STRUCTURED LIGHT Optical methods based on structured light (fringe projection) offer a 3D scanning method that is non-contact and area based. This means scanning is significantly faster (seconds, not hours) and the 3D data produced is of much higher data density representing a more accurate shape of the part. A structured light 3D snapshot sensor

Fig 1

hile standard model 3D smart sensors can handle a wide range of general inspection tasks, the trend toward highly-specialised automated factory production has resulted in a corresponding increase in demand for customised solutions designed to handle specific industry applications. In order to meet this growing demand,


LMI Technologies has developed a flexible sensor platform that supports model customisation at the manufacturing level – allowing us to customize our standard off the shelf 3D sensor models to serve application- specific requirements. Gocator Cylinder Head Volume Checker

is an example of this vertical model approach, designed specifically for volume gauging of internal combustion engines in the automotive industry.

3D SMART SENSOR SOLUTION In the automotive industry, volume gauging is an important application in engine development. Each cylinder in an engine block has to be measured for correct combustion volume. While CAD data can be used to determine nominal volume, compliance testing requires the acquisition of a large number of measurement points, their connection by line or curve approximation, and finally computation of the displacement volume. Tactile coordinate measuring machines

(e.g. CMMs) can accomplish volume gauging with a high degree of accuracy, but this method requires a tremendous amount of time. Compared to tactile methods, traditional methods using liquid, gas or acoustics are much simpler and still remain in wide use.


RIGHT: Fig 2. Gocator cylinder head volume checker in action

ABOVE: Fig 1. Gocator cylinder head volume checker in action

FAR RIGHT: Fig 3. Gocator cylinder head volume checker in action

projects a line pattern onto the cylinder head of an engine block. The line pattern is recorded by a camera from an optimal angle, yielding information on the cylinder’s surface topology calculated from the deformation of the projected lines. There is a significant advantage to

using this inspection method. Namely, when blue LED stripes with smooth value gradients are projected and moved across the engine block in close steps, the analysis of these values allows for a magnitude better position resolution than the single point measurement typical of classical triangulation methods. Stripe pattern projection provides coordinate resolution down to 1/50 of the projected stripe width. This means the cylinder head can be fully inspected with the acquisition of just a few dozen images with slightly shifted stripe positions (phases), which can be accomplished in just a few seconds.


solution. The 3210 is a metrology-grade, inline ready snapshot sensor that scans at 35μm resolution, and is ideal for detecting features on large targets such as automotive cylinders. Here are some of its notable features: • Fast scan rate (4Hz full-field) • Two-megapixel stereo camera minimises occlusions • Wide field of view (FOV) up to 154mm

GOCATOR ACCELERATOR GoX is a key part of the Cylinder Head Volume Checker solution. This PC-based application accelerates the Gocator 3210 sensors to achieve scan speeds (4Hz) that match those required for inline engine block inspection. GoX can be used to accelerate any Gocator sensor or multiple Gocators at once.


The GDK allows developers to embed their own custom measurement algorithms in the Gocator Firmware. In the case of the Cylinder Head Volume Checker, LMI has embedded a custom Volume Gauging Tool that can scan and measure cylinder heads in less than five seconds at an accuracy of +/- 0.04cm3


While it comes as a single, complete 3D solution, we can break it down into several integrated components to get a better understanding of its level of customisation. These components include: • Gocator 3210 Snapshot Sensors • Gocator Accelerator (GoX) • Custom tool using Gocator Development Kit (GDK) • Master Hub 810 for Multi-Sensor Control

LMI Technologies

GOCATOR 3210 SNAPSHOT SENSOR Gocator 3210 is the hardware platform of the Cylinder Head Volume Checker

MULTI-SENSOR CONTROL The Master Hub 810 network controller simplifies the support of multiple sensors (up to eight) by handling power, synchronization, laser safety (for laser- based sensors), encoder and digital I/O. A Master 810 is used to support the Cylinder Head Volume Checker when you want to use four such sensors to scan and measure four cylinders at once.

CONCLUSION Gocator’s flexible platform allows LMI to customise standard sensors to meet specific application requirements. We believe this approach is the future of automated quality control, where 3D solutions are configured to perform highly specialized inspection tasks.


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