Alignment Probe – Real-Time ASTM E1012 Bending & Alignment Visualization

📌 Introduction

Alignment Probe is a Windows application designed to support mechanical testing according to ASTM E1012.
The software communicates with a ME-Systeme GSV-8 amplifier (via MEGSV86x64.dll) and provides real-time visualization of axial strain and bending strain for two orthogonal measurement planes.

It is intended for:

• Mechanical testing laboratories
• Alignment verification before tensile or compression tests
• Calibration and setup of test machines
• R&D involving bending, straightness, or offset analyses
• Any workflow requiring live strain-gauge–based bending vector visualization

Figure 1: The Alignment Probe main interface.

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✨ Features

🔧 Real-Time Data Acquisition

• Reads 8 strain gauge channels at 50 Hz (default, is configurable)
• High-performance streaming via GSV86readMultiple
• Automatic buffer clearing on errors
• Clean device initialization and safe shutdown

📈 Live Visualization

• Two polar plots: Plane A and Plane B
• Real-time bending vector (ε_bx, ε_by)
• Dynamic color coding based on ASTM alignment classes
• Smooth auto-scaling of the bending radius
• Optional fixed-radius mode

📊 Alignment Calculations

• Axial strain (ε_ax)
• Bending strain magnitude (|ε_b|)
• Bending direction (φ in degrees)
• Percent bending
• ASTM alignment class assignment

🖥️ User Interface

• Modern, clean UI layout
• Dedicated info boxes for both planes
• Control panel for PNG export and view-adjustment
• PNG export captures the entire UI (plots + info boxes)

⚙️ Configuration Options

• Fully configurable via YAML
• Live adjustments through View Settings dialog
• External YAML overrides bundled embedded configuration

💼 Windows EXE Support

• Can be compiled as a single-file EXE
• Includes Python, dependencies, YAML (default), and DLL
• No Python installation required on the end-user machine

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🚀 Getting Started

In order to start up the Alignment Probe you can download a zip file of the repository with the following link: https://github.com/me-systeme/GSV-8_AlignmentProbe/archive/refs/heads/main.zip. If you have git installed you can also copy the repository in your working directory with

git clone https://github.com/me-systeme/GSV-8_AlignmentProbe.git

Folder Structure

Make sure your working directory contains:

\screenshots
alignment_viewer.py
axial_bending.py
alignment_config.yaml
MEGSV86x64.dll
build_alignment_exe.bat
README.md

If built as an EXE, PyInstaller bundles the necessary resources. You can find the latest version of the Windows DLL here: https://www.me-systeme.de/de/software/megsv86.

Running from Source

This requires a 64-bit Python installation. Install required dependencies:

pip install pyqtgraph PyQt6 pyyaml numpy

Run the program:

python alignment_viewer.py

⚙️ Configuration

All parameters are stored in:

alignment_config.yaml

Below is a summary of the most relevant sections.

Device Settings

device:
  com_port: 8
  sample_frequency: 50
  dll_name: "MEGSV86x64.dll"

Channel Mapping

Define which strain-gauge channels belong to plane A and plane B:

channels:
  section_map:
    A:
      e0: 1
      e90: 2
      e180: 3
      e270: 4
    B:
      e0: 5
      e90: 6
      e180: 7
      e270: 8

GUI / View Settings

view:
  auto_scale: true
  fixed_radius: 1500
  refresh_ms: 200
  mult_frames: 1000

• auto_scale: enables dynamic radius calculation
• fixed_radius: used when auto_scale = false
• refresh_ms: UI update interval
• mult_frames: number of samples per DLL read (boosts stability)

Alignment Classes

alignment_classes:
  classes_axial_strain_small: [...]
  classes_axial_strain_big:   [...]
  out_of_class: [...]

The user may customize bending limits, class colors, and thresholds here.

🛠️ Runtime Adjustments (View Settings)

Inside the app, press:

Controls → View settings

You can modify:

• Auto-scaling on/off
• Fixed polar radius
• Refresh interval

Figure 2: View Settings window.

Changes apply immediately without restarting the application.

📦 Building a Windows EXE

1. Install Packages

pip install pyinstaller pyqt6 pyqtgraph numpy pyyaml

2. Build the EXE

Use this command:

pyinstaller --onefile --add-data alignment_config.yaml;. --add-data MEGSV86x64.dll;. alignment_viewer.py

Explanation:

• --onefile → bundle everything into one executable
• --add-data file;. → embed YAML + DLL
• Embedded resources are accessed via sys._MEIPASS at runtime

The compiled EXE appears in:

dist/alignment_viewer.exe

Alternatively, the above can be achieved by double-clicking on build_alignment_exe.bat.

3. Deployment (End User Installation)

You only need to distribute:

alignment_viewer.exe

The EXE already contains:

• Python runtime
• All necessary dependencies
• Default YAML configuration
• Embedded MEGSV86x64.dll

End users do not need:

• Python
• pip
• Any third-party libraries

Users may override configuration by placing their own:

alignment_config.yaml

next to the EXE.

🔧 Notes for Developers

• Clean shutdown ensures GSV86stopTX and GSV86release are always called
• ESC, Ctrl+Q, window close, and Ctrl+C all exit safely
• Heartbeat timer ensures responsive SIGINT handling
• Layout is optimized for balancing info visibility and plot size
• Auto-scale transitions are smoothed for stable visualization