Load cells are very important components in a robot system. They help the robot to get feedback from the environment around it and generate control signals accordingly. However, like every other sensor, load cells need to be calibrated over time to maintain their accuracy and precision. In the current method, they need to be detached from the robot. Then known weights are hung below the load cells to get the raw signal from the load cells. These two types of values will then be used to generate the equations that convert the raw signal to the force values. This is a challenge as not many robots are maintenance-friendly so detaching the load cells can take a lot of time, not to mention the process can damage the load cells if not conducted carefully. This research project utilizes mechanical simulation to calculate the known force values acting on the load cells without taking them out of the robot system. Then these force values are used for the calibration process. In this thesis, the in situ calibration method will be conducted on the actuator-controlled pendulum, and a bipedal robot when it is hanging on the gantry and standing on the ground. Also, since mechanical simulation requires a lot of computational power, a geometry simplification method will also be introduced so this in situ calibration method can be used for ordinary personal computers. The results show that the new calibration method is easy to work with, the force values still meet the requirements for calibration, and the computer only needs 10-12 seconds to run each simulation. / Master of Science / A robotic system usually need the load cell to generate the correct control signal. However, the load cell needs to be calibrated over time for maintenance. The current calibration method requires the load cell to be detached from the robot so the user can apply known forces to the load cell. This thesis introduces an in situ calibration method that can calculate forces that are applied to the load cell so the user does not need to detach the load cell from the robot. An optimization method is also introduced to make the calibration process can be done on an ordinary personal computer.
| Identifer | oai:union.ndltd.org:VTETD/oai:vtechworks.lib.vt.edu:10919/115995 |
| Date | 07 August 2023 |
| Creators | Le, Tung Xuan |
| Contributors | Mechanical Engineering, Leonessa, Alexander, West, Robert L., Asbeck, Alan Thomas |
| Publisher | Virginia Tech |
| Source Sets | Virginia Tech Theses and Dissertation |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Format | ETD, application/pdf, application/x-zip-compressed |
| Rights | In Copyright, http://rightsstatements.org/vocab/InC/1.0/ |
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