AUTOMATED TOOLS FOR ACCURATE AND PRECISE DOSING OF GRANULAR SOLIDS
Engineering
Robotics Engineering / Electrical Engineering
Automated accurate and precise dosing of granular solids is a required task in many fields of science and engineering. The majority of affordable commercially available devices can not reach the required precision needed for scientific application. A large amount of these devices operate blindly, with no feedback loop. The automated devices which maintain their accuracy and precision over prolonged usage are limited and expensive; thus making them inaccessible.
It is believed that an automated closed-loop system that can dose granular solids with milligram accuracy is achievable. In order to achieve this, two primary elements must work together in unison. First and foremost, a feedback system is necessary due to the variable nature of powder flow. Secondly, a precision pumping element capable of making micro-adjustments to the dosage is needed. Acquiring milligram accurate feedback is useless if we cannot act upon it.
The necessity of a closed loop system for precise powder dosing is demonstrated. The following subsystems were designed, fabricated, and validated: (i) A pumping element, (ii) A mass feedback element, (iii) a dispenser body which integrates subsystems (i) and (ii) to work together. The total cost of fabrication was approximately 100 USD.
It is shown that mass feedback with an accuracy of +/- 15 milligrams is achievable, which is within the desirable range for our application. It is also shown that the pumping element can meter out dosage on the milligram scale and the output is stable. This means that meaningful action can be taken in response to the mass feedback in order to achieve the correct dosage. Finally, it is shown that a dispenser body that integrates both the feedback and pumping subsystems can be fabricated so that the entire system can run on closed loop control.
