System that reads balancing machine values with OCR, calculates vibration values and decides OK/NG for an automotive parts manufacturer in Thailand

How the brief came about

The problem in this case was to stop typing unbalance values into Excel by hand and to have the system decide the fan's vibration result from values read directly from the machine. On the fan assembly line, the balancing machine already showed unbalance values on its computer screen, but those values were not yet the vibration value used to decide the result.

Previously, operators read the Static and Couple values from the screen, then typed them into an Excel formula on a tablet to convert them into vibration values. The team leader had to recheck them. If a figure was mistyped, the decision would also be wrong, and fans and motors vibrating beyond the standard could pass through.

Requirements and constraints

The new system had to read values from the existing balancing machine without disturbing its operation. The main requirements and constraints were as follows.

• Do not modify the balancing machine's existing program, because it cannot be changed to calculate or output values itself as this requirement needs.
• The machine's original screen must display as normal, and the machine must keep working even if the new equipment fails.
• Read the unbalance angle and magnitude for all 4 fields: Upper, Lower, Static and Couple.
• Formula coefficients and OK/NG criteria can be set separately for each Part Number. These values are the customer's data, so we do not publish them.
• Operators view results on a Wi-Fi-connected tablet, and every result must have evidence that can be checked later.

Why we read values from the screen image instead of modifying the machine's program

We read values from the screen image because the figures needed are already shown on the machine's screen, and this method does not touch the balancing machine's existing program. The Splitter (video signal splitter) sends the same image to both the original screen and DoDisplay, so operators still see the machine's screen as normal. If DoDisplay fails, the machine and its existing program can keep working.

DoDisplay is a VGA screen video input box that uses OCR (Optical Character Recognition, reading characters from images) to read figures on the screen. The working steps are as follows.

1. 1

   Split the video signal from the machine's screen

   The video signal splitter sends the signal from the balancing machine's computer to the original screen and DoDisplay at the same time.

2. 2

   Read figures once the on-screen values settle

   When the Measuring message disappears from the screen, the system waits for the on-screen values to settle and then reads them. DoDisplay reads the unbalance angle and magnitude for the Upper, Lower, Static and Couple fields.

3. 3

   Calculate and decide the result

   The Auto Calculate Vibration software feeds the Static and Couple values into the formula to calculate the vibration value, then compares it with the criteria for that Part Number. The result is OK or NG.

4. 4

   Show results on the tablet and signal light

   Operators see the figures for every field with the OK/NG result on the tablet's Dashboard (results summary screen), and the Tower Light (signal light at the front of the machine) shows the result on the line.

5. 5

   Store history with screen images

   Every result is recorded with the screen image that was read, can be searched by model and date range on the History page, and can be exported as an Excel file.

Deliverables

We delivered the first set of the system in March 2026 and the improvements in September 2026, for 1 fan assembly line. The items delivered in each round were as follows.

How this work was carried out and extended

This work began with 1 fan assembly line, then added capabilities in the improvement round. The sequence of work on the first line, according to the project documents, was as follows.

1. December 2025: The customer ordered equipment and software for the fan assembly line
2. March 2026: We delivered the first set of the system
3. September 2026: We delivered the improvements, namely the Tower Light, NAS, summary Excel file and settings page password

In 2026, during the work on the first line, the customer ordered the same system to be installed as well on the motor line of another factory. This page does not yet include the results of that work.

Confirmed results and work in progress

The results that can be confirmed at present are delivery according to the documents and the end of typing figures into Excel on the fan assembly line. We delivered the first set of DoDisplay, a 10-inch tablet and a Wi-Fi 6 Router in March 2026, and delivered the improvements, namely the Tower Light, NAS, summary Excel file and settings page password, in September 2026.

The system reads the values, calculates and shows the OK/NG result for operators on the tablet. Every result has a stored screen image for later checking, and the installation is designed so that the balancing machine can keep working even if DoDisplay fails.

Project close-out and confirmation of the processing test results with the customer are in progress, so we have not yet published figures for time per piece or OCR accuracy.

What we learned

This work offers the following principles for reading values from measuring instruments that cannot output data.

• When the existing machine's program cannot be modified, read from what the machine already displays and connect the new equipment in parallel with the existing setup. If the new equipment fails, the machine must still be able to keep working.
• Reading values from a screen must happen at the moment the value is final. In this work, the system waits for the Measuring message to disappear and the on-screen values to settle before reading.
• An automatic decision can be trusted when every result can be checked later. This work therefore stores a screen image with every result and restricts changes to formulas and criteria with a password.

How to apply this approach to measuring instruments in your factory

If your measuring or test instrument shows figures on its screen but cannot output data, you can use the same approach as this case: capture the screen image, read the figures with OCR, calculate using your factory's formula, then show the result and store the image as evidence. The parts to adapt are the image capture and the calculation formula.

• Prepare clear calculation formulas, coefficients and pass/fail criteria for each model, because the system decides according to the values set.
• Check the machine screen's video signal type (such as VGA) and the position of figures on the screen, in order to design the OCR reading.
• Test with similar-looking digits under the line's actual lighting and screen brightness before going live.
• Set an acceptable time per piece that keeps up with the production cycle, and decide who is authorised to change the formula settings.