Development Of Tactile Sensor Research Articles

形状記憶ポリマーの温度による剛性変化を利用した触覚センサの開発

形状記憶ポリマーの温度による剛性変化を利用した触覚センサの開発

Flexible PZT thin film tactile sensor for biomedical monitoring.

This paper presents the development of tactile sensors using the sol-gel process to deposit a PZT thin-film from 250 nm to 1 μm on a flexible stainless steel substrate. The PZT thin-film tactile sensor can be used to measure human pulses from several areas, including carotid, brachial, finger, ankle, radial artery, and the apical region. Flexible PZT tactile sensors can overcome the diverse topology of various human regions and sense the corresponding signals from human bodies. The measured arterial pulse waveform can be used to diagnose hypertension and cardiac failure in patients. The proposed sensors have several advantages, such as flexibility, reliability, high strain, low cost, simple fabrication, and low temperature processing. The PZT thin-film deposition process includes a pyrolysis process at 150 °C/500 °C for 10/5 min, followed by an annealing process at 650 °C for 10 min. Finally, the consistent pulse wave velocity (PWV) was demonstrated based on human pulse measurements from apical to radial, brachial to radial, and radial to ankle. It is characterized that the sensitivity of our PZT-based tactile sensor was approximately 0.798 mV/g.

Optimization of Human Tactile Sensation Using Stochastic Resonance

The development of tactile sensors and its data processing are crucial to advance robotics for allowing robots to explore and handle objects. Robots must sense the tactile feelings caused by contact between their hands and a human. This paper presents an influence of the stochastic resonance (SR) on tactile sensation that can enhance sensitivity by superimposing proper noise upon otherwise undetectable weak signals to detect the target signals. To investigate the SR of human tactile sensation and elucidate the mechanism of tactile SR, we performed a sequence of psychophysical experiments applying tangential directional vibration with a size of 2.5mm and 8mm stimulus point. We examined the difference threshold (DL) variation obtained from these experiments to clarify which condition of vibration direction and stimulus size causes the strongest SR. Furthermore we compared these results of tangential stimulus with results of normal stimulus obtained from our prior study. The experimental results show that neither normal nor tangential DL is significantly affected by stimulus point size. Moreover, tactile sensing precision is enhanced by appropriate noise and the characteristics of SR with tangential stimulation are quite different from those with normal stimulation.

Development of tactile sensor for measuring hair touch feeling

In this paper, a tactile sensor system for evaluation of human hair under dry and wet conditions is developed. The polyvinylidene fluoride (PVDF) film is used as the sensory material. The sensor consists of an acrylic base, a silicone rubber, a PVDF film. A surface projection is put on the PVDF film as the contacting part. The sensor output is obtained by contacting and scanning objects. Panels imitating the physical and chemical properties of human hair surface are fabricated and used as measuring objects for stable measurement. Panels cleaned down with several kinds of hair-care products are measured by the sensor. By comparison between the sensor output and human sensory evaluation, it was confirmed that the sensor outputs have a good correlation with human sensory evaluation. It was found that the sensor system is available for monitoring hair conditions in both dry and wet conditions.

Development of tactile sensors for simultaneous, detection of normal and shear stresses

A novel tactile sensor is analyzed and verified by intensive experiments. By using micro-cantilever beams, on which the strain gauge layers (Pt/Ti) are deposited, the corresponding induced strains can be detected and converted into electric resistance change, with respect to either applied normal stress or shear stress. The four micro-cantilever beams are allocated in the fashion such that any adjacent beams are perpendicular to each other to decouple any potential measurement discrepancy due to non-ideal orthogonality. In addition, the micro-cantilever beams are curled beforehand so that they can concurrently detect normal stress and shear stress. To be protected from being damaged by strong stress, the curled cantilever beams are embedded by elastomer material. Therefore, the micro-tactile sensor can detect normal stress up to 250 kPa and shear stress up to 35 kPa. Besides, since the elastomer is made of PDMS, which is of high bio-compatibility, the tactile sensor can be used to directly contact with human body. By taking the design and fabrication parameters into account, the curled micro-cantilever beams, which are composed by four layers: polymer/Pt/Ti/Si, can be produced with high yield rate. Finally, the efficacy of the tactile sensor is verified by experiments via a micro-manipulator, a high-resolution microscope and a force sensor for calibration.

Development of tactile sensor for monitoring skin conditions

This paper is concerned with the development of a haptic sensor for monitoring the human skin conditions. The sensor is an assembly of layered media. The base of the sensor is a copper plate, on which a vulcanized rubber, a PVDF film with electrode patches and a protective surface layer of acetate film are stacked in sequence. The sensor is attached onto the tip of an elastic cantilevered beam and pressed against a sample fabric with a prescribed contact force. The beam is translated linearly over the sample fabric with a constant speed to collect the tactile information on the fabric by the piezoceramic sensor. The features on the data are extracted by calculating both the temporal average of the absolute output signal and the intensity of power in the mid-frequency range and plotting then two-dimensionally on the xy-plane. Further the sensor is slid over the human bare skin and the skin with a sticking plaster to see whether the sensor can discriminate the two skin conditions.