# Augmented Reality in a Lean Workplace at Smart Factories: A Case Study
## 2 Literature Review  
### Lean Thinking  
Lean Production is an organizational approach that resulted from the Toyota Production System (TPS), which main goal is \"doing more with less\", where less means less human effort, fewer stocks, fewer resources, less space, and less product development time [14; 19]. Additionally, it tries to enable greater production flexibility, while meeting quality standards and deadlines.  
This organizational approach aims to increase productivity and reduce costs by eliminating waste [14], which are all the activities that do not add value to the products from a client's point of view. [PERSON] [14] classified the wastes into seven categories: (1) overproduction; (2) over processing; (3) transportation; (4) defects; (5) motion; (6) inventory; and (7) waiting. Later on, [PERSON] [20] identified an extra waste, i.e., untapped human potential.  
However, successful implementation of Lean principles goes beyond process improvement, since any change in work practices or workstations has deep effects on workers and their performance, affecting their well-being, safety and security [21]. Hence, it can be said that Human Factors (HF) and ergonomics have an impact on a company's business strategy and competitiveness [22]. Most of the industrial projects implementing lean principles do not always address the ergonomics factors [23], although ergonomics and HF should be included in the lean process from the outset, which is not seen in a lot of organizations that fail to understand the potential of combining and carrying out ergonomic concepts in parallel with lean techniques [24].  
Most the organisation are focused on the gains of productivity and process improvement, instead of taking advantage of this field of study to advance organizational effectiveness, business performance and costs [21; 25], however, the right combination with lean and ergonomic design concepts will reduce errors, improve productivity and simultaneously improve the working conditions while reducing risk factors that can lead to the development of injuries or MSD [25; 26].  
It is important to ensure that people develop their tasks without waste (_muda_, in Japanese) and symptoms of waste. Beyond _muda_, there are the _mura_ and _muri_ that are considered the symptoms of _muda_. For instance, within an ergonomic context, _mura_ are the consequences of wastes that result in workplace unevenness or irregularities, such as applying a force that increases the risk of strains and injuries that causes higher fatigue, which leads to reduced work pace and productivity. Muri is the overburden or stress caused by repetitive tasks or weight lifting or, even, accidents that could occur in the workplace due to other symptoms of waste, such as unevenness or irregularity, i.e., _mura_. Together these three Japanese words are called 3M [20]. Ergonomic design focuses on the creation of efficient and appropriate body postures, reducing the amount of strength required to perform a task, avoiding incorrect postures, repetitive tasks and motions throughout the work shift [21].  
After decades, enhancing Lean Production solutions represent a huge potential for the current industrial landscape and the cutting-edge technologies enabled by Industry 4.0 paradigm bring several opportunities under the smart factories context to improve organisations competitiveness and working conditions [15].