Attachments are becoming increasingly important in the world of construction machinery and contractors. Quickly changing the "tools" on the construction machine allow a variety of different activities on a single construction machine.
However, changing attachments from different manufacturers on the respective construction machine usually presents users with unsolvable tasks when it comes to digital data acquisition.
Not every attachment also works digitally with the respective construction machine.
So what now?
MiC 4.0 provides the solution .....

The aim of cluster 7 is to create a standard for cross-manufacturer communication between attachment and construction machine. To this end, a data interface is to be developed that maps all relevant use cases for communication between tool and machine. The initial focus is on the interface between attachment and excavator.

The aim here is not to standardize the existing mechanical, hydraulic or electrical interfaces between the attachment and the construction machine, but to consider which data must be exchanged on the basis of existing systems. This data includes identification data such as serial number and tool type, status data such as measured angular position and control data for controlling the tool functions, e.g. on the tiltrotator, as well as safety-relevant data, e.g. for the safe operation of quickcouplers.

The first step on the way to this interface is the precise delimitation and definition of the interface between attachment and construction machine. For excavators, a cut through the stick pin was defined for this purpose, so that the first quick coupler already counts as an attachment (see illustration).

Use cases are then defined, on the basis of which the data transmitted in the interface are specified. At the same time, a manufacturer-independent architecture must be developed and tested.

This will be supplemented by a safety concept and specifications for the safe use of the interface. Finally, all the results of the cluster are to be summarized in a communication protocol that can be used by all manufacturers in their products.

As a basis, possible use cases for a data interface were identified by surveying the participants of the working group. The working group is made up of representatives from the construction industry, attachment manufacturers and construction machinery manufacturers, so that many different perspectives on the subject can be taken into account. After the collection, the use cases were prioritized.

Some exemplary use cases covered by the interface are:

• Identification of the tool during coupling so that information such as serial number, tool type and manufacturer is available on the machine
• Adjustment of the construction machine to the tool, for example automatic adjustment of required hydraulic pressure and quantity for the tool
• Transmission of control data from swivel rotators so that no additional HMI needs to be installed in the operator's cab
• Transmission of geometry data of the mold, which can be used, for example, to set workspace limits

Sub-clusters have been formed to elaborate the concrete data that will be provided via the interface. These sub-clusters deal with different topics based on their respective competencies. The sub-cluster of users from the construction industry contributes the requirements for the interface from the user's point of view. A sub-cluster of attachment manufacturers defines which data is required for the function of the tools and which tool information can be provided. In the quickcoupler subcluster, topics are considered separately that concern the operation of quickcouplers via the interface, since this places special requirements on function and safety.

A sub-cluster of machine manufacturers addresses the architecture required to provide the interface and considers how safe operation of attachments can be enabled via the interface. A sub-cluster with technical experts is looking at the concrete definition and implementation of the communication protocol.

The sub-clusters work on their topics in two- to four-week sprints (see figure). The results are compiled and coordinated every six to eight weeks in the entire working group. This agile approach makes it possible to work in a targeted and efficient manner, even in the large group, by parallelizing the work.

To implement the interface, the cluster decided to design a CAN communication protocol. The use of CAN bus is widespread in construction machinery, so that a simple integration of the interface into the construction machinery and attachments is guaranteed. The MIC communication protocol with the working title "MIC 4.0 BUS" is being developed on the basis of SAE J1939 and prepared so that the interface data can be transmitted.

Initial functional tests of the interface have already been successfully carried out in April 2022. The goal is to present a demonstrator at bauma22 and then publish the first version of the protocol, which covers the most important use cases. Space will be provided in the protocol for subsequent extensions so that an updated version can be published by MIC 4.0 every one to two years.

To ensure safe operation of the interface, a safety concept is being developed to enable safety-relevant functions, such as the operation of quickcouplers, via the MIC interface. In addition, methods for quality assurance will be defined and further developed in the further course of the project.

The first tests of the interface were very successful and show the great potential of the MIC 4.0 BUS. After publication, manufacturers of construction machinery and attachments can provide for the interface in their products. This offers the opportunity to develop hardware and software that can be used universally, since the standardized interface means that less bilateral coordination is required.

For users, the interface allows a freer choice of attachments and machines, as the MIC interface enables seamless cooperation of
MIC tools and construction machinery is made possible. This applies to both the exchange of data and the control of attachments, which is simplified with the interface. This also makes the installation and commissioning of tools easier, as fewer additional, tool-specific operating elements have to be fitted in the construction machine. In the context of the networked construction site 4.0, the interface also offers a manufacturer-independent uniform tool data set, on the basis of which evaluations and management can be operated. Thus, the MIC 4.0 BUS will give further impetus to the digitalization of construction sites and subsequently enable further innovations.