Human-machine collaboration

This technical article examines the intelligent networking of forklift trucks and automated guided vehicles within a single system.

Industrial trucks play a vital role in intralogistics, as the majority of internal transport tasks are carried out with their assistance. Consequently, cost-optimised control of industrial trucks is advisable in order to tap into further potential savings in logistics. The need to deploy industrial trucks economically and safely arises more strongly than ever before from the overall intralogistics concepts for the flow of materials and goods within companies. Autonomous, driverless transport systems have also long since found their way into logistics facilities. These support and optimise logistics transport tasks. This means that many companies have already gained experience in the transport operations of forklifts and driverless transport systems, though mostly in separate areas.

Thanks to greatly improved sensor technology, it is already possible today to utilise a room or area with both people and vehicles. This opens up entirely new possibilities for intralogistics, enabling humans and machines to work together in a coordinated manner. The areas of application for this collaboration can be applied to virtually all logistics processes, whether these involve empty container handling, replenishment tasks, or optimising the supply to the picking area.

However, the cooperation between manual and automated vehicles is only possible if they are connected via an intelligent control system. Strategies for cooperation are developed, but the control system must also intelligently implement aspects relating to the use of shared space as well as infrastructure requirements for mixed-operation.

Three variants of control can be distinguished here:

1. Conventional forklifts and automated guided vehicles operate in separate logistics areas.

The exchange of goods takes place via handover points. The vehicles have separate movement areas, and fixed handover points between the areas are stored in the system.

2. The vehicles share a common traffic area but use different loading and unloading points.
3. The final stage of development and the variant with the highest efficiency are achieved through mixed operation. This means that the vehicles share a common logistics area as well as parking spaces that can be used by all vehicles.

Preliminary considerations for mixed operation

Shared use of the traffic area is only possible with good sensor technology at the spaces or in the conveyor system. Once this is achieved, existing facilities such as racks, conveyor systems and staging areas can be operated by the automated system in the same way as by a forklift. The vehicle type best suited to the task should be used.

Requirements for the control system

Driverless transport systems generally require more space, not least to maintain safety distances in accordance with EN 1525 at all times. The guidance system must provide the basis for this and prevent collisions between autonomous and manned vehicles. Furthermore, unmanned journeys should preferably be scheduled for non-production periods if the transport process takes place in close proximity to production.

As the speed of a forklift is higher than that of an AGV, collisions at routes and handover points must be avoided. This requires tracking of the forklift. This is achieved through:

• Monitoring of bottlenecks
• Analysis of position data
• Detection of forklift entry
• Control of traffic lights, barriers and gates

Close following by manned vehicles poses a risk. This can bring an entire transport area to a standstill. Here too, forklift tracking must be utilised. In contrast, AGVs invariably implement the stored rules. Technical faults in the vehicles hinder the process. The control system is responsible for displaying all faults quickly and visually.

Infrastructure required for mixed operation

The following structural requirements must be implemented in the warehouse:

• Suitable racking and floor space are available in the warehouse,

Double- or multi-depth storage areas are only suitable to a limited extent.

• FIFO locations and strategies require significant management effort and are unsuitable for mixed-use operations.
• LHM must be clearly marked for identification, for example via barcode or RFID.
• There must be seamless Wi-Fi coverage in the warehouse to ensure constant communication with all vehicles.
• The positioning of the autonomous transport vehicles and the processing of this data by the control system takes place in real time. Techniques such as lasers, radio positioning, guide lines or anchor points can be used for positioning.

Requirements for the control system

Compared to a conventional transport management system, task allocation in a combined system is significantly more complex. Factors such as vehicle availability, vehicle speeds and route utilisation are taken into account. The system has also implemented traffic control measures designed to prevent collisions. Adjacent systems are connected to the control system via an interface (traffic lights, gates, or even lifts).

The control system also performs resource management to oversee battery and energy management as well as maintenance cycles. The system uses control strategies to optimally execute individual orders, pool orders or transport chains. Integrated parking space management, with geodata for each parking space, makes it possible to define preferred vehicles for specific spaces or areas.

Summary

Due to standardised processes, but also owing to labour shortages, driverless transport systems are set to be used in many areas of logistics in the future. Mixed operations involving both manned and unmanned vehicles will become the norm. To achieve this, companies must establish essential prerequisites in the areas of control and infrastructure. The key to success lies in a common control system, which in turn must meet high requirements, such as more interfaces and control parameters.