Autonomous Anthropomorphic Robotic Arm to Monitor Plant Growth in a Laboratory

162 Pages·2011·4 MB·English

by  Seelye, Mark

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Autonomous Anthropomorphic
Robotic Arm to Monitor Plant Growth
in a Laboratory

A thesis presented in partial fulfilment
of the requirements for the degree of

Masters
in
Engineering

at
Massey University
Palmerston North
New Zealand

Mark Seelye
2011

Abstract

An autonomous anthropomorphic robotic arm was designed, fabricated and
programmed for monitoring of plant tissue grown in a modified in vitro clonal
plant propagation system being developed by The New Zealand Institute for
Plant & Food Research. The custom fabricated aluminium robotic arm uses a
vertical linear ball shaft and high speed stepper motors to provide arm joints
movements enabling the arm to swivel 180 degrees horizontally. Sensors
located at the end of the arm are used to monitor plant growth and the
immediate growing environment. This includes a compact colour zoom camera
on a pan and tilt mount for image capturing, red, green and blue (RGB) colour
sensors to monitor leaf colour as well as temperature, relative humidity and
carbon dioxide sensors. The robotic arm is capable of reaching over multiple
trays (600mm x 600mm) of plantlets. Captured plant tissue images are
processed using innovative algorithms to determine tissue or whole plant
growth rates over specified time periods. Leaf colour sensors provide
information on tissue health status when compared to predetermined optimum
values. Custom software fully automates the operation of the arm and the data
capture, allowing the arm to return to specified sites (i.e. individual plantlets) at
set time intervals to identify subtle changes in growth rates and leaf colour. This
allows plant nutrient levels and the immediate environment to be regularly
adjusted in response to continuous sensing resulting in optimised rapid growth
with minimal human input.

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Acknowledgements

In completing this Masters degree in Mechatronic Engineering, I would like to
take this opportunity to sincerely thank:
My supervisor, Dr Gourab Sen Gupta from the School of Engineering and
Advanced Technology (SEAT), Massey University, Palmerston North, New
Zealand for his guidance and expertise throughout this project from start to
finish.
Mr Clive Bardell, Mr Kerry Griffiths and Mr Greg McLeay from the School of
Engineering and Advanced Technology’s (SEAT) metal workshop and CNC lab
for their guidance and expertise in teaching me the hands on skills required to
build the robotic arm and program and running of the CNC machine.
Associate professor Donald Bailey from the School of Engineering and
Advanced Technology (SEAT), for his input into colour transformations leading
to the calibration of the colour sensors.
Dr Rory Flemmer from the School of Engineering and Advanced Technology
(SEAT) for his input into the control algorithms required to control the robotic
arm and input into the image analysis.
Mr John Seelye, Scientist, Breeding Technologies Group, The New Zealand
Institute for Plant and Food Research Limited, Palmerston North, New Zealand
for sponsoring the entire project.

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Table of Contents

Abstract ................................................................................................................ i
Acknowledgements ............................................................................................. ii
List of Figures ................................................................................................... vii
List of Tables...................................................................................................... xi
1. Introduction ................................................................................................. 1
2. Literature Review ........................................................................................ 5
2.1. Robotics in the Workplace ................................................................. 5
2.2. Robotic Systems .............................................................................. 14
2.3. Summary .......................................................................................... 18
3. Robotic Arm Design .................................................................................. 21
3.1. Required Parts ................................................................................. 21
3.1.1. Z-axis Motion – (Linear Ball Shaft) ...................................... 21
3.1.2. Stepper Motors .................................................................... 23
3.1.3. Bearings .............................................................................. 23
3.1.4. Gearing System ................................................................... 23
3.1.5. Prototypes ........................................................................... 24
3.1.6. Machining ............................................................................ 30
3.2. Automation & Control ....................................................................... 32
3.2.1. Overview ............................................................................. 32
3.2.2. Motor Controller ................................................................... 33
3.2.3. Microstep Driver .................................................................. 37
3.2.4. Stepper Motors .................................................................... 38
3.2.5. Control Theory (Inverse Kinematics) ................................... 40
4. Sensors .................................................................................................... 45
4.1. Colour .............................................................................................. 45
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4.1.1. Background to Colour .......................................................... 45
4.1.2. Why an RGB Colour Space was Used ................................ 47
4.1.3. ColorPal Colour Sensor ....................................................... 49
4.1.4. TSC3200 Colour Sensors ................................................... 50
4.1.5. Selection and Calibration of Colour Sensors ....................... 51
4.2. Proximity Sensor .............................................................................. 70
4.3. Temperature and Humidity Sensor .................................................. 72
4.4. Carbon Dioxide Sensor .................................................................... 75
4.5. Microcontroller and Development Board .......................................... 75
4.6. Colour Camera ................................................................................. 77
4.6.1. Frame Grabber .................................................................... 79
4.7. Overview .......................................................................................... 80
5. Software Implementation .......................................................................... 83
5.1. Timer & Serial Port ........................................................................... 83
5.2. Motor Controller ............................................................................... 83
5.3. Microcontroller ................................................................................. 85
5.4. Sensor Programming ....................................................................... 87
5.5. Camera Control through Software ................................................... 89
5.6. Integration of a Database ................................................................. 91
5.7. Metrology methodology for plant size calculation ............................. 94
5.8. Integration of all Parts ...................................................................... 97
5.9. Automation of the Entire System ...................................................... 98
5.9.1. Homing the Robotic Arm ..................................................... 98
5.9.2. Manual Motor Control (manual control of the robot) ............ 99
5.9.3. Automatic Motor Control (Autonomous control of the
robot) ................................................................................. 100
5.9.4. Overview ........................................................................... 101
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6. Summary and Future Research.............................................................. 103
7. References ............................................................................................. 105
8. Appendix ................................................................................................ 109
8.1. Publications to Date ....................................................................... 109
8.2. Detailed SolidWorks Drawing Showing all Dimensions .................. 129
8.3. G code Generated in SolidCam of Part Shown Above ................... 130
8.4. Methodology / Information on linear transformation from XYZ
to sRGB ......................................................................................... 133
8.5. Sony VISCA Protocol for the Various Camera Controls ................. 140
8.6. Basic Stamp Program Example ..................................................... 143

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