The shape memory alloy (SMA)-based actuators have been increasingly used in different domains, such as automotive, aerospace, robotic and biomedical applications, for their unique properties. However, the precision control of such SMA-based actuators is still a problem. Most traditional control methods use the force/displacement signals of the actuator as feedback signals, which may increase the volume and weight of the entire system due to the additional force/displacement sensors. The resistance of the SMA, as an inherent property of the actuator, is a dependent variable which varies in accordance with its macroscopic strain or stress. It can be obtained by the voltage and the current imposed on the SMA with no additional measuring devices. Therefore, using the resistance of the SMA as feedback in the closed-loop control is quite promising for lightweight SMA-driven systems. This paper investigates the resistance characteristics of the SMA actuator in its actuation process. Three factors, i.e., the resistivity, the length, and the cross-sectional area, which affect the change of resistance were analyzed. The mechanical and electrical parameters of SMA were obtained using experiments. Numerical simulations were performed by using the resistance characteristic model. The simulation results reveal the change rules of the resistance corresponding to the strain of SMA and demonstrate the possibility of using the resistance for feedback control of SMA.

Lunar dust removal is one of the most important issues to be solved in lunar exploration. A lunar dust removal method based on the anomalous photovoltaic effect of lanthanum-modified lead zirconate titanate has been developed in our previous research which could be used for conductor surface dedusting. In this study, a novel lunar dust removal technique utilizing a couple of coplanar bipolar dust-removing electrodes is proposed. With this technique, lunar dust on different kinds of surface (conductor and nonconductor) can be reliably debrided. The working principle of this technique is introduced first, followed by a series of simulations and experiments which demonstrate that this technique can generate an adequate absorbing force on the lunar dust lying on the insulating or conducting surface and can provide ideal dedusting performance. Effects of electrode area and dust particle size on the dust removal efficiency are investigated. A crawler-type autonomous dust-removing device is developed in which a couple of flexible coplanar bipolar electrodes are designed as the crawler belts of the device. By controlling the path and velocity of the dust-removing device, a 95.3% dust removal rate was achieved in a dedusting test on a 500 × 400 mm ² plank. This study provides a new feasible method for future lunar dust removal mission.

The inspection, maintenance, and repair of complex pipelines have motivated the development of soft robots with highly flexible and good adaptability. In this study, inspired by the unique locomotion of earthworms, we developed a type of smart material–driven soft modular pipe robot capable of stable manipulation and performing in unstructured pipe environments, which easily assembles into more complex configurations with multiple modules for practical use. Our prototype robot consists of three soft telescopic modules connected in series with flexible bellows and a tail friction mechanism, where the modules adopt a high-energy density shape memory alloy spring as an actuator. Based on analyzing the peristaltic process of the module inside the pipe, it is ensured that the geometric constraint performance of the braided mesh pipe is reasonably matched with the thermomechanical performance of the SMA spring to realize the alternating conversion of anchoring and releasing. By optimizing the overall robotic structure, it is demonstrated that our robot achieves robust crawling in horizontal, vertical, variable-diameter, and curved pipes, wet pipes with the partial presence of water, and pipes with complex cavities through simple open-loop on/off control.