The goal of this project was to manage tolerances, avoid collisions, and control vibrations.
Asimov? It’s a robot-assisted system for minimally invasive procedures. Compact design, four arms, 5-mm instruments, for tight spaces. It’s not enough for a prototype to work well; the production model has to as well. That was our job.
We examined the joint drives of the telemanipulator along entire tolerance chains. Where does play accumulate? Where do dimensions tip in a critical direction? Where do collisions arise solely from the sum of small deviations?
Using 3D tolerance analyses of all joints, we were able to visualize critical overlaps. We then adjusted the geometries. This reduced play. Collision zones were cleared, and we eliminated tolerance-related contacts through design changes before they could occur in manufacturing or in the operating room. This saves rework. It stabilizes assembly and ensures that the system behaves consistently from device to device.
The second focus was on vibration behavior. We investigated how external influences, such as a change of instrument, induce vibrations in the system, how these vibrations are transmitted between robotic arms, and what reaches the tip of the instrument. Measurements were taken using high-precision optical 3D measurement technology. We compared free arms with realistic scenarios involving an instrument in the body model. Amplitude, frequency, and damping were critical factors. The robot simply needs to remain stable.
The analysis identified potential risk factors for unintended instrument movements. We derived corresponding optimization measures from these findings. In this way, observation led to robust development work. Collisions in CAD are still acceptable. In the OR, they are not.
Robustness in series production doesn’t stop at the individual joint; it extends to the supporting structure, the center of gravity, the interface between the tool and the robot, and the subsequent industrialization process as well. Those who consider these elements in isolation often end up with a clean drawing and a cumbersome assembly.
The benefits? Less play. Less risk of collision. Controlled vibrations.
A system that moves precisely and at the same time allows for reproducible manufacturing, assembly, and validation. From our perspective, it can be said that anyone who wants to bring robotics into series production needs robust tolerance chains, clean interfaces, and data from realistic scenarios.
“We develop robotic systems through to production readiness. To do this, we identify the most robust solutions, eliminate tolerance-related collisions, and analyze vibrations all the way down to the tip of the instrument. We prefer to identify collisions or other issues in the CAD stage rather than later during assembly.”
Martin Fischbach
Head of Medical Technology, B&W Engineering