VL53L0X food oil measurement in metal can

[1stetcgoldmedal]

hello.
I am trying to measure the level of cooking oil in a metal container using the VL53L0X chip.
The length and width of the metal container are 25 cm and the height is 35 cm.

Please refer to the picture for detailed measurement environment.

 However, the lower the level of cooking oil, the more inaccurate the sensor's measurement.
In other words, as the distance between the sensor and cooking oil increases, the error in the value increases.
In order to solve this problem, I tried to correct the value by measuring the error range by height, but it is failing to determine the range that matches greatly.
Do you know why this situation occurs? Or do you have experience solving it?

If it is not possible to solve it through the VL series, we are also considering using an ultrasonic sensor.
Thanks in advance for your comments.

thank you
kind regards

[ACHOU.18 · Accepted solution]

Hi ,

We understand that when oil level is low then sensor’s ranging accuracy is low. This is because the reflected return signal from oil is mixed with the base of the container.To improve the accuracy of your readings, we recommend using a low-reflectivity base or possible painting the inside of the container black.

We also recommend characterizing your setup that helps to measure the error deviation and improve the ranging accuracy by adopting Non-linearity correction algorithm that can compensate the error in different level. We have documented and provided example code for the VL53L4CD. This sensor has a narrow field of view (18°), better ambient immunity for shorter distances than the VL53L0X, and gives better results in liquid level measurement. You can adopt similar mechanism of your own for VL53L0X. you can refer below doc.

https://www.st.com/resource/en/application_note/an5851-water-and-liquid-level-monitoring-using-vl53l4cd-timeofflight-high-accuracy-proximity-sensor-stmicroelectronics.pdf

 We hope this information is helpful.