For a two-arm tube-handling task, the first arm may need to prepare a controlled, taut span so the second arm has a usable grasp target. A correct pose of the first gripper does not fix the shape of the flexible tube between its supports. Assess that intermediate state before treating the later pump-placement motion as ready.
Fraunhofer IPA's sterility-test feasibility project describes a two-robot handling prototype developed with SKAN. A project caption identifies force-guided tube tensioning for acquisition by the second robot; another shows placement into a substitute peristaltic-pump body. The team also addressed knots. The project ran from September 2021 to March 2022. This is prototype handling evidence, rather than a demonstrated production sterility-testing service.
A flexible span has its own grasp state
The next gripper needs an accessible part of the tube in a usable relationship to its jaws. The tube can sag, turn or become tangled while the first gripper still reaches its commanded position. A review that checks only the two robot poses can therefore miss the state that connects their actions.
Ask the application team to show the observation used to permit the second grasp. It should identify the intended span, the relevant tube configuration and how an unresolved presentation remains visible. A motion-complete signal from the first arm answers a different question from whether the second arm has acquired the intended material.
This decision also differs from relieving a cable that pulls against connector insertion. Here, controlled tension prepares a second acquisition. In the connector case, unwanted tension can obstruct the final approach. Neither situation supports a universal instruction to pull harder or always remove tension.
Follow one tube through the second grasp
Consider this illustrative review, not a recorded Fraunhofer trial. The first arm reports that it reached its presentation pose, but the tube still hangs outside the second gripper’s intended acquisition region. A pose-complete signal alone has not answered whether the intended span is available. Ask the supplier to show the presentation observation before advancing to the next acquisition.
| Proposed review state | What the evidence actually establishes | What remains to resolve |
|---|---|---|
| First arm at its pose; intended span not identified | The robot reached a pose | Which span the second gripper will acquire |
| Intended span presented; second jaws have closed | Presentation and a jaw command | Whether the intended tube is retained, rather than missed or slipped |
| Intended span retained; suspected knot remains | One acquisition result | The application’s knot/uncertainty disposition before pump placement |
| Intended span retained; handoff observations accepted | The defined intermediate handoff | Separate acceptance of the receiving pump arrangement |
These are proposed observation and decision categories, not native PLC signal names or a universal force-control sequence. For the slack-span case, a jaw-close command without retention evidence should remain an unresolved acquisition in the review. For a suspected knot, request the application’s exception route; the public prototype does not justify a generic instruction to pull harder. This keeps the supplier discussion tied to one tube state instead of counting completed arm motions.
Specify the handoff record rather than a tension number
Use the following proposed record in a supplier discussion:
- Tube and packaging configuration presented to the first arm.
- The span offered to the second gripper, with the observation that made it eligible for acquisition.
- Second-grasp result and the evidence that the intended span was actually retained.
- Knot, uncertain presentation or interrupted-transfer condition, plus the responsible disposition route.
- State passed to the pump-placement operation, including unresolved conditions.
The record describes an interface to assess, not a published Fraunhofer data format. Force settings, permitted deformation and material-contact criteria must come from the actual consumable and application owners; the public account does not supply transferable values.
Pump placement remains a separate acceptance
A successful second grasp establishes only one intermediate condition. The receiving pump arrangement and the finished test process still need their own acceptance. In particular, the source's substitute pump body should remain visible when comparing prototype evidence with a proposed installed application.
Price the sensing, tube presentation, exception handling and receiving interface alongside the two arms. The site's end-effector boundary guide provides related context for specifying the complete tool and carried-material configuration. It does not qualify this tube-handling process.
The source was reviewed October 13, 2026. No tube, pump or sterility test was run for this article. The useful procurement outcome is an explicit second-grasp handoff, with the remaining process qualification kept separate.