Posts

Week 30 (May 8, 2019): Prototype Evaluation Day, Final Circuit, Incorporating 3D printed parts, Final Presentation, Posters, & Maker Faire

-
Image
Today, we held Prototype Evaluation Day. Like the rest of the senior project classes, the advisor walks around the classroom, evaluating the senior project apparatuses, asking the student teams to demonstrate their devices, and explain their design, though processes, and results. Dr. Furman and Ron examined and inspected the Full-Scale model, then the Half-Scale model, and lastly, us, the Small-Scale Team. We had completed our circuit to power one pod car and one of the two induction charging stations prior to Evaluation Day, so we were able to successfully demonstrate the pod car driving around the track as well as the induction charging. While we were still troubleshooting issues with the tablet’s Raspberry Pi communicating with the Arduino, the Arduino is still capable of operating on its own, so we could at least demonstrate the motor driving the pod car around the track and through the offline stations. Depicted below is our final circuit that powers the pod car: Dep
Post a Comment
Read more

Week 29 (May 1, 2019): CAD of Induction Charger Hub & Podcar Door, then 3D Printing

-
Image
This week, while David worked on the Raspberry Pi and the Arduino code, Patrick completed the CAD (computer-aided-design) models. We had to create 3D solid modeling of two parts: the induction charging hub to hold the induction transmitter coil and the pod car door to hold the induction receiver coil. Over the weeks, the CAD models underwent several revisions. The induction hub saw two revisions, with the third design being the final version. Because the 3D printer available to us in the shop, the Prusa Mark3 i2, had a bed length of 10 inches, we had to restrict the length of the charging hub to a safe 9.5 inches. Version 1 simply entailed us placing the hub on the side of the bracket and then screwing it into place on the bracket’s side via the two holes at the top: For version 2, in addition to placing the hub on the side of the bracket and then screwing it into place on the bracket’s side via the two holes at the top, the bracket would wrap around the two bracke
Post a Comment
Read more

Week 28 (Apr. 24, 2019): Final motor selection – Mini-Stepper Motor

-
Image
Since last week, we have been trying to run the new brushless DC motor; however, it is still difficult to control, let alone its speed. Therefore, we had to pursue our alternative motor, the mini-stepper motor that runs at 5V. Found in Arduino starter kits, this mini-stepper motor is accompanied by its dedicated motor driver board, the ULN2003, which is a chip containing a series of Darlington pair transistors. An image of the stepper motor and the ULN2003 board is shown below:   Sources: https://www.adafruit.com/product/858 https://www.amazon.com/gp/product/B01CP18J4A/ref=ppx_yo_dt_b_asin_title_o03_s00?ie=UTF8&psc=1   We were able to successfully run the new mini-stepper motor with the sample code included with the Arduino starter kit. One benefit to using the sample code is that it utilizes the Stepper library’s functions. One use function is the setSpeed( ) function, which allows the user to set the RPM speed of the stepper motor. We found that the maximum spe
Post a Comment
Read more

Week 27 (Apr. 17, 2019): ME 195B - Presentation #2 (Prototyping Stage Continuation) Reflection

-
Image
Today, we completed Presentation 2, which is our 5 th presentation overall, throughout the entire length of senior project, since last semester. Please refer to our Presentation #2 slides, embedded below. Covering the continuation of our prototyping efforts, we discussed progress on hardware acquisition, integration of components into a working circuit, and programming. Regarding programming, we were still working on the communication between the Raspberry Pi and the Arduino. And while the circuit is also coming together, there was one piece that gave us problems yesterday: the gimbal motor broke and so we had to order another motor that is not a gimbal but is still a brushless DC motor. An image of the new motor is found in our presentation slides below. While this was disheartening at first, we found that the gimbal is not intended for continuous rotation, but instead for precise movement, as they are used for cameras on drones. However, this was still a setback bec
Post a Comment
Read more

Week 26 (Apr. 10, 2019): Programming – Python and Arduino Communication

-
Image
The Python code and the Arduino code are able to run successfully on their respective boards, i.e. the Raspberry Pi in the tablet and the Arduino in the pod car. However, the Raspberry Pi is having issues sending data to the Arduino via the XBee RF (radio-frequency) module, specifically the user-input data. Whenever the user inputs the pickup station, destination, and selects a pod car, the Serial Monitor on the Arduino IDE does not show any of the data. Investigating further, we plugged the XBee module into one of our laptops, then opened the XCTU software’s (the software which deals with RF modules) Serial port as well. Now, whenever the user inputs the stations, we can see on the XCTU Serial Monitor that the receiving XBee does get the pickup station, destination, and pod car number, but the three inputs are all found between jumbles of random characters. As displayed in the screenshot of the XCTU software below, if the user inputs pickup station 2, destination station 5, and sele
Post a Comment
Read more

Week 25 (Apr. 3, 2019): Current Amplification Solved via Buck Converter

-
Image
Today, we made the decision of going with the 12V, 600mA induction coil set, as they allowed for a greater distance between the transmitter and receiver, which was a maximum distance of 0.787 inches, as opposed to the 5V, 1500mA induction coil set, which had a maximum charge distance of 0.5 inches. As a reminder, we are implementing induction charging, also known as wireless charging, to charge the 3.7V Li-ion battery at designated charging stations within the track. This helps to enforce autonomy, which will further eliminate human intervention and manual maintenance of the system. Because the charge current is smaller, we tried to find a way to increase the charge current used to charge the battery. We settled upon using a buck converter, which decreases voltage with the advantage of increasing current. The buck converter would be placed after the induction receiver and before the battery charger. After some testing, we found that the buck converter could amplify the curren
Post a Comment
Read more

Week 24 (Mar. 27, 2019): Revised Gimbal Motor Velocity Calculations

-
Image
Today, we realized our velocity calculation was incorrect because we used the wrong radius in the circumference calculation; we erroneously used the diameter (35 mm) as the radius. Source: Carryer, J.E, et. al. (2012) Introduction to Mechatronic Design . Pps. 536-541, 547-548. We were expecting a velocity of around 1.0 m/s, but 0.88 m/s is good enough, with the new bogie, the new gimbal motor, the new 12V power supply from the boost converter, and a 2:1 gearing set.
Post a Comment
Read more