an engineering application selection guideline for reverse ... for...

The 9th Asian Symposium on VisualizationHong Kong, 4-8 June, 2007

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An Engineering Application Selection Guideline for Reverse Engineering Systems: Laser System and Optical System

S.Rodkwan1, N.Chantarapanich2, C.Chandenduang3, S.Wanchat4 and K. Sengpanich5

1. Center of Excellence in Rubber Mould, Research and Development Institute of Industrial Production Technology and Department of Mechanical Engineering, Faculty of Engineering, Kasetsart University,

Bangkok, Thailand. E-mail: [email protected] 2. Center of Excellence in Rubber Mould, Research and Development Institute of Industrial Production Technology and Department of Aerospace Engineering, Faculty of Engineering, Kasetsart University,

Bangkok, Thailand. E-mail: [email protected] 3. National Metal and Material Technology Center (MTEC), National Science and Technology Development

Agency (NSTDA), Ministry of Science and Technology, Pathumthani, Thailand: [email protected] 4. Center of Excellence in Rubber Mould, Research and Development Institute of Industrial Production Technology and Department of Aerospace Engineering, Faculty of Engineering, Kasetsart University,

Bangkok, Thailand. E-mail: [email protected] 5. Center of Excellence in Rubber Mould, Research and Development Institute of Industrial Production Technology and Department of Aerospace Engineering, Faculty of Engineering, Kasetsart University,

Bangkok, Thailand. E-mail: [email protected]

Corresponding author S.Rodkwan

Abstract This research aims to provide users the guideline on a selection on the Reverse Engineering (RE) systems; 3D laser and 3D optical scanners, in various fields of engineering. The investigated parameters are accuracy, error with the assembly model, Depth-Length (D-L) ratio, object surface texture, object color, calibration time, time used for various applications. It was found that the 3D laser scanner is suitable for scanning objects with complex shape which has a surface of unreachable area and shiny surface while the 3D optical scanner works well with objects with large and smooth surface, assemble parts and objects with dim color.

Keywords: Reverse Engineering, 3D laser scanner and 3D optical scanner 1. Introduction Currently, the product improvement is very significant for various kinds of competitive global markets. For instance, the Computer Aided Design/Manufacturing/Engineering (CAD/CAM/CAE) techniques are often used for gaining more efficiency in production system. Among available tools used nowadays, the Reverse Engineering (RE) techniques become popular in duplicating an existing component, subassembly, or product, without the aid of drawings, documentation, or computer model. In RE, a product is designed by capturing the real part shape or physical prototype, material and manufacturing process, including inspection the RE product performance. This is contrast to the conventional or forward engineering which starts from the design process [1]. The measurement methods can be divided into contact and non-contact approaches. All information on the positioning of object is fed into the Computer Aided Reverse Engineering (CARE) as [2] the point of clouds and later created as polygon, constructing Grids and finish the process with generating the surface as CAD data for future modification or engineering analysis including mold design and manufacturing process.

Due to the high cost of RE equipment and associated software, it will be benefited in providing guideline on comparison and choosing the appropriate RE system among the users where RE is needed.

S.Rodkwan, N.Chantarapanich, C.Chandenduang, S.Wanchat and K. Sengpanich

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9th Asian Symposium on Visualization, Hong Kong SAR, China, 2007.

2. Materials and Methods Two types of non-contact RE devices were used for the study, the KZ50 3D Laser Scanner (Kreon) combined with Cimcore 3000i articulated arm which available at Research and Development Institute of Industrial Production Technology (RDiPT), Faculty of Engineering, Kasetsart University and the ATOS II 3D Optical Scanner (GOM) provided by National Metal and Material Technology Center (MTEC), National Science and Technology Development Agency (NSTDA) as illustrated in Fig. 1. and 2.

a. b.

Fig. 1. (a.) KZ50 3D Laser Scanner with Cimcore 3000i articulated arm. Fig. 2. (b.) ATOS II 3D Optical Scanner

There are seven parameters studied in the research as described: 1. Accuracy: Gage Block No.2 in 4 different piece is selected; 100, 50, 10 and 5 millimetres.

The digitized data are measured the distance which determine the accuracy in CARE Software (Geomagics Studio 6) and fifteen measurements were done on each type of RE device per one piece of Gage Block.

2. Error with the assembly model: Four primitive feature models; block, cone, cylinder and sphere were divided the digitized area into 2 parts and assembled using the reference points attached on the models. The reference data created by CAD software (Unigraphics NX2) aimed to compare the error from the assembled models. The comparison carried on the CARE inspection software (Geomagics Qualify 6) with 3 times on each device per pieces as illustrated in Fig. 3.

3. D-L ratio: Five patterns of holes were tested on the criteria; circular shape, conic shape, part of spherical shape, block and Elliptical shape as illustrated in Fig. 4. All patterns varied the hole depth from 10-50 millimetres. For the circle shape, cone shape, and part of spherical shape, the diameters were varied from 20 to 50 millimetres. The block pattern, the length on 2 sides of rectangular was equivalent and the side length was varied from 20-50 millimetres. For the Elliptical shape, the cross-sectional were used as aspect ratio (Major axis divided by minor axis) varied form 1 to 5.

4. Object surface texture: Five different types of surfaces were considered; non-reflective surface, low shiny, high shiny, translucency and transparency. Three time of digitizing were used in each type of surface per RE device to observe the repeatability of result.

5. Object surface color: Twelve non-light reflective colors were painted on all sides of the 2 cubed. White, orange, pink, brown, black, yellow, blue, dark blue, light green, dark green, red and purple were used and digitized the surface data 3 times on each color per RE device to observe the repeatability of results.

6. Calibration time: Time for set up and calibration the RE devices were recorded from the starting the devices and components until devices are ready for the application.

7. Time used for various applications: Seven groups of industrial parts were used in this study. The time was recorded on each part during digitizing data and compare later.


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a. b.

Fig. 3. (a.) Error inspection process for assembly model Fig. 4. (b.) Hole patterns for D-L ratio test criteria.

3. Results Result on parameters can be seen as follows:

Accuracy: The average error measurements of both systems for 4 Gage Box pieces are shown in Table 1. Error with the assembly model: The results from the studied are shown in Table 2.

Table 1: The average distance measurement of Gage Box.

Laser System Optical System Gage Box

Length Average Error (millimetres)

Error Average Error (millimetres)

Error

5 millimetres 0.068326 1.366527 0.426762 8.513524 10 millimetres 0.328140 3.281404 0.626170 6.296174 50 millimetres 0.023745 0.29982 0.621518 1.243036

100 millimetres 0.110332 0.110331 0.651490 0.651481

Table 2: The average error and standard deviation of all features for both systems.

Feature Average Error (Millimeters) Standard Deviation (SD)

Maximum Minimum Laser System 0.813297 -0.878188 0.162793 Block Optical System 0.536011 -0.510500 0.121411 Laser System 0.794026 -0.699649 0.037920 Cone Optical System 0.633486 -0.581470 0.036108 Laser System 0.572684 -0.416195 0.101973 Cylinder Optical System 0.224973 -0.153748 0.022122 Laser System 0.794026 -0.633649 0.200999 Sphere Optical System 0.633486 -0.581470 0.188982

D-L ratio: For part of spherical pattern, both devices could capture all the surface data. Only

low aspect ratio of elliptical pattern with depth of 10 millimeters could be detected for both devices. For the other, the ability of digitizing for both system results is shown in Table 3.


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Table 3: The ability of capturing the surface on circular pattern Circular pattern

Laser System Optical System Diameter (Millimeter) Diameter (Millimeter) Depth

(Millimeter) 20 30 40 50 20 30 40 50

10 / / / / / / / / 20 / / / / X X / / 30 / / / / X X / / 40 X / / / X X X / 50 X / / / X X X X

Block pattern Side Length (Millimeter) Side Length (Millimeter) Depth

(Millimeter) 20 30 40 50 20 30 40 50

10 / / / / / / / / 20 / / / / / / / / 30 / / / / X / / / 40 X / / / X X / / 50 X / / / X X X /

Conic Pattern

Diameter (Millimeter) Diameter (Millimeter) Depth (Millimeter) 20 30 40 50 20 30 40 50

10 / / / / / / / /

20 / / / / / / / /

30 / / / / X / / /

40 / / / / X X / /

50 X / / / X X / /

Remark: / represents ability to capture surface, X represents no ability to capture surface.

Object Surface Texture: All texture types could be digitized by the 3D Laser Scanner while the 3D Optical Scanner can detect only the non-reflective surface and low shining surface.

Color Surface Texture: For 3D Laser Scanner, brown, black, dark blue and dark green could not be detected. Blue and purple, the digitization provides low cloud of point. Other colors could be captured well. In contrast to 3D Optical Scanner, all color except black give the high intensity of cloud of points.

Calibration time: Both devices, approximately 2 minute for operation Time used for various applications: The time consumption for both systems in each group of

industrial parts is shown in Table 4.


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Table 4: Time consumption for the operation in each group of application Time Consumption

Group of Application Laser System Optical System

Group1: Primitive Feature 1. Block 20 minutes 20 minutes 2. Cylinder 30 minutes 10 minutes 3. Cone 20 minutes 10 minutes 4. Sphere 20 minutes 30 minutes

Group2: Industrial Product 1. Plastic Bottle 30 minutes 45 minutes 2. Computer Mouse 30 minutes 30 minutes 3. Rubber Step 1 hour 4 hours

Group3: Mould used in industry 1. Compression Mould 3 hours 2 hours 30 minutes 2. Plastic Blow Mould 1 hours 30 minutes 2 hours 3. Soap Mould 2 hours 4 hours

Group4: Industrial component parts 1. Fan Turbine 1 hour 2 hours

Group5: Automotive component parts 1. Automotive Bumper 2 hours 30 minutes 3 hours 2. Automotive Hood 3 hours 4 hours

Group6: Aircraft Engine Parts 1. Turbine for F-5E Engine 30 minutes 1 hour

Group7: Biomedical parts 1. Artificial femur Bone 45 minutes 1 30 minutes

4. Discussions

This research presents the comparison of 3D Laser Scanner and 3D Optical Scanner used for RE application on choosing the appropriate RE system for the work. To our knowledge, most of the previous research and study have usually described about the RE device as inspection tool and as assist tool for creating CAD database by capturing the real part shape. According to the result, 3D Laser Scanner is advantage on capturing the depth hole with narrow cross-sectional area and all types of surface texture. However, translucency and transparency surface can be digitized, the cloud point are not enough in continuing the RE process and high time consumption is required in digitizing. Small and medium size objects suit for laser system. Although, large object can also be digitized, due to the limited articulated arm swing length the object division has to be done and later assembled in CARE. By laser system, the reference point detection displays as group of cloud points compact in reference point area (approximate size of 1.5 millimetres in diameter) and the assembly is manually done by the software user while 3D Optical Scanner has the ability to detect the reference point as single coordinate point. Even, the assembly for optical system has also to be done manually, but the single coordinate point has the advantage in accuracy rather than random selection group of points in laser system. Moreover, 3D optical Scanner advantage, due to the adjustable light intensity property of 3D Optical Scanner, dim color can be detected, except black and large size object can be digitized as single CAD data without assembly process which gives high accuracy in output. The calibration time for both systems require approximately 2 minutes. By the accuracy parameter, the measurement is not precise because of object surface texture properties of optical system. Thus the powder were sprayed on the front side of Gage Box (Length number is on), but for the laser system, the data could be digitized directly on the functional side of Gage Box. Also, the time used for various applications parameter, operator’s skill factor also influences the parameter rather than the properties of device alone. Therefore, both parameters will not be concluded that which system is more advanced than each


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other. 5. Conclusions In summary, 3D Laser Scanner can be used for application contained complex shape such as rubber for motorcycle, turbine and human bone. Moreover, the capturing surface of unreachable area and shiny surface detection are advantage. Large objects are not suitable for the laser system, the assembled object is required and large error is considerable while the 3D optical scanner is recommended for objects with large and smooth surface, such as, car cab, bumper, and computer mouse, fast capturing surface process can be done. However, small size objects take too longer time for digitization process. In case of assemble parts needed, the error is acceptable. Also, digitizing the object in the dark color is excellent. The guideline for the RE equipment selection of 3D Laser Scanner and 3D Optical Scanner can be represented as Fig. 5.

6. Acknowledgement The authors would like to acknowledge Research and Development Institute of Industrial Production Technology (RDiPT), Faculty of Engineering, Kasetsart University for support of various industrial parts and technical advice, National Metal and Material Center (MTEC) for donating artificial resin femur and Royal Thai Air Force Academy (RTAFA) for turbine blade of F-5E. This research was granted by the National Science and Development Agency (NSTDA), Ministry of Science and Technology.

Fig. 5. Guideline for the RE equipment selection of 3D Laser System and 3D Optical System

Remarks: represents 3D Laser Scanner and represents 3D Optical Scanner


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7. References [1] Chantarapanich, N., Raksiri, C., Chianrabutra, S., and Rodkwan, S., 2005. Reverse Engineering for

3D modelling in Turbine Application. The 19th Mechanical Engineering Network National Conference, Phuket, Thailand.

[2] Rodkwan, S., Rianmora S., Chianrabutra S., and Pungyont J., 2004. An Investigation of CAD Model Development with Reverse Engineering Technique using the 3D Laser Scanner, The 3rd Prince Songkla University Engineering Conference, Songkla, Thailand.

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