3D Laser Scanner

June 6, 2011 By admin

At Iowa State, 3D Digital Optix Helps Build the Optimal Wind Turbine Blade

scanner (June 6, 2011) The world needs clean energy like wind power, and the wind-energy industry needs affordable, top-quality wind turbine blades. The Department of Industrial and Manufacturing Systems Engineering at Iowa State University is using a 3D Digital Optix 400L laser scanner to help solve that need. When you see wind turbines high above Midwestern fields, it’s a pretty sight. But the reason you can see them from such a distance is their mammoth size—one blade is about 40 yards long and weighs over 10,000 pounds. One viable material to build them with is fiberglass, but it’s labor-intensive to make these blades, so manufacturing has traditionally been done in low-cost venues outside the U.S—but then they’ve got to be shipped.

At Iowa State’s Wind Energy Manufacturing Laboratory (WEML), the big problem to solve involves the placing of fiberglass fabric into their molds, which can be a difficult process to execute without getting wrinkles to form. Our graduate students are using the 3D Digital Optix to capture a point cloud of the fabric when we place it in molds. This gives us a three-dimensional picture of the small disturbances on the surface of the fabric. As we continue to capture this data, we hope to develop automated methods for placing and manipulating the fabric; which could speed up the process, reduce labor and related costs. The scanner is also critical in the process of understanding the final quality and finishing requirements for the turbine blade, which needs to be long, strong and very smooth (wind blades are essentially acting like wings on an aircraft). In checking for quality, we point the scanner so it gives us the “wind’s eye view” of the blade; which will hopefully tell us where quality challenges come from, and what upstream processes need to be improved.

I was introduced to 3D laser scanning at Penn State, where my PhD dissertation advisor introduced me to reverse engineering and rapid prototyping using this new technology. Early use at Iowa State for the Optix scanner was in a project for the rapid manufacturing of service parts for agricultural equipment; research in a subtractive rapid prototyping process called “CNC-RP”. The idea was to be able to deliver fully functional service parts for perhaps decades-old equipment that is still in use (a challenge for both agricultural and military equipment, in particular). This is necessary when the parts are unavailable, would require long waiting periods, or would require extensive inventories in warehouses — perhaps not acceptable when a crop needs harvesting right away or costs are prohibitive. In one example, we created a linkage for a harvester, scanning the failed component, importing it to a CAD program, modifying the file to “fix” the broken section, then rapid machining the actual new part in-house. From arrival of the failed part to boxing and shipment of the new steel part was 48 hours total.

We have a competitor’s scanner also in use at our department. It is sufficient for introductory teaching and demonstrations. I wouldn’t bring our Optix 400 into the classroom where large groups of students will have their hands on it continually; however, I don’t use the competitor scanner in our research lab for technical R/E and prototyping, either.

Dr. Matthew C. Frank, PhD, Assoc. Professor
Industrial and Manufacturing Systems Engineering
Iowa State University
Ames, Iowa

Filed Under: 3D Digital Scanner, 3D Laser Scanner, 3D Laser Scanning, News Tagged With: 3d digital corp, 3d digital corporation, 3d digital optix, rapid manufacturing, wind turbine blade

April 29, 2011 By admin

3D Digital Aids British Scientist in the Emerging Field of “Touch Perception”

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04-29-2011 The field of three-dimensional laser scanning and my field, known as “haptics,” are both fairly new on the scene. I was originally an artist—a sculptor-engraver, primarily in glass—until I was struck by a car while walking in 1986 and injured extensively. My career to that point had been a successful one, including purchase of my work by such well-regarded collections as the Corning Museum of Glass in New York and the Pilkington Collection of the Victoria and Albert Museum in London.

Physically unable to continue in my chosen field conventionally, I attempted to use computers for the artistic act of forming shapes and creating three-dimensional effects to engage the senses. One sense that could not be engaged via computer-screen programs was touch, and that omission spoiled the enjoyment of 3D digital sculpture for me. It also got me interested and involved in the field of haptics. That interest led me on a winding path to a research fellowship at Birmingham City University, where I now work.

Human haptics is the study of the human end of touch and bodily perception and machine haptics is tactile feedback technology. Via a computer, a haptic system can simulate touch sensation through forces, vibrations, and the like. One excellent application for it involves museum objects—a Classical bust, a tapestry, a carved ivory piece—that blind visitors to the museum cannot experience in any way. These visitors lack a sense of sight, and museum rules forbid touching the objects. With haptic technology, we are able to create a virtual tactile experience of that object.

This is where 3D laser scanning comes in. We use the scanner to produce a historical artifact, for example, a scan of an ivory box. We then fiddle with the file to make it “feelable.” The effect is fairly jaw-dropping when you first experience it. You are looking at a screen that shows an object in three dimensions that does not strictly speaking exist, yet you can feel its contours and tactile details.

This work depends on 3D digital scanning, which when I first investigated it, was a difficult product area to navigate. I suppose to some extent it still is. The 3D Digital scanner was the first unit our laboratory bought, but over a year of research came first. Mostly that was me, traveling to trade shows and exhibitions. Our need was for a scanning system with flexibility of setup and powerful software. Eventually we would be wishing to produce every object as surface geometry with an accurate visual overlay—a camera image. That’s our common practice, and it works well. I was reassured to see that 3D Digital’s product had such capability and ease of use for such a reasonable, affordable price. It takes some user sophistication to get the most out of 3DD’s SLIM software, but the results are well worth it.

One project we would like to tackle involves cane navigation for the blind. When you see a blind person moving confidently through a city environment using a special cane, that is the result of lengthy, specialized training. There is a long waiting list to receive that training. Haptic technology is the only way to computer-simulate the environment, but it would have to be done quite flawlessly, or the user would be put at risk. But that’s an example of what’s going on in fields like 3D laser scanning and haptic technology—wonderful new uses and applications are occurring to people all the time.

David Prytherch
Senior Research Fellow in Haptics and
Human Computer Interaction
Birmingham City University
Birmingham, UK

Filed Under: 3D Laser Scanner, 3D Scanner, 3D Scanning, News, Testimonials Tagged With: 3D Digital, 3d scanning, touch of perception

July 11, 2010 By admin

A 3D laser scanner is a high tech device that has the ability to accurately capture the surface of objects and provide real 3D data back to the user.

A 3D laser scanner works because of the principle of laser triangulation. By making a triangle between the scanner lens, laser, and object being scanned accurate 3D data can be obtained. The distance between the scanner lens and laser (parallax base) is known and with the angle of the laser given by the galvanometer, all information is provided to obtain x, y, z coordinates of the objects surface. The laser is swept across the object by the galvanometer, which rotates a small mirror that reflects the laser. The surface of the object is then focused through the lens and captured by the CCD inside the scanner. A dense point cloud is then produced through our software.

We Choose Specifics Based On Your Application

3D imagers are complicated imaging systems and their performance cannot be summed up with a single characteristic. 3D Digital Corp. is one of the few companies that provides a detailed description of the 3D scanner performance and thus allow a user to select a scanner that is ideally suited to their application and to know with high confidence that the scanner will be able to meet their requirements.

3D Laser Scanner Performance Factors

The performance of the 3d laser scanner is determined by a large number of factors. We describe the performance in terms of the following properties:

Co-ordinate System
Resolution: the smallest discernible feature on the target. Alternatively, an equivalent definition is the minimum separation between two target features where the two features are distinguishable in the image.
Accuracy: the standard deviation of the range measurement. This is often referred to as the ‘error’ in the range measurement.
Point density: The distance between neighboring range measurement points.
Depth of field: This describes the range over which the 3d laser scanner can obtain an accurate image.
Field of view: This determines how large a target can be imaged in a single scan.

3D Laser Scanner Co-ordinate System

We define a right handed co-ordinate system with an origin at the center of the 3d laser scanner imaging lens. The x-axis is parallel to the long axis of the scanner front plate (this is horizontal in the usual scanning geometry). The y-axis is parallel to the short axis of the 3d laser scanner front plate (vertical in the usual scanning geometry), and the z-axis is the range, or the distance perpendicular to the scanner front plate. The co-ordinate system is illustrated in the following figure.

3D Laser Scanner Resolution

The resolution of the 3d laser scanner refers to the ability of an imaging system to measure the angular separation between two objects (or object features) that are close together. The resolution is a limitation of the scanner in the x-y dimensions. For example if a target has embossed lettering, and the font size is smaller than the resolution of the scanner then the text will not be legible in the scanned image, regardless of the height (z-depth) of the lettering.

The resolution is determined by three major factors: the laser stripe width, the lens focal length, and the CCD resolution. The resolution is dependent on the target distance and generally gets worse with increasing range.

Accuracy of 3D laser scanners

While the resolution affects the image quality in the x and y dimensions, the accuracy refers to the image quality in the z (or depth, or range) dimension. 3DD scanners calculate the range of each point on the target object. CCD noise, imperfect optics, and fundamental laws of physics all result in some error in the calculated range. It is not possible to design a 3d laser scanner that does not have some error. The accuracy is a measure of this error. It is defined as the standard deviation of the difference between the measured range and the actual range to a target. The range error is approximately Gaussian in nature. This implies that if we scan a perfectly flat plane, at a fixed range of 245mm (10″), and if the accuracy of the scanner is 250microns (0.01″), and we build a histogram of the ranges of each of the points it would look like the one shown in the following figure. 65% of the range points will lie within +/- 1 standard deviation from the mean, i.e.: +/-250microns (+/- 0.01″). 95% of the range points will lie within +/- 2 standard deviations from the mean, i.e.: +/-250microns (+/- 0.02″).

Point Density of 3D laser scanners

Point density refers to the distance between neighboring range measurement points. This will be different in the x and y dimensions. The x density is determined by the number of scan lines, while the y density is determined by the CCD resolution. For example if the user selects to scan with 500 lines and the CCD has 480 vertical pixels the point density is 500 x 480. At a range of 300mm (12″), this corresponds to a point spacing of 0.61mm x 0.64mm (0.024″ x 0.025″).

3D laser scanner Depth of Field

The depth of field or ‘depth of focus’ refers to the range of distances over which a focused image is obtained. As with a normal camera our products are focused for a particular range. Objects outside this range will result in blurred images and inaccurate range data. Therefore the 3D Digital software automatically discards range data for objects outside the design range. This ensures that the output data is all within our specified accuracy. The following figure illustrates the concept of depth of field.

Field of View on 3D laser scanners

The field of view of the scanner determines the largest object that can be imaged using a single scan. The field of view is normally expressed as an angle and it describes the angle of a cone within which an object must be placed for the 3d laser scanner to be able to image it. The field of view cone is illustrated in the following figure. The tip of the cone is at the center of the imaging lens. Obviously the larger the target to be imaged the further away from the scanner it must be placed. A disadvantage of this is that the accuracy of the scanner generally decreases at longer ranges, so a large field of view is generally very attractive as it allows large targets to be imaged with high accuracy.