**4. Sustainable flexibility 4.0**

#### **4.1 Sustainable flexibility 4.0 tool**

The sustainable flexibility 4.0 is based on the use of production management techniques such as scheduling, theory of constraints, operational research algorithms, and artificial intelligence for defining for optimizing the exploitation of cobots, robots, machines, mobile robots, and IoTs, of the logistics and manufacturing system (**Figure 3**). It involves the optimal use of technical resources, the good management of operational tasks by operators, and the optimization of human resources. As in the previous software tool, sustainability is the kernel of flexibility optimization. It implies the flexibility of organization around the operators.

#### **4.2 Sustainable flexibility 4.0 approach**

The general approach for using the sustainable flexibility 4.0 in a company is described as follow (**Figure 4**).


*Architecture of the sustainable flexibility 4.0 tool.*

**Figure 4.** *Sustainable flexibility approach.*


*Production Systems Performance Optimization through Human/Machine Collaboration DOI: http://dx.doi.org/10.5772/intechopen.102036*


## **5. Use case**

Indeed, the framework has been used with success on SME for defining the steps the company of the digital transformation as presented in [42]. This part presents use cases that have been solved in this company. The company is an electronic card production enterprise and would like to transform digitally itself for being more competitive. The objective of the company was to be able to transfer the cobot from one production line to the other in less than 6mn for increasing the company's global performance. Indeed, the same cobot will produce an electronic card near the operator and at the end of this production will be integrated into the packaging process.

#### **5.1 Cobots utilization optimization**

Industry 4.0 concepts allow to review the operating methods of traditional industry. Operators are giving way to robots and cobots which today are mainly developed to perform specific tasks on fixed workstations. **The challenge of Industry 4.0 is to make production more flexible.** It is, therefore, necessary to improve fixed robots by making them mobile and adaptive then, production lines will be more flexible and smarter. The solution was to allow mobile robots to be able to take cobots from a station to another without human intervention to optimize production time. But the validation of the moving has to be done by operators. The development of a fully autonomous production line leads in particular to new problems of stability and precision for cobots. A mobile robotic system including mobile support and a fixed cobot has been elaborated. In the development of this solution, it was necessary to take into account the precision of the robot and thus adapt its movements. It was also important to solve the problem of cobot calibration when it arrives at the new production line. Subsequently, it was essential to ensure stability for the proper functioning of the robot, especially during high-speed actions or moving. It was also important to solve the problem of power (electric and pneumatic). Indeed, a cobot on a fixed station can be easily powered *via* a wired mains socket. For a robot moving, it is not simple. It was necessary to find alternatives that overcome these power supply problems.

For solving the use case, a cobot has been used. All the interconnected sensors allow the cobots to learn about their environment and decide on the tasks to be carried out based on the information received. Parts of the transporting system and connections have been elaborated by exploiting 3D printing as suggested in Industry 4.0 context. An AIV has been used to transport the robotic system from

one station to the other. The problem of connection between the robotic system and the mobile robot had to be solved. Indeed, this solution has been implemented in the company and has shown its effectiveness in allowing the transport of cobots to their workstations, eliminating a task that would be repetitive and tiring for operators.

The challenge of the robotic solutions described in this chapter is to be able to use a cobot at the fixed origin on several workstations. The movement of the cobot needs to be deepened. One possibility of movement is the attachment of a cobot on an interstation trolley. This system allows it to move between different fixed positions. In this chapter, the choice was made on the solution of the inter-station trolley due to its adaptability to the company industrial environment and its easiness to be transported by an AIV.

#### **5.2 Technical solutions for moving the cobot**

#### *5.2.1 Proposition 1*

The movement of the inter-station trolley is ensured by the AIV. The important aspects to consider are the fixation and the stability of the cobot on its workstation. Jacks represent a possibility of fixing the inter-station trolley to the ground when the latter is placed in front of a workstation. Four jacks are positioned on either side of the carriage. They each have a force of 90 kg. A mechanical part makes up the fixing mechanism. It allows a large contact surface with the ground. In addition, the jacks are actuated by the automaton controlling the entire production chain. The digital outputs control the analog outputs of the system. When the jack system is actuated, the trolley wheels are raised and the trolley is then secured to the ground. The advantage of this solution is that the fixed stations are not mechanically modified. The inter-station trolley is able to ensure its own stability. However, due to the low weight of the trolley, mostly made of aluminum profiles, the stability is not sufficient. The forces applied to the carriage when it is fixed to the ground cause a partial tilting of the structure. In addition, this solution is dependent on the flatness of the ground.

#### *5.2.2 Proposition 2*

Another alternative is the implementation of an electromagnets system to ensure the stability of the inter-station trolley. Electromagnets are used to lock access in many establishments. They guarantee high safety due to their holding force of 272 kg in the case studied. The electromagnets are positioned on the inter-station carriage and the metal plates on the fixed station. To ensure the mechanical insertion of the system, 3D printing supports have been created. These are installed on the aluminum profiles making up the workstation and the trolley. To complete the device, an obstacle sensor is installed on the inter-station trolley so that the electromagnets are activated at a short distance from the fixed station. When the electromagnets are activated, they are then brought into contact with the metal plates. The two parts are then locked together and ensure the attachment between the inter-station carriage and the fixed station. The advantages of this solution are the ease of installation and the low cost. The stability is higher than that with the jacks system. However, this device is sensitive to shear forces. This weakness can cause the inter-station cart to stall when the cobot is performing its tasks at the workstation.

*Production Systems Performance Optimization through Human/Machine Collaboration DOI: http://dx.doi.org/10.5772/intechopen.102036*

#### *5.2.3 Proposition 3*

The fastening solution chosen for the company is the Vero-S system from Shunk enterprise. This device is made up of tightening modules and positioning pullers. Each clamping module has a tensile force of 8000 N. The operating principle is as follows: the clamping modules are normally closed by slides. An air pressure of 5.105 to 6.105 Pa is sent to the clamping modules to release the slides. The positioning zippers then fit into the clamping modules; then the slides close with the air purge. The air supply is controlled by solenoid valves, directly linked to the cyber-physical systems of the production line. To use this system, two clamping modules are positioned on the fixed station and two pull tabs on the inter-station carriage. When the AIV approaches the truck in front of the workstation, the Vero-S system is activated and allows a strong fixation and stability between the two structures. This solution responds to all types of exerted forces. In addition, the Vero-S system allows locking in three dimensions which makes it possible to prevent shifts in flatness between the base of the robot and the fixed station, in particular in the Z direction not allowing it to be checked mechanically. On the other hand, the calibration of the cobot will be able to correct it.

#### **5.3 Power transmission**

Once the cobot is locked to the fixed and stable position, it must be powered. For the SME study, the cobot used is a techman TM5 700 developed by Omron, and it can carry maximum payloads of 6 kg for a reach of 0.700 m. The power supply required by the techman is 240 V AC and has a maximum charge current of 14 amps. The cobot is placed on a trolley, the choice of a power supply battery allowing a cobot function is possible but greatly weighs down the trolley and could hinder its movement. In this study, the choice fell on the use of electrical modules (initially a mains socket) arranged on the trolley and on the fixed station using 3D printed support. The brackets have been adjusted so that the electrical modules are connected only when the fastening system is in place and no operator can receive a discharge. The modules located on the fixed station are supplied by the mains. The system works well and allows power to the cobot. To go further the main plugs have been replaced by more advanced electrical modules composed of 19 power supply passages, which allowed to power the cobot but also to supply the cobot. Other components of the truck (example: solenoid valve), have been implemented, in order to transmit information via the inputs and outputs of the cobot.

The cobot is able to use pneumatic grippers, so it is necessary to think of a system similar to the electrical modules that allow air transmission. By using pneumatic modules fixed on the trolley and the stationary station using 3D printed support, they connect when the fastening system is in place.

## **6. Conclusions**

In this chapter, a new framework sustainable Industry 4.0 concepts implementation has been presented. Then, an intelligent logistics and manufacturing humanmachine collaboration system has been exposed. An approach for implementing sustainable flexibility 4.0 in SMEs has been explained and the supporting tool shown. A focus has been made in the flexibility technical problems that have been

presented through a use case of an electronic card production company. This chapter exposes the interests for SMEs of robotic mobility and human-machine collaboration in a sustainable Industry 4.0 context and the new technological challenges that are issued from flexibility deployment. The adaptability of systems is a major issue in the context of the industry of the future. The concepts and solutions provided in this chapter illustrate new possibilities for logistics and manufacturing optimization. These improvements make the workstations of the production lines autonomous by putting the operator as the operational manager of the workstations (including IoTs, cobot, and mobile robot management). Operators are then less exposed to repetitive and stressful tasks. In addition, this flexibility helps to reduce development costs by increasing the versatility of cobots. Finally, the solutions presented in this chapter contribute to the digitalization of companies and strengthen the field of use of new technologies and humans at the heart of the industry.
