Embedded Files
Overview of Design
The entire device consists of electronic components (sensors, an SD card, a battery and an antenna), a Blue Robotics watertight enclosure, an exterior enclosure, and two ankle straps with adjustable clips on either end. The sensors are the means through which data is obtained, the SD card stores data, the battery ensures that the electronic components have the power to operate, and the antenna transmits data wirelessly to the external environment. The external housing unit was 3D-printed out of Polycarbonate Acrylonitrile Butadiene Styrene (PC-ABS) and was designed to hold the Blue Robotics internal waterproofing structure, which will be discussed in greater detail further on. The watertight enclosure contained the electronic components, ensuring that the sensors were protected from water and mud. The watertight enclosure was encased by the external enclosure, and had the purpose of shielding the sensors from forces that an elephant could exert. The anklet was attached to the exterior enclosure by having straps run through slots in the enclosure and was designed to wrap around an elephant ankle via metal clasps.
After a scale model underwent a compression test, it was determined that the full scale model would fail under a load of 20 kN. This result showed that the external enclosure ultimately failed to meet the requirement that the enclosure is able to withstand the force of an elephant stepping on it. There are a few reasons why these results came about, some of which include the accuracy of the scale model, the lack of fasteners in the scale model, and the infill that the model was 3D printed at. While the external enclosure failed to meet all the requirements, Team 20 learned a lot from the model.
Four Major Components
Waterproofing Component
The waterproof tube is an outsourced Blue Robotics watertight enclosure to protect the sensors. The enclosure consisted of a cast acrylic tube that had a length of 100 mm long, an outer diameter of 58 mm, an inner diameter of 49.5 mm, and a depth rating of 400 m. Each end of the tube has a flange with three O-rings, a locking cord, and an end cap attached to the flange with screws. The Blue Robotics watertight enclosure was chosen to serve as the waterproofing component because of its exceptional ability to remain waterproof even when being placed in water at high depths and/or prolonged durations.
2. Internal Sensor Stand
3D printed with PLA material, the internal sensor stand is designed to keep the sensors in place while inside the Blue Robotics tube. The bottom of the sensor stand is attached to one of the Blue Robotics acrylic plates with Gorillaweld epoxy. There is 1 mm of clearance between the sensor stand and the flange hole to allow easy access to the sensors for data retrieval. The printed circuit board and the accelerometer are screwed into the screw holes on the front side of the middle plate. The battery and antenna are secured in a pocket on the back side of the middle plate.
3. External Strength Component
The outer enclosure was made out of two pieces that are 3D-printed out of PC-ABS and was designed to enclose the Blue Robotics waterproof component for added strength. Each piece had 3 concentric holes that allowed screws to be inserted inside the parts and fasten them together. The surfaces of the pieces facing toward the elephant ankle are concave so that when the enclosure is strapped on the elephant ankle, those surfaces would be more flush on that feature. The radius of curvature of those surfaces was based on measurements collected at the San Diego Wildlife Safari Park, where elephant-care specialists measured the circumference of the slimmest section of the front leg, which was then averaged. 3D-printing was chosen as the fabrication method for the enclosure because the enclosure consists of multiple curvatures that would be easier to create via 3D-printing than machining and the sponsors have 3D printers readily available at their facility for use.
4. Dual-Strap Adjustable Anklet
The anklet strap consisted of firehose material in which the ends were connected with alloy metal clips. Firehose was chosen as the strap material because it is a commonly utilized material at zoos in general, meaning that it is a readily accessible and relatively familiar item to the sponsors, and designed to be durable and weather-resistant. The firehose purchased was 19.05 mm (3/4" inch) white garden fire hose because it fit the necessary size parameter the team was interested in, with a lay-flat diameter of 31.75 mm (1 14” inch). In addition, the adjustable clips that were chosen were stainless steel lock buckle sliders that had a clearance of 6.35 mm (14” inch) wider than the firehose for a comfortable fit. They are difficult to adjust, making it perfect for being fit onto an elephant as they will struggle significantly if trying to remove.
Page updated
Report abuse