LIST OF TABLES
2. LITERATURE REVIEW
2.5 Cobots in Manufacturing (Collaborate Robots)
The research in this section was conducted due to the combined knowledge gathered from previous sections. A factor largely contributing to the research carried out in this section related to past research dictating a dependency of progression in manufacturing being human-robot
Page | 26 collaboration. The section that follows evaluates the state of human-robot collaboration and its implications on Advanced Manufacturing systems.
Cobots (Collaborate robots) is a category of robotics that is designed at the outset to interact and work together with humans. As manufacturing systems grow and develop, it becomes seemingly difficult to incorporate complex flexibility and reconfigurability requirements into manufacturing systems attempting to transition into customizable manufacturing. Combining the strength of robotic systems with the problem solving and dexterity traits of humans, it becomes possible to solve tasks that cannot be fully automated, essentially improving the working conditions, employment opportunities and production quality of manufacturing systems [40].
A key consideration when working with cobots is task distribution, essentially, trying to understand the task allocation between robots and humans. This is an integral part of effective collaboration. The distribution will need to account for the inherent strengths of humans and robots and provide tasks to these members associated with their strengths. One such task planner developed by Roncone et al provided for task allocations and role assignment. When interactions were investigated, it was found that interactions were mainly based on graphical user interfaces and buttons, with general trends considering multi-modal interactions, and gesture expressions being used to counteract the problems presented in noisy environments [41].
One of the main problems presented with cobots is that research is confined to the student and laboratory environment, with less emphasis being placed on introducing people active in the industrial domain. This presents additional problems such as lack of knowledge for implementation in industry and industrial acceptance. This needs to change if cobots are to be introduced into industry. Communication with industrial work-men will provide critical insight into the industrial domain and will undoubtedly provide useful insight into potential human-robot collaborations [42].
2.5.1 Applications of cobots
Incorporating cobots into manufacturing can be highly advantageous. Areas of growth can be seen from the implementation of cobots in Brussels, Belgium. in this particular case, cobots were developed and introduced into an automated assembly line. The assembly line manufactured Audi A1 vehicles. For the production of an Audi A1, 550 industrial robots were used in the body shop, 30 in the paint shop and 6 in the assembly line. Brussels attempted to evaluate the potential of cobots for improving the manufacturing process. The constraining factors presented in the assembly process at Brussels was as follows:
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Products have very high variability, this being due to a variation in product customizability’s,
Materials used for production had a very high sensitivity,
Automation is challenging due to the complex nature of product assemblies, and
Injuries and workload challenges associated with an aging workforce.
Audi Brussels tried to focus on using a cobot for applying glue to reinforced plates for supporting the roof racks of their vehicles, with humans focusing on workpiece arrangement. This operation was focused on due to the inconsistencies presented by manual gluing by workmen. This was a serious concern due to products of lower quality being produced. The cobot implemented, made use of gestures for communication due to the noisy environment. Gestures were captured using a RoboSense camera and proved to be easily detectable with consistent performance. Face recognition was also used incorporating neural network and deep learning for operator recognition.
The concluding results showed that cobot Walt contributed to the improved quality of cars produced. With gluing quality being based on flatness parameters, results showed a reduction of 15% for cars not meeting the flatness criteria, additionally, the quantity of overall glue used (as compared to humans carrying out the task), decreased by 20% [43].
Due to the limiting factors such as confinement of cobots to laboratories and students, applications in the industrial environment do not readily present themselves. However, advances are being made in the field of cobots in relation to a more advantageous human-robot working environment.
A few examples of these advances that present themselves include;
Development of a safe and performant control system for compliant robotic joint manipulators – In relation to joint manipulators, two problems present themselves, firstly, the elastic elements of the actuators have the potential to store energy that could be potentially dangerous. Secondly, nonlinearities and uncertainties are introduced by the compliance [44].
The development of new actuator system that allows for haptic interfaces for collaborative robots – In industrial environments, robotic systems are very insensitive to their environment, though, for cobots, close cooperation between humans and robots needs to be established. As such, force sensing and control capabilities for interferences is required for stable interactions between operators, cobots, and the environment [45].
Page | 28 2.6 Chapter conclusion
The Literature Review Chapter summarised the key focus areas from the Advanced Manufacturing Systems. A summarized view of potential areas of growth and improvement for Advanced Manufacturing Systems can be viewed in Figure 2-11.