Vibrotactile frequency discrimination on the wrist of visually impaired people

Development of devices for the visually impaired people equipped with a vibrating interface was the motivation of the research presented in the paper. Knowledge about discriminative ability of touch is crucial when designing devices which use tactile interfaces. The paper presents results of psychophysical studies on determining the vibrotactile frequency discrimination threshold on the wrist of blind and partially sighted people. The transformed adaptive method 1 up/2 down was used in the presented research. Thresholds were obtained on the ventral wrist at 5 frequencies: 25, 31.5, 63, 125 and 250 Hz. Results were examined to find factors which could influence the threshold value. Additionally, the guidelines for devices with vibrating interfaces supporting spatial orientation of the blind and partially sighted people was developed based on results and analysi

Vibrotactile frequency discrimination on the wrist of visually impaired people

Development of devices for the visually impaired people equipped with a vibrating interface was the motivation of the research presented in the paper. Knowledge about discriminative ability of touch is crucial when designing devices which use tactile interfaces. The paper presents results of psychophysical studies on determining the vibrotactile frequency discrimination threshold on the wrist of blind and partially sighted people. The transformed adaptive method 1 up/2 down was used in the presented research. Thresholds were obtained on the ventral wrist at 5 frequencies: 25, 31.5, 63, 125 and 250 Hz. Results were examined to find factors which could influence the threshold value. Additionally, the guidelines for devices with vibrating interfaces supporting spatial orientation of the blind and partially sighted people was developed based on results and analysi

GUITAR PLAYING ROBOT, A TOOL ASSISTING INSTRUMENTAL RESEARCH

The article is about use of automatic mechanism able to play an instrument in research about play repeatability. Repeatability in this case refers to the time delays between played notes in the sequences. Subject will be discussed based on a guitar playing robot. During the research with the use of guitar playing robots, some conclusions were made that confirm, that human is unable to play twice sound sequences maintaining high repeatability . It is also proven, that use of robotic musical instrument (RMI) helps to obtain play repeatability of the sound sequences much higher than the one obtained by the human musician

Piezoelectric square based sensor-actuator hybrid in vibration reduction

This paper presents the results of comparison of vibration reduction levels between standard square based piezo actuators and piezoelectric sensor-actuator hybrids. Modelling was done using FEM method in ANSYS software. Model consisted of a steel plate with piezo elements attached. One of the elements was used as an actuator to excite plate’s vibrations. The other was either a standard homogeneous square based actuator or a sensor actuator hybrid with 2 possible sizes of the sensor part of said hybrid. Harmonic analyses were performed for the 1st, 2nd, 4th and 5th mode shapes with the goal function being the minimalization of displacement vector sum of a number of nodes (there were 3 possible cases). Significant vibration reduction levels were obtained with no significant differences in said levels between standard actuators and sensor-actuator hybrids. Reducing the size of sensor part of sensor-actuator allowed for lower voltages needed to achieve vibration reduction levels

Numerical analyses of the effectiveness of an integrated disc based piezoelectric sensor-actuator

This paper deals with numerical analyses of plates vibration reduction effectiveness of an integrated disc based piezoelectric sensor-actuator compared to standard type disc based piezoelectric actuator. For that purpose 400 x 400 x 2 mm plate clamped on all sides was modelled with 2 piezo elements attached to it. One was a standard square based piezoelectric actuator used to excite the plate. The second one is disc based and can be either a standard element or an integrated sensor-actuator and is used for vibration reduction. The harmonic analyses were performed for the 1st, 2nd, 4th and 5th mode. Voltage used for plates excitation was always set to 100 V. The amplitude of voltage applied to the actuator was selected using internal ANSYS optimization procedures. The goal function for this was the minimum of the displacement vector sum of n nodes of the plate, with n having 3 possible values

Impact of the size of the sensor part on sensor-actuator efficiency

This paper presents numerical analyses of the impact of the size of the sensor-actuator part on sensor-actuator efficiency. For that purpose, numerical models of a steel plate clamped on all sides were created with two piezoelectric actuators attached to it. One was used to excite the plate and the second (which could be either a standard actuator or a sensor-actuator, having different shapes and sensor part size) to reduce plates vibrations. Harmonic analyses were performed with the goal function being the minimum of the displacement vector sum of n nodes, where n can have different values depending on the case study

COMPARISON OF PASSIVE AND ACTIVE METHODS FOR SOUND RADIATION REDUCTION FROM THE CLAMPED PLATE

The paper is an analytical and experimental study of smart structure, which consist of steel plate with bonded PZTs and porous elastomer layer. Active control of sound radiation from a clamped at the edge square plate is examined. Simulations and numerical computation of the experiment are performed in ANSYS environment. Calculations of plate vibration and sound radiation under stepped harmonic force are performed. The experimental set-up is placed in coupled reverberation chambers and the test plate is placed in the hole. A variety o test cases were studied for three different plates: steel plate + PZT, steel plate + elastomer layer, steel plate + PZT + elastomer layer. The aim of the paper is to illustrate the possibilities of using piezoelectric materials as an active control and elastomer layers as passive methods in one structure to improve the transmission loss

Vibrotactile amplitude discrimination on the wrist of visually impaired people

Support for spatial orientation and mobility of the blind and partially sighted people is still a hot and unsolved topic. It is well known that in supporting devices non-acoustic communication is recommended due to the role of the sense of hearing in the spatial orientation of the visually impaired people. Knowledge about discriminative ability of touch is crucial when designing devices which use tactile interfaces. The paper presents results of psychophysical studies connected with vibration perception on the wrist of blind and partially sighted people. The presented research examined the ability to identify the changes of amplitude of vibration on the wrist. Research was carried out on students of Special Schools for the Blind and Partially Sighted Children in Krakow. Thirty blind, partially and normal sighted people were examined. Transformed up/down method was used to determine vibrotactile amplitude discrimination threshold. Thresholds were obtained on the ventral wrist at 5 frequencies: 25, 32, 63, 125 and 250 Hz. Results were examined to find factors which could influence the threshold value

Acoustic indicators in the analysis of the acoustic environment of the Koscieliska Valley in the Tatra National Park

The development of our civilization and increasing noise pollution are strongly connected. In 2021, the Tatra National Park was visited by a record number of tourists - about 4 million 600 thousand. The previous record was broken in 2018 - then the Polish Tatra Mountains were visited by 3 million 800 thousand. people. The aim of the paper is the analysis of noise pollution and soundscape of the most popular national park in Poland - Tatra National Park. The Koscieliska Valley was selected for the study, because it is the second area in the park in terms of the number of tickets sold according to the statistics kept by the Tatra National Park. The paper presents the results of the analysis of acoustic measurements and ambisonic recordings made during four seasons using classical method and the soundscape method. In addition, psychoacoustic parameters and soundecology indicators such as: loudness, sharpness or roughness, ACI (acoustic complexity index), NDSI (normalized difference soundscape index), BIO (bioacoustic index), ADI (acoustic diversity index), AEI (acoustic evenness index) were calculated

Application of a Musical Robot for Adjusting Guitar String Re-Excitation Parameters in Sound Synthesis

Sound synthesis methods based on physical modelling of acoustic instruments depend on data that require measurements and recordings. If a musical instrument is operated by a human, a difficulty in filtering out variability is introduced due to a lack of repeatability in excitation parameters, or in varying physical contact between a musician and an instrument, resulting in the damping of vibrating elements. Musical robots can solve this problem. Their repeatability and controllability allows studying even subtle phenomena. This paper presents an application of a robot in studying the re-excitation of a string in an acoustic guitar. The obtained results are used to improve a simple synthesis model of a vibrating string, based on the finite difference method. The improved model reproduced the observed phenomena, such as the alteration of the signal spectrum, damping, and ringing, all of which can be perceived by a human, and add up to the final sound of an instrument. Moreover, as it was demonstrated by using two different string plucking mechanisms, musical robots can be redesigned to study other sound production phenomena and, thus, to further improve the behaviours of and sounds produced by models applied in sound synthesis