Interim Report SS

8/9/2019 Interim Report SS

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Shikha Page 1 04/04/2010

Sensor Networking and Data Fusion for Condition

Monitoring: A Hands-On Exploration

Interim Progress

The first few weeks went into defining the project objective and title. After having decided

on the project title, the first phase of the project was primarily focused on making high level

technology choices, purchasing equipment, setting up a test framework and defining the

conceptual design. The process that I am following in executing this project may be

described by the following flow diagram.

Figure 1. The Projects Process

The idea underpinning this project may be summarized as follows:

"To develop a modular and inexpensive condition monitoring system that can be easily

deployed in a wide variety of applications"

The key design goal is to be able to distribute sensor nodes on monitored sites (factory,

shipboard environment, home, farm animals etc.) and collect the data remotely for analysis

and fault diagnosis. I intend to use a combination of microcontroller, micro-sensor and ad-

hoc mesh networking technologies to achieve this goal. The architecture of the system may

be seen as a network of inexpensive communicative nodes distributed over objects of

interest in a monitored site. Each such node would have multiple sensors attached, and

would have capability to communicate the sensor readings to designated computer(s),

where purpose-designed software would be used to fuse the monitored data. This data

fusion process would give rise to a global situational awareness about the entire monitored

site. The conceptual design of each node is shown by the following diagram.


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Figure 2. Conceptual Model of a Monitoring Node

The first two conceptual designs I made are shown in Figures 3 and 4. Those could be used

for condition monitoring but these ideas had to be rejected due to cost concerns.

Figure 3. Conceptual Model Version 1 (the first iteration)

The cost per node for such systems would be very high thereby making a full deployment

prohibitively expensive. The problem is that the data acquisition card at the center is very

expensive and is not a programmable piece of hardware and comes with an unnecessary

USB interface. A single microcontroller with analog input pins would do just as good for a

much lower price. What we need for a minimalist and inexpensive design is a

microcontroller with a few analog pins (for the sensors) that has enough memory to host the

networking protocol stack and the sensor data buffering logic. A PIC or Atmel

microcontroller would be just fine. I made a choice in favour of PIC because I already had a

PIC programmer hardware from my 3rd year coursework project, and wanted to reuse it forreduce costs. However it turned out that the programmer did not support the larger


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microcontrollers from the PIC family (as was necessary for hosting the networking protocol

stack). So I bought another programmer that supported the PIC16F77 chips.

Figure 4. Conceptual Model Version 1 (the first iteration)

It was necessary to decide on a networking protocol stack. There are several proprietary and

open protocol solutions. On reading a number of online articles it seemed that going for an

open protocol stack was a better idea because that way there would be a wider base of

component suppliers to choose from. This would make better commercial sense because

commoditized components reduce the cost of large scale production. A proprietary protocol

stack (e.g. ANT+) would lead to vendor lock in (having to buy everything from the same

vendor). There are a few protocol implementations based on the open IEEE 805.15.4

standard (eg. Zigbee, WirelessHart, ISA 100.2), of which the Zigbee stack was chosen due to

its relatively widest supplier base and lower price per unit.

As per the current conceptual design, the communication architecture is shown in thefigures 5 and 6.

Figure 5. Message Hopping Communication in the Wireless Network


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Figure 6. Link between Zigbee modules and Computer

The Zigbee module has two digital I/O pins which would have to be connected to with two

digital I/O pins of the microcontroller. Figure 7 shows the connections to be made between

the Zigbee RF module and the microcontroller. The subsequent pictures (Figures 8, 9, 10

etc.) show the key hardware units acquired for the prototyping to be done during this

project.


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Figure 7. Connection between Zigbee Module and Microcontroller

Figure 8. Zigbee RF modules


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Figure 9. Microcontroller Programmer

Figure 10. Data acquisition card

Figure 8. Microcontrollers


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Figure 11. Acoustic, temperature, and vibration sensors

Figure 12. Microcontroller programmer from 3rd

year coursework

Work done so far include the following:

1. Experimental verification of sensor functioning (using the DAQ USBconnection).

2. Writing of a DLL that picks up data from a USB connection with the DAQ card. Thiswhen combined with a plotting software will serve as a poor mans (low frequency

handling) oscilloscope to inspect sensor signals.3. A detailed survey of technologies and applications of sensors.The following section presents the literature survey I have carried out.


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Literature Survey: The State of the Art in Sensor and Monitoring

Technologies

Sensors:

A sensor is a transducer that responds to a specific physical stimulus and produces a

measurable corresponding electrical signal. A sensor can be electrical, mechanical,

optical or electrochemical.

Energy

Recent advancement of microdevice technology, chemical processes,microfabrication, digital signal processing, etc. have enabled the development of

micro and nanosized low power and low cost microsensors. Microsensors are

applied successfully in many sectors including telecommunication, medical devices,

space equipments, manufacturing, military equipments, etc.

Microsystems are intelligent micro scale machines that combine sensors and

actuators, electronics and mechanical structures to sense information from the

environment and react to it.

MEMS + Electronics + Package Microsystem

Microsensors and Microsystems have certain advantages when compared with

traditional or conventional sensors in various respects.

Low cost Minimise energy and materials used in manufacturing Can be used in narrow spaces and harsh environments Faster devices Wider dynamic range Performance advantages Improved accuracy and reliability

Classification of sensors according to their working principle:

Sensing principle Sensors

Resistance change Potentiometer, thermistor, resistance temperature

detector(RTD), strain gauge, photo-resistive sensor,

piezo-resistive sensor

Inductance change Liner variable differential transformer(LVDT), inductive

angular position sensor, inductive torque meter

Capacitance change Capacitance level sensor, capacitive-type torque meter

Photo electric effect Phototransistor, photodiode, photo-interrupter(optical

encoder)Thermoelectric effect Thermocouple

Sensor Electrical SignalInput Output


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Piezoelectric effect Piezoelectric accelerometer, sound navigation and

ranging (SONAR)

Electromagnetic induction Electromagnetic flow meter

Hall effect Hall sensor

Table: 1

Temperature sensors:

Thermocouple

Thermocouple is a sensor for measuring temperature.

A thermocouple is created when two dissimilar

metals touch and the contact point produces a small

open-circuit voltage as a function of temperature.

This thermo-electric voltage is known as Seebeck

voltage. They are self-powered, low cost, simple,

rugged, available in a wide variety, has reasonably

short response time and has a wide temperature

range.

Limitations: They are least sensitive, least stable, non-

linear and reference is required.

Figure: Thermocouple

ThermistorThermistors are thermally sensitive resistors. They are

used in circuits which are temperature dependent.

For example in fire alarms. They typically work over a

relatively small temperature range, compared to

other temperature sensors, and can be very accurate

and precise within that range.

Limitations: These are fragile, non-linear, have limited

temperature range, self-heating and the current

source is required. Figure: Thermistor

Resistive Temperature Detector (RTD)

RTDs are temperature sensors that contain a resistor

which changes resistance value as its temperature

changes. Typical elements used for RTDs include

nickel (Ni) and copper (Cu), but platinum (Pt) is by far

the most common because of its wide temperature

range, accuracy, and stability. RTD has long-term

stability, very accurate and exhibit the most linear

signal with respect to temperature of any electronic

temperature sensor.

Temperature

Resistance

Vout (mV)

Temperature0C


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Limitations: These are expensive, low absolute

resistance, self-heating and the current source is

required.

Figure: RTD

I.C. Sensor

A silicon temperature sensor or an Integrated circuit

temperature sensor is an integrated circuit. It includes

extensive signal processing circuitry within the same

package as the sensor and comparator or ADCcircuits. It doesn't require designing cold-junction

compensation or linearization circuits for

temperature sensor ICs.

A temperature sensor IC can operate over the

nominal IC temperature range of -55C to +150C.

Some devices go beyond this range. These are most

linear and low cost.

Limitations: I.C. sensors are slow, self-heating,

requires power supply and has limited configurations.

Figure:

Radiation thermometers

Radiation Thermometers (Pyrometers) are non-

contact temperature sensors that measure

temperature from the amount of thermal

electromagnetic radiation received from a spot on the

object of measurement and relate this to its

temperature by means of the Planck law of radiation.These devices enable improvements in processes,

maintenance, health and safety. They are used widely

in many manufacturing process. Figure:

Resistance temperature curve for a

100 Ohm Platinum RTD


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Micro and Nano sensors:Micro-electro-mechanical (MEMS) devices are an integration of micro-sensors,

analog-to-digital converters, signal-processing circuits, programmable memory and a

microprocessor. Modern MEMS contains an antenna for radio signal transmission.

Evolution of smart wireless micro-sensors (Crossbow Technology Inc.)

A wireless micro-sensor

is the integration of a

sensing unit, a

processing unit a power

unit and a

communication unit.

The signal processing

functions are performed

in the processing unit.

The communication part

consists of a receiver, a

transmitter and an

amplifier. All individual

sensor nodes are

operated by a limited

battery power.

Figure: Wireless MEMS model

Nanosensors are used in chemical

and biological sensory

applications to communicate

information about nanoparticles.

For example nanotubes are used

to sense various properties of

gaseous molecules.

Three-dimensional model of

three types of single-walled

carbon nanotubes.


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Literature Survey: The State of Monitoring Technologies in Healthcare

Human body temperature monitoring:

Accurate measurement of the human body's internal temperature is essential in many areas

of healthcare - from cancer treatments, fever screening, monitoring premature babies, to

heart attack or stroke treatments. The traditional approach to temperature monitoring is

through a manual process which often results in unreliable records and paper trails due to

the "human element".

Temperature Sensors:

Vital Sense Monitor:The monitor stores and display core and dermal

temperature data as well as heart rate of up to 10

sensors. Sensors are wireless transmitters and are pre-

calibrated at the factory to simplify activation and

eliminate data entry errors. Vital Sense can provide

multi-day 24 hour monitoring and data logging without

wires or probes.

After sensor activation, each sensor transmits its first

value to the monitor within 15 seconds and then takes

another reading every 15 seconds. The subject must

wear the monitor in order for data to be received. In

Medic mode, the monitor will detect and collect signals

from any sensor in its range. In Medic Mode, data is time

stamped as it is collected.

Human Temperature Monitoring

Device, Bio-Lynx Scientific Equipment

inc.

Jonah Temperature Capsule:Ingestible core body temperature capsule transmitswirelessly to monitor every 15 seconds. The capsule, the

size of a large gel capsule, is swallowed with liquid,

travels and passes through the GI tact within 12 to 24

hours without affecting other bodily functions.

Human Temperature Monitoring

Device, Bio-Lynx Scientific Equipment

inc.

DataTherm Veterinary Temperature Monitor:The DataTherm Vet continuously monitors a patients

body temperature and features a real time temperature

display, updated every 4 seconds. A range of 62.6F to

113F temperatures makes it applicable for most speciesincluding exotics. Features include; programmable high

and low alarms, dual scale Fahrenheit or Celsius,

memory recall for up to 70 readings, and flexible 2mm

diameter x one meter long rectal probe with 25 covers(

core temp). Weighing less than 2 ounces and battery

operated, it is lightweight, portable and easy to use.

Ideal for surgery, recovery, and intensive care.DataTherm Veterinary Temperature

Monitor, Paragon Medical


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Pressure Sensors:

NPC-100 Pressure Sensor:NovaSensors NPC-100 pressure sensor is specifically

designed for use in disposable medical applications.

The device is compensated and calibrated per the

Association for the Advancement of MedicalInstrumentation (AAMI) guidelines for industry

acceptability. The sensor integrates a high-

performance, pressure sensor die with temperature

compensation circuitry and gel protection in a small,

low-cost package.

NPC-100 Pressure Sensor, GE

Sensing and Inspection

Technologies

Intra-uterine Pressure Sensor:Silicon MEMS-based pressure sensors are used in

intrauterine pressure (IUP) sensors to measure

contraction pressure and frequency during childbirth.

This method is more reliable than conventional belts

and is used in critical cases. Additional features can bebuilt into these sensors such as amnion fluid infusion

and extraction. These sensors are inserted through the

uterus and reside in the amnion sack.Intra-uterine Pressure Sensor,

Measurement Specialties, Inc.


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ECG:

The electrocardiogram, or ECG / EKG are

a surface measurement of the electrical

potential generated by electrical activity

in cardiac tissue. Current flow, in theform of ions, signals contraction of

cardiac muscle fibres leading to the

heart's pumping action. The ECG records

the electrical activity that results when

the heart muscle cells in the atria and

ventricles contract. Interpretation of

these details allows diagnosis of a wide

range of heart conditions. These

conditions can vary from minor to life

threatening.

ECG Sensors:

Vital Sense XHR Sensor:The Vital Sense XHR Sensor is an innovative, rechargable,

compact device that wirelessly transmits Heart rate and

respiration rate to the VitalSense monitor. This chest-worn

wireless physiological monitor incorporates an ECG-signal

processor reporting average heart and respiration rate

every 15 seconds to the VitalSense Monitor.

Vital Sense XHR Sensor, Bio-Lynx

Scientific Equipment inc.

Thought Technology ECG/EKG Sensor (SA9306M):

The Thought Technology pre-amplified electrocardiograph

(ECG/EKG) sensor (T9306M) for the Procomp Infiniti

Systems or Procomp+. Used for directly measuring

electrical activity of the heart. The T9306M EKG Sensor

connects via extender cables for a single channel hook up.

Operating Principle:

Use the Sensor Extender Cable (TTL T8720M). The surface

electrodes monitor electrical activity from the heart

muscle. Place the active electrodes along the central axis

of the heart and the reference electrode on the opposite

side of the chest.

Thought Technology ECG/EKG

Sensor (SA9306M)

Condition Monitoring in Maritime Sector

Safety and performance are the top concerns in a cruise ship. Fault monitoring and

failure prevention of the machineries are thus essential in a cruise ship operation.

Preventive maintenance and predictive maintenance also known as condition

monitoring of the machines are thus considered to be very important in determining

the state of the ship engine room machines.


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Maintenance management methods:

Reactive maintenance:Reactive maintenance is the run till failure maintenance mode. This

method is very expensive. It has increased labour cost as it is very

likely to be associated with overtime payments. It also has increased

cost due to unplanned downtime of equipment. It is often involved

with costly possible secondary equipment or process damage from

the failure of the equipment.

Preventative maintenance:Preventive maintenance is a schedule of planned maintenance actions

aimed at the prevention of breakdowns and failures. The primary goal

of preventive maintenance is to prevent the failure of equipment

before it actually occurs. Time based maintenance is not totally

effective when the time to failure of the part cannot be determined

accurately.

Predictive maintenance:Predictive maintenance or condition monitoring is the process of

monitoring equipment as it operates. The main issue is to identify a

suitable parameter which can be used to reliably predict the failure.

Nearly 25% of casualties at sea caused by machinery failure. Land based industries

claim up to 40% savings when switching from planned to predictive maintenance.

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