Simple and effective new type of tactile device is presented and investigated, which transfers 2D graphic information to the visually impaired people. It consists of piezoelectric bimorph cantilever, acting as an oscillating probe, and, when changing operational signal, could transfer information to visually impaired people, e.g. by crossing the lines/contours on the screen of tablet PC or determining the color of them. Determining the amplitude of tip’s oscillation, attached to bimorph PZT cantilever and contacting with finger, is presented. It is established that tactile device’s body and integrated bimorph cantilever oscillations and their effect on the human finger are different. The visually impaired people better percept the oscillations of Braille pins, which are attached to cantilever tip; maximum perception of tip’s oscillations are achieved, when bimorph tip generates approximately 0.5 N force

A. Žvironas

M. Gudauskis

R. Bansevičius

V. Jūrėnas

English

Bansevičius, R.

Jūrėnas, V.

Gudauskis, M.

Žvironas, A.

Journal of Mechatronics and Artificial Intelligence in Engineering

Investigation of tactile characteristics of the piezoelectric bimorph type actuators

Journal of Vibroengineering

  © JVE INTERNATIONAL LTD. JOURNAL OF VIBROENGINEERING. MAY 2014. VOLUME 16, ISSUE 3. ISSN 1392-8716 1343 
1243. Investigation of tactile characteristics of the 
piezoelectric bimorph type actuators 
R. Bansevičius1, V. Jūrėnas2, M. Gudauskis3, A. Žvironas4 
Kaunas University of Technology, Kaunas, Lithuania 
1Corresponding author 
E-mail: 1ramutis.bansevicius@ktu.lt, 2vytautas.jurenas@ktu.lt, 3marius.gudauskis@ktu.lt, 
4arunas.zvironas@ktu.lt 
(Received 3 January 2014; received in revised form 5 March 2014; accepted 16 March 2014) 
Abstract. Simple and effective new type of tactile device is presented and investigated, which 
transfers 2D graphic information to the visually impaired people. It consists of piezoelectric 
bimorph cantilever, acting as an oscillating probe, and, when changing operational signal, could 
transfer information to visually impaired people, e.g. by crossing the lines/contours on the screen 
of tablet PC or determining the color of them. Determining the amplitude of tip’s oscillation, 
attached to bimorph PZT cantilever and contacting with finger, is presented. It is established that 
tactile device’s body and integrated bimorph cantilever oscillations and their effect on the human 
finger are different. The visually impaired people better percept the oscillations of Braille pins, 
which are attached to cantilever tip; maximum perception of tip’s oscillations are achieved, when 
bimorph tip generates approximately 0.5 N force. 
Keywords: piezoelectric actuator, bimorph, tactile stylus, oscillating probe. 
1. Introduction 
A lot of research activity today is devoted to developing touch sensing systems, exploiting 
different effects and materials: electromechanical, piezoelectric, magnetostrictive, etc. All these 
materials are described as smart materials. Using smart materials provides the possibility to create 
small, effective and usable tactile device that could transfer varied kind of information. Many 
systems are developed for visually impaired people; plenty of them are using matrix of Braille 
pins. Some of these devices are based on the application of piezoelectric cantilevers [1-3]. The 
pins could simulate Braille letters and are based on changing the surface of finger touching area. 
In this paper we present new type of tactile device, which exploits the specific properties of 
piezoelectric bimorph cantilever. It consists of piezoelectric bimorph cantilever, acting as an 
oscillating probe, and, when changing operational signal, could transfer different information to 
visually impaired people, e.g. crossing the lines/contours or determining the color of lines or 
background. 
2. The oscillating tip of the bimorph piezoelectric cantilever 
In the experiment we used piezoelectric cantilever, developed by Johnson Matthey Catalyst 
GmBH (Germany); the technical parameters are presented in Table 1. The Fig. 1 represents 
structure of piezoelectric cantilever. 
Fig. 1 presents piezoelectric cantilevers  (strain that defines the bending); it can be expressed 
by Eq. (1) with the equilibrium condition ∑  = 0 ; ∑  = 0  for no external loads. For the 
complete triple-layer bender [6, 11]: 
 = −
6
ℎ ℎℎ + ℎ + ℎℎ + ℎ 

− 6

 + ℎℎℎ + ℎ + 2ℎ
 , 
(1)
where: 
1243. INVESTIGATION OF TACTILE CHARACTERISTICS OF THE PIEZOELECTRIC BIMORPH TYPE ACTUATORS.  
R. BANSEVIČIUS, V. JŪRĖNAS, M. GUDAUSKIS, A. ŽVIRONAS 
1344 © JVE INTERNATIONAL LTD. JOURNAL OF VIBROENGINEERING. MAY 2014. VOLUME 16, ISSUE 3. ISSN 1392-8716  
 = ℎ! 
"
+ 2ℎ2ℎ + ℎ  + 3ℎ" + ℎ" ℎ + 2ℎ + ℎℎ" 
+ ℎ + ℎ
! + 12ℎℎℎ + ℎℎ + 12ℎℎℎ"  ". 
(2)
 
Fig. 1. Structure of the piezoelectric cantilever 
Table 1. Johnson Matthey bending actuators’ typical characteristic values [4, 5] 
& = 0.038 m; 
' = 0.0072 m; 
ℎ = 0.00025 m*; 
ℎ = 0.00030 m*; 

 = –315 ∙ 10-12 C/N; 
 = 14.20 ∙ 10-12 m2/N; 
  = 1/  = 70.423 ∙ 109 N/m2; 
 = 70 ∙ 109 N/m2; 
 = 1/  = 14.29 ∙ 10-12 m2/N; 
 = (")*+, = 57.692 ∙ 10
3
 V/m; 
ℎ = 0.0008 m; 
 = 4500; 
- = 8.10 ∙ 103 kg/m3; 
- = 1.60 ∙ 103 kg/m3; 
. = 30 V. 
 
*the exact parameters are not known (manufacturer’s commercial secrecy). 
All data are given by experimental measure. 
Piezoelectric cantilevers’ strain value is calculated by Eq. (1); applied voltage is 30 V. The 
voltage is sufficient to provide wide range of amplitude of cantilever tip. The strain value is: 
 = 0.0157. 
The theoretical cantilever‘s deflection is calculated multiplying strain value by cantilever 
length (parameter & value). Tip deflection value is: 
1 = 0.0157 ∙ 0.038 = 0.5966 ∙ 105 m. 
With symmetric bimorph of the length & and the layer thickness ℎ, clamped on one side, the 
deflection of the free end, calculated with Eq. (3), becomes (with  = 7/2 h): 
1& = 3
&
"
8ℎ" 7 =
3
&"
4h . 
(3)
And finally: 
1& = 0.5970 ∙ 105 m. 
All these calculations were made taken into account equilibrium condition ∑  = 0; ∑  = 0 
for no external loads. The piezoelectric cantilever’s tip can be loaded by force (for example, 
human touch). This force can be calculated by Eq. (4) and this value will represent the blocking 
force. If this force will be applied to the cantilever’s tip, the deflection of tip will be 0. 
Following Yao piezoelectric actuator’s expression [7, 12], the blocking force could be 
calculated by: 
1243. INVESTIGATION OF TACTILE CHARACTERISTICS OF THE PIEZOELECTRIC BIMORPH TYPE ACTUATORS.  
R. BANSEVIČIUS, V. JŪRĖNAS, M. GUDAUSKIS, A. ŽVIRONAS 
 © JVE INTERNATIONAL LTD. JOURNAL OF VIBROENGINEERING. MAY 2014. VOLUME 16, ISSUE 3. ISSN 1392-8716 1345 
;< =
3'ℎ"
8& 
. 
(4)
The blocking force of piezoelectric cantilever, calculated by Eq. (4): 
;< = 0.0605 N. 
This parameter shows that human finger, developing force 60 mN, will stop cantilever from 
bending. 
3. Experimental results 
3.1. Tactile pen design 
The main characteristics of piezoelectric plate are shown in Table 1. The device is designed 
using stylus pen. Piezoelectric bimorph cantilever is mounted inside it, so that the free end of 
cantilever is placed near pen tip. Fig. 2 is showing scheme of tactile probe. 
 
Fig. 2. Piezoelectric probe : 1 – body, 2 – touch screen sensitive tip,  
3 – piezoelectric bimorph cantilever, 4 – cantilever tip, 5 – Braille pin,  
6 – bimorph cantilever view from top, 7 – bimorph cantilever view from side 
3.2. Research of piezoelectric bimorph cantilever 
The tip’s oscillations were determined using KEYENCE Laser Displacement Sensor LK-G82 
[8], (Fig. 3). 
Resonant frequency was found by impact test and is 250 Hz (Fig. 4). 
 
Fig. 3. General view of experimental set-up: 1 – tactile piezo bimorph cantilever; 2a – laser sensor head,  
2b – laser sensor controller; 3a – Pico Scope 3202 device, 3b – PC with Pico Scope software;  
4 – signal generator; 5 – signal amplifier 
1243. INVESTIGATION OF TACTILE CHARACTERISTICS OF THE PIEZOELECTRIC BIMORPH TYPE ACTUATORS.  
R. BANSEVIČIUS, V. JŪRĖNAS, M. GUDAUSKIS, A. ŽVIRONAS 
1346 © JVE INTERNATIONAL LTD. JOURNAL OF VIBROENGINEERING. MAY 2014. VOLUME 16, ISSUE 3. ISSN 1392-8716  
 
Fig. 4. Piezo cantilever’s impact test ( =	250 Hz) 
Earlier research established that operator could feel oscillations of the tip with frequency from 
5 to 300 Hz [9]. Resonant frequency is near this maximal value, so testing could be done up to 
this frequency. 
The cantilever coefficient of elasticity was established using laser for measuring the 
displacements and external force – to load cantilever. The test results are presented in Table 2. 
Table 2. Piezoelectric bimorph displacement for different force 
Force, N 0 0.2 0.5 1 
Displacement, µm 0 221 551 1134 
Braille pins are sticking out about 0.5 mm [10]. Bimorph cantilever deflection of 0.5 mm is 
generated by 0.5 N force. To define what control signal parameter should be, we have to calculate 
stiffness = of the cantilever; in our case = 	888.889 N/m (Fig. 5). 
 
Fig. 5. Displacement of tip in relation to applied force 
3.3. Piezoelectric cantilever’ oscillation effects on tactile probe body 
In this research we used scanner of Polytec Laser Vibrometer and the probe with lower 
resonance frequency due to bigger effective length of cantilever. 
Probe’s body is made from aluminum alloy; the diameter is 8.5 mm, length – 122 mm. 
Scanned area was ¼ off tactile probe body, where user holds it. Area was about 30 mm length 
from tactile probe’s end. Fig. 6 show scanning area, divided in 281 finite number of elements. 
Green color is probe’ body, blue – cantilever Braille pin. The investigated piezoelectric cantilever 
1243. INVESTIGATION OF TACTILE CHARACTERISTICS OF THE PIEZOELECTRIC BIMORPH TYPE ACTUATORS.  
R. BANSEVIČIUS, V. JŪRĖNAS, M. GUDAUSKIS, A. ŽVIRONAS 
 © JVE INTERNATIONAL LTD. JOURNAL OF VIBROENGINEERING. MAY 2014. VOLUME 16, ISSUE 3. ISSN 1392-8716 1347 
probe was excited with harmonic signal of 2 Vpp voltage and frequency range between 0 Hz to 
10 kHz. 
 
Fig. 6. Tactile probe body and cantilever scanning area 
From the frequency response presented in Fig. 7, the piezoelectric cantilever has several 
resonance frequencies. The first resonant frequency is 168 Hz. The second resonance at 1 kHz is 
highest, but it could be neglected, because the operating frequency range is 15-500 Hz. Operating 
frequency range was chosen experimentally. 
 
Fig. 7. Frequency response of probe’s body in the range of 0-10 kHz and driving voltage 2 Vpp 
The first resonant frequency of 168 Hz of the cantilever is in the operating frequency range 
and the amplitude of the cantilever oscillations is 32 μm at the 2 Vpp. 
This investigation helps us to find out the oscillation amplitudes of probe’s body and cantilever 
Braille pins’ displacements. Probe’s body amplitude can be evaluated in tens of nanometers, while 
cantilever Braille pins – in the order of micrometers. 
4. Conclusion 
This research describes how to calculate the deflection of bimorph piezoelectric cantilever, 
used in new design of tactile device, transferring information by changing frequency of oscillation 
in relation to color of lines or background. The amplitudes of cantilever and probe’s body 
oscillations are very diverse and operator better percept the oscillations of Braille pin, attached on 
bimorph piezoelectric cantilever tip. 
Acknowledgement 
This work has been supported by Lithuanian Agency for Science, Innovation and Technology 
1243. INVESTIGATION OF TACTILE CHARACTERISTICS OF THE PIEZOELECTRIC BIMORPH TYPE ACTUATORS.  
R. BANSEVIČIUS, V. JŪRĖNAS, M. GUDAUSKIS, A. ŽVIRONAS 
1348 © JVE INTERNATIONAL LTD. JOURNAL OF VIBROENGINEERING. MAY 2014. VOLUME 16, ISSUE 3. ISSN 1392-8716  
(MITA), Project TactileApps, No. 31V-38. 
References 
[1] Kyung Ki-Uk, Seung-Woo Son, Dong-Soo Kwon, Mun-Sang Kim Design of an integrated tactile 
display system. Proceedings of the 2004 IEEE International Conference on Robotics & Automation 
New Orleans, 2004, p. 776-781. 
[2] Takeshi Hommal, Shuichi Ino, Hayato Kuroki, Takashi Izumi, and Tohru Ifukube Development 
of a piezoelectric actuator for presentation of various tactile stimulation patterns to fingerpad skin. 
Proceedings of the 26th Annual International Conference of the IEEE EMBS San Francisco, USA, 
2004, p. 1-5. 
[3] Yiru Zhou, Masahiro Ohka, Tetsu Miyaoka A tactile display presenting pressure distribution and 
slippage force. Symposium on Haptic Interfaces for Virtual Environments and Teleoperator Systems, 
Nevada, 2008, p. 13-14. 
[4] Johnson Matthey Catalysts Overview of bending actuators – typical characteristic values. 
http://www.piezoproducts.com/fileadmin/user_upload/pdf/jm_piezoproducts_datenblatt_biegewandl
er_en_02_07_2013.pdf 
[5] Johnson Matthey Catalysts Bending actuator. 
http://www.piezoproducts.com/fileadmin/user_upload/pdf/jm_piezoproducts_funktionsweise_biege
wandler_en_01_04_2009.pdf 
[6] Smits J. G., Ballato A. Dynamic admittance matrix of piezoelectric cantilever bimorphs. J. 
Microelectromech, Vol. 3, 1994, p. 105-12. 
[7] Qing-Ming Wang, Eric Cross L. Performance analysis of piezoelectric cantilever bending actuators. 
Ferroelectrics, Vol. 215, Issue 1, 1998, p. 187-213. http://dx.doi.org/10.1080/00150199808229562 
[8] Keyence High-speed, high-accuracy CCD laser displacement sensor (LK-G series) specifications. 
http://www.keyence.com/products/measure/laser/lkg/lkg_specifications_3.php 
[9] Bansevičius Ramutis Petras, Žvironas Arūnas, Gudauskis Marius Investigation of control signal 
of tactile device with electromagnet. 7th international conference of Mechatronic Systems and 
Materials, 2011, p. 244-245. 
[10] Mami Tanaka, Kaoru Miyata, Tatsuo Nishizawa, Seiji Chonan Development of a tactile sensor 
system for reading Braille: fundamental characteristics of the prototype sensor system. Smart Mater. 
Struct., Vol. 14, 2005, p. 483-487. http://iopscience.iop.org/0964-1726/14/4/004/ 
[11] Dunsch R., Breguet J. M. Unified mechanical approach to piezoelectric bender modeling. 
Sciencedirect, Sensors and Actuators. 
http://www.sciencedirect.com/science/article/pii/S0924424706004365 
[12] Yao L., Zhang J., Lu L., Lai M. Nonlinear static characteristics of piezoelectric bending actuators 
under strong applied electric field. Sensors and Actuators, Vol. 115, 2004, p. 168-175. 


JVE International

  © JVE INTERNATIONAL LTD. JOURNAL OF VIBROENGINEERING. MAY 2014. VOLUME 16, ISSUE 3. ISSN 1392-8716 1343 1243. Investigation of tactile characteristics of the piezoelectric bimorph type actuators R. Bansevičius1, V. Jūrėnas2, M. Gudauskis3, A. Žvironas4 Kaunas University of Technology, Kaunas, Lithuania 1Corresponding author E-mail: 1ramutis.bansevicius@ktu.lt, 2vytautas.jurenas@ktu.lt, 3marius.gudauskis@ktu.lt, 4arunas.zvironas@ktu.lt (Received 3 January 2014; received in revised form 5 March 2014; accepted 16 March 2014) Abstract. Simple and effective new type of tactile device is presented and investigated, which transfers 2D graphic information to the visually impaired people. It consists of piezoelectric bimorph cantilever, acting as an oscillating probe, and, when changing operational signal, could transfer information to visually impaired people, e.g. by crossing the lines/contours on the screen of tablet PC or determining the color of them. Determining the amplitude of tip’s oscillation, attached to bimorph PZT cantilever and contacting with finger, is presented. It is established that tactile device’s body and integrated bimorph cantilever oscillations and their effect on the human finger are different. The visually impaired people better percept the oscillations of Braille pins, which are attached to cantilever tip; maximum perception of tip’s oscillations are achieved, when bimorph tip generates approximately 0.5 N force. Keywords: piezoelectric actuator, bimorph, tactile stylus, oscillating probe. 1. Introduction A lot of research activity today is devoted to developing touch sensing systems, exploiting different effects and materials: electromechanical, piezoelectric, magnetostrictive, etc. All these materials are described as smart materials. Using smart materials provides the possibility to create small, effective and usable tactile device that could transfer varied kind of information. Many systems are developed for visually impaired people; plenty of them are using matrix of Braille pins. Some of these devices are based on the application of piezoelectric cantilevers [1-3]. The pins could simulate Braille letters and are based on changing the surface of finger touching area. In this paper we present new type of tactile device, which exploits the specific properties of piezoelectric bimorph cantilever. It consists of piezoelectric bimorph cantilever, acting as an oscillating probe, and, when changing operational signal, could transfer different information to visually impaired people, e.g. crossing the lines/contours or determining the color of lines or background. 2. The oscillating tip of the bimorph piezoelectric cantilever In the experiment we used piezoelectric cantilever, developed by Johnson Matthey Catalyst GmBH (Germany); the technical parameters are presented in Table 1. The Fig. 1 represents structure of piezoelectric cantilever. Fig. 1 presents piezoelectric cantilevers  (strain that defines the bending); it can be expressed by Eq. (1) with the equilibrium condition ∑  = 0 ; ∑  = 0  for no external loads. For the complete triple-layer bender [6, 11]:  = −6ℎ ℎℎ + ℎ + ℎℎ + ℎ − 6 + ℎℎℎ + ℎ + 2ℎ , (1)where: 1243. INVESTIGATION OF TACTILE CHARACTERISTICS OF THE PIEZOELECTRIC BIMORPH TYPE ACTUATORS.  R. BANSEVIČIUS, V. JŪRĖNAS, M. GUDAUSKIS, A. ŽVIRONAS 1344 © JVE INTERNATIONAL LTD. JOURNAL OF VIBROENGINEERING. MAY 2014. VOLUME 16, ISSUE 3. ISSN 1392-8716   = ℎ! "+ 2ℎ2ℎ + ℎ  + 3ℎ" + ℎ" ℎ + 2ℎ + ℎℎ" + ℎ + ℎ! + 12ℎℎℎ + ℎℎ + 12ℎℎℎ"  ". (2) Fig. 1. Structure of the piezoelectric cantilever Table 1. Johnson Matthey bending actuators’ typical characteristic values [4, 5] & = 0.038 m; ' = 0.0072 m; ℎ = 0.00025 m*; ℎ = 0.00030 m*;  = –315 ∙ 10-12 C/N;  = 14.20 ∙ 10-12 m2/N;   = 1/  = 70.423 ∙ 109 N/m2;  = 70 ∙ 109 N/m2;  = 1/  = 14.29 ∙ 10-12 m2/N;  = (")*+, = 57.692 ∙ 103 V/m; ℎ = 0.0008 m;  = 4500; - = 8.10 ∙ 103 kg/m3; - = 1.60 ∙ 103 kg/m3; . = 30 V.  *the exact parameters are not known (manufacturer’s commercial secrecy). All data are given by experimental measure. Piezoelectric cantilevers’ strain value is calculated by Eq. (1); applied voltage is 30 V. The voltage is sufficient to provide wide range of amplitude of cantilever tip. The strain value is:  = 0.0157. The theoretical cantilever‘s deflection is calculated multiplying strain value by cantilever length (parameter & value). Tip deflection value is: 1 = 0.0157 ∙ 0.038 = 0.5966 ∙ 105 m. With symmetric bimorph of the length & and the layer thickness ℎ, clamped on one side, the deflection of the free end, calculated with Eq. (3), becomes (with  = 7/2 h): 1& = 3&"8ℎ" 7 =3&"4h . (3)And finally: 1& = 0.5970 ∙ 105 m. All these calculations were made taken into account equilibrium condition ∑  = 0; ∑  = 0 for no external loads. The piezoelectric cantilever’s tip can be loaded by force (for example, human touch). This force can be calculated by Eq. (4) and this value will represent the blocking force. If this force will be applied to the cantilever’s tip, the deflection of tip will be 0. Following Yao piezoelectric actuator’s expression [7, 12], the blocking force could be calculated by: 1243. INVESTIGATION OF TACTILE CHARACTERISTICS OF THE PIEZOELECTRIC BIMORPH TYPE ACTUATORS.  R. BANSEVIČIUS, V. JŪRĖNAS, M. GUDAUSKIS, A. ŽVIRONAS  © JVE INTERNATIONAL LTD. JOURNAL OF VIBROENGINEERING. MAY 2014. VOLUME 16, ISSUE 3. ISSN 1392-8716 1345 ;< =3'ℎ"8& . (4)The blocking force of piezoelectric cantilever, calculated by Eq. (4): ;< = 0.0605 N. This parameter shows that human finger, developing force 60 mN, will stop cantilever from bending. 3. Experimental results 3.1. Tactile pen design The main characteristics of piezoelectric plate are shown in Table 1. The device is designed using stylus pen. Piezoelectric bimorph cantilever is mounted inside it, so that the free end of cantilever is placed near pen tip. Fig. 2 is showing scheme of tactile probe.  Fig. 2. Piezoelectric probe : 1 – body, 2 – touch screen sensitive tip,  3 – piezoelectric bimorph cantilever, 4 – cantilever tip, 5 – Braille pin,  6 – bimorph cantilever view from top, 7 – bimorph cantilever view from side 3.2. Research of piezoelectric bimorph cantilever The tip’s oscillations were determined using KEYENCE Laser Displacement Sensor LK-G82 [8], (Fig. 3). Resonant frequency was found by impact test and is 250 Hz (Fig. 4).  Fig. 3. General view of experimental set-up: 1 – tactile piezo bimorph cantilever; 2a – laser sensor head,  2b – laser sensor controller; 3a – Pico Scope 3202 device, 3b – PC with Pico Scope software;  4 – signal generator; 5 – signal amplifier 1243. INVESTIGATION OF TACTILE CHARACTERISTICS OF THE PIEZOELECTRIC BIMORPH TYPE ACTUATORS.  R. BANSEVIČIUS, V. JŪRĖNAS, M. GUDAUSKIS, A. ŽVIRONAS 1346 © JVE INTERNATIONAL LTD. JOURNAL OF VIBROENGINEERING. MAY 2014. VOLUME 16, ISSUE 3. ISSN 1392-8716   Fig. 4. Piezo cantilever’s impact test ( =	250 Hz) Earlier research established that operator could feel oscillations of the tip with frequency from 5 to 300 Hz [9]. Resonant frequency is near this maximal value, so testing could be done up to this frequency. The cantilever coefficient of elasticity was established using laser for measuring the displacements and external force – to load cantilever. The test results are presented in Table 2. Table 2. Piezoelectric bimorph displacement for different force Force, N 0 0.2 0.5 1 Displacement, µm 0 221 551 1134 Braille pins are sticking out about 0.5 mm [10]. Bimorph cantilever deflection of 0.5 mm is generated by 0.5 N force. To define what control signal parameter should be, we have to calculate stiffness = of the cantilever; in our case = 	888.889 N/m (Fig. 5).  Fig. 5. Displacement of tip in relation to applied force 3.3. Piezoelectric cantilever’ oscillation effects on tactile probe body In this research we used scanner of Polytec Laser Vibrometer and the probe with lower resonance frequency due to bigger effective length of cantilever. Probe’s body is made from aluminum alloy; the diameter is 8.5 mm, length – 122 mm. Scanned area was ¼ off tactile probe body, where user holds it. Area was about 30 mm length from tactile probe’s end. Fig. 6 show scanning area, divided in 281 finite number of elements. Green color is probe’ body, blue – cantilever Braille pin. The investigated piezoelectric cantilever 1243. INVESTIGATION OF TACTILE CHARACTERISTICS OF THE PIEZOELECTRIC BIMORPH TYPE ACTUATORS.  R. BANSEVIČIUS, V. JŪRĖNAS, M. GUDAUSKIS, A. ŽVIRONAS  © JVE INTERNATIONAL LTD. JOURNAL OF VIBROENGINEERING. MAY 2014. VOLUME 16, ISSUE 3. ISSN 1392-8716 1347 probe was excited with harmonic signal of 2 Vpp voltage and frequency range between 0 Hz to 10 kHz.  Fig. 6. Tactile probe body and cantilever scanning area From the frequency response presented in Fig. 7, the piezoelectric cantilever has several resonance frequencies. The first resonant frequency is 168 Hz. The second resonance at 1 kHz is highest, but it could be neglected, because the operating frequency range is 15-500 Hz. Operating frequency range was chosen experimentally.  Fig. 7. Frequency response of probe’s body in the range of 0-10 kHz and driving voltage 2 Vpp The first resonant frequency of 168 Hz of the cantilever is in the operating frequency range and the amplitude of the cantilever oscillations is 32 μm at the 2 Vpp. This investigation helps us to find out the oscillation amplitudes of probe’s body and cantilever Braille pins’ displacements. Probe’s body amplitude can be evaluated in tens of nanometers, while cantilever Braille pins – in the order of micrometers. 4. Conclusion This research describes how to calculate the deflection of bimorph piezoelectric cantilever, used in new design of tactile device, transferring information by changing frequency of oscillation in relation to color of lines or background. The amplitudes of cantilever and probe’s body oscillations are very diverse and operator better percept the oscillations of Braille pin, attached on bimorph piezoelectric cantilever tip. Acknowledgement This work has been supported by Lithuanian Agency for Science, Innovation and Technology 1243. INVESTIGATION OF TACTILE CHARACTERISTICS OF THE PIEZOELECTRIC BIMORPH TYPE ACTUATORS.  R. BANSEVIČIUS, V. JŪRĖNAS, M. GUDAUSKIS, A. ŽVIRONAS 1348 © JVE INTERNATIONAL LTD. JOURNAL OF VIBROENGINEERING. MAY 2014. VOLUME 16, ISSUE 3. ISSN 1392-8716  (MITA), Project TactileApps, No. 31V-38. References [1] Kyung Ki-Uk, Seung-Woo Son, Dong-Soo Kwon, Mun-Sang Kim Design of an integrated tactile display system. Proceedings of the 2004 IEEE International Conference on Robotics & Automation New Orleans, 2004, p. 776-781. [2] Takeshi Hommal, Shuichi Ino, Hayato Kuroki, Takashi Izumi, and Tohru Ifukube Development of a piezoelectric actuator for presentation of various tactile stimulation patterns to fingerpad skin. Proceedings of the 26th Annual International Conference of the IEEE EMBS San Francisco, USA, 2004, p. 1-5. 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Investigation of tactile characteristics of the piezoelectric bimorph type actuators

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