Bio-Inspired PVDF-Based, Mouse Whisker Mimicking, Tactile Sensor

Single Channel Based Interference-Free and Self-Powered Human-Machine Interactive Interface Using Eigenfrequency-Dominant Mechanism

The recent development of wearable devices is revolutionizing the way of human-machine interaction (HMI). Nowadays, an interactive interface that carries more embedded information is desired to fulfill the increasing demand in era of Internet of Things. However, present approach normally relies on sensor arrays for memory expansion, which inevitably brings the concern of wiring complexity, signal differentiation, power consumption, and miniaturization. Herein, a one-channel based self-powered HMI interface, which uses the eigenfrequency of magnetized micropillar (MMP) as identification mechanism, is reported. When manually vibrated, the inherent recovery of the MMP causes a damped oscillation that generates current signals because of Faraday's Law of induction. The time-to-frequency conversion explores the MMP-related eigenfrequency, which provides a specific solution to allocate diverse commands in an interference-free behavior even with one electric channel. A cylindrical cantilever model is built to regulate the MMP eigenfrequencies via precisely designing the dimensional parameters and material properties. It is shown that using one device and two electrodes, high-capacity HMI interface can be realized when the magnetic micropillars (MMPs) with different eigenfrequencies have been integrated. This study provides the reference value to design the future HMI system especially for situations that require a more intuitive and intelligent communication experience with high-memory demand.

A novel whisker sensor with variable detection range for object positioning

The design of a whisker sensor, inspired by mammalian whisker characteristics, is presented in this paper. It uses a novel spring structure to transfer the deformation generated by the whisker tip when it touches an object at the base, which drives the permanent magnet installed at the base to change its position. It achieves precise positioning of the object by using the magnetic induction intensity data output from the Hall sensor MLX90393. Based on the results of the finite element model analysis, the detection range of the whisker sensor can be expanded by replacing the artificial whisker material and selecting a permanent magnet of a suitable size. Calibration experiments and positioning tests were conducted on the sensor. The experimental results showed that the detection radius of the sensor was 24, 30, 33, and 39 mm for the carbon fiber, acrylic, acrylonitrile butadiene styrene plastic (ABS), and nylon whiskers, respectively, when they were matched with a NdFeB annular permanent magnet with an aperture of 3 mm and a thickness of 3 mm. The sensor is small and simple to manufacture with good sensitivity, linearity, hysteresis, and repeatability. The maximum positioning errors of the X and Y positions in the detection plane of the sensor were within ±1.3 mm, and the positioning was accurate. The sensor can be used to identify the shape of an object.

Design and fabrication of an E-whisker using a PVDF ring

Mammalian whiskers can perceive obstacles and airflows. In this study, an electronic whisker (E-whisker) sensor was designed and fabricated by setting a PVDF ring with symmetrical electrodes on the root of a fiber beam. Vibration displacements with different waveforms were applied at the free end of the E-whisker beam to study the relationship between the vibration displacements and the output signals. The E-whisker protrusion sensing ability was investigated by driving it to sweep through the surface of a base platform. A static E-whisker beam and a swinging E-whisker were then separately placed in a wind tunnel to detect the airflow perception of the sensor. The experimental results suggested that the E-whisker could sense the frequencies and amplitudes of displacements at its free end, the height and width of a platform or the heights of other irregular protrusions; the static E-whisker could sense the magnitude or direction of an impact airflow, while the swinging E-whisker could sense the magnitude of a constant airflow. Thus, this kind of E-whisker could perceive the environment and airflow through touch sensation and could be used as a physical model to study the principles and abilities of animal whiskers to perceive obstacles and airflows.

Experimental Research on PVDF Sensing Surface Characteristic Curve Applied to Topography Perception

With the development of intelligent technology, it is of great significance to develop intelligent equipment with topography self-sensing function. The micro morphology perception technology applied to intelligent equipment is the key technology for development. In this paper, at first, topography perception theory based on the PVDF (Polyvinylidene Fluoride) technology is researched, then an experimental study is conducted to sense the characteristic points of the geometric curve of the preset topography surface used in the PVDF film, and then the Ferguson curve model is used to reconstruct the topography characteristic curve. The experimental results show that the reconstruction curve can truly reflect the features of the characteristic curve of the surface of the preset topography, and the feasibility of topography surface sensing technology by PVDF sensing technology is verified. The research provides technical support for the development of intelligent equipment with topography self-sensing function.

Magnetostrictive Bioinspired Whisker Sensor Based on Galfenol Composite Cantilever Beam Realizing Bidirectional Tactile Perception

A magnetostrictive bioinspired whisker sensor based on a galfenol/beryllium-bronze/galfenol composite cantilever beam was developed in this work. According to the new design concept, the proposed whisker can output positive and negative voltages under different bending directions. Besides, the proposed whisker sensor can realize the bidirectional distance and microforce perception. Using the classical beam theory, a theoretical model was used to predict the output performance of the whisker. An experimental system was established to test the whisker's output performance. In the experiment, the designed whisker, compared with a traditional unimorph whisker, displayed an output voltage range of -240 to 240 mV. The parameters were as follows: the distance was 0-22 mm, with the microforce sensing range of 9.8-2744 mN, the average distance was 10.90 mm/mV, and the force sensitivity was 11.4 mN/mV. At last, obstacle perception was applied. The experiment showed that the proposed whisker sensor can realize the bidirection tactile perception in one-dimensional space. The work expands the function of the magnetostrictive bioinspired whisker, acquiring the multi-information for single-sensor system.

The Static and Dynamic Sensitivity of Magnetostrictive Bioinspired Whisker Sensor

Magnetostrictive bioinspired whisker is a new kind of sensor that can realize tactile and flow sensing by utilizing magnetoelastic effect. The sensitivity is a key technical indicator of whisker sensor. The paper presented a new magnetostrictive whisker based on Galfenol cantilever beam, as well as its operation principle. Then, the static and dynamic sensitivity of the whisker sensor was investigated by using a self-made experimental system. The results illustrated that the proposed sensor has a high sensitivity. Its static sensitivity is 2.2 mV/mN. However, its dynamic sensitivity depends on the vibration frequency. When working at the natural frequency of the cantilever beam, the dynamic sensitivity performs an obvious increase—1.3 mV/mN at 3.5 Hz (the first-order natural frequency) and 2.1 mV/mN at 40 Hz (the second-order natural frequency), respectively.