Cobots and Digitization To Support Manual Assembly

Last December, Fiam organized an interesting workshop with the aim of talking about the state of the art of manual assembly stations in “4.0” production environments. From the new trends made possible by the use of collaborative robots to the very first industrial tests of the “connected” assembly stations, we have discussed with the speakers about some possible scenarios. A changing framework indeed that relies strongly on the operators.

by Fabrizio Dalle Nogare

In addition to machines as well as automatic and semi-automatic lines, the concepts of digitization, connectivity and extreme control of production can certainly be applied also to manual assembly stations. With great potential benefits in terms of greater efficiency, increased productivity and well-being of the operators.
Fiam, a leading company from Vicenza, organized on December 5th, 2018, the workshop titled “The evolution of the industrial assembly station in Industry 4.0 environments” (see box), involving as speakers two professors from the University of Padua: Giulio Rosati, professor of Mechanics Applied to Machines and Industrial Robotics, and Maurizio Faccio, professor of Mechanical Systems and Management of Industrial Plants. The speeches provided by the professors, the intervention of Ivan Casetto from SMAC – a Vicenza-based company working in industrial automation – and especially the exchange of ideas and information with those who deal with assembly every day have brought out some very interesting ideas on the evolution of manual assembly workstations and their integration with robots. Especially with the new collaborative robots that, due to their peculiarities, are designed not only to share the work area with the operator, but also to carry out assembly operations.

Collaborative robots and assembly: the possible integration
Although having a much lower performance in terms of speed compared to traditional industrial robots, collaborative robots allow users to rely on a sort of functional ecosystem in which the best peculiarities of humans and robots are enhanced. “Assembly is an activity featured by quite a high added value, also requiring a lot of manual skills and experience by the operator. This activity is also quite difficult to automate”, said professor Rosati, who spoke during the event diffusely of robotics applied to assembly systems. “Let’s consider, in fact, that in Italy only 3 out of 100 robots installed carry out actual assembly operations, compared to 65 robotd out of 100 dealing with handling tasks, for example”.
A share still evidently low, which could however in the near future increase thanks to collaborative robots, which are, according to Giulio Rosati, “a real novelty, perhaps the most important that has affected robotics in the last 30 years. In fact, while so far we were used to a dual vision – on the one hand the operator using mechanical tools, on the other the full automated assembly processes -, it is now possible to combine the operator’s ability with the characteristics of the robots, thus achieving a simplified automated operation. In addition, the operator can bring the extra degree of flexibility into the robotic cell. A feature that is indeed quite expensive, as well as difficult to get in purely automated operations”.

Obstacles and criticalities
So far, everything seems quite OK. However, some more aspects should be considered when it comes to integrating collaborative robots into assembly stations. These affect a very sensitive topic such as safety. “Although the robot itself is certified as safe when it is sold, as far as it is equipped with an end-effector, like a gripper, the risk factor changes and the application may not be certifiable”, explains professor Rosati. “The classic example is that of a robot handling a sharp object, with the expected risks when approaching the operator. All this severely limits the flexibility of the collaborative robot, which is very attractive because it is seen as easy to set up especially by the SMEs. In fact, these are generally reluctant to purchase automation, especially when it comes to robots, considered as high-tech tools, also quite difficult to manage”. There is little doubt, however, about the fact that collaborative robots can help improve the ergonomics and working conditions of the operators, relieving them from tiring or repetitive tasks. “Screwing operations can be an excellent example – concludes Rosati – just because they are particularly difficult to carry out, as the torque needed to carry out the task has to be balanced by the operator”.

The “connected” assembly cell
The University of Padua, in collaboration with some local companies, has developed a “connected” assembly cell, that is able to adapt to the key elements of a workstation, which are the product to be assembled and the operator. Depending on these and on the activities foreseen by the production cycle, the cell changes its configuration. “All this gives the operator two main advantages – says professor Faccio – that is to reduce the space to be covered in the micro-logistics of the station, with a direct effect on productivity, and to improve ergonomics. In fact, the gripping positions of the components are managed with the aim of putting the operator in the easiest working conditions”.
But how does the cell, which has already been tested in some companies, actually works? “The cell – continues professor Faccio – has a series of actuators managing the height of the workbench, the position of the materials in front of the operator according to the size of the product, and a dimensional camera that monitors the position of the operator’s hands. Our goal is to obtain a cell that adjusts in real-time according to the task to be carried out by the operator thanks to the control provided by the vision systems”. Supporting the operator, instructing him on the sequence of activities, selecting the products to be picked: these are the main functions of a connected workstation. In the field of screwing, for example, there are different sequences depending on the angle to be applied or the type of task that has to be performed.

Increase people’s skills: the added value of job enlargement
Naturally, cells of this type could be applied to nearly any industrial sector, but they are particularly suited for industries, such as the automotive one, requiring the production of safety components. “Wherever there is the need to certify an assembly cycle, we have to be sure that the operator has correctly performed an activity, using the right components”, adds professor Faccio. “So far we have tested the connected cell in applications and environments featured by high variability. Once experienced the benefits, the operators welcomed this new solution: those who started working in new production lines would not want to go back to more traditional solutions. So today, the feedback on operators in the industrial field is very positive”.
It is important to understand how people welcome innovations of this kind precisely because it is the same working habit of factory operators that presumably will change in the coming years. According to the lecturers from the University of Padua, in fact, “the role of operators is expected to change quite a lot and will be featured by increasing added value. We need to broaden the skills of human activities through a job enlargement mechanism in which operators are required to perform more relevant activities. Such a mechanism makes daily work much more stimulating”.