Tactile sensors enabling human-like perception are crucial for modern intelligent robotics. This study developed a biomimetic magnetostrictive tactile sensor consisting of Galfenol wires, permanent magnets, and a Hall sensor. This novel tactile sensor exhibits a static sensitivity of 23.86 mV/N and a measurement range up to 3 N. The sensitivity is stable up to 4 Hz. A theoretical model of the tactile sensor unit was derived to correlate the output voltage with the applied force. The modeling result shows an error of 1.65% in sensitivity compared to the experimental data. The response time and recovery time of the sensor are only 11 ms and 10 ms, faster than nanoscale type of sensor. A 3×3 magnetostrictive sensor array was constructed by integrating multiple magnetostrictive tactile sensors on a flexible printed circuit board. Since the outputs of the sensing units are not affected by each other, the array can be expanded as needed. Experimental results show that the sensor array is able to detect the geometry of the object in contact.

A new high-sensitivity magnetostrictive tactile sensor array is designed based on the inverse magnetostrictive effect and tunnel magnetoresistance to enable intelligent robots to have a sensitive sense of touch and perform delicate operations. The output voltage model of the tactile sensor is developed. The optimal bias field and spacing of the sensor unit are determined using COMSOL Multiphysics. Test platforms for static and dynamic characteristics are built. The output characteristics of the tactile sensor under static and dynamic forces are tested. The sensitivity is compared with that of other types of tactile sensors. The tactile sensor units are set into a $2\times3$ sensor array and the coupling effect of the output voltage of each unit in the array is tested. The experimental results show that the experimental value of the output voltage matches the calculated value with a maximum error of 3.47%. The sensitivity of the tactile sensor is 323 mV/N at 0–4 N static force, which is higher compared to other types of tactile sensors. The sensitivity of the sensor unit changes less than 1.15% at 1–4 Hz dynamic force. The interaction of output voltage between units in the $2\times3$ tactile sensor array does not exceed 1.5% and is negligible. The $2\times3$ tactile sensor array is attached to a three-finger manipulator for grasping objects with a different hardness. The results of the study have guiding significance to the design of high-sensitivity tactile sensors for intelligent robots.

According to the actual operation conditions, a kind of high-frequency losses testing system of magnetostrictive materials under dc bias is built. The dynamic hysteresis loops for Terfenol-D samples at different ac driving frequencies and magnetic densities are studied experimentally under variable dc bias excitation. The magnetic energy losses are obtained from these dynamic hysteresis loops. The three-variable magnetic energy loss matrix is established by these measured data. On the basis of Bertotti loss separation theory, the high-frequency losses calculating model of magnetostrictive materials considering variable dc bias excitation is proposed by using the algorithm of Levenberg–Marquardt and the method of matrix transformation. In this model, according to the multivariate parametric regression, the loss coefficients are modified by introducing dc bias-related terms. The loss comparison at different operating conditions shows that the computed results in this proposed model are in good agreement with the experimental ones.

Experimental and calculating analysis of magnetic losses for Terfenol-D is a necessary step for the design of high-power magnetostrictive transducer. In order to further research the magnetic energy losses characteristics, a Terfenol-D rod is sectioned along different directions, and these slices are made into several square annular sheet samples. The influences of material magnetization direction on the losses are compared and analyzed. The values of magnetic energy losses are measured to investigate their variations at different frequencies and magnetic densities of driving magnetic field. Furthermore, the traditional losses formula is improved. The values of the hysteresis losses, eddy-current losses, and anomalous losses are separated out, and the losses coefficients are achieved through polynomial curve fitting. This paper can provide theoretical and experimental guidance for the high-frequency applications of magnetostrictive materials.

This paper presents a fully coupled, nonlinear electromagnetic-mechanical-thermal model for Terfenol-D devices which include active magnetostrictive materials and passive components. The model includes two parts: (1) a material-level discrete energy-averaged model (DEAM) to describe the magnetomechanical coupling and thermal effect of Terfenol-D and (2) a system-level finite element model formulated in weak form using Maxwell's equations, Newton's law, and heat transfer equations. The objective is to describe the electromagnetic, mechanical, and thermal dynamics of the device. The system finite element model is constructed in COMSOL Multiphysics, and the nonlinear behavior of Terfenol-D is coupled through lookup tables generated by the DEAM. Preliminary results of the output capacity of a Terfenol-D actuator with respect to ambient temperature are presented in terms of blocked force, free displacement, and output power. The blocked force and free displacement decrease by 8.0% and 29.8%, respectively, for a 12 A (RMS) excitation current, as the temperature increases from 20 °C to 180 °C. One of the key contributions of this study is that it accounts for both the temperature-dependent Terfenol-D properties and the thermal effects of surrounding passive systems.

Magnetostrictive materials have excellent magneto-mechanical properties and are widely used in the field of energy conversion. Temperature has an important influence on the magnetic properties of them. Accurately studying the temperature dependence of magnetostrictive materials is a necessary prerequisite for the design of precision actuators. In this paper, we constructed a high-frequency magnetic property measurement system that can control the temperature. The magnetic characteristics of Terfenol-D, Fe-Ga and Fe-Co were measured at temperatures ranging from 10 °C to 80 °C, the frequencies from 1 kHz to 20 kHz and magnetic induction amplitudes from 0.01 T to 0.07 T. The temperature dependence of the three materials under different exciting conditions was comprehensively compared. The variation trends and temperature sensitivities of the coercivity, permeability, equivalent inductance, equivalent resistance and the magnetic energy losses are analyzed respectively. The results of this paper are oriented to practical engineering applications and can be used for high-frequency loss prediction and temperature control system design.