward the network latency L . More intuitive results of the motion delay τ and the peak amplitude error ε peak from the robot motion perspective is shown in Fig. 10 . The robot motion indicators under the Ethernet condition are chosen as the baseline, and the robot motion performance using the raw data and the filtered data is analyzed under four wireless network conditions. From Fig. 10(a) and (b) , the wireless network leads to a larger ε peak , which means decreasing the accuracy of robot control. Further, it is clear in Fig. 10(c) and (d) that the filter reduces the ε peak , improving the accuracy, but introducing an additional delay. In order to prove the validity of the simulated YuMi robot model in Robot Studio, we implemented the same control framework on the real YuMi robot using Ethernet and compared the key metrics of the control performance with the N-HiL simulation experiments. The results on the real YuMi robot show the average motion delay ¯ T of 0.3174 s and the average peak amplitude error E peak
9262 IEEE TRANSACTIONS ON INDUSTRIAL INFORMATICS, VOL. 19, NO. 9, SEPTEMBER 2023 Fig. 11. Statistical analysis of robot motion performance under the four wireless conditions compared to Ethernet, using the raw data: (a)–(d) are the PDF curves of the motion delay; (e) is the CCDF comparison of the motion delay; (f)–(i) are the PDF curves of the peak amplitude error; (j) is the CCDF comparison of the peak amplitude error. of 1.9755°, which is consistent with the N-HiL simulation results under the Ethernet condition. C. Impacts of Wireless to Control Performance For the motion delay τ of the robot, the PDF curves un- der the wireless network conditions compared to the Ethernet condition are shown in Fig. 11(a) (d) . It is clearly shown that the motion delay under the 5G network condition and the three Wi-Fi 6 network conditions are almost at the same level while using the raw data. For the peak amplitude error ε peak , the corresponding PDF curves are listed in Fig. 11(f) (i) . Fig. 12. Statistical analysis of robot motion performance under the four wireless conditions compared to Ethernet, interacting with the control strategy by deploying a filter on robot controller: (a)–(d) are the PDF curves of the motion delay; (e) is the CCDF comparison of the motion delay; (f)–(i) are the PDF curves of the peak amplitude error; and (j) is the CCDF comparison of the peak amplitude error. Furthermore, the CCDF curves of motion delay and peak am- plitude error are calculated and plotted in Fig. 11(e) and (j) . For the motion delay, the righter the CCDF curve, the greater the motion delay. For the peak amplitude error, the righter CCDF curve means the smaller error (negative values). In Fig. 11(e) , the motion delays under the Wi-Fi 6 condition are smaller than that under the 5G network condition, which shows the advantage of Wi-Fi 6 compared to 5G in this situation for the high response. In Fig. 11(j) , the errors under wireless network conditions are obviously larger compared to the wired Ethernet condition, and the 5G has smaller errors compared to all Wi-Fi 6 conditions.
LV et al.: IMPACTS OF WIRELESS ON ROBOT CONTROL 9263 Fig. 13. Representative test showing how the robot motion performance is affected by sudden changes in network conditions: (a) network downstream and upstream latency of part1 in this test; (b) overall performance of the robot motion and network; and (c) network downstream and upstream latency of part 2 in this test. D. Interplay Between the Wireless and Control Strategy Afterimplementingalow-passfilterontheEGMinterface,the differences betweenthemotiondelayunder the5G andtheWi-Fi 6aremagnified,whichisreasonableduetotheconvolutionofthe filter in the control loop. From Fig. 12(a) (d) , the motion delay using the raw data under the Wi-Fi 6 @long condition is larger than in the Wi-Fi 6 @short and Wi-Fi 6 @medium conditions. And motion delay under a 5G connection is larger than all Wi-Fi 6 conditions. This shows that the motion delay under 5G network conditions is more sensitive to network latency compared to Wi-Fi 6. The peak amplitude errors under the wireless conditions using the filtered data are shown in Fig. 12(f) (i) , where the ε peak under the 5G network condition and the three Wi-Fi 6 network conditions are almost at the same level as wired Ethernet. By comparing the CCDF curves in Fig. 12(e) using the filtered data to Fig. 11(e) using raw data, it is obviously shown that the implemented filter on the robot side increased the motion delay under all network conditions, especially the 5G and Wi-Fi 6 @long. By comparing Fig. 12(j) with Fig. 11(j) , it is clear that the filter works, reducing the errors introduced by the wireless to a level that rivals the performance of wired Ethernet. E. Impacts of Wireless Network Fluctuation Fig. 13 shows a test with wireless fluctuation, which aims to investigate the impacts of the wireless network fluctuation on the robot control. The wireless condition is changed by involving extra AP connections with the same radio band, where the test is separated into part 1 and part 2. In Fig. 13(b) , it is obvious that the latency increased in part 2 after introducing radio interference. This fact also can be proved by the statistical analysis of the latency L forbothupstreamanddownstreaminFig. 13(a) and (c) , where the CCDF curves have a “longer tail” in part 2 compared to part 1. The “longer tail” of CCDF means larger latency. TABLE II C OMPARISONS OF W IRELESS P ROFILES W ITH C ONTROL S TRATEGIES Corresponding to network performance, the motion delay ¯ T in Fig. 13(b) is increased obviously due to the increased network latency in part 2. F. Future Perspectives Last but not the least, we hope to give some directional recommendations and suggestions for robot developers and communication developers in the field so that they can get the most benefits from the efforts of both sides through the so-called “control-communication co-design.” From the comparisons in Figs. 11 and 12 , we can observe that the communication strate- gies (i.e., wireless network with LHST or SHLT profile) and control strategies (i.e., using the filter or not) may have opposite impacts on different control expectations (i.e., responsiveness or accuracy), as summarized in Table II . 1) If users emphasize the control responsiveness, we rec- ommend disabling the filter in control and choosing the wireless network with an SHLT profile. In this combi- nation, the latencies introduced by the control filter and wireless network are both reduced, with the expense of low control accuracy. 2) If users emphasize the control accuracy, we recommend enabling the filter in control and choosing the wireless
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9264 IEEE TRANSACTIONS ON INDUSTRIAL INFORMATICS, VOL. 19, NO. 9, SEPTEMBER 2023 network with a LHST profile. In this combination, the la- tency of the wireless network is longer but more bounded (i.e., smaller tail), which is beneficial to reducing control error,andthefilterincontrolcanfurtherreducethecontrol error caused by the network latency. Since it is only verified in limited test cases, these recommen- dations are preliminary. In the future, we will further investigate some data-driven and even reinforcement learning methods so that the robot control system can “negotiate” with the commu- nication infrastructure to achieve the best tradeoffs, especially when there are multiple objectives to be optimized. Moreover, current tuning on the robot local controller only involved a low-pass filter, which is just a small step towards the “control communication co-design.” In future article, we will employ more advanced control methods, such as the time-domain pas- sivity approaches in the N-HiL framework. VI. C ONCLUSION In this article, we propose a novel N-HiL simulation frame- work to effectively and efficiently investigate the impacts of wireless on robot control under real network conditions. Two representative robot applications, which are sensitive to com- munication latency, safe multirobot coordination, and human- motion-based teleoperation, are investigated using the proposed N-HiL framework. The Wi-Fi 6 and 5G wireless networks are tested and compared, drawing the network profiles of SHLT and LHST with the CCDF curves. Results show that the proposed N-HiL framework provides more trustworthy results compared to the statistical modeling method while eliminating the huge efforts and costs of building and testing the entire physical robot system in real life. From the statistical analysis of the wireless latency and the robot motion performances, a preliminary answer is drawn on how the wireless networks affect robot control. Furthermore, the interplay between the wireless and the control strategy is investigated by comparing the robot control performances under the wireless with different latency profiles. The experiment results will be helpful for both robot developers and communication developers to find the best tradeoffs between costs and performances. R EFERENCES [1] W. Dai, H. Nishi, V. Vyatkin, V. Huang, Y. Shi, and X. Guan, “Industrial edge computing: Enabling embedded intelligence,” IEEE Ind. Electron. Mag. , vol. 13, no. 4, pp. 48–56, Dec. 2019. [2] A. Wichmann, T. Korkmaz, and A. S. Tosun, “Robot control strategies for task allocation with connectivity constraints in wireless sensor and robot networks,” IEEE Trans. Mobile Comput. , vol. 17, no. 6, pp. 1429–1441, Jun. 2018. [3] J. Gielis and A. Prorok, “Improving 802.11p for delivery of safety-critical navigation information in robot-to-robot communication networks,” IEEE Commun. Mag. , vol. 59, no. 1, pp. 16–21, Jan. 2021. [4] D. Baumann, F. Mager, U. Wetzker, L. Thiele, M. Zimmerling, and S. Trimpe, “Wireless control for smart manufacturing: Recent approaches and open challenges,” Proc. IEEE , vol. 109, no. 4, pp. 441–467, Apr. 2021. [5] C. L. Fall et al., “A multimodal adaptive wireless control interface for people with upper-body disabilities,” IEEE Trans. Biomed. Circuits. Syst. , vol. 12, no. 3, pp. 564–575, Jun. 2018. [6] Y. Maddahi, S. Liao, W.-K. Fung, E. Hossain, and N. Sepehri, “Selec- tion of network parameters in wireless control of bilateral teleoperated manipulators,” IEEE Trans. Ind. Inform. , vol. 11, no. 6, pp. 1445–1456, Dec. 2015. [7] S. Manfredi, E. Natalizio, C. Pascariello, and N. R. Zema, “Stability and convergence of a message-loss-tolerant rendezvous algorithm for wireless networked robot systems,” IEEE Trans. Control Netw. Syst. , vol. 7, no. 3, pp. 1103–1114, Sep. 2020. [8] A. Kadian et al., “Sim2Real predictivity: Does evaluation in simulation predictreal-worldperformance?,” IEEERobot.Automat.Lett. ,vol.5,no.4, pp. 6670–6677, Oct. 2020. [9] Y.-C. Liu, T.-C. Lin, and M.-T. Lin, “Indirect/direct learning coverage control for wireless sensor and mobile robot networks,” IEEE Trans. Control Syst. Technol. , vol. 30, no. 1, pp. 202–217, Jan. 2022. [10] J. D. Herath and A. Seetharam, “A Markovian model for analyzing opportunistic request routing in wireless cache networks,” IEEE Trans. Veh. Technol. , vol. 68, no. 1, pp. 812–821, Jan. 2019. [11] H. Li and A. V. Savkin, “Wireless sensor network based navigation of micro flying robots in the industrial Internet of Things,” IEEE Trans. Ind. Inform. , vol. 14, no. 8, pp. 3524–3533, Aug. 2018. [12] A. Mannucci, L. Pallottino, and F. Pecora, “Provably safe multi-robot coordination with unreliable communication,” IEEE Robot. Automat. Lett. , vol. 4, no. 4, pp. 3232–3239, Oct. 2019. [13] V. Digani, M. A. Hsieh, L. Sabattini, and C. Secchi, “Coordination of multiple AGVs: A quadratic optimization method,” Auton. Robots , vol. 43, no. 3, pp. 539–555, 2019. [14] L. Zhou, L. Liu, M. Li, and J. Wang, “HLSP/UWAC: A hardware-in-loop simulation platform for underwater acoustic communication,” in Proc. IEEE 6th Int. Conf. Wireless Commun. Netw. Mobile Comput. , 2010, pp. 1–4. [15] Y. Chen and D. J. Braun, “Hardware-in-the-loop iterative optimal feed- back control without model-based future prediction,” IEEE Trans. Robot. , vol. 35, no. 6, pp. 1419–1434, Dec. 2019. [16] M. D. Stefano, H. Mishra, A. M. Giordano, R. Lampariello, and C. Ott, “A relative dynamics formulation for hardware-in-the-loop simulation of on-orbit robotic missions,” IEEE Robot Autom. Lett. , vol. 6, no. 2, pp. 3569–3576, Apr. 2021. [17] J. Kumar and E. Amutha, “Control and tracking of robotic manipulator using PID controller and hardware in loop simulation,” in Proc. IEEE Int. Conf. Commun. Netw. Technol. , 2014, pp. 1–3. [18] A. P. Lamping, J. N. Ouwerkerk, and K. Cohen, “Multi-UAV control and supervision with ROS,” in Proc. Aviation Technol., Integr., Oper. Conf. , 2018, Art. no. 4245. [19] C. Qi, F. Gao, X. Zhao, Q. Wang, and Q. Sun, “Distortion compensation for a robotic hardware-in-the-loop contact simulator,” IEEE Trans. Control Syst. Technol. , vol. 26, no. 4, pp. 1170–1179, Jul. 2018. [20] M. Aleksy, F. Dai, N. Enayati, P. Rost, and G. Pocovi, “Utilizing 5G in industrial robotic applications,” in Proc. IEEE 7th Int. Conf. Future Internet Things Cloud , 2019, pp. 278–284. [21] S. Hayat, E. Yanmaz, and R. Muzaffar, “Survey on unmanned aerial vehicle networks for civil applications: A communications view- point,” IEEE Commun. Surv. Tut. , vol. 18, no. 4, pp. 2624–2661, Oct.–Dec. 2016. [22] H. Lv, Z. Pang, M. Xiao, and G. Yang, “Hardware-in-the-loop simulation for evaluating communication impacts on the wireless-network-controlled robots,” in Proc. IEEE IECON 48th Annual Conf. Ind. Electron. Soc. , 2022, pp. 1–6, doi: 10.1109/IECON49645.2022.9968471 . [23] P. Park, S. C. Ergen, C. Fischione, C. Lu, and K. H. Johansson, “Wireless network design for control systems: A survey,” IEEE Commun. Surv. Tut. , vol. 20, no. 2, pp. 978–1013, Apr.–Jun. 2018. [24] H. Andreasson et al., “Autonomous transport vehicles: Where we are and what is missing,” IEEE Robot. Automat. Mag. , vol. 22, no. 1, pp. 64–75, Mar. 2015. [25] L. Zhang, H. Gao, and O. Kaynak, “Network-induced constraints in networked control systems—A survey,” IEEE Trans. Ind. Inform. , vol. 9, no. 1, pp. 403–416, Feb. 2013. [26] K. Sakurama and T. Sugie, “Generalized coordination of multi-robot systems,” Found. Trends Syst. Control , vol. 9, no. 1, pp. 1–170, 2021. [27] R. Baranitha, R. Mohajerpoor, and R. Rakkiyappan, “Bilateral teleop- eration of single-master multislave systems with semi-markovian jump stochastic interval time-varying delayed communication channels,” IEEE Trans. Cybern. , vol. 51, no. 1, pp. 247–257, Jan. 2021. [28] S. Chen, Z. Wang, A. Chakraborty, M. Klecka, G. Saunders, and J. Wen, “Robotic deep rolling with iterative learning motion and force control,” IEEE Robot. Automat. Lett. , vol. 5, no. 4, pp. 5581–5588, Oct. 2020. [29] F. Pecora, H. Andreasson, M. Mansouri, and V. Petkov, “A loosely-coupled approach for multi-robot coordination, motion planning and control,” in Proc. Int. Conf. Automat. Plan. Scheduling , 2018, pp. 485–493.
LV et al.: IMPACTS OF WIRELESS ON ROBOT CONTROL 9265 [30] H. Lv et al., “GuLiM: A hybrid motion mapping technique for teleoper- ation of medical assistive robot in combating the COVID-19 pandemic,” IEEE Trans. Med. Robot. Bionics , vol. 4, no. 1, pp. 106–117, Feb. 2022. [31] J. Fu, J. Zhang, G. Ding, S. Qin, and H. Jiang, “Determination of vehicle requirements of AGV system based on discrete event simulation and response surface methodology,” Proc. Inst. Mech. Eng. B J. Eng. Manuf. , vol. 235, no. 9, pp. 1425–1436, 2021. Honghao Lv (Student Member, IEEE) received the B.E. degree in mechanical engineering from the China University of Mining and Technology, Xuzhou, China, in 2018. He is currently working toward the Ph.D. degree in mechatronic engi- neering with the School of Mechanical Engi- neering, Zhejiang University, Hangzhou, China. He was with the School of Electrical Engineer- ing and Computer Science, KTH Royal Institute of Technology, Stockholm, Sweden, as a joint Ph.D. Student, from 2021 to 2022, under the financial support from the China Scholarship Council. He developed dual-arm robotic teleoperation systems based on the motion capture techniques. He worked on mobile robotics, multirobot coordination, and network hardware-in-the-loop simulation as a Guest Researcher with the ABB Corporate Research, Västerås, Sweden. His research interests include dual-arm robotic teleoperation, human–robot intelligent inter- face, and safe interaction. Zhibo Pang (Senior Member, IEEE) received MBA degree in innovation and growth from the University of Turku, Turku, Finland, in 2012, and the Ph.D. degree in electronic and computer systems from the KTH Royal Institute of Tech- nology, Stockholm, Sweden, in 2013. He is currently a Senior Principal Scientist with the ABB Corporate Research Sweden, Västerås, Sweden, and an Adjunct Professor with the University of Sydney, Camperdown, NSW, Australia, and the KTH Royal Institute of Technology. He works on enabling technologies in electronics, com- munication, computing, control, artificial intelligence, and robotics for Industry4.0 and Healthcare4.0. Dr. Pang is a Member of IEEE IES Industry Activities Committee and a Co-Chair of the Technical Committee on Industrial Informatics. He is an Associate Editor of IEEE TII, IEEE JBHI, and IEEE JESTIE. He was General Chair of IEEE ES2017, General Co-Chair of IEEE WFCS2021, and Invited Speaker at the Gordon Research Conference AHI2018. He was the recipient of the “Inventor of the Year Award” by ABB Corporate Research Sweden, three times in 2016, 2018, and 2021, respectively. Koushik Bhimavarapu (Member, IEEE) re- ceived the B.Tech. degree in electronics and communication engineering from the Jawahar- lal Nehru Technological University, Hyderabad, India, in 2020, and the M.Sc. degree in electri- cal engineering with emphasis on telecommu- nication systems from the Blekinge Institute of Technology, Karlskrona, Sweden, in 2022. He is currently working as an Associate Sci- entist on industrial automation with the ABB Corporate Research Center, Västerås, Sweden. His research interests include industrial wireless communication net- works, internet of things, cloud computing, low-latency communication, and time-sensitive networking. Geng Yang (Member, IEEE) received the B.E. and M.Sc. degrees in instrument science and engineering from the College of Biomedical Engineering and Instrument Science, Zhejiang University (ZJU), Hangzhou, China, in 2003 and 2006, respectively, and the Ph.D. degree in elec- tronic and computer systems from the Depart- ment of Electronic and Computer Systems, the Royal Institute of Technology (KTH), Stockholm, Sweden, in 2013. From 2013 to 2015, he was a Postdoctoral Researcher with the iPack VINN Excellence Center, School of Informa- tion and Communication Technology, KTH. He is currently a Professor with the School of Mechanical Engineering, ZJU. His research interests include bioinspired flexible and stretchable sensors for robot sensing and human–robot interaction, focusing on key enabling technologies for Human-Cyber-Physical-System and Healthcare 4.0. Dr. Yang is the Associate Editor of IEEE J OURNAL OF B IOMEDICAL AND H EALTH I NFORMATICS and Bio-Design and Manufacturing .

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