In this paper, we design application specific mechanisms and control systems to test and deduce the lifetime of custom-designed hinges and batteries. These hinges and batteries are part of prototypes for smart toilet seats. The work done here was used to improve the existing design and to identify a replacement cycle for these seats. The target audience for this smart seat is airports and venues with large crowds. The consumer of this product needed detailed information on the failure and failure modes of the said seats. This boils down to the cost of replacing failed or about-to-fail seats and the lifetime of each part. This paper mainly focuses on the design of the testing equipment and the control methods used. The optimization of the lifetime of the battery or the hinges was not a concern for the industry partner and is not the focus of this paper.With recent advances in microcontroller technologies and the wide availability of support libraries for microcontrollers, automation of the entire testing equipment was done at a very low cost to the industry partner. The test system was entirely controlled by a custom Raspberry Pi 4 and an Arduino microcontroller. Custom libraries were created to address the testing scenarios for the battery and the hinge, these were based on the sensors selected and the output of the selected sensors. The smart seat has a cleaning solution that is contained within the seat in a cartridge, which can be easily replaced by facilities. The seat includes a motion sensor, battery, and slow hinges inside of it. Each time a user wants to use it, they wave their hand near a side panel of the seat, which triggers a pump mechanism to push an environmentally friendly cleaning solution from ports on the seat for easy cleaning. This seat employs a slow hinge which reduces the impact of repetitive opening and closing of the seat. This is essential for this seat as the seat is not a solid piece, but hollow on the inside to facilitate cleaning solution to rise out of the ports. Any unexpected wear of the slow hinge could cause slamming of the hollow seat onto the bowl, resulting in cracking or failure of the seat.The battery powering the pumping mechanism was tested until failure, where the battery voltage fell below a specific value and could no longer pump the cleaning solution out of the ports. For finding the hinge lifetime, we designed a complex mechanism that included two electrical motors, multiple position sensors, and a control arm to lift a drop the seat. First, when the seat is in a down location, will be detected by two sensors, the first motor connected to the control arm lifts the seat to the top position. The mechanism validates the location of the seat at the top position and after a brief pause, a mechanism at the top position pushes the seat to a set angle from the vertical so that the seat may continue under its own weight to the closed/bottom position over the bowl. This ensures that the hinge is supporting the weight of the seat during the repetitive cycles and no other external force is applied to the seat. When the seat reaches the bottom position, one cycle is completed. The time for lifting up and going down for the seat and the number of cycles is counted and recorded by the controller.

Mechanisms Design for the Hinge & Battery Lifetime Tests for a Prototype

Paper Proceedings: https://asmedigitalcollection.asme.org/IMECE/IMECE2021/volume/85543

ASME 2021 International Mechanical Engineering Congress and Exposition (IMECE2021)

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