The paper investigates a modified adaptive super-twisting sliding mode control (ASTSMC) for robotic manipulators with input saturation. To avoid singular perturbation while increasing the convergence rate, a modified sliding mode surface (SMS) is developed in this method. Using the proposed SMS, an ASTSMC is developed for robot manipulators, which not only achieves strong robustness but also ensures finite-time convergence. The boundary of lumped uncertainties cannot be easily obtained. A modified adaptive law is developed such that the boundaries of time-varying disturbance and its derivative are not required. Considering input saturation in practical cases, an ASTSMC with saturation compensation is proposed to reduce the effect of input saturation on tracking performances of robot manipulators. The finite-time convergence of the proposed scheme is analyzed. Through comparative simulations against two other sliding mode control schemes, the proposed method has been validated to possess strong adaptability, effectively adjusting control gains; simultaneously, it demonstrates robustness against disturbances and uncertainties.

Ionic polymer metal composite (IPMC) is regarded as the mainstream application material for achieving flexible driving technology in various engineering fields. In this article, aiming at the non-independence of the current IPMC electric driving method, an IPMC optical-controlled flexible driving method based on the photoinduced effects of lanthanum-modified lead zirconate titanate (PLZT) ceramic is proposed. To this end, a mathematical model for IPMC optical controlled flexible driving is built on the basis of the photovoltaic characteristic of PLZT ceramic, and the driving performance is experimentally analyzed through different lengths of IPMC under the excitation of different direct currents and light intensities. From the analysis and experimental results, when PLZT ceramic is irradiated by different light intensities, the output deformation of IPMC increases with increases in light intensity, and finally reaches a stable state. Moreover, the actuation curves obtained by light excitation and direct current excitation are consistent, and the motion coefficient reflects the driving performance more accurately. In addition, using light energy as an excitation source to drive IPMC not only provides new ideas for its development in the flexible driving field, but also provides a theoretical basis for its practical application.

Ionic polymer-metal composite (IPMC), as an intelligent material, exhibits advantages such as rapid responsiveness, large deformation angles, and high flexibility, leading to its extensive application in biomimetic machinery, biomedicine and other fields. In this paper, based on the previous proposed IPMC optical-controlled composite driving method under lanthanum-modified lead zirconate titanate (PLZT) ceramic configuration, the output energy characteristic is analyzed by establishing a novel model and conducting a series of experiments. The analysis and experimental results show that under different light intensities, the driving force and output deformation of IPMC with varying dimensions exhibit similar trends, both increasing gradually and reach a maximum value. Furthermore, the deformation curves of IPMC driven by light source are consistent with those driven by direct current, confirming that IPMC under light excitation also possesses stable and excellent energy output properties. Therefore, the research on the energy output of IPMC optical-controlled composite driving not only provides deeper theoretical guidance for its application in flexible driving area, but also promotes the vigorous development of IPMC in other innovative technological fields.