Innovative laser light sensor in smart camera outfit

3D object measurement now available in standstill

Pepperl+Fuchs: Miniaturization provides us ever more efficient, more compact and more intelligent sensors. In this way, designers can profit from advanced methods in both new machines as well as plant modernization, without the necessity of engaging in the underlying and sometimes very complex technologies. The product concept of the world’s first multi-line laser light sensor in the form of a smart camera shows that advance also includes light sensors.

The light section process is long established in industry and science for accurately detecting objects two or three-dimensionally. As well as large discrete systems consisting of a light source, camera and PC-based control interface, compact industrial grade laser light sensors have long been available on the automation components market. With static objects they allow the detection of a two-dimensional section or contours in the x and z projection planes. To detect and measure objects three-dimensionally, the objects are always passed in a movement in the y direction, e.g. how it is on a conveyor belt. However, in many applications this is not the case, because amongst other things, many robots are used in object handling.

Now it can be done without movement

In a product study, with the LineRunner400 (LR400) multi-line laser light sensor Pepperl+Fuchs shows that the technological possibilities of laser light sensors in connection with the triangulation process are not yet exhausted. As the world’s first laser light sensor, the device combines several laser projectors into one, and is therefore capable of measuring idle objects three-dimensionally. As before, the LR400 can of course also detect moving objects. While the device delivers the usually high resolutions of the laser light process in x and z directions, one is limited to a discrete resolution in the y direction depending on the number of laser beams. With 3D measurements in movement, the resolution in the y direction is naturally dependent upon the feed rate.

Remarkably, the product concept is presented in a smart camera outfit. All necessary system components such as the laser projectors, CMOS sensor and the lens system as well as the interfacing unit are contained in a single compact housing. That promises uncomplicated use and simple integration in machines and plants. No separate PC is required and there are as few connections and as little wiring as possible. A progressive user guide for parameterization and operation rounds off the innovative product concept.

Freedom for customer-specific attributes

Pepperl+Fuchs wants to closely agree with the client on the technical data of a specific LR400 product realization and optimally align it to the relevant area of use. In particular, the free activation of each individual laser line in any order permits a permutation of various measurement strategies to reduce measurement times, to solve special tasks ideally etc. Whether the projection lines are activated after each other in a certain direction or several in parallel, e.g. from outside to inwards, can be defined completely freely. As the size of the detectable object in standstill is also in direct connection with the physical expansion of the sensor or number and density of the projection beams, we are open to the wishes of the user. The current product concept provides a detection field of 60 mm length (y direction) and 30 mm width (x direction) in standstill. The measurement distance is approximately 120 mm.

In principle, the laser light process guarantees robust measurements even under harsh boundary conditions. It functions reliably for any object and background colors and is highly immune to extraneous light. The LR400 fulfils laser protection class 1 and does not require complex and expensive protective measures.

Summary

The LR400 permits very precise 3D measurement of objects both at a standstill and in motion. The activation of the individual laser lights of emerging height profiles together produce a 3D image. The multi-line laser light process is a refined development of the conventional laser light sensor and opens up new solution strategies to designers in areas such as mounting, production, packaging and logistics. Typical applications of sensors in the smart camera outfits include presence checks, 3D shape and volume measurements, position and height controls, tolerance controls and much more.

Laser Light Process
In the laser light process, a line is projected with the aid of a laser light source at a certain angle onto the object to be determined and detects the light reflected from the object from a second divergent position with a suitable CCD or CMOS image sensor. Illumination, the sensor element and respectively observed point form a triangle, hence the term triangulation principle. As on the one hand the offset between the laser source and observation unit is known, on the other hand so too is the angle of the laser beam and alignment of the sensor, which allows geometric determination of the distance to the observed point or its location in relation to a reference point. The laser light method therefore enables the calculation of distance information to all illuminated points of the projection line from a single camera image. The laser beam provides high contrast and sharp illustration of the contours, even under the influence of extraneous light and unfavorable coloring.