Investigation of Vial Position Controls for the Development of a Cave Auto-Sampler
Researchers at the University of Waikato visit caves on a periodic basis to collect samples of drip water, which over geological timeframes form stalagmites and other formations. However, most caves are remotely located, which makes it an arduous task to reach the study site and is economically unfeasible for frequent visits. This paper presents the position control aspect of the cave auto-sampler, which is a crucial operation to store water samples in an airtight container. The primary challenge was to position airtight sample vials under the needles for sample collection, within 3.5mm from the centre of the silicone septa. Various methods and makes of stepper motors were tested to find the balance between precision and power saving. A high gear ratio stepper motor was chosen as the primary drives due to its high precision and its ability to hold position when power is turned off between operations. Testing in lab conditions showed satisfactory consistency regarding position control and is integrated into the auto-sampler.
R. Jangali et al., "Investigation of Vial Position Controls for the Development of a Cave Auto-Sampler", Applied Mechanics and Materials, Vol. 884, pp. 86-92, 2018