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International Conference on Computer Systems and Technologies - CompSysTech’10
Ultrasonic Device for Non-Contact Studying of Materials
Raycho Ilarionov, Ivan Simeonov, Hristo Kilifarev,
Stanimir Yordanov, Nikolay Shopov, Hristo Ibrishimov
Abstract: In this paper is described the design and implementation of a device for non-contact
ultrasonic studying of materials. Presented is a scheme solution of the device, into which are
provided several key features for work with purpose for greater versatility. There are presented
block diagrams of algorithms of the software necessary for some modes of work of the device with
microcontroller PIC16F84A. These modes are related to the way for excitation of the ultrasonic
transmitter and the synchronization of measurement. Principle of work of the system is described
in detail.
Key words: Ultrasonic, Ultrasonic sensors, Non-contact method, PIC16F84A.
INTRODUCTION
In the automation systems increasingly is required total integration into automation
(Totally Integrated Automation) [1]. Some of these tasks are related to studying (research)
of materials for their identification. They are equally applicable to both light and in heavy
industry. For example, in industries of food industry, foundry, machine construction
(engineering), and etc. Solving these problems is related to the collection and processing
of data on the course of the related technological process. Different methods are used -
contact and non-contact. The last are have precedence when used. From the famous
modern methods for studying of materials of interest for many technological applications is
a non-contact ultrasonic method, which uses acoustic echo sounding principle. It is based
on the use of acoustic waves with ultrasonic frequency range located between 20 kHz and
10 MHz. It is based on the effect of reflection. The measuring converter is not in direct
contact with the object of measurement and control. In determining of the distinctive
characteristics of different physical mediums and materials with purpose for their
recognition (identification) the echo signal is analyzed, which is in the result of reflection of
the ultrasound waves. This analysis includes discretization of the returned signal,
mathematical processing for extracting of distinctive characteristics and its recognition on
selected criteria [2]. The actual process of recognition is multiaspect process according the
specific technological application. For example, the presence of an object, distance to the
object, classification of materials by specific characteristics, identification, and etc.
The development aims at designing and implementing of a device for non-contact
ultrasonic studying of materials.
Base stages in the development are:
• Synthesis of principal electrical scheme of the device for non-contact
ultrasonic studying of materials;
• Development of algorithm for work and software support for the measuring
device;
• Analysis of the results of measurements made with different ultrasonic
sensors.
REALISATION
In order for greater flexibility and convenience are formulated the following features of
the device:
• Working with different ultrasonic sensors;
• Work with internal excitation of the ultrasound transmitter with programmable circuit;
• Choice of operating frequency for internal excitation of the ultrasound transmitter
with programmable circuit;
International Conference on Computer Systems and Technologies - CompSysTech’10
• Working with external excitation of ultrasonic transmitter;
• Feature for manually starting of the excitation of the ultrasonic transmitter with a
programmable circuit;
• Feature for externally starting of the excitation of the ultrasonic transmitter with a
programmable circuit.
In Fig. 1 is shown the functional block scheme for ultrasonic studying of materials.
The main blocks in the scheme are three:
- Ultrasonic device - the main function of this unit is to transmit and receive signals
from the ultrasound range, according to the set mode of work and to produce output
signals (analogue and digital) with appropriate parameters for further processing;
- Multifunctional module - built on the basis of module USB-6251 M Series, made by
company National Instruments. Serves to control the measurement process and the
storing of the information. The transfer of data and its control is by USB interface with PC;
- Personal computer (PC) – there is realized virtual instrument built in an environment
of LabView, and with the help of which is controlled the work of the multifunction module.
The data obtained from the measurement process are processed, demodulated and
evaluated by specialized software (eg. MATLAB).
The ultrasonic device consists of several main functional blocks:
- Transmitter and receiver – they are matched on parameters couple ultrasonic
transducers with the same resonance work frequency. The piezoceramic elements of the
sensors are shaped as disk;
- Pulse former - used to form the excitation signal for the transmitter;
- Amplifier - serving for amplifying of the reflected echo signal from the studying
material to the necessary for its further processing level;
- Elements for control and adjustments – jumpers, through which is set the desired
mode of operation of the device,
buttons for manually starting of the
measurement and to restart the
microcontroller. The choice of the
frequency of pulses for excitation, the
time delay after the receiving of the
start signal;
- Power Supply - provides
voltages to all blocks of the scheme;
- Clock oscillator - provides a
stabilized clock frequency for operation
of the microcontroller;
- Microcontroller - serve to
generate a packet of pulses to block
Pulse former for excitation of the
transmitter. It works according the set
mode from block Elements for control
and adjustments.
In Fig. 2 is presented principal
electrical scheme of the developed
device.
For the excitation of the ultrasound transmitter based on reverse piezoeffect are used
CMOS inverters 4069. The last are connected in parallel by two to increase the power and
amplitude of the transmitted signal. The voltages applied to the leads of the ultrasound
transmitter are with phases at 180 degrees. For the purpose on the couples of inverters
(the leads of the transmitter BQ2), the signal from the collector of the transistor VT2 is
Fig. 1. Functional block scheme of the device for non-
contact ultrasonic study
Multifunctional
module
NI USB-6251 M
Series
PC
USB
Pulse former
Elements for
control and
adjustments
Clock
oscilator
Amplifier
Power
Supply
Microcontroller
Ultrasonic device
Transmitter Receiver
International Conference on Computer Systems and Technologies - CompSysTech’10
inverted by the element IC3E. Because of the C5 the voltage over the leads of the
transmitter is higher than the supply voltage.
The piezoceramic elements (transmitter and receiver) according to the set mode of
work of the device can be for 40 kHz (UST40T and UST40R) [3] or 125 kHz (125SR250B)
[4].
The excitation signal for the ultrasound transmitter is a packet of pulses with
rectangular form with its resonant frequency. According the recommendation of the
company manufacturer of ultrasonic transmitters, for the full excitation of the
piezoelements it is necessary to provide a packet of six pulses with specified parameters.
The transistors VT1 and VT2 are controlled by the same excitation signal, which
according to the position of jumpers in JP3, may be either from the output RA2 from the
microcontroller PIC16F84A or to be obtained externally from the output of the
multifunctional module NI USB-6251 M Series. To obtain more rapid fronts at switching of
the transistors, there are placed forcing circuits realized by C8, R21 and R22 for VT1 and
C11, R24 and R25 for VT2. VT1 and VT2 are used to coordinate the PIC16F84A levels to
those of CMOS inverters 4069.
The reflected from the studied material ultrasound wave acoustically influence over
the receiver. Because of the straight piezoeffect from the ultrasound receiver is obtained
an electrical signal which through the C6 is supplied to the input of operational amplifier
IC2A (LM833N). The amplification can be adjusted by jumper from JP1. Depending on its
place the amplification coefficients are set - 200, 100, 51 or through potentiometer R1 can
20MHZ
Y1
18pF
C1
18pF
C2
GND
GND
GND
1
2
J_Serial_Prg
1
2
3
4
5
H_Serial_Prg
GND
DC5V
Vpp
PClock
PData
GND
BQ1
1nF
C6
0,1
C3
BQ2
0,1
C5
Uic
Uic
1nF
C4
RA0
17
RA1
18
RA2
1
RA3
2
RA4/T0CKI
3
RB0/I NT
6
RB1 7
RB2 8
RB3 9
RB4 10
RB5 11
RB6 12
RB7 13
VSS
5
MCLR
4OSC1/CLKIN
16 OSC2/CLKOUT 15
VDD 14
PIC16F84IC1
DC5V
GND GND
GND
GND
GND GND
1
2
NI
H_AOut
GND
8
1
4
3
2
1
LM833
IC2A
Uic
GND
GND
1
2
NI
H_DIn
X3
X4
X1
X2
1
2
NI
H_DOut
1 2
3 4
5 6
JP3
GND
DC5V
22uF
C18
DC5V
12
CD4069UBCN
IC3A
34
CD4069UBCN
IC3B
56
CD4069UBCN
IC3C
GND
7
VDD 14
O
8I9
CD4069UBCN
IC3D
10 11
IC3E
Uic
GND
But_ 1
GND
But_Res et
2T3168
VT1
2T3168
VT2
4.7V
DZ2
GND
DC12V
DC9V 1 2
3 4
JP4 Uic
100nF
C15
GND
DC5V
100nF
C16
GND
Uic
100nF
C17
GND
GND
1 2
3 4
5 6
JP2
12
DS1
GND
12
DS2
GND
GND
1nF
C8
1nF
C11
GND
470K
R1
10K
R9
10K
R11
10K
R12 10K
R13
2M
R3 1M
R4 510K
R5
1 2
3 4
5 6
7 8
JP1
3.3K
R21
3.3K
R24
10K
R17
1K
R19 1K
R20
1K
R22
1K
R25
10K
R6 10K
R7 10K
R8
20K
R18
360
R15 360
R16
GND
750
R10
D1
100nF
C7
GNDGND
4.7V
DZ1
GND
1K
R2
Vin Vout
GND
7812
VR1
100nF
C9
100nF
C10
470uF
C19
BR1
GND GNDGND GND
GND
DC12V
220V/12V
T1
1
2
220V
H_Power
SW- SPST
S1
Vin Vout
GND
7805
VR3
100nF
C14
GND GND
DC5V
220V/0.5A
F1
12
DS3
GND
Vin Vout
GND
7809
VR2
100nF
C12
100nF
C13
GND GNDGND
DC9VDC12V
360
R23
750
R14
X7
X8
X5
X6
Fig. 2. Principle electrical scheme of the ultrasonic device
International Conference on Computer Systems and Technologies - CompSysTech’10
smoothly varying from 1 to 47. It is also possible to obtain a different gain than those by
the parallel connection of resistors selected in the feedback of the operational amplifier, by
placing additional jumpers at JP1. In the scheme is used single-stage amplifier because of
the gain coefficients provided to achieve adequate output level of the signal for its further
processing.
The scheme works with single polar power supply. To achieving of uniform
amplification of the positive and the negative part of the AC signal is created a virtual
ground, raised with the half of the supply voltage by divider R12 and R13, which is
submitted as a voltage to the positive input of operational amplifier LM833N (IC2A). The
capacitor C3 is included for stabilization of the virtual ground and for filtering of signals.
In sequence to the output of the operational amplifier capacitor C4 is placed to
separate the DC component from the output signal. Thus obtained analogue signal is
output from the device for further processing.
In order to register the return echo signal from the microcontroller, in the scheme is
placed detector-integrator composed of elements D1, R10, R14, R2 and C7. Setting of a
different time constant of integration (and thus the threshold of activation) is by using the
potentiometer R2. To limit the maximum voltage that is fed to the input RA1 of the
microcontroller is connected a zener diode for 4.7V DZ1.
In the scheme is provided feature for selection of the signal source for starting a
package of excitation pulses generated by the microcontroller. The choice is made by a
jumper from JP3. The source of the start signal may be digital signal from an external unit
or a signal obtained by pressing a button But_1. In both cases, the resulting signal is fed
into the input RB0/INT of the microcontroller. To protect the microcontroller from a signal
with a higher level from 5V, into the scheme is placed a zener diode for 4.7V DZ2.
The outlet of the digital signal from the output RA3 of the microcontroller to an
external module is made by the connector H_DOut. This signal is necessary to be
synchronized the work of the external module with the moment of sending of the packet
with the excitation pulses to the transmitter.
For the normal operation of the device are used voltages +12 V, +9 V and +5 V.
There is feature to change the supply voltages of the excitation scheme (IC3) of the
transmitter BQ2, of the amplifier block IC2A and of the transistors VT1 and VT2 - from
+12V to +9V and vice versa. This change is set by the jumper in JP4. If there is a +5 V
supply voltage through the circuit R23, DS3 is current flow, resulting in the LED as an
indicator lights.
Using elements R15, DS1, and R16, DS2 respectively connected to the outputs RB4
and RB5 of the microcontroller is provided a digital indication in operating frequency 125
kHz for excitation of the transmitter (lights the LED DS1) and mode of operation with a 10
ms delay after receiving the starting signal (lights the LED DS2).
The time-setting chain R6, C8 determine the delay of the actual start of the
microcontroller. This requires the voltage over the lead MCLR to rise to the level of logical
one. The slow increasing of the voltage over this input is needed to be started the program
when there is already set stable power supply.
Into the scheme is provided a connector for serial programming in-place by a
programmer of the microcontroller without the need to remove it from the circuit board.
Software for the microcontroller
The work of the developed device according the specified requirements is
supported by the creation of corresponding software for the microcontroller in it -
PIC16F84A [5].
In Fig. 3 is presented the algorithm of the main program in the microcontroller. Its
work began with the switching-on the power.
International Conference on Computer Systems and Technologies - CompSysTech’10
At first there is executed an
initialisation: the type of the leads
for port A and port B are set, the
pull-up resistors of port B are
switched off, and in the variable
STATE is set, that in the moment
the mode of work of the
microcontroller is “waiting”. The
next are readings of the current
state of the inputs RA1 and RA2, to
which are connected the jumpers
from JP2 and setting of the values
of the bits in the variable STATE.
Log. 1 RB1 set to not delay,
and a log. 0 - to have delay around
10ms after receiving the
synchronization pulse on input
RA3. Since synchronizing (starting)
pulse can be set by the button
But_1 in the scheme, in which case
it is necessary to be waited until his
contacts are settle. When it is set
to have such delay, this is
indicated by LED DS2, which is
connected to lead RB4.
Log. 1 on RB2 set the
frequency of the pulses in the
packet to 40kHz, and log. 0 -
125kHz. When working with
125kHz this is indicated by LED
DS1, which is connected to lead
RB5.
At the end of initialization
are set and enabled the interrupts
at transition from 0 to 1 of the input
RB0/INT.
The rest of the main
program is an infinite loop, where
consequently are performed the
following actions:
- the signals to the leads
RA2 (signal for excitation of the
transmitter) and RA3 (signal for
synchronization of the external
unit);
- the Cnt is set to be equal to the doubled number of pulses in the packet - 12;
- the global interruptions are enabled;
- begins a cycle, which will not end until the bit 0 of the STATE variable becomes 1 -
this occurs when the interrupt is caused in receipt of a start pulse on the input RB0;
- the outputs RA2 and RA3 are set to log. 1 - this is the beginning of the packet of
pulses;
Begin
Initialization:
PortA:
- RA0, RA1, RA4 – inputs;
- RA2, RA3 – outputs
PortB:
- RB0, RB1, RB2, RB3, RB6,
RB7 – inputs;
- RB4, RB5 – outputs;
- pull-up resistors – OFF
STATE, 0 = 0 – waiting mode
RA2 = 0, RA3 = 0
Cnt = C_Cnt
Enable Global Interrupts
1
STATE,0 = 1
no
yes
RA3 = 1, RA2 = 1
STATE,2 = 0
yes
no
Delay_10μs
Delay_2μs
RA3 = 0, STATE,0 = 0
1
Set and enable Interrupts from
RB0/INT input at 0->1 edge
RB1 = 0
no
yes
STATE,1 = 0, RB4 = 0
STATE,1 = 1, RB4 = 1
RB2 = 0
no
yes
STATE,2 = 0, RB5 = 0
STATE,2 = 1, RB5 = 1
Fi
g
. 3. Block dia
g
ram of the main
p
ro
g
ram
International Conference on Computer Systems and Technologies - CompSysTech’10
- depending on the chosen frequency
of the ultrasonic transmitter (bit 2 from
STATE) procedure is called with the
corresponding delay, where it produced a
series of 6 pulses (Fig. 5 and Fig. 6);
- after returning from the procedure
RA3 is set to zero and bit 0 of STATE is set
to 0 (goes to standby mode waiting for the
next start pulse), then the cycle continues
with the first step.
In Fig. 4 is presented a block diagram
of the procedure for handling of interrupts. In
the main program of the microcontroller is
set to generate an interrupt at the transition
from 0 to 1 on input RB0/INT. The procedure
proceed as follows:
- the interrupt flag for RB0/INT in
register INTCON (INTF) is checked – if it is
0 it is the return from the procedure, if it is 1
– the execution continues;
- the interrupt flag INTF is set to 0;
- the bit 1 of variable STATE is
checked – if it is 1 is called a procedure for
time-delay of 10ms, and if 0 - continues with the next step;
- reading of the current state of RB0 – if it is 0 means that it was a false activation of
the input and returns from the interrupt procedure, if it is 1 is passed to the next step;
- the global interrupts are disabled;
- bit 0 of STATE is set to 1, which indicates that the microcontroller is in the mode of
transmission of pulses;
- end of the procedure for handling of interrupts.
In the next moment the execution of the main program will start sending pulses and
will output a synchronizing pulse to the external module.
The time delays in the program of the microcontroller can be implemented in three
ways, since it is known that the internal clock frequency of execution of instructions is
5MHz (external clock frequency is 20MHz), i.e. execution time of one instruction is 200ns:
- Using the built-in timer module TMR0
overflow and interrupts from it and having set a
corresponding value in the timer before started;
- Time delay generated by software using
a series of NOP (No OPeration) instructions;
- Time delay generated by software using
a series of instructions that are repeated a
specified number of times in a cycle.
In the software is used the second
approach, because the times for delay must be
set with high accuracy (by this approach the time
can be adjusted by increments of 200ns) and
because in the time interval for transmitting of
pulses the microcontroller is not necessary to
carry out other actions.
In Fig. 5 and Fig. 6 are presented block
diagrams of algorithms for software generation of
Delay_Xs
1
Cnt = 0
yes
no
RA2 = RA2 xor RA2_MASK
NOP, NOP, NOP, NOP, NOP,
NOP, NOP, NOP, NOP, NOP,
…
NOP, NOP, NOP, NOP, NOP
Cnt = Cnt - 1
Return
1
Fig. 5. Block diagram of the
procedure for X time delay
INT
Return
INTCON,INTF
= 1
no
yes
1
INTCON,INTF = 0
STATE,1 = 1
yes
no
Delay_10ms
RB0 = 1
no
yes
1
Enable Global Interrupts
STATE,0 = 1
1
Fig. 4. Block diagram of the procedure
for interrupts
International Conference on Computer Systems and Technologies - CompSysTech’10
time delay - respectively by NOP instructions and by using of a cycle.
One exemplary implementation of the algorithm from Fig. 6 with assembler is
presented in Fig. 7. Every instruction when executed
takes one clock or time 200ns. Exceptions are instructions
for transition that take 2 clocks (400ns) and the
instructions for conditional jumps in which when condition
is false it takes 1 clock, and when the condition is true - 2
clocks.
If we calculate the time delay for the execution of
the source code of Fig. 7 we can obtain the following:
Delay = 200ns*(2+1+1+C_Delay_X*(1+2)-2+1+2) =
= 200ns*(5+3*C_Delay_X) = 1μs + 600ns*C_Delay_X,
where C_Delay_X sets the number of repeats of the
cycle.
To calculate the value of C_Delay_X for the
specified time delay (Delay) should be used the above
depending in reverse:
C_Delay_X = (Delay - 1μs)/ 600ns
We see that in this method the step of
modifying of the set time delay is 600ns,
which makes it inapplicable to this case.
The pause of about 10ms for manual
generating of starting pulse by the button
But_1 is implemented in the procedure
Delay_10ms, where are organized two
nested cycles of instructions, each of which
is repeated defined number of times.
CONCLUSIONS AND FUTURE WORK
The developed hardware-software environment allows for non-contact non-
destructive analysis of materials. Under development is a mobile device intended for
embedding into automated manufacturing systems, which is based on the described in this
paper ultrasonic device.
REFERENCES
[1] Yordanov, D. Integrating of the PC and PLC controllers into workshops.
Computers, 2-8 July 2001, issue 2, pp. 6-9.
[2] Baltes, H., W. Göpel, J. Hesse. Sensors Update. Volume 3. Sensor Technology-
Applications-Markets. Weinheim-Berlin-New York-Chichester- Brisbane-Singapore-
Toronto, Wiley-VCH Verlag GmbH, 1998.
[3] GM Electronic spol. s r.o. 1990-2008, UST40T,
http://www.gme.cz/cz/index.php?page=product&detail=641-019, 2008.
[4] Pro-Wave Electronic Corp., Air Ultrasonic Transducer - Matching Layer Type,
125SR250, http://www.prowave.com.tw/english/products/ut/sml/125sr250.htm, 2003.
[5] PIC16F84A Data Sheet. Microchip Technology Inc, 2001.
ACKNOWLEDGEMENTS
This study was carried out in the framework of the DRNF 02/9 project titled "Design
and development of a device for non-contact ultrasonic investigation of materials aimed at
embedding in automated manufacture systems ", financed by the National Science Fund
of the Bulgarian Ministry of Education, Youth and Science.
Fig. 6. Block diagram of the
alternative procedure for X
time dela
y
Delay_Xs
1
Buff = 0
no
yes
Return
1
Buff = C_Delay_X
Buff = Buff - 1
D_Xs ;2 clk when called
movlw C_Delay_X ;1 clk
movwf Buff ;1 clk
Loop decfsz Buff, f ;1(2) clk
goto Loop ;2 clk
return ;2clk to return
Fig. 7. Source code of the alternative
procedure for time delay
International Conference on Computer Systems and Technologies - CompSysTech’10
ABOUT THE AUTHOR
Assoc. Prof. Raycho Ilarionov, PhD, Department of Computer Systems and
Technologies, Technical University of Gabrovo, Phone: +359 66 800 224, Е-mail:
Ilar@tugab.bg.
Chief Assist. Prof. Ivan Simeonov, PhD, Department of Computer Systems and
Technologies, Technical University of Gabrovo, Phone: +359 66 827 479, Е-mail:
isim@tugab.bg.
Senior Assist. Prof. Hristo Kilifarev, Department of Automation, Information and
Control Systems, Technical University of Gabrovo, Phone: +359 66 827 593, Е-mail:
hri_100@abv.bg
Assoc. Prof. Stanimir Yordanov, PhD, Department of Automation, Information and
Control Systems, Technical University of Gabrovo, Phone: +359 66 827 571, Е-mail:
sjjordanov@mail.bg.
Chief Assist. Prof. Nikolay Shopov, PhD, Department of Computer Systems and
Technologies, University of Food Technologies - Plovdiv, Phone: +359 32 603 868, Е-mail:
nikshop@abv.bg.
MS Eng. Hristo Ibrishimov, Center for Information Systems and Technologys,
Technical University of Gabrovo, Phone: +359 66 82 432, Е-mail:
hristo_ibrishimov@abv.bg
