Wydział Mechatroniki
Mechatronic Systems - Design Project (tutorial)
Team “1”
1. Ananda Sudhan, Nagappan
2. Vishnu Thiruvathira, Balakrishnan.
Time of Flight 3-D Scanner
Student group: Z1
Lecturers:
Jakub Wierciak, DSc PhD Eng.
Marcin Adamczyk, MSc Eng.
Warsaw, 2016/17
Authors of the project:
1. Ananda Sudhan, Nagappan
2. Vishnu Thiruvathira , Balakrishnan
Table of Contents
Table of Figures ............................................................................................................................. 2
Abstract ......................................................................................................................................... 3
Introduction: ................................................................................................................................. 4
Description of the principle of working: ....................................................................................... 4
The main function of the system is: .............................................................................................. 5
Essential requirements: ................................................................................................................ 5
Structural Diagram of the System: ................................................................................................ 5
Operation Algorithm: .................................................................................................................... 6
Functional Block Diagram of the System: ..................................................................................... 7
Conclusions ................................................................................................................................... 7
References: ................................................................................................................................... 8
Table of Figures
Figure 1: Stuctural Diagram...........................................................................................................5
Figure 2: Operational algorithm....................................................................................................6
Figure 3: Functional Block diagram of the system.........................................................................7
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Abstract
We describe a method for 3D object scanning by aligning depth scans that were
taken from around an object with a time-of-flight Sensor. Due to comparably simple
technology they bear potential for low cost for production and can done domestically
without any industrial instruments.
Our easy-to-use, cost-effective scanning solution based on such a sensor could
make 3D scanning technology more accessible to everyday users. In this paper we show
the surprising result that 3D scans of reasonable quality can also be obtained with a
sensor of such low data quality.
3D time of flight operates by illuminating an area with modulated IR light. By
measuring the phase change of the reflected signal the distance can be accurately
determined for every pixel in the sensor creating a 3D depth map of the object using
computer algorithm.
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Introduction:
Nowadays, 3D geometry models of real world objects are essential in many
application scenarios, such as design and virtual prototyping, quality assurance or
applications in visual media, such as games, virtual worlds and movie special effects -
to name just a few. Existing 3D shape scanning technology is often based on rather
specialized and complex sensors, such as structured light camera/projector systems or
laser range finders, Even though they produce data of high quality, they are quite
expensive and often require expert knowledge for their operation. It is thus no wonder
that semi-professional or everyday users have usually no access to such technology.
On the other hand, if easy-to-operate and cheap 3D scanners were more
amenable, 3D shape models could turn into a much more widely used asset, just as
image and video data are today. This could open the door for many new applications,
for instance in community web platforms or online shopping.
In this Project, we therefore propose a new easy-to-use 3D object scanning
approach based a time-of-flight (ToF) 3D Sensor. A ToF camera has a variety of
advantages over alternative 3D scanning technology:
• It is an active sensor that measures the travel time of infrared light, and therefore
it does not interfere with the scene in the visual spectrum.
Description of the principle of working:
Time-of-Flight imaging is based on measuring the time that light, emitted by an
illumination unit, requires to travel to an object and back to a detector. where this
process helps us with a full-fledged fabricated module to make a 3D scan of an object.
So, We use a Time of flight sensor which will be attached in a Z-axis
mechanical system, where the system is powered by a stepper motor. It is used to move
the sensor in vertical Z-axis direction. Then we keep the object on a turn table which is
also powered by a stepper motor which makes the turn table to rotate in 1.8° step angle
where it takes 200 steps to complete a 360° rotation.
The sensor takes Reading for every 1.8° step angle till the turning table stepper
motor reaches 200 turns, then the Turn table stepper motor stops and the z axis stepper
motor rotates till it reaches 1 mm. Then the process starts in a loop where again the
Turn table starts to Rotate to 200 turns. This process stops when the sensors reading is
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constant at the distance 300 mm. The process stops and sends the sensor carraige to
home position, and stops the device.
The main function of the system is:
To Scan any solid object within the specified dimensions regardless of object color or
the material with which the object is made. Analyze the deformities and imperfections
in the object surface. We can add system for remote scanning using interfaces with
wireless function. Use the scanner for performing scans for both personal as well as
industrial applications.
Essential requirements:
• Indoor (can be used in any climatic conditions if the temperature is controlled)
• Power: computer system: 18.5v, 3.5A, Microcontroller: 5v,4A
• Proper controllers, motors and adaptors designed within standard regulations to
be used.
Structural Diagram of the System:
Fig 1 : Stuctural Diagram
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Operation Algorithm:
Fig 2: Operational algorithm
At first, we start the Time of Flight Sensor and capture the distance of the object
then the turn table of the stepper motor starts to rotate, check if the turntable has
completed 200 steps if not it goes into a loop and takes the reading. After that the Z axis
stepper motor Rotates till the carriage is raised 1 mm and again it goes into loop 1.
When the data appears to be constant for more than 20 counts then the process will stop
accordingly. The turn table motor is stopped, the z-axis shaft motor is returned to home
position. The data is sent to computer system, and the process is finished.
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Functional Block Diagram of the System:
Fig 3: Functional Block diagram of the system
In this functional block diagram, we can clearly see how the system works. We
have two actuator which is actually controlled using pulse width modulation by the
control system where one motor is controlled using a Z-axis linear mechanism, the other
motor is connected to the Turn table gear mechanism. Then comes the sensor
transmitting element which sends the output data to the control system through General
purpose input output communication protocol.
Conclusions
- Got a basic idea how the 3-D scanner works.
- Basic principle of ToF
- At first, we thought that IR distance sensor can be used for this type of 3-D
scanner, Then I realized that this project is about ToF and its application in 3d
scanner so found out there is a ToF sensor available as per my specifications.
Finally understood various types and working of 3-D scanner and also the
implementations of the scanners and Tof in various fields.
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References:
1. https://www.youtube.com/watch?v=-qeD2__yK4c Basic Concept and Design Concept
2. https://www.pololu.com/file/0J1187/VL53L0X.pdf Tof sensor Data Sheet
3. http://www.pbclinear.com/Download/DataSheet/Stepper-Motor-Support-Document.pdf
Stepper motor data sheet
4. https://learn.adafruit.com/adafruit-vl53l0x-micro-lidar-distance-sensor-breakout/wiring-
and-test Sensor working
5. http://fritzing.org/download/ Circuit software.
6. http://www.solidworks.com/ Design Software.
7. http://ai.stanford.edu/~schuon/sr/cvpr10_scanning.pdf ToF Sensor Scanner Paper.
8. https://www.creaform3d.com/blog/2012/12/short-range-3d-scanning-technologies-an-
overview/ Scanning Principle.
