Week 14 Progress (12 -16 Aug 2024)
| 12 August | We continued to collect data on the performance of the dispensing accessory. We managed to print the final design of the lid for the LCD and keyboard.
We started to collect more manual weighing data from other people. |
| 13 August | We continued to collect data on the performance of the dispensing accessory and took many videos and photos for the video submission. |
| 14 August | We started on the video editing, and also continued to collect data on the performance of the dispensing accessory. We got more people to manually weigh, such that we have more data, and we also continued filming videos. |
| 15 August | The video submission has been completed. We also continued working on the slides for the final presentation. We started compiling and analysing the data. We also rehearsed for the presentation. |
| 16 August | We completed the slides and rehearsed for the presentation. We presented and demonstrated the product. |
Week 13 Progress (5 – 9 Aug 2024)
| 5 August | The new docking station has been successfully 3D printed and put together. Instead of the female connector on the vibration motor, and the male pins on the docking station, we flipped the design, such that the male pins are on the vibration motor and the female connectors are on the docking station. This way, the male pins will not go out of alignment, and it is easier to dock the sample dispenser on the docking station.
We further optimised and tested the algorithm, and modified it such that the buzzer is not hot to the touch. We also started 3D printing a box to hold the LCD screen and the keypad. In addition, we also started planning for the video. |
| 6 August | We performed more testing on the dispensing accessory, and collected more data on human weighing. |
| 7 August | We started to collect data on the performance of the dispensing accessory. We also assembled the final product, with the box for the Arduino UNO and PCB and the holder for the LCD and keypad attached to the metal frame. However, the cover for the LCD and keyboard has not been completed.
We also recorded more data on manual weighing to set some comparisons. |
| 8 August | We continued to collect data on the performance of the dispensing accessory. The 3D model of the keypad and LCD lid has to be further adjusted.
We also started on making the slides for the final presentation. |
Week 12 Progress (29 July – 2 Aug 2024)
| 29 July | The de-clumping mechanism had some success. We have to perform more runs to obtain data on its robustness. As the PCB shield arrived, we started soldering the connectors and wires according to the circuit board. |
| 31 July | We continued soldering the new wires for the electronic devices, and finish up the PCB soldering. We started 3D modelling the box to house the Arduino UNO and PCB shield.
Other than flour, we started to use baking soda and salt to optimise the algorithm. All 3 solids display different physical properties, thus testing all 3 can give us more perspectives on the scalability and range of our product. We also started manual weighing of solid samples to obtain some comparisons. We will follow the specifications set for our weighing accessory to ensure fairness. For all weights and type of solid, we will perform 10 runs each. |
| 1 August | Further testing and optimising of algorithm, as well as 3D modelling and printing the box to house the Arduino UNO and PCB shield.
The male pins on the docking station kept going out of alignment, and in the process of trying to hot glue the pins such that they do not move, all the pins ended up getting hot glued. Since the previous design had flaws, the docking station will be redesigned. |
| 2 August | We timed ourselves weighing flour at different weights, and used it as a comparison against the dispensing accessory.
We were also prototyping the new docking station design. |
Week 11 Progress (22 – 26 July 2024)
| 22 July | We started working on the algorithm. As we planned on the specification being 10 to 200mg, we accounted for this large range within the algorithm. The main principle of the algorithm revolves around the changing of tilt and vibration strength, based on predetermined threshold ranges that changes those settings to achieve an optimal dispensing rate.
Our first idea involves around 2 settings: -Fast mode -Slow mode Let X be the target weight we want Slow : X – 0.01g Fast: X – 0.05g
The difference between the 2 modes lies in the changes in tilt angle and vibration strength, with slow mode being less extreme for increased precision. After each pulse cycle, the current weight data is received from the analytical balance to calculate the weight change. 1) Vibration pulses per pulse cycle How many times we pulse the vibration motor at the same setting (tilt angle and vibration) Fast mode: 1 time Slow mode: 2 times 2) stable check The balance returns weight values that are stable and not stable. We are looking for consecutive stable values before looping the process, such that we let the weighing balance have time to equilibrate before dispensing more. Fast (2 times) Slow (3 times) Problems we encountered – Didn’t implement a max tilt angle Large tilt angle result in large clumps which clogged the dispensing hole and reduced dispensing capability significantly. 2) Fast mode not fast enough At the current settings, it took extremely long. It also resulted in inconsistent dispensing. Perhaps we need to introduce a medium mode and speed up the fast mode We also started designing the printed circuit board (PCB) shield. |
| 23 July | Updated algorithm idea
We decided to include a medium mode to prevent sudden spikes in weight. This makes the dispensing more consistent as the transition from fast to slow resulted in overshooting. We also increased the number of pulses for fast mode to make it even faster. We also added in a max tilt. Let X be the target value we want and Y be the current weight Slow: X – Y ≤ 0.01g 1 pulse Med: 0.01g ≤ X – Y ≤ 0.06g 2 pulse Fast: X – Y ≥ 0.06g 3 pulse During every transition into a new mode, the tilt of the sample dispenser will be reset. We then made the serial monitor output the various parameters of the devices to make debugging easier. The serial monitor outputs the:
We were also considering using PID. However, we decided against it as it is too ambitious to characterize the tilt and vibration level for different types of solids. We also finished the designing for the PCB shield thanks to the lab assistant’s help (Thank you Jeremy :D) and also placed the order for them. |
| 24 July | We performed further testing on the algorithm’s ability to dispense flour, and further optimised the algorithm. Although the dispensing accessory has the ability to be precise, the time taken is quite long. Clumping was also still an issue but happened less frequently. We decided to brainstorm ideas on how to de-clump the powder when it clogs the dispensing hole. |
| 26 July | De-clumping ideas:
Idea 1 complicates the design to a large extent as the sieve has to be clean, and it introduces addition hassle. The main focus of our idea was to remove the cleaning aspect by using weighing paper. Therefore, it’s counterproductive. Idea 2 is possible, however the added step in sample preparation is undesirable as we aim to make it easier for the user. We can consider this idea again as a last resort. We decided to try idea 3 by implementing a code that detects clumping. After a long duration of unchanging weight, the code will attempt to de-clump by tilting back slightly and vigorously vibrating. The regular algorithm will then be executed again. |
Week 10 Progress (15 – 19 July 2024)
| 15 July | We 3D printed and designed a holder to hold up the other end of the shaft.
We finally were able to complete the full set-up
We 3D printed a sample dispenser to accommodate the cone shaped folded weighing paper:
We attached the vibration motor:
We also added an additional attachment, which had ridges, allowing the sample dispenser to attach on the docking station (like Lego pieces).
The vibration motor was plugged in with jumper wires.
The final set up was shown below
We did some tests of our set up. As an interim solution, we were using a power supply provided by the workshop.
The dispenser was able to dispense powder onto the weighing paper. However, the length of the container was too long, and it was unable to dispense powder onto the center of the weighing paper. In addition, the output hole was too small, and the hole kept getting clogged. It was also very hard to install the sample dispenser to the docking station, and the jumper wires had to be bent to one side.
We therefore shortened the length of the sample dispenser, increased the hole size and moved the vibration motor closer to the center of the sample dispenser.
|
| 16 July | We brought more wires |
| 18 July | We further adjusted the sample dispenser and made the hole slightly smaller.
During testing, we noted that the connecting of the vibration motor to the jumper wires is cumbersome. It was annoying as we had to insert each wire to the underside of the container. There was also a risk of the wire detaching. As such, we changed the design by soldering on female ports on the vibration motor, and hot gluing male pins on the docking station. This allowed for the connecting of the wires to the vibration motor, and the docking of the sample dispenser to the docking station to be done simultaneously, simplifying the installation.
|
Week 9 Progress (8 – 12 July 2024)
| 8 July | We needed to determine the precision of the 3D printer, and as such we printed several prints to test it out. We also tested a variety of shapes and sizes for the shaft for the stepper motor. We decided to 3D print the rod because online shops do not have the dimensions needed. We also did some trial and error regarding the assembling of pieces to form a well-fitted rod.
However, the 3d printed motor coupler does not consistently fit properly onto the stepper motor despite multiple tweaks in the dimensions. We also designed a motor holder.
|
| 9 July | We added the lcd screen and controller into the set-up. It works as intended.
|
| 10 July | We did not realise that the base of the stepper motor was slanted slightly. Our initial design of the holder was flat. This resulted in a slight tilt in the motor shaft when we connected the coupler and rod. We decided to change the design as we needed the shaft to be straight.
We created a new design, and screwed the motor on to make it straight.
We also created a base for the motor holder to attach onto the angle bracket which was connected to the linear profile rails.
We measured the length but didn’t account for the height of the base. It was too tall for the T-nut to attach to the screw.
So we updated it with a thinner base. Our rod can now be installed.
|
| 12 July | With the advice of the workshop assistants, we tweaked the design of the coupler. A screw can be inserted into the top of the coupler and tightened to fit the stepper motor.
We obtained more aluminum linear profile rails from the lab staff. We are now one step closer to finishing the prototype.
|
Week 8 Progress (1 – 5 July 2024)
| 1 July | New wire arrived. We tried it out but to no avail, data is still not being received. Tips from the lab staff indicate that the wire itself may not be compatible despite fitting perfectly into the port.
Our group needs to take a look at the datasheet of the analytical balance and determine what each pins in the socket mean. |
| 2 July | We did it!!
After directly wiring using jumper wires at specific pins, we managed to receive some information from the analytical balance. However, this is quite a primitive method. We probably need to solder the wires to an actual RS232 plug in the future.
We moved on to connecting it to the Arduino UNO.
We could directly receive data now. When connected to the Arduino UNO, the data received were gibberish. We shall try again another day. |
| 5 July | RS232 data communication issue is solved. Turns out the gibberish data received was correct but inversed, so we just had to correct that in the code. Hooray! |
Week 7 Progress (24 – 28 June 2024)
| 24 June | Our group purchased more electronics. |
| 25 June | We decided on the stepper motor for the tilting of the container
This simple motor works fine because the only goal is to tilt and maintain the tilt. The sample dispenser itself is also light so there would be no issue in terms of power and torque to maintain the tilt of the sample dispenser. We put together a basic circuit diagram of the electronics.
We also did more electronic purchases. |
| 26 June | We had a few sample dispenser designs:
Rectangular sample dispenser -Base design -Easy filter paper placement -Inefficient spreading of sample (powder will accumulate and clump together) -Inconsistent in dispensing weight (due to clumping)
Triangle Valley -Easy filter paper placement -More efficient spreading of sample -Funnels solids to centre, reducing inconsistency -Clumping of solids remains an issue
Cone shape -More efficient spreading of sample -Funnels solids to center near the end, reducing inconsistency -Reduced clumping, solids exit out of funnel at steady rate -Harder to fit filter paper into container |
| 27 June | We encountered an issue with the RS232 port. When connecting the Arduino UNO to it, no data is being received by the Arduino UNO. The issue remains unknown for now. Perhaps we received a faulty wire? We decided to purchase a new wire to find out. |
Week 6 Progress (17 – 21 June 2024)
| 18 June | We gathered the datasheet information of the motors we purchased and started to think about how to assemble the prototype. |
| 20 June | We fixed up a rough set-up for the dispensing mechanism which functions as our proof of concept.
We also spent the time trying to get the Arduino UNO and vibration motor to work
We also came up with a picture of how the final product should look like.
|
| 21 June | Our group presented our original idea and the transition to the automated solid dispensing idea.
After the presentation session, our group tested the vibration mechanism. Notes: 1) Vibration strength ranges from 0 to 255 in code At 75 vibration -> start, stop (0.0001g to 0.0009g per cycle) (low robustness) <55 results in no movement of the vibration motor >150 results in very strong vibration 2) Leveling of powder is an issue Vibration at higher strength pushed the powder away from the motor. Motor was taped to the middle, so solids pushed to back of container and out of container 3) Current balance unable to detect sub-milligram changes Analytical balance had a smallest division of only 1 mg. 4) Vibration motor is too strong Higher ranges is quick to push samples off the sample dispenser onto balance. Need to keep strength at low levels most of the time. 5) Dirtying of container
Vibration resulted in the solids moving to the back, slipping under the filter paper. We aim to ensure this does not happen to prevent washing of the container between measurements of different samples. As a whole, we proved that it is possible to create a powder dispenser with a vibration motor. As such, we proceeded with this design. |
Week 5 Progress (10 – 14 June 2024)
| 10 June | Block Diagram for the solids dispensing machine is completed (vibration mechanism)
|
| 11 June | Items have not arrived yet….this week our group are just fiddling our thumbs…
We decided to work on the 3d modelling of the prototypes in the meantime |
Week 4 Progress (3 – 7 June 2024)
| 3 June | We brainstormed for more dispensing ideas. Tony deemed the horizontal sweeping design too hard, as it is difficult to control a robotic arm to move in 2 axes of motion. We also realised that the resolution for the prototype with varying hole sizes is not high enough. As such, we settled on three new ideas to test:
Firstly, an improved version of the solid Dispenser using horizontal sweeps. We will replace the dispensing mechanism with a wheel powered by a stepper motor/servo motor, as shown below. Different spoon sizes can be inserted into the wheel to vary the weight dispensed per time, widening the range of the prototype.
Secondly, we wanted to test dispensing via vibration. By controlling the tilt of the container and strength of the vibration, solids will be dispensed consistently onto the analytical balance.
Lastly, design 3 is very similar to design 2, just that instead of a vibration motor, it is a rotating barrel.
|
| 4 June | We did some preliminary testing for the three ideas. To ensure consistency during experiments, we decided to use flour as the solid. It’s safe to use and consists of fine powders. For design 1, we used a spoon of different sizes to scoop flour into the weighing balance. However, a spoon proved troublesome as the amount dispensed was too large. As such, the resolution would be dependent on the spoon size, and a very small spoon will be required.
For design 2, we used a DC motor and made it unbalanced, causing it to vibrate. We used a flat board and put flour on it, manually vibrating flour onto the balance. Consistent measurements below 5mg can be obtained. For design 3, we rolled up weighing paper and filled it with some flour. We then rotated it while tilting one end into the analytical balance. We realised that the flour would tend to dispense out in large clumps, and that the resolution would be low. As such, we settled on design 2 and aimed to create a proof of concept. |
| 5 June | Our group purchased wires and electronics for prototype.
Discussion with Tony on the specification of the product. Our group decided to fix these criterias: 1) Error of final weight be within 5mg difference. 2) Quantities between 50 to 200 mg 3) Dispensing time of less than 5 minutes 4) Sufficiently small to fit within a lab weighing scale 5) Ease of use 6) Low cost |
Week 3 Progress (27 – 31 May 2024)
| 27 May | Our group met Tony to discuss the feasibility of the solvent dispensing system. The user will input into the UI interface the desired ratio and the machine will dispense accordingly.
After the discussion, we realised that flash chromatography presented 2 issues. The experiment requires an air pump to facilitate chemical separation at a reasonable timing. The solvent must also not dip below the silica level; the material in the column responsible for separation. This means that a system must be designed to switch between refilling of solvent and pumping air into the column within a closed system. The immediate issue surrounding this was the regulation of pressure as a buildup could cause an explosion. This meant installing a pressure regulator and programming multiple servos to turn depending on the readings of it. Determining the solvent level was also difficult as the usage of a laser detector was deemed too inconsistent. Another pressing issue was the organic solvents involved which made sourcing building parts difficult. In addition, the act of manually refilling solvent is faster and easier than designing an automated system to refill it. Therefore, the team decided to pivot towards a solid dispensing machine for weighing samples within the milligram range. |
| 28 May | Brainstorming design ideas on how to dispense solids onto the analytical balance.
Idea 1: Usage of different hole sizes allow for a wider range of dispensing rate. Larger holes will be used first, followed by smaller holes upon nearing the desired weight.
Figure: Solid dispenser using revolving containers of different hole sizes Idea 2: A flat spoon controlled by an arm will carefully sweep the solid down onto the analytical balance.
Figure: Solid Dispenser using horizontal sweeps |
| 29 May | We did more brainstorming on other dispensing designs. |
Week 2 Progress (20 – 24 May 2024)
| 20 May | A meeting session was done to delegate tasks such as block diagrams, risk assessment and procuring of items. The group decided to split the workload amongst the current idea of solvent dispensing system and a new idea: an automated solid dispensing machine for milligram weighing. |
| 24 May | Our group completed the risk assessment and updated Dr Ho and Hanyang on the progress on ideation. |
Week 1 Progress (13 – 17 May 2024)
| 13 May 2024 | The group attended the Safety Briefing and discussed the distribution of roles and responsibilities. |
| 15 May 2024 | Our very first meeting with Tony to discuss the technical feasibility of the semi-auto chromatography machine.
This idea revolves around an automated system for Flash Chromatography. Using a syringe pump, a mixed ratio of two different solvents can be regularly dispensed into the column to ensure a smooth continuous flow of solvent while servos close/open to allow for the air pump to push the solvent through the column and separate the organic compounds. We learned about the importance of block diagrams and the difficulties in building such a machine as Tony believed that there were too many moving parts for it to be completed within this module. Our group decided to take a step back and analyze which portion of the machine to focus on. Our group participated in the 3D motion workshop led by Hanyang |
| 16 – 17 May | We decided to focus on the automatic solvent dispensing part of the system. Using a 3D printer skeleton as a base, with stepper motors to control the rotation and vertical motion of a syringe, we wanted to automatically transfer liquid using a regular syringe.
Our group also started brainstorming other ideas as backup. |
