Project
| # | Title | Team Members | TA | Documents | Sponsor |
|---|---|---|---|---|---|
| 76 | Watt Balance |
John Howard Julian O'Hern Justin Ansell |
Abhisheka Mathur Sekar | design_document1.pdf final_paper2.pdf other2.jpeg other1.pdf photo1.jpeg proposal1.pdf proposal2.pdf |
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| # Watt Balance (Pitched Project) Team Members: - John Howard (johnlh3) - Justin Ansell (jansell2) - Julian O’Hern (johern2) # Problem In 2019, the universal kilogram standard was redefined from the physical definition based on a platinum-iridium alloy object to a relation to Plank’s constant. Researchers have developed a method of measuring mass in relation to the velocity and force of an induced field from the balance usually called a Watt or Kibble Balance.. A group of graduate researchers in the ABE department at UIUC made their own watt balance, but found their measurements are often off by up to 30%. They pitched a project hoping to find ways to improve the accuracy of the Watt Balance. # Solution To solve the problem of inaccurate results, we are proposing improvements to iterate on the current design. We plan to increase the accuracy of the sensors for current readings and velocity readings, reduce the friction from the fulcrum, and allow for better user control of the device through updated control software. We also plan to make the device as reliable as possible by shielding from external electromagnetic interference and ensuring that the voltage supply delivers a precise constant voltage. With these changes, we believe that we can significantly improve the accuracy of the mass readings of the balance. # Solution Components ## Velocity Measurement In order to properly calculate the mass on a Watt Balance, two measurements are needed: velocity and force. Velocity measurement entails calculating the movement of the scale, which will require a sensor to detect the rotational movement. This velocity is used in one half of calculating the mass of the object on the scale. ## Force Measurement Measuring the force requires applying a precise current to one coil, while measuring the resulting induced current in the other coil by the motion of the permanent magnet through it. This force is used in the other half of calculating the mass of the object on the scale. Combined with the velocity calculations, an accurate mass can be determined. ## Data Processing The method for processing data on the existing model is an Arduino with several breakout boards, which is not ideal for quickly gathering and processing the data required. Our plan is to create a custom PCB with all the necessary components to streamline the process of data collection, and improve the PID control. ## Balance Control and Display Currently the graphical interface for the display consists of a rudimentary program in MATLAB with the control buttons and data. Improving the GUI to both be able to see more in-depth information about the feedback from the scale, along with more sophisticated tuning methods that will help to more quickly debug and fix issues with the balance. # Criteria For Success Our device must: - Accurately determine the magnetic force generated by measuring the induced current in the coil - Accurately determine the rotational velocity of the balance by measuring the rotational position of the fulcrum. - Calculate and display the mass of the object placed on it - Allow for control and parameter modification from a computer application We have some stretch goals as well, such as auto-calibration given a known mass, but the items listed above are the minimum criteria for success. |
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