1
Recommended Practice for Signal Treatment Applied to Smart Transducers
ISO/IEC/IEEE 21451-001Sponsoring Society and Committee: IEEE Industrial Electronics Society/Industrial Electronics Society Standards Committee (IES/IES)Sponsor Chair: Victor Huang
Joint Sponsor: IEEE Instrumentation and Measurement Society/TC9 - Sensor Technology (IM/ST) Chair Kang Lee- NIST-USA
Working Group Chair – IES: Gustavo Monte (Universidad Tecnologica Nacional, Argentina)Working Group Co-Chair – IMS: Ruqiang Yan (SouthEast Univ, China)
Recommended Practice for Signal Treatment Applied to Smart Transducers
2
Recommended Practice for Signal Treatment Applied to Smart Transducers
ISO/IEC/IEEE 21451-001 Development Status
The purpose is to define a standardized and universal framework that allows smart transducers to extract features of the signal being generated and measured. With the definition of these practices, the raw data can be converted into information and then into knowledge. In this context, knowledge means understanding of the nature of the transducer signal. This understanding can be shared with the system and other transducers in order to form a platform for sensoryknowledge fusion.
PURPOSE
3
Recommended Practice for Signal Treatment Applied to Smart Transducers
ISO/IEC/IEEE 21451-001 SCOPE
Scope: This recommended practice defines signal processing algorithms and data structure in order to share and to infer signal and state information of an instrumentation or control system.
These algorithms are based on their own signal and also on the transducers attached to the system. The recommended practice also defines the commands and replies for requesting information and algorithms for shape analysis such as exponential, sinusoidal, impulsive noise, noise, and tendency.
4
Recommended Practice for Signal Treatment Applied to Smart Transducers
The future of smart sensors and Why we need a standard for sensor signals
Smart Sensor
Data transmission Wired or Wireless Bottleneck (channel capacity, regulations,spectrum,power constrains)
More processing power .For example, The Play Station 3 has the same peak processing (1.8 Teraflops) than the Sandia Lab Supercomputer in 1997.
(IEEE SPECTRUM , February 2011 pag, 48)
In the near future, the sensor signal will be entirely processed into the sensor, even for small and cheap sensors.
Today, This is done but only for complex signal processing related to specific issues. In general, we are wasting processing power.
POM Point Of Measurement (The world is inferred from here)POA Point Of Adquisition
5
Recommended Practice for Signal Treatment Applied to Smart Transducers
ISO/IEC/IEEE 21451-001 Development Status
Assuming that the sensor signal will be processed in the POM. What the sensor should report?
DATA
INFORMATION
KNOWLEDGE
BA
ND
WID
TH
Data=> Samples
Information=> Preprocessed data without a particular objective.
Knowledge-=> Feature extraction of particular interest.
( the lowest bit rate is obtained with questions with yes/no answer that require signal processing)
This standard could be very important for the IoT
6
Recommended Practice for Signal Treatment Applied to Smart Transducers
Actuator(Heater)
Temperature SensorTemperature SensorActuator(Heater)
Does your signal exhibit an exponential behavior?
yes
You are validated
Actuator-Sensor dialogue
Brand A Brand B
Thank You!Working properly state
Working properly state
The whole system is validated, actuator OK, temp sensor OK, liquid inside
If something is wrong, we realize of it before a timeout!.
Few bits/sec
EXAMPLE
7
P1451-001 Status
PAR Request Date: 18-Oct-2011PAR Approval Date: 06-Feb-2012PAR Expiration Date: 31-Dec-2016
1. WG P&P Working Group Policies and Procedures ( based on IEEE templates)
2. Conform a main WG ( In this case from IES and IMS)
3. Initial Draft document – (Important to establish the ideas that fired the proposal)
4. Call for Participation (IEEE SA)
5. Meeting (WEB based).(aprox every two months). Occasionally face to face meetings.
IES and I&MS are co-sponsors.
IMPORTANT DATES
STEPS:
Recommended Practice for Signal Treatment Applied to Smart Transducers
8
OUTINE OF THE PROPOSED STANDARD
The smart sensor should recognize the evolution of its signal like an observer does.
The sensor should see the “big picture”
Recommended Practice for Signal Treatment Applied to Smart Transducers
9
OUTINE OF THE PROPOSED STANDARD
SEGMENTATION ALGORITHM LIN1
SEGMENT CLASSIFICATION ALGORITHM SA
INTRA SEGMENT ANALYSIS
OVERSAMPLED SENSOR SIGNAL
Signal vectorization
Signal abstraction
Feature extraction
To higher order information processing tools ,Neural Networks,
Fuzzy logic,Genetic Algorithms
RTSAL
Algorithm
The proposal is to standardized the sensor signal behavior based on time domain analysis for any kind of sensor.
Recommended Practice for Signal Treatment Applied to Smart Transducers
10
OUTINE OF THE PROPOSED STANDARD
a
b
h
g
f
e
d
c
constant
linear +
linear (-)
+exp+
(-)exp+
noisy
c-exp(-)
c+exp(-)
Establish the relationship between tagged samples. This can be seen as a new concept for sampling process.
Recommended Practice for Signal Treatment Applied to Smart Transducers
Interpolation errorxi
Xi+1Upper
subspace
Interpolation error
xi
Xi+1Lower subspace
Interpolation error
xiXi+1
Upper subspace
Interpolation error
xi Xi+1
Lower subspace
11
OUTLINE OF THE PROPOSED STANDARD
Three vectors describe the signal: (M,C,T)
M (Mark)={ 1.8,1.7,-0.3…..
C (Class)={g,g,e,d,d,g,e….
T (TempPos)={6,8,12,14,………
Recommended Practice for Signal Treatment Applied to Smart Transducers
12
DIAGRAM OF THE PROPOSED STANDARD
Recommended Practice for Signal Treatment Applied to Smart Transducers
13
OUTLINE OF THE PROPOSED STANDARD: EXPONENTIAL DETECTION
Segments class “e”
Segments class “d”
Segments class “f”
Segments class “g”
INPUT PARAMETERS: •Number of consecutive segments required to start the algorithm.•Number of samples for predicted signal.
OUTPUT PARAMETERS: •Exponential detection (yes/no).•Type of detection. ( four types of exponential shape)•Steady state value.•Predicted signal (yes/no), value.
The steady state value can be predicted
Recommended Practice for Signal Treatment Applied to Smart Transducers
14
OUTLINE OF PROPOSED STANDARD: NOISE DETECTION
Noise detectionNoise is detected by computing the distance in
samples among maximums and minimums. If a maximum occurs, then the next one is a minimum and vice versa. If the temporal difference between these two singularities is less than a prefixed value for N times, a noisy flag is turned on.
INPUT PARAMETERS:Maximum amount of samples between max-min-max
to be considered as a noisy signal.Number of consecutive detection of noisy signal.
OUTPUT PARAMETERS:NOISY (yes/no)
a
b
h
g
f
e
d
c
constant
linear +
linear (-)
+exp+
(-)exp+
noisy
c-exp(-)
c+exp(-)
Local minimum at the union of:
fd, fg,ed, eg segments.
Local maximum at the union of
df,de,ge,gf.
Recommended Practice for Signal Treatment Applied to Smart Transducers
15
OUTLINE OF PROPOSED STANDARD: IMPULSIVE NOISE DETECTION
An abrupt reduction of the segment length starts the algorithm. This indicates the presence of noise. To be considered as impulsive noise, the change in amplitude must be significant.
Once the algorithm has started, it looks for the first maximum or minimum. Then, it computes the amplitude change from the value before the length reduction.
The length of the impulsive noise is computed from the temporal difference between the first segment and the last one.
For example, the sequence “dddffff” indicates the occurrence of a maximum, and the impulse length is the difference between the temporal position of the last “f” and the first “d”.
INPUT PARAMETERS:Relative amplitude change to be considered as an impulsive noise.OUTPUT PARAMETERS:Detection yes/no.Type of impulse (“df”,”eg”….)Amplitude of impulse.Length of impulse in samples.
Recommended Practice for Signal Treatment Applied to Smart Transducers
16
OUTLINE OF PROPOSED STANDARD: SINUSOIDAL PATTERN DETECTION
a
b
h
g
f
e
d
c
constant
linear +
linear (-)
+exp+
(-)exp+
noisy
c-exp(-)
c+exp(-) Dots indicate tagged samples. Class(n)=[ g,g,g,e,e,e,f,f,f,f,g,g].
INPUT PARAMETERS:NoneOUTPUT PARAMETERS:Detection of pattern (yes/no)Estimated Period (samples)
Stable or unstable oscillations.
The sinusoidal patter is composed of the four class segment “gefd” including repetitions of the same class.
For example “gggeeefffdddd” is also a valid sinusoidal pattern. The maximum occurs at the union of “ge” segments and the minimum at “fd”. The period is the difference between singularities of the same kind.
By computing peak to peak values, we can determine if the oscillations are increasing or decreasing.
Recommended Practice for Signal Treatment Applied to Smart Transducers
17
1 1minmin
1 1min
( )( )
( )x x x x
x x x x
T T M MTrend
T T M M
T1 T2 T3 T4 Tx
Max 1 Max 2
Max x
Max 3Max 4
1 1maxmax
1 1max
( )( )
( )x x x x
x x x x
T T M MTrend
T T M M
OUTLINE OF PROPOSED STANDARD: TENDENCY ESTIMATION
min max 2
Trend TrendTrend
INPUT PARAMETERS:Windows size in samples.OUTPUT PARAMETERS:Tendency for max.[-1,1]Tendency for min.[-1,1]
Tendency is computed taking into account the increment or decrement of both, the maximums and minimums in a temporal window.
Growing trend is normalized to +1 when all the new maximums are higher than the previous ones in the window.
On the other hand, the trend is decreasing, and normalized to -1, when all the new maximums are lower than the previous ones in the window.
The same procedure is executed for minimums.
Recommended Practice for Signal Treatment Applied to Smart Transducers
18
Recommended Practice for Signal Treatment Applied to Smart Transducers
OUTLINE OF PROPOSED STANDARD: MORE RELIABLE VALUE
Since that there is information about the signal shape, it is possible to exclude in the mean estimation of the signal some artifacts. In this algorithm, segments that belong to impulsive noise are discarded in the mean computation.
INPUT PARAMETERS:Window length for mean computation.OUTPUT PARAMETERS:Mean including all the segments.Mean without impulsive noise.
Low pass filtered signal
19
Recommended Practice for Signal Treatment Applied to Smart Transducers
OUTLINE OF THE PROPOSED STANDARD: COMPLEX PATTERN DETECTION
Detection of normal QRS complex in ECG signals
Unexpected sequence of segments in a real signal. In this case too many “f” and “d” types.
20
Recommended Practice for Signal Treatment Applied to Smart Transducers
COMPLEX PATTERN DETECTION: EEG spike detection with noise
EEG signal (eeg_3_01) from MatLab EEG signal with normal noise added
EEg after 3 iterations of RTSAL err=0.001 EEg after 10 iterations of RTSAL err=0.001
21
Recommended Practice for Signal Treatment Applied to Smart Transducers
OUTLINE OF PROPOSED STANDARD: filtering
Sinusoid detection with noise. FS=22050, f=345 Hz SNR=7dB. Iterations=10. Interpolation error: 1%. Red: original signal. Green: signal reconstructed from MCT vectors. A new set M’C’T’ is obtained.
22
Recommended Practice for Signal Treatment Applied to Smart Transducers
Working Group objectives
We will try to keep the smart sampling process (MCT vectors) as a platform for every algorithm in this WG.
•Review and define the proposed algorithms for layer one.
•Propose new algorithms.
•Develop user defined application code based on MCT vectors.
•Propose the data structure including commands scheme.
•Propose a time synchronization scheme.
•Define and propose the interface with the IEEE 1451 standards.
•Propose learning algorithms for specific patterns.
•Propose filtering and signal compression.
23
Recommended Practice for Signal Treatment Applied to Smart Transducers
Working group organization
Coordination subgroup IES &IMS
Impulse, noise detection mean estimation. Tendency, exponential and sinusoidal patterns.
Interface with IEEE 1451 Standards and Data structure
Filtering, signal compression and prediction
New and learning Algorithms. User Defined Application Code
Testing
Subgroups
24
Recommended Practice for Signal Treatment Applied to Smart Transducers
Working group organization
Subgroups
SUBGROUP SG1 Objectives: To define, propose, and validate first layer algorithms based on MCT vectors. Review the initial proposal, modify it and suggest changes.
LEADER: Dr. Antonio Pietrosanto - University of Salerno- ITALY email: [email protected]
SUBGROUP SG2 Objectives: To define and coordinate commands and data structure consistently with IEEE 1451 standards. Review and propose a time synchronization scheme for data. Normalize name of variables and data.
LEADER: Dr. Eugene Song- National Institute of Standard Technology (NIST) - USA email: [email protected]
25
Recommended Practice for Signal Treatment Applied to Smart Transducers
Working group organization
SUBGROUP SG3
Objectives: To define, review and propose algorithms based on MCT vectors and first layer outputs for filtering, signal compression and prediction.LEADER: Dr. Ruqiang Yang - School of Instrument Science and Engineering, Southeast University, Nanjing , China [email protected]
SUBGROUP SG4 Objectives: To propose new algorithms that the group considers that they must be included. Define the data structure for embedding user defined application code and pattern learning algorithms. LEADER: Dr. Zheng Liu- Toyota Technological Institute- JAPAN email: [email protected]
SUBGROUP SG5 Objectives: To test and validate proposed algorithms using simulation software (MatLab, Octave, Scilab…) and C code for microcontrollers.LEADER: Dr. Vincenzo Paciello-Università degli Studi di Salerno- ITALY email: [email protected]
26
Recommended Practice for Signal Treatment Applied to Smart Transducers
Thank you!