Solution Manual for Sensors and Actuators: Engineering System Instrumentation, 2nd Edition
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SOLUTIONS MANUAL FOR
SENSORS AND
ACTUATORS
Engineering System Instrumentation
SECOND EDITION
Clarence W. de Silva
by
SENSORS AND
ACTUATORS
Engineering System Instrumentation
SECOND EDITION
Clarence W. de Silva
by
iii
CONTENTS
Preface
Chapter 1 Instrumentation of an Engineering System
Chapter 2 Component Interconnection and Signal Conditioning
Chapter 3 Performance Specification and Instrument Rating Parameters
Chapter 4 Estimation from Measurements
Chapter 5 Analog Sensors and Transducers
Chapter 6 Digital and Innovative Sensing
Chapter 7 Mechanical Transmission Components
Chapter 8 Stepper Motors
Chapter 9 Continuous-Drive Actuators
CONTENTS
Preface
Chapter 1 Instrumentation of an Engineering System
Chapter 2 Component Interconnection and Signal Conditioning
Chapter 3 Performance Specification and Instrument Rating Parameters
Chapter 4 Estimation from Measurements
Chapter 5 Analog Sensors and Transducers
Chapter 6 Digital and Innovative Sensing
Chapter 7 Mechanical Transmission Components
Chapter 8 Stepper Motors
Chapter 9 Continuous-Drive Actuators
iii
CONTENTS
Preface
Chapter 1 Instrumentation of an Engineering System
Chapter 2 Component Interconnection and Signal Conditioning
Chapter 3 Performance Specification and Instrument Rating Parameters
Chapter 4 Estimation from Measurements
Chapter 5 Analog Sensors and Transducers
Chapter 6 Digital and Innovative Sensing
Chapter 7 Mechanical Transmission Components
Chapter 8 Stepper Motors
Chapter 9 Continuous-Drive Actuators
CONTENTS
Preface
Chapter 1 Instrumentation of an Engineering System
Chapter 2 Component Interconnection and Signal Conditioning
Chapter 3 Performance Specification and Instrument Rating Parameters
Chapter 4 Estimation from Measurements
Chapter 5 Analog Sensors and Transducers
Chapter 6 Digital and Innovative Sensing
Chapter 7 Mechanical Transmission Components
Chapter 8 Stepper Motors
Chapter 9 Continuous-Drive Actuators
v
PREFACE
This manual is prepared primarily to assist the instructors who use the book SENSORS
AND ACTUATORS—Engineering System Instrumentation, 2nd Edition. It includes hints
for structuring the material for a course in the subject and provides complete solutions to
the end of chapter problems of the textbook.
The book SENSORS AND ACTUATORS—Engineering System Instrumentation,
2nd Edition, introduces the subject of Engineering System Instrumentation, with an
emphasis on sensors, transducers, actuators, and signal modification devices.
Specifically, it deals with “instrumenting” an engineering system through the
incorporation of suitable sensors, actuators, and associated interface hardware. It will
serve as both a textbook for engineering students and a reference book for practicing
professionals. As a textbook, it is suitable for courses in control system instrumentation;
sensors and actuators; instrumentation of engineering systems; and mechatronics. There
is adequate material in the book for two fourteen-week courses, one at the junior (third-
year undergraduate) or senior (fourth-year undergraduate) level and the other at the first-
year graduate level. In view of the practical considerations, design issues, and industrial
techniques that are presented throughout the book, and in view of the simplified and
snap-shot style presentation of more advanced theory and concepts, the book will serve as
a useful reference tool for engineers, technicians, project managers, and other practicing
professionals in industry and in research laboratories, in the fields of control engineering,
mechanical engineering, electrical and computer engineering, manufacturing engineering,
and mechatronics.
The material presented in the book serves as a firm foundation, for subsequent
building up of expertise in the subject—perhaps in an industrial setting or in an academic
research laboratory—with further knowledge of hardware, software, and analytical skills
(along with the essential hands-on experience) gained during the process. Undoubtedly,
for best results, a course in sensors and actuators, mechatronics, or engineering system
instrumentation should be accompanied by a laboratory component and class projects.
Sensors are needed to measure (sense) unknown signals and parameters of an
engineering system and its environment. This knowledge will be useful not only in
operating or controlling the system but also for many other purposes such as process
monitoring; experimental modeling (i.e., model identification); product testing and
qualification; product quality assessment; fault prediction, detection and diagnosis;
warning generation; and surveillance. Actuators are needed to “drive” a plant. As another
category of actuators, control actuators perform control actions, and in particular they
drive control devices. Since many different types and levels of signals are present in a
dynamic system, signal modification (including signal conditioning and signal
conversion) is indeed a crucial function associated with sensing and actuation. In
particular, signal modification is an important consideration in component interfacing. It
is clear that the subject of system instrumentation should deal with sensors, transducers,
actuators, signal modification, and component interconnection. In particular, the subject
should address the identification of the necessary system components with respect to
type, functions, operation and interaction, and proper selection and interfacing of these
components for various applications. Parameter selection (including component sizing
and system tuning) is an important step as well. Design is a necessary part of system
PREFACE
This manual is prepared primarily to assist the instructors who use the book SENSORS
AND ACTUATORS—Engineering System Instrumentation, 2nd Edition. It includes hints
for structuring the material for a course in the subject and provides complete solutions to
the end of chapter problems of the textbook.
The book SENSORS AND ACTUATORS—Engineering System Instrumentation,
2nd Edition, introduces the subject of Engineering System Instrumentation, with an
emphasis on sensors, transducers, actuators, and signal modification devices.
Specifically, it deals with “instrumenting” an engineering system through the
incorporation of suitable sensors, actuators, and associated interface hardware. It will
serve as both a textbook for engineering students and a reference book for practicing
professionals. As a textbook, it is suitable for courses in control system instrumentation;
sensors and actuators; instrumentation of engineering systems; and mechatronics. There
is adequate material in the book for two fourteen-week courses, one at the junior (third-
year undergraduate) or senior (fourth-year undergraduate) level and the other at the first-
year graduate level. In view of the practical considerations, design issues, and industrial
techniques that are presented throughout the book, and in view of the simplified and
snap-shot style presentation of more advanced theory and concepts, the book will serve as
a useful reference tool for engineers, technicians, project managers, and other practicing
professionals in industry and in research laboratories, in the fields of control engineering,
mechanical engineering, electrical and computer engineering, manufacturing engineering,
and mechatronics.
The material presented in the book serves as a firm foundation, for subsequent
building up of expertise in the subject—perhaps in an industrial setting or in an academic
research laboratory—with further knowledge of hardware, software, and analytical skills
(along with the essential hands-on experience) gained during the process. Undoubtedly,
for best results, a course in sensors and actuators, mechatronics, or engineering system
instrumentation should be accompanied by a laboratory component and class projects.
Sensors are needed to measure (sense) unknown signals and parameters of an
engineering system and its environment. This knowledge will be useful not only in
operating or controlling the system but also for many other purposes such as process
monitoring; experimental modeling (i.e., model identification); product testing and
qualification; product quality assessment; fault prediction, detection and diagnosis;
warning generation; and surveillance. Actuators are needed to “drive” a plant. As another
category of actuators, control actuators perform control actions, and in particular they
drive control devices. Since many different types and levels of signals are present in a
dynamic system, signal modification (including signal conditioning and signal
conversion) is indeed a crucial function associated with sensing and actuation. In
particular, signal modification is an important consideration in component interfacing. It
is clear that the subject of system instrumentation should deal with sensors, transducers,
actuators, signal modification, and component interconnection. In particular, the subject
should address the identification of the necessary system components with respect to
type, functions, operation and interaction, and proper selection and interfacing of these
components for various applications. Parameter selection (including component sizing
and system tuning) is an important step as well. Design is a necessary part of system
vi
instrumentation, for it is design that enables us to build a system that meets the
performance requirements—starting, perhaps, with a few basic components such as
sensors, actuators, controllers, compensators, and signal modification devices. The main
objective of the book is to provide a foundation in all these important topics of
engineering system instrumentation.
A Note to the Instructors
A syllabus for a fourth year undergraduate course or a first year graduate course in the
subject is given below.
CONTROL SENSORS AND ACTUATORS
Prerequisites
For engineering graduate students: motivation
For undergraduate students: A course in feedback controls
+ consent of the instructor
Introduction
Actuators are needed to perform control “actions” as well as to directly “drive” a plant
(process, machine, engine). Sensors and transducers are necessary to “measure” output
signals for feedback control, to “measure” input signals for feedforward control, to
“measure” process variables for system monitoring, diagnosis and supervisory control,
and for a variety of other purposes of measurement.
The course will study a selected set of sensors, actuators, and signal modification
devices as employed in robotic and mechatronic systems. General and practical issues of
sensors and actuators in an engineering system will be discussed. Operating principles,
modelling, design considerations, ratings, specifications, selection, and applications of
typical sensors and actuators will be studied. Filtering amplification, error analysis, and
estimation from measured data will be covered as complementary topics.
Textbook
De Silva, C.W., SENSORS AND ACTUATORS—Engineering System Instrumentation,
Taylor & Francis, 2nd Edition, Taylor & Francis/CRC Press, Boca Raton, FL, 2015.
instrumentation, for it is design that enables us to build a system that meets the
performance requirements—starting, perhaps, with a few basic components such as
sensors, actuators, controllers, compensators, and signal modification devices. The main
objective of the book is to provide a foundation in all these important topics of
engineering system instrumentation.
A Note to the Instructors
A syllabus for a fourth year undergraduate course or a first year graduate course in the
subject is given below.
CONTROL SENSORS AND ACTUATORS
Prerequisites
For engineering graduate students: motivation
For undergraduate students: A course in feedback controls
+ consent of the instructor
Introduction
Actuators are needed to perform control “actions” as well as to directly “drive” a plant
(process, machine, engine). Sensors and transducers are necessary to “measure” output
signals for feedback control, to “measure” input signals for feedforward control, to
“measure” process variables for system monitoring, diagnosis and supervisory control,
and for a variety of other purposes of measurement.
The course will study a selected set of sensors, actuators, and signal modification
devices as employed in robotic and mechatronic systems. General and practical issues of
sensors and actuators in an engineering system will be discussed. Operating principles,
modelling, design considerations, ratings, specifications, selection, and applications of
typical sensors and actuators will be studied. Filtering amplification, error analysis, and
estimation from measured data will be covered as complementary topics.
Textbook
De Silva, C.W., SENSORS AND ACTUATORS—Engineering System Instrumentation,
Taylor & Francis, 2nd Edition, Taylor & Francis/CRC Press, Boca Raton, FL, 2015.
vii
Course Plan
Week Starts on Topic Read
1 Jan. 06 Introduction Chapter 1
2 Jan. 13 Performance Specification,
Instrumentation of Engineering
Systems
Chapter 3
3 Jan. 20 Component Matching, Amplifiers,
Filters, and Other Interface Hardware
Chapter 2
4 Jan. 27 Estimation from Measured Data Chapter 4
5 Feb. 03 Analog Motion Sensors Chapter 5
6 Feb. 10
Project proposals due.
Torque and Force Sensors Chapter 5
7 Feb. 17 Digital Motion Sensors, Tactile
Sensors, and Innovative Sensors
Chapter 6
8 Feb. 24 Mechanical Transmission Devices Chapter 7
9 Mar. 02 Stepper Motors Chapter 8
10 Mar. 09 DC and AC Motors Chapter 9
11 Mar. 16
(Exam on Mar. 16)
Hydraulic Actuators Chapter 9
12 Mar. 23 Review Chapters 1-9
13 Mar. 30 Project presentations.
14 Apr. 6 Project presentations.
Note: Final Take-Home Exam/Project Report due on April 12th.
Grade Composition
Intermediate exam = 30%
Project proposal = 10%
Attendance/Participation = 10%
Final Take-Home Exam/Project = 50%
100%
====
Clarence W. de Silva
Vancouver, Canada
Course Plan
Week Starts on Topic Read
1 Jan. 06 Introduction Chapter 1
2 Jan. 13 Performance Specification,
Instrumentation of Engineering
Systems
Chapter 3
3 Jan. 20 Component Matching, Amplifiers,
Filters, and Other Interface Hardware
Chapter 2
4 Jan. 27 Estimation from Measured Data Chapter 4
5 Feb. 03 Analog Motion Sensors Chapter 5
6 Feb. 10
Project proposals due.
Torque and Force Sensors Chapter 5
7 Feb. 17 Digital Motion Sensors, Tactile
Sensors, and Innovative Sensors
Chapter 6
8 Feb. 24 Mechanical Transmission Devices Chapter 7
9 Mar. 02 Stepper Motors Chapter 8
10 Mar. 09 DC and AC Motors Chapter 9
11 Mar. 16
(Exam on Mar. 16)
Hydraulic Actuators Chapter 9
12 Mar. 23 Review Chapters 1-9
13 Mar. 30 Project presentations.
14 Apr. 6 Project presentations.
Note: Final Take-Home Exam/Project Report due on April 12th.
Grade Composition
Intermediate exam = 30%
Project proposal = 10%
Attendance/Participation = 10%
Final Take-Home Exam/Project = 50%
100%
====
Clarence W. de Silva
Vancouver, Canada
Loading page 6...
Chapter 1 Instrumentation of an Engineering System
Solution 1.1
Open-Loop Control System
This does not use information on current response of the “plant” to establish the control
action. E.g., so-called feed-forward control of a robot arm. The joint torques (or motor
input signals) are computed using a dynamic model of the robot (inverse plant) with
desired angles of rotation as inputs. These signals drive the joint motors, which in turn
produce the actual joint angles. In the open-loop case these are not measured and
feedback.
Another example would be a household stove (gas or electric). The heat setting is
manually selected. The actual heat flow is not measured.
Feedback Control System
This uses information on plant response to establish the control input. E.g., in feedback
control of robot arms, joint angles (and angular velocities) are measured using suitable
sensors (optical encoders, resolvers, pots, tachometers, RVDT’s, etc.). This information
is used in feedback to compute the control action.
In thermostatic control of temperature in a building, the temperature is measured,
compared with the set point value (reference input) and the sign of the difference is used
to turn on or shut off the heat source.
Simple Oscillator:
The oscillator (mass-spring-damper) is considered the plant in this case. The “apparent”
feedback path (through k) is a “natural” feedback within the plant. The response y is not
sensed and used to determine f(t) to control the oscillator. Hence the system
configuration is not a feedback control system.
If, however, mass m is considered the plant, then the spring can be interpreted as a
“passive” feedback element. The spring “senses” the position of the mass and feeds back
a force to restore the position of the mass. In this sense it is a (passive) feedback control
system.
___________________________________________________________________________
Solution 1.2
Lights On-off System for an Art Gallery
There are two essential measurements in this system
(a) Light intensity detection
(b) People count.
We should not measure the light intensity inside the gallery because there will be
ambiguity as to the control action. Specifically, when the lights are on at night, the
sensor would probably instruct the lights to be turned off thinking it is the day time
because it could not differentiate between daylight and artificial light. To avoid this, a
simple timer to indicate a rational time interval as the night time (e.g., 7:00 p.m. - 12:00
Solution 1.1
Open-Loop Control System
This does not use information on current response of the “plant” to establish the control
action. E.g., so-called feed-forward control of a robot arm. The joint torques (or motor
input signals) are computed using a dynamic model of the robot (inverse plant) with
desired angles of rotation as inputs. These signals drive the joint motors, which in turn
produce the actual joint angles. In the open-loop case these are not measured and
feedback.
Another example would be a household stove (gas or electric). The heat setting is
manually selected. The actual heat flow is not measured.
Feedback Control System
This uses information on plant response to establish the control input. E.g., in feedback
control of robot arms, joint angles (and angular velocities) are measured using suitable
sensors (optical encoders, resolvers, pots, tachometers, RVDT’s, etc.). This information
is used in feedback to compute the control action.
In thermostatic control of temperature in a building, the temperature is measured,
compared with the set point value (reference input) and the sign of the difference is used
to turn on or shut off the heat source.
Simple Oscillator:
The oscillator (mass-spring-damper) is considered the plant in this case. The “apparent”
feedback path (through k) is a “natural” feedback within the plant. The response y is not
sensed and used to determine f(t) to control the oscillator. Hence the system
configuration is not a feedback control system.
If, however, mass m is considered the plant, then the spring can be interpreted as a
“passive” feedback element. The spring “senses” the position of the mass and feeds back
a force to restore the position of the mass. In this sense it is a (passive) feedback control
system.
___________________________________________________________________________
Solution 1.2
Lights On-off System for an Art Gallery
There are two essential measurements in this system
(a) Light intensity detection
(b) People count.
We should not measure the light intensity inside the gallery because there will be
ambiguity as to the control action. Specifically, when the lights are on at night, the
sensor would probably instruct the lights to be turned off thinking it is the day time
because it could not differentiate between daylight and artificial light. To avoid this, a
simple timer to indicate a rational time interval as the night time (e.g., 7:00 p.m. - 12:00
Loading page 7...
SENSORS AND ACTUATORS2
midnight) could be used. Alternatively a photo-voltaic sensor could be installed outside
the windows of the gallery or on top of a sunroof.
People count has to be made directionally (i.e., entering or leaving) at each door.
Hence a pair of probes is needed. Force sensors on the floor, turnstile counters, or light-
pulse sensors may be used for this purpose. For example, consider the following
arrangement:
The light beams are generated by laser or LED visible-light sources. They are received
by a pair of photo-voltaic cells. When the beam is intercepted for a short period of time,
an output pulse is generated at the corresponding photo cell (see Figure S1.2(a). The
order of the pulses determines the direction (entrance or exit) of travel.
Even though measurements are made in the system, this is essentially an “open-
loop” control system, as clear from the system schematic diagram shown in Figure
S1.2(b).
Figure S1.2: (a) People counting device; (b) Control system.
The system output is the on/off status of the switch controlling the gallery lights. Even
though the number of people in the gallery is counted and the light intensity is measured
to control the switch, the status of the switch is not used to control the number of people
in the gallery, or the day-light intensity. Hence there is no feedback path.1 2
Output Pulses
Photo-Voltaic Sensor
Light-Beam
Sources
(a)Micro-
controller
Clock
Pulse Pairs
From Each
Door
ADC
Signal From
Light-Intensity
Sensor
DAC
On/off
Logic Amplifier,
Solenoid
On/off
Switch
(b)
midnight) could be used. Alternatively a photo-voltaic sensor could be installed outside
the windows of the gallery or on top of a sunroof.
People count has to be made directionally (i.e., entering or leaving) at each door.
Hence a pair of probes is needed. Force sensors on the floor, turnstile counters, or light-
pulse sensors may be used for this purpose. For example, consider the following
arrangement:
The light beams are generated by laser or LED visible-light sources. They are received
by a pair of photo-voltaic cells. When the beam is intercepted for a short period of time,
an output pulse is generated at the corresponding photo cell (see Figure S1.2(a). The
order of the pulses determines the direction (entrance or exit) of travel.
Even though measurements are made in the system, this is essentially an “open-
loop” control system, as clear from the system schematic diagram shown in Figure
S1.2(b).
Figure S1.2: (a) People counting device; (b) Control system.
The system output is the on/off status of the switch controlling the gallery lights. Even
though the number of people in the gallery is counted and the light intensity is measured
to control the switch, the status of the switch is not used to control the number of people
in the gallery, or the day-light intensity. Hence there is no feedback path.1 2
Output Pulses
Photo-Voltaic Sensor
Light-Beam
Sources
(a)Micro-
controller
Clock
Pulse Pairs
From Each
Door
ADC
Signal From
Light-Intensity
Sensor
DAC
On/off
Logic Amplifier,
Solenoid
On/off
Switch
(b)
Loading page 8...
CONTROL, INSTRUMENTATION, AND DESIGN 3
The operation of the control system is straightforward. The pulse signals from
each door are detected and timed. This determines the people entering and leaving. A
count (COUNT) is kept. Furthermore, the light intensity (INT) is measured and
compared with a desired level (INTD). A logic circuit can be developed to realize the
following logic: . .0 . . . .LOGIC COUNT GT AND INT LT INTD
If this function is TRUE, the lights are turned on using a suitable actuator (e.g., a
solenoid actuated by a current). Otherwise the lights are turned off.
___________________________________________________________________________
Solution 1.3
Component Component
Type
Stepper Motor Actuator
PID Circuit Controller
Power Amp Signal Modifier
ADC Signal Modifier
DAC Signal Modifier
Optical Encoder Sensor/transducer
Process Computer Controller
FFT Analyzer Signal Modifier
DSP Signal Modifier/Controller
___________________________________________________________________________
Solution 1.4
(a) Modeling errors, system parameter variations, random disturbances
(b) Use feedback control.
___________________________________________________________________________
Solution 1.5
Advantages of Analog Control:
Simple, extensive past experience is available, relatively easy to troubleshoot.
Disadvantages of Analog Control:
Assumes linear behavior (Coriolis and centrifugal forces, nonlinear damping, payload
changes may be present, which are nonlinear)
Bulky and costly.
Difficult to implement complex control schemes.
The operation of the control system is straightforward. The pulse signals from
each door are detected and timed. This determines the people entering and leaving. A
count (COUNT) is kept. Furthermore, the light intensity (INT) is measured and
compared with a desired level (INTD). A logic circuit can be developed to realize the
following logic: . .0 . . . .LOGIC COUNT GT AND INT LT INTD
If this function is TRUE, the lights are turned on using a suitable actuator (e.g., a
solenoid actuated by a current). Otherwise the lights are turned off.
___________________________________________________________________________
Solution 1.3
Component Component
Type
Stepper Motor Actuator
PID Circuit Controller
Power Amp Signal Modifier
ADC Signal Modifier
DAC Signal Modifier
Optical Encoder Sensor/transducer
Process Computer Controller
FFT Analyzer Signal Modifier
DSP Signal Modifier/Controller
___________________________________________________________________________
Solution 1.4
(a) Modeling errors, system parameter variations, random disturbances
(b) Use feedback control.
___________________________________________________________________________
Solution 1.5
Advantages of Analog Control:
Simple, extensive past experience is available, relatively easy to troubleshoot.
Disadvantages of Analog Control:
Assumes linear behavior (Coriolis and centrifugal forces, nonlinear damping, payload
changes may be present, which are nonlinear)
Bulky and costly.
Difficult to implement complex control schemes.
Loading page 9...
SENSORS AND ACTUATORS4
Tuning and adaptation cannot be carried out in real time.
Not very flexible (not adaptable to different processes and process conditions).
___________________________________________________________________________
Solution 1.6
The schematic diagram of an automated bottle-filling system is shown in Figure S1.6.
Figure S1.6: Schematic diagram of an automated bottle-filling system.
The operation of the automated bottle-filling system can be described by the following
series of steps:Container
Full Level Sensor
Empty Level Sensor
Proximity Sensor
(for Bottle Alignment)
Nozzle
Tank
Valve Actuator
Inlet Valve Controller
Valve Actuator
Exit Valve
Conveyor
MMotor
Sensor
Input
Power
Tuning and adaptation cannot be carried out in real time.
Not very flexible (not adaptable to different processes and process conditions).
___________________________________________________________________________
Solution 1.6
The schematic diagram of an automated bottle-filling system is shown in Figure S1.6.
Figure S1.6: Schematic diagram of an automated bottle-filling system.
The operation of the automated bottle-filling system can be described by the following
series of steps:Container
Full Level Sensor
Empty Level Sensor
Proximity Sensor
(for Bottle Alignment)
Nozzle
Tank
Valve Actuator
Inlet Valve Controller
Valve Actuator
Exit Valve
Conveyor
MMotor
Sensor
Input
Power
Loading page 10...
CONTROL, INSTRUMENTATION, AND DESIGN 5
1. When the power is on, the controller checks the sensor input to see (1) is the filling
container full, and (2) is there an empty bottle under the nozzle?
2. If the first condition is not satisfied, the inlet valve is opened to fill the container until
“full container” signal from the corresponding sensor is received.
3. If only the first condition is satisfied, the motor is activated to move an empty bottle
under the nozzle.
4. The motor is stopped when “bottle in position” is detected (from the proximity sensor).
5. The exit valve is opened to fill the bottle.
6. When “container is empty” signal is received (from empty level sensor) the exit valve is
closed. The motor is turned on again and the conveyor moves away the filled bottle.
7. Go to Step 1. The whole process is repeated again and again until either power is off or
the “process stop” command is received by the controller.
___________________________________________________________________________
Solution 1.7
Note that one component may perform several functions.
Controller: Thermostat
Actuator: Valve actuator
Sensor: Thermocouple, pilot flame detector
Signal Modification: Transmitters and signal conditioning devices for thermostat signal
to the valve, thermocouple signal, and pilot flame detector signal.
Operation: The thermocouple measures the room temperature, compares it with the set
point, and determines the error (= set point - actual temperature). If the error is positive,
a signal is transmitted to turn on the natural gas valve. If negative, the valve is turned
off. The pilot flame detector checks if the pilot flame is off. If so it overrides the
actuator signal and turns off the valve.
For better performance, measure the water flow rate, the inlet water temperature,
and the outside temperature and incorporate a feedforward control as well as the original
feedback scheme. In particular, the time delay in the process reaction can be considerably
reduced by this method. Also a more sophisticated control scheme may be able to
produce an improved temperature regulation, but it is not necessary in typical situations.
___________________________________________________________________________
Solution 1.8
(a) Load torque (using a dynamometer), or armature current of the dc motor
(b) Input temperature of the liquid (using a hot-wire device)
(c) Flow rate of the liquid (using a flow meter); Temperature outside the room (using a
thermocouple); Temperature of steam at radiator input
(d) Tactile forces at the gripper (using piezoelectric, capacitive or strain gauge sensors);
Weight of the part to be picked up
(e) Torque transmitted at manipulator joints (using strain gauge torque sensor); Curvature
of the seam contour (using image processing).
___________________________________________________________________________
1. When the power is on, the controller checks the sensor input to see (1) is the filling
container full, and (2) is there an empty bottle under the nozzle?
2. If the first condition is not satisfied, the inlet valve is opened to fill the container until
“full container” signal from the corresponding sensor is received.
3. If only the first condition is satisfied, the motor is activated to move an empty bottle
under the nozzle.
4. The motor is stopped when “bottle in position” is detected (from the proximity sensor).
5. The exit valve is opened to fill the bottle.
6. When “container is empty” signal is received (from empty level sensor) the exit valve is
closed. The motor is turned on again and the conveyor moves away the filled bottle.
7. Go to Step 1. The whole process is repeated again and again until either power is off or
the “process stop” command is received by the controller.
___________________________________________________________________________
Solution 1.7
Note that one component may perform several functions.
Controller: Thermostat
Actuator: Valve actuator
Sensor: Thermocouple, pilot flame detector
Signal Modification: Transmitters and signal conditioning devices for thermostat signal
to the valve, thermocouple signal, and pilot flame detector signal.
Operation: The thermocouple measures the room temperature, compares it with the set
point, and determines the error (= set point - actual temperature). If the error is positive,
a signal is transmitted to turn on the natural gas valve. If negative, the valve is turned
off. The pilot flame detector checks if the pilot flame is off. If so it overrides the
actuator signal and turns off the valve.
For better performance, measure the water flow rate, the inlet water temperature,
and the outside temperature and incorporate a feedforward control as well as the original
feedback scheme. In particular, the time delay in the process reaction can be considerably
reduced by this method. Also a more sophisticated control scheme may be able to
produce an improved temperature regulation, but it is not necessary in typical situations.
___________________________________________________________________________
Solution 1.8
(a) Load torque (using a dynamometer), or armature current of the dc motor
(b) Input temperature of the liquid (using a hot-wire device)
(c) Flow rate of the liquid (using a flow meter); Temperature outside the room (using a
thermocouple); Temperature of steam at radiator input
(d) Tactile forces at the gripper (using piezoelectric, capacitive or strain gauge sensors);
Weight of the part to be picked up
(e) Torque transmitted at manipulator joints (using strain gauge torque sensor); Curvature
of the seam contour (using image processing).
___________________________________________________________________________
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SENSORS AND ACTUATORS6
Solution 1.9
(a) Muscle contraction, body movements, body temperature, heart rate
(b) Decisions, profits, finished products
(c) Electric power, pollution rate.
(d) Front wheel turn, direction of heading, noise level, pollution level.
(e) Joint motions, position, velocity, acceleration, torque, end-effector motion.
___________________________________________________________________________
Solution 1.10
Lowest level: 1ms
Highest level:1 day 24 60 60sec 61 Hz 11 10
24 60 60
Hz
By Shannon’s sampling theorem, control bandwidth may be taken as half this value.
___________________________________________________________________________
Solution 1.11
The key features of a modern day cost effective process controller are:
(i) Programmability - This increases the flexibility of control by allowing
different control algorithms to be implemented without
the need to having to change any hardware.
(ii) Modularity - Extensions or modifications to existing hardware is
made least expensive by employing different modules of
control units to carry out different tasks, rather than using
an all-in-one approach. It also increases the reliability
since the failure of one module does not affect the
operation of others. Maintenance and repair become
easier and faster.
(iii) General
Purpose Hardware
- Use of such components allows replacement easier
and inexpensive.
___________________________________________________________________________
Solution 1.12
The programmable logic controller is an electronic device, which can switch on or off its
outputs depending on the status of its inputs. The switching characteristics can be
programmed to respond to almost any combination of input states. In Figure S1.12, a PLC is
employed to sort fruits on a conveyor into various categories depending on their size and
quality. At the feeding end of the conveyor is a camera, which captures images of the
incoming fruits and sends them to the image processing station for analysis. The output of
Solution 1.9
(a) Muscle contraction, body movements, body temperature, heart rate
(b) Decisions, profits, finished products
(c) Electric power, pollution rate.
(d) Front wheel turn, direction of heading, noise level, pollution level.
(e) Joint motions, position, velocity, acceleration, torque, end-effector motion.
___________________________________________________________________________
Solution 1.10
Lowest level: 1ms
Highest level:1 day 24 60 60sec 61 Hz 11 10
24 60 60
Hz
By Shannon’s sampling theorem, control bandwidth may be taken as half this value.
___________________________________________________________________________
Solution 1.11
The key features of a modern day cost effective process controller are:
(i) Programmability - This increases the flexibility of control by allowing
different control algorithms to be implemented without
the need to having to change any hardware.
(ii) Modularity - Extensions or modifications to existing hardware is
made least expensive by employing different modules of
control units to carry out different tasks, rather than using
an all-in-one approach. It also increases the reliability
since the failure of one module does not affect the
operation of others. Maintenance and repair become
easier and faster.
(iii) General
Purpose Hardware
- Use of such components allows replacement easier
and inexpensive.
___________________________________________________________________________
Solution 1.12
The programmable logic controller is an electronic device, which can switch on or off its
outputs depending on the status of its inputs. The switching characteristics can be
programmed to respond to almost any combination of input states. In Figure S1.12, a PLC is
employed to sort fruits on a conveyor into various categories depending on their size and
quality. At the feeding end of the conveyor is a camera, which captures images of the
incoming fruits and sends them to the image processing station for analysis. The output of
Loading page 12...
CONTROL, INSTRUMENTATION, AND DESIGN 7Image
Processing
Station
Programmable
Logic Controller
Size Attributes (On/Off)
Quality Attributes (On/Off)
Trigger
Synchronizing Signal
Gate Control Signals (On/Off)
Solenoids For
Gate Control
Conveyor
Camera
the image processor is a series of two state signals, each of which has a single attribute of
either size or quality, associated with it. That is, for each sample of fruit, only one size
attribute signal and only one quality attribute signal can be in the ON state, and all other
attribute signals must be in the OFF state. The PLC is programmed to switch ON one of its
outputs for a particular combination of its inputs. A series of such outputs drive, through
amplifiers (not shown), separate solenoids, which control the output ports for fruits. The
whole arrangement is synchronized by the PLC through a signal derived from an object
sensing device on the conveyor.
Figure S1.12: An automated grading system for fruit.
___________________________________________________________________________
Solution 1.13
Measure inputs for feedforward control.
Measure outputs for system monitoring, failure detection, and diagnosis.
Measure signals for security (safety) reasons and to sound an alarm.
Measure outputs during the teach mode and store for use in the repeat mode, in
teach/repeat applications.
1. Detonation sensor
2. Hot film mass-flow sensor
3. Crack sensor
4. Throttle position sensor
5. Cam sensor
Processing
Station
Programmable
Logic Controller
Size Attributes (On/Off)
Quality Attributes (On/Off)
Trigger
Synchronizing Signal
Gate Control Signals (On/Off)
Solenoids For
Gate Control
Conveyor
Camera
the image processor is a series of two state signals, each of which has a single attribute of
either size or quality, associated with it. That is, for each sample of fruit, only one size
attribute signal and only one quality attribute signal can be in the ON state, and all other
attribute signals must be in the OFF state. The PLC is programmed to switch ON one of its
outputs for a particular combination of its inputs. A series of such outputs drive, through
amplifiers (not shown), separate solenoids, which control the output ports for fruits. The
whole arrangement is synchronized by the PLC through a signal derived from an object
sensing device on the conveyor.
Figure S1.12: An automated grading system for fruit.
___________________________________________________________________________
Solution 1.13
Measure inputs for feedforward control.
Measure outputs for system monitoring, failure detection, and diagnosis.
Measure signals for security (safety) reasons and to sound an alarm.
Measure outputs during the teach mode and store for use in the repeat mode, in
teach/repeat applications.
1. Detonation sensor
2. Hot film mass-flow sensor
3. Crack sensor
4. Throttle position sensor
5. Cam sensor
Loading page 13...
SENSORS AND ACTUATORS8Controller
Sophistication
PhysicalComplexity
Passive
Damper
PID Controller
Nonliner Feedback
Controller
Fuzzy
Controller
Impedance
Cotnroller
6. Temperature sensor
7. Pressure sensor
___________________________________________________________________________
Solution 1.14
A graphical representation of controller classification is given in Figure S1.14.
Figure S1.14: A graphical method of controller classification.
___________________________________________________________________________
Solution 1.15
By digital it does not mean that X-ray is not used. It implies that since the X-ray images are
digitized and enhanced, lower X-ray levels can be used to obtain the images. So, the ‘digital”
aspect enters not in the sensor but rather in the image representation and processing.
___________________________________________________________________________
Solution 1.16
Plant: Wood Drying Kiln
Drying is the final process before the wood is available for general use, and to achieve the
required serviceability in furniture manufacture, building, millwork and other wood product
processes. The drying process is used to remove the moisture content of wood to assure high
product quality, and is essential for imparting desirable properties to wood, including
dimensional stability, workability, and hardening (e.g., as is required for tools), and
promoting better absorption of treatments or adhesives. Properly dried wood provides a
desirable surface texture as compared to wood that has not been dried, and can be machined
Sophistication
PhysicalComplexity
Passive
Damper
PID Controller
Nonliner Feedback
Controller
Fuzzy
Controller
Impedance
Cotnroller
6. Temperature sensor
7. Pressure sensor
___________________________________________________________________________
Solution 1.14
A graphical representation of controller classification is given in Figure S1.14.
Figure S1.14: A graphical method of controller classification.
___________________________________________________________________________
Solution 1.15
By digital it does not mean that X-ray is not used. It implies that since the X-ray images are
digitized and enhanced, lower X-ray levels can be used to obtain the images. So, the ‘digital”
aspect enters not in the sensor but rather in the image representation and processing.
___________________________________________________________________________
Solution 1.16
Plant: Wood Drying Kiln
Drying is the final process before the wood is available for general use, and to achieve the
required serviceability in furniture manufacture, building, millwork and other wood product
processes. The drying process is used to remove the moisture content of wood to assure high
product quality, and is essential for imparting desirable properties to wood, including
dimensional stability, workability, and hardening (e.g., as is required for tools), and
promoting better absorption of treatments or adhesives. Properly dried wood provides a
desirable surface texture as compared to wood that has not been dried, and can be machined
Loading page 14...
CONTROL, INSTRUMENTATION, AND DESIGN 9
or glued relatively easily. Moreover, drying of wood increases the strength, kills infestation,
hardens pitch, preserves color, reduces weight (advantages in shipping and storing), and
controls shrinkage. Fresh cut wood is dried in many different ways. The common
commercial method is uses a wood-drying kiln, for accelerated drying.
Kilns are perhaps the only practical means of rapid and high-volume drying of fresh
forest lumber. Kilns are controlled enclosures used to dry products like lumber, poles, and
raw materials such as the veneered wood and core fiber used in plywood panels. Stacks of
wood are placed in the drying chamber (kiln) and the heated air is circulated through them.
Typically, rail-mounted platforms carry the wood material in and out of a kiln. The kiln
chamber is then sealed and heat is applied by steam or direct-fired air. Sometimes pressure or
a vacuum is introduced into the chamber, depending on the product. The flow, temperature
and humidity of the air have to be properly controlled in order to produce good drying
results.
Performance Requirements
Typical kiln temperatures range between 200 and 230 F. While absolute estimates of the
energy used in kiln drying are highly specific to the conditions of a given operation,
engineering data indicate that steam applied and maintained at a temperature of near the 230
F limit permitted by the American National Standards Institute standard will apply heat to a
product surface at a potential rate of roughly 22,000 Btu per square inch. Drying times
generally vary from 1 to 6 days. Longer drying times are required for wood that receives
oilborne or preservative treatments. Subjective anecdotal information indicates that the
energy required to dry about 500 cubic feet of lumber from an as-received condition to a 20
% wet basis moisture content is approximately 10 million Btu.
The specific application of wood is mainly determined by its final moisture content
(m.c.) after drying. For example, an application like furniture making requires a final m.c. of
12% or lower. Quality of the dried lumber product is unpredictable, unreliable and non-
repeatable. Kiln operators should frequently monitor the kiln operation and should make
parameter adjustments as appropriate. Many years of experience would be required before an
operator is given charge of carrying out these tasks. Problems can arise due to unattended
operation during off-hours. The common practice of lowering the desired operating
temperature during off-hours would lead to energy inefficiency. Also, an unexpected
situation may occur during the unattended period, and may lead to undesirable defects in the
drying boards. Furthermore, in view of the complexity, nonlinearity, and time-variant and
distributed nature of the drying process, the quality of the dried wood may not be uniformly
satisfactory in general. The fact that the drying results are unpredictable and that the entire
process requires humans to close the control loop, provide an opportunity to use advanced
technologies of sensing, actuation and control industrial kilns, with the goals of reducing the
energy consumption and improving the quality of dried product.
About 65% of the $250 billion/year forest product sales is attributed to lumber and
various wood products. Innovations in sensing, actuation, and control can result in significant
reductions in energy usage in kilns. The study summarized here provides an indication of the
technologies that are appropriate and the energy savings that are possible.
or glued relatively easily. Moreover, drying of wood increases the strength, kills infestation,
hardens pitch, preserves color, reduces weight (advantages in shipping and storing), and
controls shrinkage. Fresh cut wood is dried in many different ways. The common
commercial method is uses a wood-drying kiln, for accelerated drying.
Kilns are perhaps the only practical means of rapid and high-volume drying of fresh
forest lumber. Kilns are controlled enclosures used to dry products like lumber, poles, and
raw materials such as the veneered wood and core fiber used in plywood panels. Stacks of
wood are placed in the drying chamber (kiln) and the heated air is circulated through them.
Typically, rail-mounted platforms carry the wood material in and out of a kiln. The kiln
chamber is then sealed and heat is applied by steam or direct-fired air. Sometimes pressure or
a vacuum is introduced into the chamber, depending on the product. The flow, temperature
and humidity of the air have to be properly controlled in order to produce good drying
results.
Performance Requirements
Typical kiln temperatures range between 200 and 230 F. While absolute estimates of the
energy used in kiln drying are highly specific to the conditions of a given operation,
engineering data indicate that steam applied and maintained at a temperature of near the 230
F limit permitted by the American National Standards Institute standard will apply heat to a
product surface at a potential rate of roughly 22,000 Btu per square inch. Drying times
generally vary from 1 to 6 days. Longer drying times are required for wood that receives
oilborne or preservative treatments. Subjective anecdotal information indicates that the
energy required to dry about 500 cubic feet of lumber from an as-received condition to a 20
% wet basis moisture content is approximately 10 million Btu.
The specific application of wood is mainly determined by its final moisture content
(m.c.) after drying. For example, an application like furniture making requires a final m.c. of
12% or lower. Quality of the dried lumber product is unpredictable, unreliable and non-
repeatable. Kiln operators should frequently monitor the kiln operation and should make
parameter adjustments as appropriate. Many years of experience would be required before an
operator is given charge of carrying out these tasks. Problems can arise due to unattended
operation during off-hours. The common practice of lowering the desired operating
temperature during off-hours would lead to energy inefficiency. Also, an unexpected
situation may occur during the unattended period, and may lead to undesirable defects in the
drying boards. Furthermore, in view of the complexity, nonlinearity, and time-variant and
distributed nature of the drying process, the quality of the dried wood may not be uniformly
satisfactory in general. The fact that the drying results are unpredictable and that the entire
process requires humans to close the control loop, provide an opportunity to use advanced
technologies of sensing, actuation and control industrial kilns, with the goals of reducing the
energy consumption and improving the quality of dried product.
About 65% of the $250 billion/year forest product sales is attributed to lumber and
various wood products. Innovations in sensing, actuation, and control can result in significant
reductions in energy usage in kilns. The study summarized here provides an indication of the
technologies that are appropriate and the energy savings that are possible.
Loading page 15...
SENSORS AND ACTUATORS10
Constraints
A conventional wood-drying kiln basically consists of electric coils for heating the air, which
is circulated by rows of fans along the upper deck of the kiln. The heated, dry air is directed
through the stacked lumber by a plenum chamber. The water removed from the wood is
turned into water vapor by evaporation, and the saturated air is then released through air
vents. A conventional kiln operates in an open-loop manner based on a pre-specified drying
schedule. This process requires a full-time operator to frequently monitor and manually
adjust all parameters according to the preset schedule. Due to the complex and distributed
nature of the wood drying process, the end product is usually unpredictable, unreliable and
unrepeatable. Energy efficient and automated lumber drying facilities are desirable. As well,
the quality of the dried end product has to be acceptable, uniform, and repeatable. In
summary, the following problems are faced by the existing conventional wood-drying kilns:
They operate according to a predetermined drying schedule;
They rely too heavily on experienced kiln operators for kiln configuration setting and for
modification of the drying schedules;
They require dedicated attention of on-site operators;
They are left unattended during off-hours;
They are subjected to lower operating temperatures during off-hours in order to reduce
the energy consumption; and are not monitored during unattended periods – possibly
resulting in product defects; e.g., splits or cracks.
Kiln drying is an energy-intensive process. In addition to the energy that is used for the
drying process itself, some energy (electrical) is used for operating the fans in a kiln and for
product repositioning during drying. The United States Department of Agriculture's Forest
Product Laboratory research indicates that drying operations more commonly burn wood
wastes rather than fossil fuels for their energy source. Proper air circulation and optimum
temperature and residence schedules can result in significant reductions in kiln drying
energy. In addition, Environmental concerns involve emissions from kilns, combustion
systems, and treating agents. Waste heat from kilns can be recovered by means of heat
exchangers. Wood-drying kilns have been suggested as a candidate technology using ground-
source heat pumps for supplemental energy. These observations indicate that wood drying
kilns provide a major opportunity for achieving significant benefits in energy efficiency
through the use of advanced technology.
Sensors
Consider the prototype wood-drying kiln shown in Figure S1.16(a), which is a downscaled
version of a conventional kiln that is used in industry, and has the dimensions of
approximately9 4 3 . The kiln has 12 thermocouples strategically positioned within it, to
measure the kiln temperature; 2 relative humidity (RH%) sensors (wet-bulb/dry-bulb type),
to measure the RH inside the kiln; one air velocity transmitter (hot-wire anemometer) to
measure the air flow rate in the plenum; and 8 pairs of wood moisture content (MC) sensors
that are nailed into the wood.
Actuators
The prototype kiln is equipped with a pulse-width-modulated (PWM) filament heater and a
variable speed fan as the actuators for heating and air circulation.
Constraints
A conventional wood-drying kiln basically consists of electric coils for heating the air, which
is circulated by rows of fans along the upper deck of the kiln. The heated, dry air is directed
through the stacked lumber by a plenum chamber. The water removed from the wood is
turned into water vapor by evaporation, and the saturated air is then released through air
vents. A conventional kiln operates in an open-loop manner based on a pre-specified drying
schedule. This process requires a full-time operator to frequently monitor and manually
adjust all parameters according to the preset schedule. Due to the complex and distributed
nature of the wood drying process, the end product is usually unpredictable, unreliable and
unrepeatable. Energy efficient and automated lumber drying facilities are desirable. As well,
the quality of the dried end product has to be acceptable, uniform, and repeatable. In
summary, the following problems are faced by the existing conventional wood-drying kilns:
They operate according to a predetermined drying schedule;
They rely too heavily on experienced kiln operators for kiln configuration setting and for
modification of the drying schedules;
They require dedicated attention of on-site operators;
They are left unattended during off-hours;
They are subjected to lower operating temperatures during off-hours in order to reduce
the energy consumption; and are not monitored during unattended periods – possibly
resulting in product defects; e.g., splits or cracks.
Kiln drying is an energy-intensive process. In addition to the energy that is used for the
drying process itself, some energy (electrical) is used for operating the fans in a kiln and for
product repositioning during drying. The United States Department of Agriculture's Forest
Product Laboratory research indicates that drying operations more commonly burn wood
wastes rather than fossil fuels for their energy source. Proper air circulation and optimum
temperature and residence schedules can result in significant reductions in kiln drying
energy. In addition, Environmental concerns involve emissions from kilns, combustion
systems, and treating agents. Waste heat from kilns can be recovered by means of heat
exchangers. Wood-drying kilns have been suggested as a candidate technology using ground-
source heat pumps for supplemental energy. These observations indicate that wood drying
kilns provide a major opportunity for achieving significant benefits in energy efficiency
through the use of advanced technology.
Sensors
Consider the prototype wood-drying kiln shown in Figure S1.16(a), which is a downscaled
version of a conventional kiln that is used in industry, and has the dimensions of
approximately9 4 3 . The kiln has 12 thermocouples strategically positioned within it, to
measure the kiln temperature; 2 relative humidity (RH%) sensors (wet-bulb/dry-bulb type),
to measure the RH inside the kiln; one air velocity transmitter (hot-wire anemometer) to
measure the air flow rate in the plenum; and 8 pairs of wood moisture content (MC) sensors
that are nailed into the wood.
Actuators
The prototype kiln is equipped with a pulse-width-modulated (PWM) filament heater and a
variable speed fan as the actuators for heating and air circulation.
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Engineering