Mental Workload and Human-Robot Interaction in Collaborative Tasks: A Scoping Review

Figures & data

Table 1. Set of keywords used in the search.

HRC	Impact on workers	Context
Cobot OR co-robot OR collaborative robot OR human robot collaboration OR HRC	Mental workload OR fatigue OR stress	Work* OR industry* OR manufact*

Figure 1. Flow chart of the screening process.

Figure 2. Number of papers per year (up to June 2022).

Table 2. Studies main characteristics.

N.	Title	Authors	Year	Journal/Proceedings	Country	Area of research	Study aims
1	Human-robot collaboration in cellular manufacturing: Design and development	Tan J. T. C., Duan F., Zhang Y., Watanabe K., Kato R., Arai T.	2009	the 2009 IEEE/RSJ International Conference on Intelligent Robots and Systems	Japan	Robotics	Developing solution to reduce MWL
2	Development of advanced cellular manufacturing system with human-robot collaboration	Kato R., Fujita M., Arai T.	2010	19th International Symposium in Robot and Human Interactive Communication	Japan	Robotics	Investigating MWL factor in HRC
3	Assessment of operators’ mental strain induced by hand-over motion of industrial robot manipulator	Fujita M., Kato R., Tamio A.	2010	19th International Symposium in Robot and Human Interactive Communication	Japan	Robotics	Investigating MWL factor in HRC
4	Assessment of operator stress induced by robot collaboration in assembly	Arai, T., Kato R., Fujita M.	2010	CIRP ANNALS - Manufacturing Technology	Japan	Robotics	Investigating MWL factor in HRC
5	Dynamic affection-based motion control of a humanoid robot to collaborate with human in flexible assembly in manufacturing	Rahman, S.M.M., Wang, Y.	2015	ASME 2015 Dynamic Systems and Control Conference	USA	Engineering	Developing solution to reduce MWL
6	Human-robot collaboration on an assembly work with extended cognition approach	Ustunel, Z., Gunduz, T.	2017	Journal of Advanced Mechanical Design, Systems and Manufacturing	Turkey	Engineering	Investigating MWL factor in HRC
7	Subjective Stress in Hybrid Collaboration	Müller, S.L., Stiehm S., Jeschke S., Richert A.	2017	Social Robotics, ICSR 2017	Germany	Social robotics	Investigating MWL factor in HRC
8	Effects of movement speed and predictability in human–robot collaboration	Koppenborg M., Nickel P., Birgit N., Lungfiel A., Huelke M.	2017	Human Factors and Ergonomics in Manufacturing	Germany	Occupational health	Investigating MWL factor in HRC
9	Transparent role assignment and task allocation in human robot collaboration	Roncone A., Mangin O., Scassellati B.	2017	2017 IEEE International Conference on Robotics and Automation (ICRA)	United States	Robotics	Developing solution to reduce MWL
10	An Effective Model for Human Cognitive Performance within a Human-Robot Collaboration Framework	Rabby K. M., Khan M. Karimoddini A., Jiang S. X.	2019	2019 IEEE International Conference on Systems, Man and Cybernetics (SMC)	USA	Human-robot interaction	Investigating MWL factor in HRC
11	Stress in manual and autonomous modes of collaboration with a cobot.	Pollak, A., Paliga M., Pupopulos M.M., Kozusznik B., Kozusznik M. W.	2020	Computers in Human Behavior	Poland	Human-robot interaction	Investigating MWL factor in HRC
12	Using Virtual Reality to test Human-Robot Interaction during a collaborative task	Etzi R., Huang S.Y., Scurati G.W., Lyu S., Ferrise F., Gallace A., Gaggioli A., Chirico A., Carulli M. Bordegoni M.	2020	IDETC-CIE International Design Engineering Technical Conferences & Computers and Information in Engineering Conference	Italy	Engineering	Investigating MWL factor in HRC
13	Task Interdependence in Human-Robot Teaming	Zhao F.Y., Henrichs C., Mutlu B.	2020	19 IEEE International Workshop on Robot and Human Communication (ROMAN)	USA	Social robotics	Investigating MWL factor in HRC
14	Towards a Real-Time Cognitive Load Assessment System for Industrial Human-Robot Cooperation	Rajavenkatanarayanan A., Nambiappan H.R., Kyrarini M., Makedon F.	2020	2020 29th IEEE International Conference on Robot and Human Interactive Communication (RO-MAN)	USA	Human-robot interaction	Developing solution to reduce MWL
15	Mutualistic and adaptive human-machine collaboration based on machine learning in an injection moulding manufacturing line	Bettoni A., Montini E, Righi M., Villani V., Tsvetanov R., Borgia S., Secchi C., Carpanzano E.	2020	53rd CIRP Conference on Manufacturing Systems	Switzerland	Engineering	Developing solution to reduce MWL
16	Augmenting the human-robot communication channel in shared task environments	Arntz A., Eimler S C., Hoppe H. U.	2020	26th International Conference, CollabTech 2020 Tartu	Germany	Human-robot interaction	Developing solution to reduce MWL
17	Effect of Cognitive Fatigue, Operator Sex, and Robot Assistance on Task Performance Metrics, Workload, and Situation Awareness in Human-Robot Collaboration	Hopko S. K., Khurana R., Mehta R. K., Pagilla P. R.	2021	IEEE Robotics and Automation Letters	USA	Robotics	Investigating MWL factor in HRC
18	Human-Robot Collaboration: Optimizing Stress and Productivity Based on Game Theory	Messeri C., Masotti G., Zanchettin A.M., Rocco P.	2021	IEEE Robotics and Automation Letters	Italy	Robotics	Developing solution to reduce MWL
19	Cognitive interaction analysis in Human-Robot Collaboration using an asssembly task	Chacón, A., Ponsa P., Angulo C.	2021	Electronics	Spain	Engineering	Investigating MWL factor in HRC
20	Prevention of occupational risks related to the Human-Robot Collaboration	Brun L., Wiol, L.	2021	IHIET 2020: Human Interaction, Emerging Technologies and Future Applications III	France	Human-robot interaction	Investigating MWL factor in HRC
21	Robot Trajectory Adaptation to Optimise the Trade-off between Human Cognitive Ergonomics and Workplace Productivity in Collaborative Tasks	Lagomarsino, M., Lorenzini, M., De Momi, E., Ajoudani, A.	2022	IEEE/RSJ International Conference on Intelligent Robots and Systems	Italy	Robotics	Developing solution to reduce MWL
22	The Impacts of Human-Cobot Collaboration on Perceived Cognitive Load and Usability during an Industrial Task: An Exploratory Experiment	Fournier E., Kilgus D., Landry A., Hmedan B., Pellier D., Fiorino H, Jeoffrion C.	2022	IISE Transactions on Occupational Ergonomics and Human Factors	France	Occupational health	Investigating MWL factor in HRC
23	On the effects of leader-follower roles in dyadic human-robot synchronisation	Messeri C., Zanchettin A.M., Rocco P., Gianotti E., Chirico A., Magoni S., Gaggioli A.	2023	EEE Transactions on Cognitive and Developmental Systems	Italy	Human-robot interaction	Investigating MWL factor in HRC

Legenda: MWL = Mental Workload; Cobot = Collaborative Robot; HRC = Human Robot Collaboration

Table 3. MWL measures used in the selected studies.

N.	Study	Self-report	Physiological	Performance
1	Tan et al., 2009	==	EDA	Completion time and quality
2	Kato et al., 2010	NASA RTLX (Hart, 2006)	EDA	Completion time
3	Fujita et al., 2010	==	EDA	==
4	Arai et al., 2010	==	EDA	==
5	Rahman and Wang, 2015	NASA RTLX (Hart, 2006)	==	Accuracy and efficiency
6	Ustunel and Gunduz, 2017	NASA RTLX (Hart, 2006)	==	==
7	Müller et al., 2017	Short Stress State-Questionnaire (Helton, 2004)	==	==
8	Koppenborg et al., 2017	NASA RTLX (Hart, 2006)	IBI	Completion time and accuracy
9	Roncone et al., 2017	Open questions	==	Completion time
10	Rabby et al., 2019	==	==	==
11	Pollak et al., 2020	Four items from Primary and secondary appraisal scale (PASA - Gaab at al., 2009)	HR	==
12	Etzi et al., 2020	Questions on feelings and user experience	EDA, HR	Completion time and accuracy
13	Zhao et al., 2020	NASA RTLX (Hart, 2006)	HRV	Completion time
14	Rajavenkatanarayanan et al., 2020	==	HRV, and EDA	==
15	Bettoni et al., 2020	Questionnaire adapted from NASA RTLX (Hart, 2006)	HRV	Productivity
16	Arntz et al., 2020	Cohen's perceived stress scale (Cohen, 1994); Frustration from NASA TLX Load index (Hart, 2006)	==	==
17	Hopko et al., 2021	Questions about fatigue; NASA TLX (Hart, 2006)	HRV	Efficiency and accuracy
18	Messeri et al., 2021	==	HRV	Productivity
19	Chacón et al., 2021	NASA RTLX (Hart, 2006)	==	Completion time
20	Brun and Wioland, 2021	Interviews	==	==
21	Lagomarsino et al., 2022	NASA RTLX (Hart, 2006)	HRV	==
22	Fournier et al., 2022	NASA RTLX (Hart, 2006)	==	Completion time and accuracy
23	Messeri et al., 2023	==	HRV	Completion time

Notes. MWL = Mental Workload; Cobot = Collaborative Robot; EDA = Electrodermal Activity; IBI = Interbeat interval of heart rate; HR = Heart Rate.

Table 4. Study design and findings.

N.	Study	Setting	Cobot	Task	Sample Size	Dependent Variable	Independent Variable	MWL Source 1	MWL Source 2	MWL Source 3	Findings
1	Tan et al., 2009	Lab	Twin-manipulator	Assembly	5	EDA and performance	Cobot speed and distance	x	==	==	Mental workload increases as robot motion increases and human-robot distance decreases
2	Kato et al., 2010	Lab	Twin-manipulator	Assembly	13	EDA and performance	Cobot speed, distance, and notice	x	==	==	Cognitive and emotional stress increases as robot speed increases, as human-robot distance decreases and in absence of adequate information about the robot's motion and speed
3	Fujita et al., 2010	Lab	Twin-manipulator	Assembly	5	EDA and performance	Cobot speed, distance, and notice	x	==	==	Cognitive and emotional stress increases as robot speed increases, as human-robot distance decreases and in absence of adequate pre-knowledge about robot motion
4	Arai et al., 2010	Lab	Twin-manipulator	Assembly	5	EDA and performance	Cobot speed, distance, and notice	x	==	==	Cognitive and emotional stress increases as robot speed increases, as human-robot distance decreases and in absence of adequate pre-knowledge about robot motion
5	Rahman and Wang, 2015	Lab	Dual arm	Assembly	20	Subjective MWL, and performance	Cobot's affective expression	==	x	==	Mental workload is lower when working with a robot able to use dynamic affective expression compared to a standard machine
6	Ustunel and Gunduz, 2017	Lab	Single arm	Assembly	40	Subjective MWL	Extended cognition	==	x	==	Cognitive load is lower when information about collaborative task is provided
7	Müller et al., 2017	Virtual Scenario	Virtual industrial and humanoid	Assembly	112	Subjective stress level	Cobot appearance and reliability	x	==	==	Stress levels are unrelated to robot appearance and behavior
8	Koppengborg et al., 2017	Virtual Scenario	Virtual robotic arm	Pick and place	28	Subjective MWL, IBI, and performance	Cobot's speed and predictability	x	==	==	High mental workload is associated with high robot speed
9	Roncone et al., 2017	Lab	Dual arm	Assembly	8	subjective MWL and performance	Cobot role	==	==	x	Cognitive load is lower when interacting with a robot able to reason about role assignment and task
10	Rabby et al., 2019	Simulated Scenario	Virtual robotic arm	Pick and place	==	Cognitive WL (mathematical model)	Cobot performance	==	x	==	Higher cognitive workload and lower cognitive performance are associated with decrease in robot performance
11	Pollak et al., 2020	Lab	Single arm	Pick and place	45	Subjective MWL and HR	Cobot modes (autonomous and manual)	==	==	x	Stress levels increase with the decrease of operators’ control during HRC
12	Etzi et al., 2020	Lab	Virtual robotic arm	Assembly	10	Subjective experience; EDA, HR, and performance	Cobot speed	x	==	==	Perceived pressure and stress, as well as excitement increase with higher robot motion speed
13	Zhao et al., 2020	Lab	Single arm	Assembly	31	Subjective experience; HRV and performance	Cobot role	==	==	x	Perceived stress is lower in the condition of reciprocal interdependence, in which the cobot works as a teammate to reach the shared goal
14	Rajavenkatanarayanan et al., 2020	Lab	Single arm	Assembly	25	HRV, EDA	Cobot role	x	==	==	Mental exertion increases with time constraints, such as following the robot speed
15	Bettoni et al., 2020	Field	Single arm	Moulding	4	Subjective experience, HRV and performance	Cobot role	x	==	==	Mental workload is lower when interacting with a robot able to dynamically assign tasks based on the worker’s fatigue
16	Arntz et al., 2020	Virtual Scenario	Virtual single arm	Assembly	80	Subjective perceived stress	Augmented communication	==	x	==	Lower stress and higher positive affect are reported working with a robot-arm equipped with social communication interface
17	Hopko et al., 2021	Lab	Single arm	Surface polisthing	16	Subjective experience, HRV and performance	Cobot role	==	==	x	Perceived cognitive workload is lower in high assistant condition than low assistance.
18	Messeri et al., 2021	Lab	Dual arm	Assembly	15	HRV, EDA, and performance	Cobot speed	x	==	==	Lower stress and higher productivity are associated with robots’ ability to adjust their pace to operators’ stress level
19	Chacón et al., 2021	Lab	Single arm	Assembly	18	Subjective MWL and Performance	Task to perform	==	==	x	Mental workload during a high-demanding cognitive task is not increased by adding a secondary assembly task carried out with a cobot
20	Brun and Wioland, 2021	Field	n.a.	Packaging	8	Perceived stress	==	==	==	x	Lower stress, nervousness, and fatigue at the end of the day are associated with the introduction of cobots in the production line
21	Lagomarsino et al., 2022	Lab	Single arm	Pick and place	12	HRV, EDA, and performance	Cobot motion trajectories	x	==	==	Cognitive load is lower when working with a robot able to perform tasks autonomously, providing feedback about its ongoing actions, compared to a not autonomous machine. Automation is perceived more cognitively demanding by naïve operators than experts.
22	Fournier et al., 2022	Lab	Dual arm	Pick and place	54	Subjective MWL and performance	Cobot presence	x	==	==	No change in cognitive load levels was reported when working with a cobot compared to working alone.
23	Messeri et al., 2023	Lab	Dual arm	Assembly	33	HRV and performance	Cobot role	==	==	x	Stress is higher when in a collaborative task the operator follows the robot, rather than taking the lead

Notes. HRC = Human Robot Collaboration; MWL = Mental Workload; Cobot = Collaborative Robot; MWL Sources: 1 = Motions, predictability and proximity; 2 = Robot Communication skills; 3= Task organization.

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