Lean Manufacturing and Ergonomics Integration: Defining Productivity and Wellbeing Indicators in a Human–Robot Workstation

Abstract

Lean Manufacturing (LM), Ergonomics and Human Factors (E&HF), and Human–Robot Collaboration (HRC) are vibrant topics for researchers and companies. Among other emergent technologies, collaborative robotics is an innovative solution to reduce ergonomic concerns and improve manufacturing productivity. However, there is a lack of studies providing empirical evidence about the implementation of these technologies, with little or no consideration for E&HF. This study analyzes an industrial implementation of a collaborative robotic workstation for assembly tasks performed by workers with musculoskeletal complaints through a synergistic integration of E&HF and LM principles. We assessed the workstation before and after the implementation of robotic technology and measured different key performance indicators (e.g., production rate) through a time study and direct observation. We considered 40 postures adopted during the assembly tasks and applied three assessment methods: Rapid Upper Limb Assessment, Revised Strain Index, and Key Indicator Method. Furthermore, we conducted a questionnaire to collect more indicators of workers’ wellbeing. This multi-method approach demonstrated that the hybrid workstation achieved: (i) a reduction of production times; (ii) an improvement of ergonomic conditions; and (iii) an enhancement of workers’ wellbeing. This ergonomic lean study based on human-centered principles proved to be a valid and efficient method to implement and assess collaborative workstations, foreseeing the continuous improvement of the involved processes.

Ergonomics and Human Factors as a Requirement to Implement Safer Collaborative Robotic Workstations: A Literature Review

“…Regarding the year of publication, our study shows that the oldest paper presented in this review dates to 2013 [31] (Figure 3). Moreover, the largest number of studies found have been published in 2021 [11,12,19,22,27,32,33,37,38]. These two findings point ou that E&HF as a requirement in HRC systems is an emergent/recent research topic.…”

“…Related to this, three papers were found in which workstations were studied Another finding that denotes this research field's novelty is that most of the studies have been performed in a laboratory environment (Figure 4). Only five articles presented a study in a real-industry context; two of them are related to physical ergonomics [8,19], and three to cognitive ergonomics [11,33,38]. This evidence is sustained by the fact that innovative research fields start from laboratory context and then are exploited to realworld context [39].…”

“…Another finding from our study is related to the ergonomics domain, namely physical or cognitive, and related to its ergonomic application, if offline or online (Figure 5). Sixteen [1,4,7,8,13,17,19,22,[27][28][29][30][31]36,37,40] of nineteen studies are related to physical ergonomics, while only six [11,32,34,35] are related to cognitive ergonomics. Regarding its application, only studies related to physical ergonomics presented an online application [1,12,18,22,33,38,40].…”

“…In offline ergonomic applications, the ergonomic criteria are oriented towards workstation or Cobot mechanical design [18], where the central assumption is to combine the benefits of automation with the human workers' skills and cognitive flexibility [6,12]. Therefore, the tasks that require a high level of knowledge, individual decision-making, and complex movements are allocated to the human, and tasks with repeatability and fatigue proof are allocated to the robot [19,20]. However, offline applications are not suitable in industrial functions with fast-reconfigurability demands (such as dynamic task variation or human workers' limitations) since there is a need for real-time adjustments of the Cobots [21].…”

Comparative analysis of the manual and robotic upholstery frame assembly processes. Study based on many years of research

“…Robots substitute humans in technological processes with repetitive operations, without variation. The advantages of robotic production lines include better process parameters and improved working conditions, especially moving operators away from activities that are dangerous (e.g., they are associated with excessive body overload, noise, or risk of accidents) [4], [5]. Robotization, apart from the obvious advantages, also brings new challenges, forces the use of new methodologies to solve line balancing problems [6], or can increase the consumption of electricity [7].…”