EUTEF on ISS
In 1998 and 1999 the institute and its Italian industrial partner CARLO GAVAZZI developed subsystems for the ESA-project EUTEF (EUropean Technology Exposure Facility). Detailed concepts were elaborated concerning the mounting of pallets on the outer structure of ISS (either on the long grid structure or at the European COF-module), where a robot arm should perform operational payload handling; i.e., grasping payload-boxes and drawers, inserting them into measurement devices or exposing them in a dedicated way to space radiation and illumination (stars, sun, etc.).
We developed a force-controlled intelligent end effector as key element of such a system, involving local stereo vision and its counterpart, the exactly matching locking and grasping mechanism in the boxes and drawers. Following the concept of virtual design, these components were not only constructed in 3D-CAD systems, but realistically simulated in all their kinematic-dynamical interactions, so that they could be built up without iterative prototype developments. The key topic was that whenever the robot has grasped an object, there should be no way to accidentally release it (e.g., by programming errors or some malfunctioning of electronics) until it has mounted and locked it safely on some other position.
The figure above gives a more detailed idea of the locking mechanism. The blades are operated via a high-force spindle driven knee-lever-mechanism, two electric plugs being firmly connected to the blades. During manipulation of the payload the end effector provides power supply and data link. Whenever the robot would try to grasp an object, the stereo cameras and simple visual patterns on the boxes should guarantee the accurate 6-dimensional fine-positioning before inserting the guiding bolts using a force-torque sensor and sensor-controlled on-board autonomy.
Unfortunately the project had to be stopped after the prototype status due to design problems with COF and fund cuttings.