M.Soleimani@bath.ac.uk

1. Magnetic induction tomography –
current development and potential industrial
applications
Presented in Kuwait,
Electronics and Electrical Engineering Faculty
4th October 2011
Presenter: Kent Wei,
on behalf of Dr. Manuchehr Soleimani

2. Magnetic Induction Tomography (MIT) work in Bath

3. Outline
• Introduction to Magnetic Induction Tomography (MIT)
– Background
– MIT Theory
– System Design
– Software Design
– Image Reconstruction Algorithm
– Rotational MIT
– MIT in Pipeline imaging
– Other tomography techniques

4. Background (MIT)
• Feature:
– Most recently explored electrical tomography
technique, compare with other electrical tomography
systems, such as EIT and ECT
– Contactless Electromagnetic Imaging.
• Application:
– Metal detection
– Industrial non-destructive testing (NDT)
– Medical application

5. MIT Theory
• Mutual Inductance
• Sensor response

6. MIT System Design
Bath MIT
Mk-I and Mk-II

7. MIT Instrumentation Design
• LabView
• NI-USB 6259

8. Image Reconstruction
Forward Model (MIT)
Conductivity Distribution Forward Model Sensor Measurement
Inverse Model (MIT)
Sensor Measurement Inverse Model Conductivity Distribution

9. Forward Problems
H-field (d/dt)
excitation coil
measuring coil
Object
eddy current
H-field (d/dt)
1 
     E  i (  i )E   iJ e
 

10. Inverse Problems
Solving Linearised Inverse Problem:
does not exist, as A is generally under-determined, i.e. not symmetrical

11. Inverse Problem with Tikhonov Regularisation
Solving Inverse Problem:
Regularisation
Parameter

12. Imaging Result
Images are reconstructed using a linearised reconstruction
method based on inversion of a sensitivity Jacobian matrix
with Tikhonov regularisation

13. More Imaging Result
Suitable for metallic object imaging!
HY Wei, M Soleimani, A simple magnetic induction tomography system
and the image reconstruction (Published: The 4th World Congress on
Industrial Process Tomography)

14. Rotational MIT (RMIT)
• Electrical Tomography – low imaging resolution
• Coil array can be rotated with respect to the central axis
• Better Image Quality with the same amount of sensors
HY Wei, M Soleimani, Theoretical and experimental evaluation of rotational magnetic induction
tomography (Accepted: IEEE TRANSACTIONS ON INSTRUMENTATION AND
MEASUREMENT)
No rotation: 28 One rotation: 28x2=56 Two rotations: 28x3=84
measurements measurements measurements

15. Rotational MIT
0
10
No rotation
One rotation with 22.5 degree
Normalised singular values
-1 Two rotations with 15 degrees
10
-2
10
-3
10
0 10 20 30 40 50 60 70 80 90
Measurement number

16. RMIT Image Result
No rotation One rotation Two rotations

17. RMIT Image Result
No rotation One rotation Two rotations

18. Pipeline Inspection
• Pipeline Inspection is important in industry:
– undiscovered damaged pipelines => huge
operational cost + environmental disaster
• Current Techniques
– Non-destructive testing (NDT)
– In-service testing: pipeline inspection gauges (PIG)
– High Cost and Highly skilled technicians required

19. MIT in Pipeline Imaging
• Low cost, but yet provide a satisfactory imaging
• In-situ imaging

20. Narrow Band-pass MIT in Pipeline Imaging
• Narrowband filtering is a technique that can
increase the image quality at the area of interest
Reconstructed Image Reconstructed Image
without narrowband with narrowband
filtering filtering

21. More narrowband filtering MIT result
Damaged Tube
with medium
Hollow Tube opening
with no opening
Damaged Tube
Damaged Tube with large
with small opening
opening

22. 3D Industrial MIT - Simulation
Sensitivity Map

23. Movement of the centre of mass - Result
Copper bar Predefined Movement of the center of
pattern mass extracted from the
image reconstructions

24. Movement of the centre of mass (Simulated Result)
Woods metal
phantom
Movement of the centre of
mass extracted from the
image reconstructions

25. Flow Imaging Result
Aluminium cone-
shaped phantom
Reconstructions of the boundaries
for every 2 consecutive images Reconstructions of the boundaries
for every 2 consecutive images

26. Conclusion
• MIT is a suitable technique for conductive
material imaging and NDT testing
• Low cost
• Image quality can enhance further by
implementing different measuring techniques or
reconstruction algorithms
• Satisfactory Imaging Result
• Close to commercialisation state

27. Improved FEM Model for 3D ECT
an insulation (15mm)
an outer screen
imaging
volume
a mounting pipe (3mm) a top view of sensor

28. Electrical Capacitance Tomography
2D 3D 4D

29. Question?
Kent Wei: H.Wei@bath.ac.uk
Manuchehr Soleimani: M.Soleimani@bath.ac.uk