Advanced Design and Fabrication
Automated Inspection of Precast Components
Background and Current Practice
Quality inspections are required at different stages of the precast fabrication process to ensure that the precast components are constructed accurately according to the required specifications. The inspections are done before the concrete is poured (“pre-pour”) to check the mould, reinforcements, lifting hooks, splice bars, and connectors; and also, after the concrete has hardened (“post-pour”) to check the resulting concrete size, shape and quality, and other items on the checklist (see below).
These inspections are done by Resident Technical Officers or Resident Engineers representing the fabrication plant or consultant. The fabrication process needs to pause for inspection before it can proceed to the next stage. The inspectors need to be present on site to visually inspect the precast components and verify the measurements by taking those measurements with measuring tape and the assistance of other workers. They also need to capture photographic evidence for documentation purposes.
Opportunity Areas and Key Challenges
Greyform has already adopted robotics to automate the fabrication of various 2D precast components such as wall, column and slab, and is now looking for solutions to automate the quality inspection process.
We are keen to explore the use of advanced imaging and laser-based technologies together with AI to accurately inspect, measure and analyze the precast components to generate the information needed for inspection. The solution must be able to:
- Measure dimensions with a precision of +2mm for panel dimension and +10mm for opening/recess.
- Compare the actual precast components against their Building Information Modelling (BIM) to identify any deviations or defects during post-pour. The comparison is done with the consideration of allowed tolerance for each inspected item.
- Differentiate the rebar mesh from the bottom slab or metal pallet, taking into consideration that the different items can have a similar colour.
The solution should also consider how it can be integrated with Greyform’s Automated Pallet Circulation Plant system.
An AI-based automated inspection system utilizes imaging and/or laser technologies to determine whether precast components are fabricated accurately. For each inspected item, the system produces an inspection report supported by photographic evidence with the measurement (if applicable) and highlights any abnormalities for further action.
The solution reduces the manpower required to support the inspectors by eliminating the need for manual measurement and capturing the inspection data during the fabrication process, so that the process does not need to stop for inspection. In the future, the solution could support remote inspection procedures.