MODKOM
Modular components as Building Blocks for application-specific configurable space robots
Robotic systems will be of particular interest in the future for service operations on satellites or the exploration of other planets, as they are relatively inexpensive compared to manned spaceflight and at the same time flexible enough to respond to unforeseen events. However, the solutions developed and used to date have been highly mission-specific and are therefore highly specialized. In contrast, the definition of standards and modules should enable a rapid response to future exploration and service missions. The project described here focuses on the technological, mechatronic, and software development of modular functional units for reconfigurable and mobile robot systems. The performance of the modules developed in this project will be demonstrated through the implementation of a mobile manipulation system. To this end, existing functional units that are indispensable for exploration missions will be used within the project and further developed in such a way that the TRL is increased. Once a pool of functional units is available, robotic systems can be reconfigured according to the task at hand based on the modular system.
Project details
The MODKOM project presented here focused on the technological, mechatronic, and software development of modular functional units for reconfigurable robot systems. These are intended for use in various space missions. The establishment of a modular system, the possibility of subsequently adding or adapting system functions, the reusability of functional units, and the integration of existing technologies are intended to shorten development and qualification cycles. Artificial intelligence methods support the modular approach and enable the modules to act autonomously.
The top-level requirements of the modular system can be summarized as follows: reconfigurability, external compatibility, multi-purpose use, the possibility of further development and expansion, and a terrestrial environment for performance demonstration.
To meet these requirements, a corresponding modular system was developed within MODKOM. This comprises several modular components that were designed and built as part of the project. They can be combined according to mission-specific specifications with the aid of a software solution. The modular construction kit includes a 6-DoF manipulator arm, base modules with electronic slots, various payload modules (battery, camera, gas sensor), adapters for multifunctional interfaces, and a robot joint.
To ensure modularity, the DFKI's multifunctional interface (EMI-MOD) was further developed within MODKOM. It allows all systems, modules, and subsystems to be combined with each other in a Lego-like manner, provided they are equipped with EMI-MOD.
In addition, the construction kit contains third-party systems, such as the Rover Hunter SE from AgileX Robotics. This has been equipped with a platform developed by DFKI with integrated EMI-MODs. This allows it to accommodate systems that also have EMI-MOD, such as the payload modules or the manipulator arm. Another purchased component is the iSSI® from iBOSS GmbH, which is also a multifunctional interface. It has been demonstrated that systems with iSSI® can be connected to the modules developed by DFKI using a specially developed adapter. This confirms the flexibility of the modular concept and its great potential for future space missions.
With a view to space applications, a particular focus was placed on the development of a dynamic quasi-direct-drive robot joint. This was developed in an iterative process. First, prototypes for the motor and the associated motor electronics were designed and tested. Based on this, the final iteration, the DFKI-X2D joint, was created, which achieved Technology Readiness Level (TRL) 5 in qualification tests. This represents an important step toward practical application in space.
Beyond the original project goal, markerless visual servoing was successfully implemented. This represents an important milestone for software-specific solutions for the autonomous (re)configuration of modular subsystems that can be used during a mission via a multifunctional interface.
In addition, a software solution was developed that maps both hardware and software components of the modular system in the form of a catalog. These components can be combined according to mission-specific requirements. Missions can be modeled in advance using a simulation. As a result, suitable components available in the catalog are recommended. The catalog is expandable and can also be used for additional hardware and software components, including those from third-party providers, provided that compatible interfaces are available.
Finally, results from the MODKOM construction kit have already been applied in other projects. For example, the strawberry-picking rover SHIVAA and the rover Artemis2, developed for planetary applications, were built with modular structural components and electronic modules whose foundations were developed in MODKOM.
Overview of developed components
Qualification tests of the DFKI-X2D joint
Schematic diagrams
MODKOM: Vibration testing of the Z-axis of DFKI prototypes at ZARM
To test components for the loads of a rocket launch, they are subjected to vibration tests in advance. The video shows parts of the vibration tests for the prototypes of the robot joints with sinusoidal loads in the direction of the Z-axis. Based on the findings from these tests, the mechanical design was optimized and the final space variant of the DFKI-X2D was developed. (Video: Jonas Eisenmenger, DFKI)