This presentation discusses adaptive active noise control in smart rooms. It introduces the concept of using active noise control to reduce noise in smart rooms like living rooms, office rooms, hospital rooms, and classrooms. It then discusses some of the challenges of active noise control stability in real-life applications and smart rooms. The presentation proposes using root locus analysis and introducing a compensator to improve stability. It also explores using remote acoustic sensing to replace the error microphone and allow more effective use of space in the quiet zone.
3. Background
Why ANC in Smart rooms:
① Evolving technological approaches
② Future of living rooms, hospital rooms
office rooms & class rooms
③ Research with impact
Smart Rooms
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4. Background
① Interesting theory in Physics
② Interesting theory in Control Engineering
③ High-tech design & implementation, e.g.
FPGA, DSP
④ New challenges (when integrated
with smart rooms)
Active Noise Control
4
5. Background
Active Noise Control / Smart Sensor Networks for Passenger Cars
Professional Research on ANC and Smart Rooms
- Founder of Unitec Smart Rooms
- Adaptive ANC in Smart Rooms
- Finalist of IBM Innovation Award 2014
PhD & FRDF Postdoctoral Research on Adaptive ANC
- More than 30 journal/conference papers on ANC
- International research collaboration
- Nominated for UoA Top Doctoral Thesis Award (by FoE)
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13. AdaptiveANCinSmartRooms–ByImanArdekani
Why ANC in Smart Rooms?
Acoustic
Sig Pro
Intelligent
Agents
Noise
Why Noise Control?
1. Human productivity (especially in open plan office rooms)
2. Quality of life (more pleasant rooms)
3. Quality of interaction between smart room and occupants (speech)
Why not Passive Noise Control?
• Passive Noise Control is bulky and inefficient for low frequency.
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16. AdaptiveANCinSmartRooms–ByImanArdekani
Acoustic Sensing in ZoQ
- It is essential to place an Error Microphone (Err Mic.) in the desired quiet zone to
sense the residual noise.
- The size of the quiet zone is very limited.
- Can we use one of the smart room’s built-in microphone instead?
- If we can, then
- 1) more effective use of space in the quiet zone
- 2) more cost effective hardware design
10 dB ZoQ
Noise
P
S
𝜆
20
Err Mic
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17. STABILIZATION OF ANC IN
SMART ROOMS
Root Locus
(RL) Method
ANC RL Plots
Stabilization
Process
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18. AdaptiveANCinSmartRooms–ByImanArdekani
Numerical
methods
Root Locus Method
Char Eq.
𝐵 𝑧 = 0
LTI Digital
Systems
Numerical
methods
x
x
x
z-plane
𝐺(𝑧) 𝐺(𝑧)
Char Eq.
𝐵(𝑧) + 𝑘𝐴(𝑧) = 0
RL
𝑘 = 0
✗
𝐺 𝑧 =
𝑎0 + 𝑎1 𝑧 + 𝑎2 𝑧2
+ ⋯
𝑏0 + 𝑏1 𝑧 + 𝑏2 𝑧2 + ⋯
𝐺 𝑧 =
𝐴(𝑧)
𝐵(𝑧) 𝐻 𝑧 =
𝐺(𝑧)
1 + 𝑘𝐺(𝑧)
=
𝐴(𝑧)
𝐵(𝑧) + 𝑘𝐴(𝑧)
𝑘
𝑘 = ∞
x
x
z-plane
x
x
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19. AdaptiveANCinSmartRooms–ByImanArdekani
2
1
Root Locus Methods
LTI Digital
Systems
Char Eq.
𝐵(𝑧) + 𝑘𝐴(𝑧) = 0
RL
𝐺(𝑧) 𝐺(𝑧)
𝑘
Char Eq.
𝐵 𝑧 = 0
Numerical
methods
x
x
x
z-plane
𝐺 𝑧 =
𝑎0 + 𝑎1 𝑧 + 𝑎2 𝑧2
+ ⋯
𝑏0 + 𝑏1 𝑧 + 𝑏2 𝑧2 + ⋯
𝐺 𝑧 =
𝐴(𝑧)
𝐵(𝑧) 𝐻 𝑧 =
𝐺(𝑧)
1 + 𝑘𝐺(𝑧)
=
𝐴(𝑧)
𝐵(𝑧) + 𝑘𝐴(𝑧)
x
z-plane
x
x𝑘 = 0
𝑘 = ∞
x
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21. AdaptiveANCinSmartRooms–ByImanArdekani
𝐴(𝑧)
ANC RL Plots
• Adaptation process performed by the FxLMS in adaptive ANC is a
recursive and non-linear process.
• However, by using the Independence Assumptions, a linear
approximation for the FxLMS adaptation process can be obtained.
• FxLMS stability is highly related to the adaptation step-size k so a
stability analysis w.r.t. k is needed.
𝑧 𝑄 − 𝑧 𝑄−1 + 𝑘 𝑃𝑥
𝑚=𝑞
𝑄−1
𝑠 𝑚
2
𝑧 𝑄−1−𝑚 = 0
𝐵(𝑧)
2
Char Eq.
𝐵(𝑧) + 𝑘𝐴(𝑧) = 0
1
LTI Digital
Systems
𝑘 is an available parameter but 𝐴(𝑧) and
𝐵(𝑧) do not physically exist .
𝑞 𝑄 − 1
Room impulse response
Amplitude
Time index
𝑠 𝑞
𝑠 𝑄−1
noise power.
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22. AdaptiveANCinSmartRooms–ByImanArdekani
ANC RL Plots
𝐴(𝑧) coefficients are
always positive .
𝐴(𝑧)
𝑧 𝑄
− 𝑧 𝑄−1
+ 𝑘 𝑃𝑥
𝑚=𝑞
𝑄−1
𝑠 𝑚
2
𝑧 𝑄−1−𝑚
= 0
𝐵(𝑧)
𝐵 𝑧 = 𝑧 𝑄
− 𝑧 𝑄−1
Typical Trajectories for
the FxLMS Root Locus
(independent of the room acoustics)
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27. AdaptiveANCinSmartRooms–ByImanArdekani
ANC RL Plots
z-plane
𝑥 𝐵
B1
B2
B4
B3
o
o
to infinite end points
to infinite end points
Finite End Points at roots of A(z).
A(z) coefficients: sq
2: positive
so all the finite end points are in
the left side of Imaginary axis.
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36. STABILIZATION OF ANC IN
SMART ROOMS
Summary
• A novel method based on RL theory is developed.
• RL analysis of the adaptation process leads to develop new adaptive ANC algorithms.
• The new algorithms show good stability behavior in smart rooms.
• It is proved mathematically.
• Simulation and practical results support the theoretical findings.
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40. AdaptiveANCinSmartRooms–ByImanArdekani
ANC Analysis in Acoustic Domain
• Since 𝑈 𝑥(𝑧) and are 𝑈 𝑦(𝑧) unknown, we cannot implement 𝑊𝑜𝑝𝑡 𝑧 directly
but The FxLMS algorithm can adaptively adjust the adaptive filter to an estimate
of 𝑊𝑜𝑝𝑡 𝑧 .
𝑊𝑜𝑝𝑡 𝑧 =
𝑈 𝑥(𝑧)
𝑈 𝑦(𝑧)
𝐾𝑥𝑦 𝑧−∆ 𝑥𝑦
Room Impulse
Response
x
Ref Mic.
Err Mic.
+
Current Filter
Parameters
Updated Filter
Parameters
⟶ 𝑊𝑜𝑝𝑡 𝑧
FxLMS Algorithm
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51. Contributions
Investigated practical problems with adaptive ANC2
Moved towards the integration of ANC into Smart Rooms3
1 Improved the theoretical understanding of ANC
Developed a flexible and high-performance experimental setup for ANC4
Published the results in high ranking journals5
Made international collaboration6
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53. AdaptiveANCinSmartRooms–ByImanArdekani
Future Work – Smart Rooms
Acoustic
Sig Pro
Medical
Technology
Room Book
Intelligent
Agents
- Smart Hospital Rooms
- Smart Assistive Rooms (for elderly and people with disabilities )
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Editor's Notes
Good morning everyone. Thank you for being here and thank you for giving me the opportunity of talking about my research.
My name is Iman. I am a graduate of UoA electrical engineering department.
BSc… MSc… both from…
PhD...
Then I did a FRDF postdoc.
Currently, I am working as a research fellow there. Also, I am working with Unitec. What I am doing is research and teaching in the field of embedded systems, computer vision, robotics and acoustic signal processing.
Well… this seminar title is “Adaptive Active Control of Sound in Smart Rooms” or adaptive active noise control in smart rooms, or we can say “adaptive ANC in smart rooms”. Shortly, I will tell you why I have chosen this topic.
I have put SMART ROOMS as 1 of the 2 components of this seminar for some reasons.
I would like to look at ANC in smart rooms because smart rooms are evolving technological approaches for improving human life. They are future of living rooms, hospital rooms, office rooms and even classrooms. Also because I can introduce my other research interests while introducing smart rooms.
In addition to these, smart rooms are where we can show the impacts of our engineering research on NZ society. There are important factors like quality of life for people in living places, quality of care for patients in hospitals and human productivity for companies and several other factors. Everyone is looking at this factors. Even NZ government looks at all of these factors. In this situation, we need to show the impact of our engineering research on these factors. I believe that smart rooms are very flexible and reliable frameworks for this purpose and for creating Research with Impact.
I have different ongoing research on smart rooms by my self or by my students.
For example, fall detection in smart rooms that is useful for elderly and people with disabilities.
Or RoomBook which is something similar to Facebook. This is a knowledge-based web application for sharing information between smart rooms.
Or Robotic applications in smart rooms.
Or using computer vision for improving the performance of physiotherapy at home. I could have chosen them but I have chosen ANC for some reasons.
ANC has an interesting theory in Physics.
Also, it has an interesting theory in control and signal processing engineering.
It needs high-tech design and implementation, technologies like FPGA, DSP and so on.
Also, when we want to introduce ANC to smart rooms we will face new theoretical challenges. Theoretical challenges that can affect the operation of ANC in practice. Dealing with these challenges are the main concern of this presentation.
My first experience with ANC goes back to about 10 years ago when I was working for PEGEOT and BMC. I was working on ANC for passenger cars and also smart sensor networks for cars.
In BMC, I was working on active suspension for commercial vehicles. Active Suspension is similar to active noise control.
Then, both of my PhD and Postdoc research were on ANC. I published more than 30 papers on ANC and run several workshops and tutorial word wide. I need to emphasis that this is not my only area that I have published on. I have other areas for my publications such as power systems, electro-mechanic energy conversion and so on.
We have made an international collaboration with different universities, specially in Japan and in Singapore.
Recently, I have founded Unitec Smart Room. Unitec smart room is a collection of research areas like robotic, image processing, acoustical signal processing, knowledge based systems and sensor networks technologies. and I have kept adaptive ANC research as a part of this collection.
Also, due to my research on smart rooms, I have been chosen as the finalist of IBM innovation award in NZ. The winner will be introduced this Thursday.
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This seminar is not about …. Although it is within my research interests.
This seminar is not about …. Although it is within my research interests.
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