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The project was organized into six main phases. They were planning, designing, purchasing, manufacturing, assembling, and closing phases.
Planning Phase
Planning Phase
The planning phase of the project began on January 5, 2024, and the following activities were planned for this phase. Project concept, a pool of ideas (document 1), hand sketch (document 2), risk assessment (document 3), project scope (document 4), Google site creation, initial Gantt chart (document 5), and initial budget (document 6). All the documents above-mentioned can be seen in the documents and references section of this report.
The planning phase is a crucial part of any project because its activities will dictate the project`s flow. Initially, the design concept was discussed and approved by all members. However, the drawing concept was updated based on Professor Volkening's recommendation and suggestion. The substitution of a metallic roller chain for a 3D printed roller chain was the main change performed on the design concept.
Risk assessment and project scope were identified and did not suffer any alteration along the project. An estimation based on team members' experience was performed for the budget. The project's Google site creation allowed the team to upload all documentation and assignments necessary for the capstone project as well as for grading purposes.
The order and duration of the tasks were identified based on individual capabilities. Figure 3 displays the planning phase with its dates and duration on the Gantt chart. However, some adjustments were required in the following phases based on the deadlines of the project. The project management section of this report explains more about it.
The first milestone of the project was to have the planning phase finished on February 2. The achievement of this milestone on time reinforced the team`s confidence in the project.
Figure 3 - Snip of the Gantt chart for the planning phase.
Designing Phase
Designing Phase
The design phase of the project began on February 5, 2024, the completion of mechanical and electrical design and drawings was required in this phase. To access the mechanical drawings (document 7), and electrical drawings (document 8) developed in the design phase please visit the documents and references section of this report.
The initial task of the trash rack design was to create, design, and 3D print an initial chain and sprocket concept to validate the idea and functionality of the trash rack. This task was crucial for the project given the uncertainty if the 3D printer roller chain would work.
Mechanical calculations regarding the chain pitch, sprocket size, and number of teeth were necessary. Figure 4 illustrates how mechanical design calculated sprocket sizes. With the SolidWorks models for the sprockets and roller chain finished, the 3D print of those parts was requested and performed at Fanshawe College.
Figure 4 - Chain and sprocket calculation.
After the initial test with the 3D-printed parts, an issue with the pin strength and fitting was encountered. The design needed to be modified with some changes in dimensions, and the addition of fillets and chamfers to provide ease of assembly. Figure 5 displays pins breaking easily forcing the team to change the mechanical design.
The second milestone of the project was set to be the validation of the 3D-printed parts and their mechanical design. The assembly was performed after design changes were executed and new parts were 3D-printed. In the second attempt, the fitting and strength were perfect and the milestone was achieved on February 9. Figure 6 shows sprockets and roller chains assembled and matching perfectly.
Figure 5 - Pins breaking easily required mechanical design changes.
Figure 6 - 3D-PrintedChain and sprocket 3D print.
After this milestone achievement, the focus was redirected to the trash rack frame design and integration of other devices. In this phase, the material was defined to be aluminum due to being lighter and easier to machine. Sizes were also defined, such as flat bars for the trash rack frame (1”x1/8”), shaft (8mm), and angle bars for the pillow block brackets (1.5”x1.5”x1/8”).
Alongside the chain and sprocket design the electrical circuit started to be developed on a virtual breadboard. Tinkercad was the online website chosen for the initial simulation due to the availability of all components required for the prototype.
The initial design shown in Figure 7 contemplates the basic elements of the prototype, such as a DC motor, logic gates, switches, and a 12 VDC power supply. Some requirements changed until the end of the design phase. A 5 VDC power supply to avoid logic gate malfunction, a main power switch, an Estop, and a photoelectric sensor were added to the prototype until the end of the design phase.
Figure 7 - Initial electronic design on Tinkercad.
During the design phase, uncertainty about the sensing range and the voltage output of the photoelectric sensor when powered up with 12 VDC arose. It was decided to check if the range and output signal would be enough for the project and if additional treatment in this signal was required. Three sensors were tested.
Only one sensor had an acceptable sensing range and worked properly at 12 VDC. Therefore, it was suitable for the prototype. However, its output was 11.02 VDC. The voltage was too high to be connected directly to a logic gate. The solution created by the team was a voltage divider that dropped the voltage to 5 VDC. Figure 8 displays the voltage measurement in the sensor output when detecting an object.
After reading the DC motor technical specifications, it was realized that a transistor as a switch was necessary. A MOSFET was added to the electric schematics to allow enough current flow to the DC motor. Implementing that, the logic gates were able to drive the motor when needed through the transistor. Figure 9 shows how the transistor was operated as a switch. To check the entire electrical schematics (document 8) please check the documents and references section of this report.
Figure 8 - Photoelectric sensor being tested to check sensing distance and voltage output.
Figure 9 - Snip of the electrical schematic showing the transistor wiring.
Purchasing Phase
Purchasing Phase
In the third phase the materials quotation, evaluation, and purchase were performed. The initial plan was to buy all mechanical and electrical materials online. However, the shipping time was too long. A decision to shop in local stores and order it directly there was taken. The only materials ordered online were the DC motor, power supplies, and pillow blocks.
After orientation from our Project Manager Advisor, Professor Volkening, a list of local stores where materials for the prototype could be found was created. Before going to stores, an evaluation of the material listed to check if it was within budget and similar to the mechanical and electrical design specifications was performed.
Afterward, local stores were visited and almost all the required materials for electrical and mechanical were found. The exception was the aluminum bars, the material sizes needed were unavailable. A list of material sizes similar to the material needed for the project was provided by the metal store. Figure 10 shows the original material list and Figure 11 shows the material quotation from the metal store.
Figure 10 - Original materials list
Figure 11 - Materials list quotation from store
With the quotation from the metal store, it was decided to buy the materials that were available from the store since it is easier and cheaper to change the design rather than buy materials online. Furthermore, if ordering online the materials would take too long to arrive. Figure 12 shows all the materials ordered.
After ordering the power supply, it was realized that they were not CSA or ULC approved. That issue was discussed with the Project Manager Advisor, and he reinforced that the power supplies should be CSA or ULC listed to follow safety protocol. A new order was placed after precise research on the online store. This time the power supplies were the correct ones. However, this rework did not affect the progress of the project since electrical assembly could still be tested at the B1020 homework laboratory.
Figure 12 - The purchasing of materials allowed the project to move to the next phase.
Manufacturing Phase
Manufacturing Phase
Only two tasks were performed during the manufacturing phase. However, at the end of the project, it was the phase with the longest duration.
After the validation of the chain and sprockets 3D-printed design, the remaining parts had to be manufactured. This task was quickly finished due to 3D printer availability and no extra work was required.
Besides taking more days than planned, as explained on the project management page of this report, the machining process went smoothly. The flat bars, angle bars, shafts, and sprocket threads were manufactured during this phase. Having very detailed mechanical drawings facilitated the work performed at the machine shop. All the drawings (documents 7 and 8) created for this project can be checked in the documents and references.
After the bars were cut to size using a band saw machine, the milling process started. The equipment required to machine the features in the aluminum bars were a file, vernier caliper, center drill, 0.250” drill, 0.180” drill, and 0.250” flat endmill. The endmill became handy while machining the slots required in the mechanical drawing. Figure 13 illustrates one of the slots created on the pillow block support to ease prototype assembly.
Figure 13 - Slots created to allow ease of assembly and small adjustments that could be required in the assembly phase.
Assembly Phase
Assembly Phase
Alongside the manufacturing stage, the wiring and electronics were assembled. Key lock switches with 2 positions and 2 sets of normally open contacts were installed to provide 5VDC and 12 VDC power to the circuit. The wiring was organized using terminal blocks to facilitate the installation of components and troubleshooting.
A great decision in this phase was the implementation of color coding. The following colors were defined according to prototype input and output signals as well as for easy troubleshooting:
Red for power
Black for ground
Green for automatic
Blue for manual
Yellow for sensor
White for motor
The panel board was 3D printed to accommodate two toggle switches, an emergency stop button, and the key lock switches. The toggle switches were soldered properly to ensure reliable connections. Switch 1 is designated for selecting mode between manual or automatic mode. Switch 2 controls the power state between on and off when the system is in manual mode. In addition, breadboard holders were 3D printed for a better setting of the breadboard on the plywood surface.
For mechanical assembly, once all parts were fabricated, a wide space in the college where the team could assemble the entire prototype was found. Everything went smoothly at the first stage of assembly. Each part was segregated to make it fast and easy to find it when needed. Mechanical drawings and the SolidWorks model were checked for orientation references.
In the middle of the assembly, it was noticed that some bolts were missing. It was realized that after the frame support was added to the design the bill of materials was not updated, and therefore, it was forgotten to add some bolts to the purchasing order.
The continuation of the assembly was scheduled for the following day and after buying the missing bolts the assembly was finished. This time, no problem happened because the assemblers already knew what to do.
After the trash rack assembly was finished, the structural assembly was started. In this task, the trash rack was installed on plywood. Since other devices would be placed on the plywood, attention was taken to leave enough space for the other items. Figure 14 shows the trash rack frame assembled in the plywood.
Figure 14 - Trash rack assembled in the plywood and room for the other devices.
With electrical and mechanical systems assembled apart, it was time to integrate them. For the final assembly, all the electrical and mechanical assemblies were installed on the plywood. The subassembly that was installed first was the trash rack assembly. Since the plywood board was not that spacious a way to maximize the space was found.
The motor was connected first to the trash rack shaft, followed by the operator panel on the opposite side, and then the sensor support and photoelectric sensor were installed beside the panel. Finally, the last device was the breadboard.
The team struggled a bit with the wiring, and it took time to neatly install everything since some parts of the assembly were too tight to install. But the effort and persistence of the team were so good that a way to make it clean and neat was achieved. Figure 15 shows the wiring on the breadboard and terminal blocks.
A buffer time for the assembly was created in case some updates or changes were necessary. And that was indeed utilized to finish the assembly on time and to avoid going too much over budget in some tasks. The third milestone was achieved on March 26 with the prototype assembled and ready for testing.
Figure 15 - Wiring and terminal blocks neatly arranged in the final assembly.
Final Phase
Final Phase
The final phase embraced prototype testing, troubleshooting, and documentation for closing the project.
Once everything was set and assembled, the prototype's initial test was executed. During the troubleshooting phase, the logic gates were behaving differently than on the Tinkercad simulation. The components’ inputs presented an undefined state when their respective switch was in the off position. Voltage measurements, wiring checks, and online research on the component technical documentation were performed. It was discovered that a pull-down resistor was required to provide 0VDC for the inputs when the switch was in the off position.
As a solution, four 10k ohms pull-down resistors were installed in the circuit, one in each of the motors' manual and automatic connections, and one each on the on and off state when the system is in manual mode.
The team also decided to simplify the breadboard to avoid issues due to a lack of proper space and wires jumping between the breadboards. To solve nonprofessional wiring techniques and to eliminate potential malfunctioning, the wiring was moved to one single breadboard.
Additionally, during the testing, it was realized that the delay required for the conveyor to continue running after the sensor stopped detecting any object present was too long. An RC constant recalculation was required to keep the system running only for 8 seconds. To achieve this, the 470 ohms resistor and 10uF capacitor were replaced with a 100 ohms resistor and 1uF capacitor, which rotated the chain almost a full revolution, sufficient for collecting garbage. Furthermore, to consume stored energy when the circuit is in the off state, A 5.6 mega ohms and 10 mega ohms resistor were added to the circuit and wired in a series resistor association.
After the prototype was assembled and tested, a meeting was booked with the Technical Advisor to discuss if the project could be considered completed or if any changes were necessary.
Due to team members' hard work and effort, the Technical Advisor approved the design and said it was ready for the final presentation. Documentation regarding the final report and presentation started to be developed. The documentation presented in this final report covers the problems the team encountered, how it was solved, and the lessons that they learned on this project. Through good teamwork and consistency in making their project, they were finally able to deliver the final prototype.
During the final test, some pieces of paper were added to represent debris and to allow a visual representation of how the prototype works. It can be seen the roller chain moving, stopping, and dropping the paper on the end of the conveyor. Video 1 shows the prototype`s final test.
Video 1 - Prototype final test collecting debris and running in automatic and manual mode.
Individual Contribution
Individual Contribution
Charlito
Charlito was assigned as the electrical designer and assembler. Throughout the project, Charlito demonstrated flexibility in each phase. Charlito created the Google site during the planning phase, assisted Gian and Ray in the electrical and mechanical design phase, procured parts from local stores alongside the team during the purchasing phase, cut parts using the band saw machine, and fabricated the parts on the milling machine during the machining phase. Figure 16 shows Charlito machining the chamfers on the pillow block support. In addition, Charlito wired the electrical circuit on the breadboard and assembled structural parts during the assembly phase.
Kudos to Ray and Gian, who showcased their skills and hard work on the project. The completion of the project on time was the result of the team's collective effort and determination headed by project manager, Gian. This project provided valuable experience for Charlito to apply in real-world work situations.
Gian
As a project manager, Gian was in charge of controlling the project schedule and arranging team meetings to complete tasks on time. Another contribution was regarding the development and organization of project documentation as well as publishing them on the website.
A second role Gian performed was as an assembler. Since all assembly tasks involved all team members, Gian assisted in both mechanical and electrical assembly. After that, troubleshooting skills were also a contribution to the project. Figure 17 shows Gian and Charlito powering up the electronic circuit and integrating it with the trash rack frame for the prototype’s initial test. Gian also assisted in ordering components from online stores and fabricating the aluminum parts following the mechanical drawings for the trash rack frame.
Ray
Ray was the mechanical designer and assembler on this project, He was assigned to do the hand sketch design concept and 3D modeling. Starting from the hand sketch, he ensures that his hand sketch design is clear and easy to understand by everyone. After confirming the final hand sketch, he then started making the detailed parts and assembly in SolidWorks. Figure 18 shows Ray reviewing the assembly drawings. He ensured that the detailed components were clearly defined for the manufacturing process. While performing his main task, he also helped create project documents like general design safety review and tolerance stack up. He also contributed to the final assembly of the trash rack, ensuring that parts were assembled correctly based on his design and checking if there was some interference.
Figure 16 - Charlito machining mechanical parts.
Figure 17 - Gian and Charlito integrating electrical and mechanical systems for an initial test.
Figure 18 - Ray reviewing mechanical assembly drawing.
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