Project Overview
At the raw material receiving and feeding facility of a major plastics manufacturer, we fully automated the manual unloading of plastic granule sacks from pallets into processing silos using vision-guided robotics and custom image processing algorithms.
Previously, each shift required at least 3 operators for strenuous, repetitive manual lifting of heavy sacks, posing severe ergonomic risks and occupational safety hazards.
The goal was to enable an industrial robot to reliably locate, pick, and transfer sacks directly from uneven pallets to the discharge silos in a continuous, uninterrupted, and safe operation.
The Challenge: Irregular Packaging & Deformed Pallets
In robotic sack depalletizing, the robot's success depends entirely on accurate coordinate calculation. Two major hurdles were present:
- Fluid Granule Dynamics: The loose plastic pellets inside cause sacks to deform, bulge, and shift irregularly on the pallet.
- Glossy Foil Reflection & Pallet Shift: Shiny plastic packaging reflects ambient lighting unpredictably, and sagging pallet frames make hardcoded robotic coordinates completely ineffective.
This previously caused gripper slippage, dropped sacks, silo jams, and line stoppages.
The ANAVIS Solution: Vision Guidance for the Robot
To eliminate reliance on static teaching points, we developed a gripper-integrated 2D machine vision system that acts as the robot's active eye.
The camera captures the pallet surface in real time, algorithms evaluate the boundaries and contours of each individual sack, and dynamically determine its true center of gravity coordinates (X, Y, and rotation angle). The robot adjusts its trajectory on-the-fly to execute a centered, secure grip.
How the System Works
- 01 Vision Scanning: The vision sensor on the gripper captures the top layer of sacks on the pallet.
- 02 Contour Analysis: The vision processor identifies deformities, tilt angles, and boundaries.
- 03 Dynamic Center Calculation: Millimeter-accurate grip centers are calculated for the target sack.
- 04 Robot Coordinate Dispatch: Spatial coordinates are transmitted over industrial Ethernet to the robot controller.
- 05 Centered Vacuum/Clamping Grip: The gripper engages the sack precisely at its center of gravity.
- 06 Silo Discharge: The sack is transferred to the cutting and discharging silo, and the cycle repeats automatically.
