Temperature controlled water faucet

1
Temperature controlled water faucet

• Tarek Fathy
• Wesam Salama

Project 36 Spring 04
April 28, 2004
2
Overview

• Objectives
• Features
• Block diagram
• Microcontroller
• Motors and Valves
• Potentiometers
• Temperature Sensor
• Buttons and Infrared
• Motor Driver circuit
• LCD
• Software
• Control
• Narrow Down
• Testing
• Modular
• Integrated
• Cost
• Possible Enhancements

3
Objectives

• Objectives
• Features
• Block diagram
• Microcontroller
• Motors and Valves
• Potentiometers
• Temperature Sensor
• Buttons and Infrared
• Motor Driver circuit
• LCD

• To design and build a temperature controlled
  water faucet
• To provide user with a simple one-button
  user-friendly interface
• To provide user with unvarying water temperature
  and flow
• To eliminate the need for manual temperature
  adjustment

4
Features

• Objectives
• Features
• Block diagram
• Microcontroller
• Motors and Valves
• Potentiometers
• Temperature Sensor
• Buttons and Infrared
• Motor Driver circuit
• LCD

• Infrared activation of faucet
• Button to cylce through five settings Hot,
  Hot-Warm, Warm, Cold-Warm, and Cold
• Fast speed of response settling time lt6sec
• Temperatures accurate to within 2 C
• LCD screen displaying current water temperature
  and setting

5
Block Diagram

• Objectives
• Features
• Block diagram
• Microcontroller
• Motors and Valves
• Potentiometers
• Temperature Sensor
• Buttons and Infrared
• Motor Driver circuit
• LCD

6
Microcontroller

• Objectives
• Features
• Block diagram
• Microcontroller
• Motors and Valves
• Potentiometers
• Temperature Sensor
• Buttons and Infrared
• Motor Driver circuit
• LCD

• Utilized the BasicX-24 microcontroller
• Powerful yet easily programmed
• Built-in ADC feature
• Effortlessly integrated with LCD module

7
Motors and Valves

• Objectives
• Features
• Block diagram
• Microcontroller
• Motors and Valves
• Potentiometers
• Temperature Sensor
• Buttons and Infrared
• Motor Driver circuit
• LCD

• Used two 12 VDC motors
• Gear ratio 65.51
• Two quarter-turn ball valves

8
Motors and Valves (contd)

• Objectives
• Features
• Block diagram
• Microcontroller
• Motors and Valves
• Potentiometers
• Temperature Sensor
• Buttons and Infrared
• Motor Driver circuit
• LCD

• Load(valve) torque measurement
• T (I INL)(KT N h)
• where
• I Current
• INL Current with no load
• KT torque constant
• N Gear ratio
• h gear head efficiency
• T (0.9A 0.3A) (0.0182 oz.in/A 65.5
  0.66)
• 0.472 oz.in
• Max continuous Torque 6.1 oz.in

9
Potentiometers

• Objectives
• Features
• Block diagram
• Microcontroller
• Motors and Valves
• Potentiometers
• Temperature Sensor
• Buttons and Infrared
• Motor Driver circuit
• LCD

• Replaced initial use of encoders
• High cost of encoders
• Unnecessary complexity
• Uses a large amount of input pins
• Two 5KO 10-turn pots provide sufficient accuracy
• 21 gear ratio needed between motor and pot
• Calibrated as 600O for fully open, and 4.5 KO for
  fully closed

10
Temperature Sensor

• Objectives
• Features
• Block diagram
• Microcontroller
• Motors and Valves
• Potentiometers
• Temperature Sensor
• Buttons and Infrared
• Motor Driver circuit
• LCD

• MTS102 provides linear response between 0 -
  100 C
• Fast response and accurate to within 2 C
• VBE varies linearly with change in temperature
• of 0-100 C from 425mV to 650mV
• Amplification of VBE needed to allow good A-D
  conversion

11
Temperature Sensor (contd)

• Objectives
• Features
• Block diagram
• Microcontroller
• Motors and Valves
• Potentiometers
• Temperature Sensor
• Buttons and Infrared
• Motor Driver circuit
• LCD

• Difference amplifier opamp circuit used
• Vout(Voffset VBE)(R2/R1)
• Need output range 0-5V
• Gain ß 22.2
• T (0.595- VBE)/2.265E-3 25
• Equation used by microcontroller
• Temp 19.896 Vout 0.617

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Buttons and Infrared

• Objectives
• Features
• Block diagram
• Microcontroller
• Motors and Valves
• Potentiometers
• Temperature Sensor
• Buttons and Infrared
• Motor Driver circuit
• LCD

• Normally-Open push-button changes microcontroller
  setting
• Matched IR emitter and detector pair at 950nm
  wavelength
• Detector outputs a high to microcontroller when
  infrared detected, which turns water on

13
Motor Driver circuit

• Objectives
• Features
• Block diagram
• Microcontroller
• Motors and Valves
• Potentiometers
• Temperature Sensor
• Buttons and Infrared
• Motor Driver circuit
• LCD

• Microcontroller output current insufficient for
  dirving motors
• H-Bridge used between BX-24 and motors
• H-Bridge allows reversal of high-current load and
  very fast switching of motor current

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LCD

• Objectives
• Features
• Block diagram
• Microcontroller
• Motors and Valves
• Potentiometers
• Temperature Sensor
• Buttons and Infrared
• Motor Driver circuit
• LCD

• 2X16 Serial LCD compatible with BX-24 was used
• Displays actual current temperature and state of
  microcontroller

15
Software

• Objectives
• Features
• Block diagram
• Microcontroller
• Motors and Valves
• Potentiometers
• Temperature Sensor
• Buttons and Infrared
• Motor Driver circuit
• LCD

• Code in Basic is uploaded to the microcontroller
  which in turn controls motors, LCD, using inputs
  from button, sensors, and potentiometers
• Divided mainly into two subroutines
• Control Employed when tempdiff gt 7 C
• Pulses are sent to motors without continuous
  temperature comparison
• Narrow down Employed when tempdiff lt 7 C
• One pulse is sent after every comparison
• tempdiff desired temp actual temp

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Software (control)

• Objectives
• Features
• Block diagram
• Microcontroller
• Motors and Valves
• Potentiometers
• Temperature Sensor
• Buttons and Infrared
• Motor Driver circuit
• LCD

• We implemented proportional control with
  temperature feedback
• Measured number of pulses necessary to open/close
  valves completely (85 pulses)
• Measured water temperature extremes at several
  locations (11 C 55 C)
• Used this data to produce a linear curve of
  pulses vs. temp change

17
Control (contd)

• Objectives
• Features
• Block diagram
• Microcontroller
• Motors and Valves
• Potentiometers
• Temperature Sensor
• Buttons and Infrared
• Motor Driver circuit
• LCD

• If tempdiff gt 7 C, of pulses K tempdiff
• Complimentary opening and closing of valves
• K is determined as the slope of this curve
• K 1.9318

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Narrow Down

• Objectives
• Features
• Block diagram
• Microcontroller
• Motors and Valves
• Potentiometers
• Temperature Sensor
• Buttons and Infrared
• Motor Driver circuit
• LCD

• Employed when tempdiff lt 7 C
• Fine tuning the output to match the desired
  temperature
• Complimentary routine is also employed after each
  pulse to maintain constant flow

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Testing

• Objectives
• Features
• Block diagram
• Microcontroller
• Motors and Valves
• Potentiometers
• Temperature Sensor
• Buttons and Infrared
• Motor Driver circuit
• LCD

• Modular testing
• Potentiometers
• Sensor compared LCD readings to digital
  thermometer readings
• Motor driver (H-bridge)
• Button and LCD

20
Testing (contd)

• Objectives
• Features
• Block diagram
• Microcontroller
• Motors and Valves
• Potentiometers
• Temperature Sensor
• Buttons and Infrared
• Motor Driver circuit
• LCD

• Integrated testing
• Tested all possible state transitions
• Max Settling time 5 sec

21
Cost

• Objectives
• Features
• Block diagram
• Microcontroller
• Motors and Valves
• Potentiometers
• Temperature Sensor
• Buttons and Infrared
• Motor Driver circuit
• LCD

22
Cost (contd)

• Objectives
• Features
• Block diagram
• Microcontroller
• Motors and Valves
• Potentiometers
• Temperature Sensor
• Buttons and Infrared
• Motor Driver circuit
• LCD

• Labor costs per person 30/hr 2.5 120
  9000
• Total Labor costs 9000 2 18,000
• Total Costs
• Parts costs Labor costs 18,160.29

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Possible Enhancements

• Objectives
• Features
• Block diagram
• Microcontroller
• Motors and Valves
• Potentiometers
• Temperature Sensor
• Buttons and Infrared
• Motor Driver circuit
• LCD

• Flow Control
• Current system assumes linearity of flow,
  improvement of control could be made by modeling
  closer to actual rates

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Possible Enhancements(contd)

• Objectives
• Features
• Block diagram
• Microcontroller
• Motors and Valves
• Potentiometers
• Temperature Sensor
• Buttons and Infrared
• Motor Driver circuit
• LCD

• Auto-calibrate
• PCB board (unable to complete on time)
• Allow user to set system to any temperature
  he/she desires

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Thank YouQuestions?