Presenter: Yang Fei

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Sensors and Robotic Environment for Care of the
ElderlyS. C. Mukhopadhyay and G. Sen Gupta
Massy University, Palmerston North, New
ZealandSingapore Polytechnic, Singapore

• Presenter Yang Fei
• yangfei_at_islab.ulsan.ac.kr
• The 10th of December, 2011

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System developed for the elder care

• Sub-systems
• 1 Selective Activity Monitoring(SAM)
  system(detect the electric appliances)
• 2 Low-cost Physiological Parameters
  Monitoring(PPM) system
• 3 Web-enabled, robot-based vision system
  (get pictures)

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Selective Activity Monitoring(SAM) system

• Objective monitor electrical appliances

Cellular modem
Appliance
Sensor Unit
RS232
RS232
PC
Appliance
Sensor Unit
Central Controller Unit
Appliance
Sensor Unit
1 The Sensor Units 2 The Central Controller
Unit 3 A PC and a cellular modem
Function block diagram
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System architecture

• Electrical appliance such as a reading lamp,
  room heater. (detect the current)
• Communication between PC and the central
  controller RS232.
• Communication between sensor units and the
  central controller Radio.
• Radio communication
• frequency 418MHz
• maximum data transfer rate 40kbps
• A cellular modem send short messages

Wavecom Wismo cellular modem-WISMO218 (GSM/GPRS
wireless communication module)
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Core components of the Sensor Unit(SU)
microcontroller
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Design of the Sensor Unit

• Power 230V/50Hz AC mains
• 5V3.3V DC mains
• Radio Frequency module
• Radiometrix(company) BiM418
  transceiver
• half-duplex operation at 418MHz

LeftTXM-418-5 transmitter right SILRX-418-5
receiver
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Parameters of the system

• TxSelect/ RxSelect configure the transmit or
  receive mode of the RF transceiver
• Tx/Rx transmit and receive data (data rate
  38400 bauds)
• series communication ports
• Microcontroller SiLab C8051F020

radio frequency module
TxSelect
RxSelect
Rx
Tx
microcontroller
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Microcontroller
ATmega128
9
Baud

• One concept in analog modulation symbols per
  second or pulses per second.
• M different voltage levels
• R bps
• fs baud

0
1
0 1
0
1
0 0 0
0 1
1 1
0 0
1 0
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Current transformer connections and circuitry

• CT(Current Transformer) coil based on
  electromagnetic induction
• AC current
• DAC programmable voltage of the
  Digital-to-Analog(DAC) converter output of the
  microcontroller
• LM329(? voltage regulator) op-amp (opposite
  amplifier) based comparator. National
  Semiconductor Corporation(USA)
• Professional comparators LM339, LM393
• Comparators LM324, LM358, ,
  TL081/2/3/4, OP07, OP27

µA741
Nonlinear current change
Nonlinear magnetism change
Nonlinear current change
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Current transformer connections and circuitry

• External interrupts a series of pulses(50Hz)
  sent to microcontroller
• Power need single 5V DC.
• Peak voltage 2V (when load current is 10A)
• Resistor 120 O
• Voltage shifted up 2.5V (avoid negative voltage
  at the input of the comparator)

Coil inductance
2.5V
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Detect the status of an appliance

• Detection software continuously evaluate whether
  the load is active or not
• Interrupt every 500ms
• Active 10 external interrupts occur within 500ms.

External interrupt
Receive timer generated interrupt
Count numbers of current pulses
If number of current pulses is greater than 10
Set activity variable high
Set activity variable low
Restart the timer and clear the current pulses
count
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Design of the Central Controller Unit(CCU)

• Similar to the SU(Sensor Unit)
• LED 1 indicate the power to the CCU is on
• 2 show that the CCU is in transmit
  mode
• 3 indicate that the CCU is in
  receive mode
• RS232 115200bauds (115200bps)

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Radio Frequency Communication protocol

• All the sensor units communicate with the central
  controller unit on the same frequency
• Method the sensors will respond only when told
  to do so.

PC
PC requests data from a particular sensor
PC receives the data from the specified sensor
Central Unit
Controller initializes the particular sensor
Controller interprets the data and relays it to
the PC
Sensor Unit
Sensor responds with the activity data
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Radio frequency communication packets

• RF communication packet sent by the controller
• RF communication packet sent by the sensor unit

Start byte ID byte end byte
Start byte ID byte activity byte end byte
Description Hex Value Binary Value
Start byte 0x55 01010101
End byte 0x6C 01101100
ID byte 1 0x63 01100011
ID byte 2 0x33 00110011
ID byte 3 0x36 00110110
ID byte 4 0x3A 00111010
Activity byte active 0x53 01010011
Activity byte inactive 0x69 01101001
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conclusion

• This paper presented the design of a Selective
  Activity Monitoring system and the applied
  research into the implementation issues.

completely fabricated system
the sensor unit