Design and Analysis of a Compliant Parallel Robot with Cardan Joints for a Cryogenic Working Environment

Automation is ubiquitous and is finding its way into more and highly specialized applications - including cryo-conservation. However, manual handling of biological or toxic samples is still the norm in research and commercial storage facilities. In biobanks, samples are stored, retrieved or moved by hand wearing rigid, protective clothing due to the significant risk of injury to personnel from cold burns. In addition, sample integrity is compromised by temperature changes or contamination.

In this paper, we present an approach for the automation of handling processes in cryobanks for cryopreservation at temperatures below −130 ℃. The automation system is based on a parallel robot, as its structure allows the positioning of the drives outside the cooled workspace. The robot’s joints and manipulators are located inside the biobank, cooled with liquid nitrogen. The passive joints of the robot are implemented as Cardan joints, which are composed of multiple flexure hinges. In the following, we describe the design of the kinematic chains of the parallel robot’s structure. The elaboration of these is based on the results of FE-modeling of individual components under cryogenic conditions. We then subject the overall structure to static mechanical simulations, both in its initial position and under deflection of the actuator and compare the occurring deviations with the calculations based on the inverse solution.