Fully Automated Measuring Cell in the Automotive Industry

Project Report, 2017

12 Pages, Grade: 1,0



Table of Contents

List of Figures

List of Tables

1. Abstract

2. Introduction

3. Control systems
a. Tactile control system
b. Optical control system
c. Comparison of tactile and optical measurement
d. Future Development

4. Fully automated optical measuring cell
a. Function of the measuring cell
b. Future development

5. Evaluation and Conclusion

6. References

List of Figures

Figure 1: Principle of the scanning probe for the tactile measurement
(Christoph & Neumann, 2017)

Figure 2: Scanning with a measuring probing system (Christoph & Neumann, 2017)

Figure 3: Optical Measurement Sensor Setup

Figure 4: Fully automated optical measuring cell (Wirth & Lassas, 2017, p.3)

Figure 5: Setup in the optical measurement cell (Fringe Technology, 2017)

Figure 7: Working part as a digital version (Benthack, 2015, p.87)

List of Tables

Table 1: Advantages and Disadvantages of Tactile and optical measurement

1. Abstract

The main objective of the project work is to identify problems, which are related to computer-aided manufacturing and to show new perspectives to solve them. Especially in the automotive industry, the automation of processes is playing an increasingly significant role. New process’s like fully automated measuring cells enable the companies to achieve their goals efficiently. So, in this composition, the most common measurement principles, tactile and optical, will be explained. Moreover, the advantages and disadvantages of each system will be described. This report ends up with a conclusion and the central result is, that fully automated optical measurement cells are highly competitive to other measurement technologies, but still needs a lot of development and time.

2. Introduction

The worldwide automotive industry is highly competitive. Customers have a stronger emphasis on product quality and pricing. For aesthetic and functional reasons, narrow, exactly parallel gaps on the doors, bonnet, and tailgate are now regarded as the obvious quality features of modern vehicles. To fulfill the customer and market requirements the investment in fully automated measuring technologies are continuing to rise (wikiinvest, 2012).

3. Control systems

There are two various basic types of Inspection techniques. The contact inspection uses a mechanical probe that contacts the measured object, tactile control system, and the noncontact inspection which measures the object with a sensor from a certain distance, optical control system. These two inspection systems will be explained in the following.

a. Tactile control system

In case of a tactile control system, the sensor is prepared with measuring systems for all coordinates axes (e.g. scales, inductive sensors, etc.). At the measuring process, a stylus sphere which is shown in figure x is contacting the surface of the workpiece. If the stylus is deflected in any direction, the size of this deflection can be determined by reading the path measurement system. (Fig. 20). The point of measurement will be created by overlaying the sensor coordinates of the coordinates of the measuring machine. The deflection of the stylus is also considered in the result (Christoph & Neumann, 2017).

To measure several surfaces of the same working part, it is not necessary to remove the stylus from the part. The coordinate axes of the measuring machine are controlled so that the sensor continuously remains in its measuring range, thus follows the surface of the workpiece during tangential movements. The software moves the sensor in a computer-generated coordinate system. The point of contact between the probe and the workpiece is defined as the origin. This control process of scanning is shown in the figure below. The scanning can be done in predefined planes. The problem of corrections of the stylus especially on unknown surfaces must be considered (Christoph & Neumann, 2017)

Figure 2: Scanning with a measuring probing system (Christoph & Neumann, 2017)

b. Optical control system

In this chapter, the basics of optical control systems will be explained. It is important to understand the technology for the applied tasks. For a greater view of the products and developments in Research and development, the industry is using optical measuring systems since the early 1900s. In figure 4 the basics of optical measurement: lighting, optics, XY Stage, and a Z-axis that handles the focus are shown. (Bibee, 2009)

There are three basic lighting schemes used to illuminate the workpiece:

Figure 3: Optical Measurement Sensor Setup

Abbildung in dieser leseprobe nicht enthalten

-“Backlight is used to light the part in silhouette to measure outer profiles and features such as through holes.” (Bibee, 2009)
- “Direct lighting is integrated into the optical beam path and lights the part from a direct vertical angle.” (Bibee, 2009)
- “A ring light is a light source that is mounted around the optics and illuminates the workpiece at indirect angles.” (Bibee, 2009)

“The optical sensor has a set of lenses through which the reflected light (or direct light in the case of backlighting) passes” (Bibee, 2009). The sensor contains an optical chip within a camera and a light for focusing on. The chip has a pixel array that is light-sensitive. Each pixel will be converted with a corresponding value, by the chip light intensity, into an electrical signal. This gray-scale value is a number between 0 and 255. By determining where the gray-scale value between two neighboring pixels changes drastically, the software discovers an edge. The optical sensor takes the positions of these edges and accumulates it with the XYZ-position of the machine to allocate the coordinate positions. An edge finder system connects some of these boundaries together for building the contours of the working part. The measurements in the Z-axis are made by the contrast or “autofocus” method. An automatic cycle moves the Z-axis of the machine and thus the focus of the optics through the surface of the part. Numerous images are taken and evaluated for the best contrast. By selecting the image with the best contrast which is when it is exactly in the focal plane. And knowing the Z-position of the axis for that image, the calibrated focal point distance of the optics and the height of the part at any XY-position can be calculated (Bibee, 2009).

c. Comparison of tactile and optical measurement

There are advantages and disadvantages of both systems. The following table shows the advantages and disadvantages opposed for both measurement types (Hemmerle, 2013, p.11-13).

Table 1: Advantages and Disadvantages of Tactile and optical measurement

Abbildung in dieser Leseprobe nicht enthalten


Excerpt out of 12 pages


Fully Automated Measuring Cell in the Automotive Industry
Catalog Number
ISBN (eBook)
ISBN (Book)
CAM, Computer Aided Manufacturing, measuring cell
Quote paper
Anonymous, 2017, Fully Automated Measuring Cell in the Automotive Industry, Munich, GRIN Verlag, https://www.grin.com/document/438286


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