Soft robots, with their unique and outstanding capabilities of environmental conformation, natural sealing against elements, as well as being insensitive to magnetic/electrical effects, are ideal candidates for extreme environment applications. However, sensing for soft robots in such harsh conditions would still be challenging, especially under large temperature change and complex, large deformations. Existing soft sensing approaches using liquid-metal medium compromise between large deformation and environmental robustness, limiting their real-world applicability. In this work, we propose a multimodal solid-state soft sensor using hydrogel and silicone. By exploiting the conductance and transparency of hydrogel, we could deploy both optical and resistive sensing in one sensing component. This novel combination enables us to benefit from the in-situ measurement discrepancies between the optical and electrical signal, to extract multifunctional measurements. Following this approach, prototype solid-state soft sensors were designed and fabricated, a dedicated neural network was built to extract the sensory information. Stretching and twisting were measured using the same sensor even at large deformations. In addition, exploiting the distinctive responses against temperature change, we could estimate environmental temperatures simultaneously. Results are promising for the proposed solid-state multimodal approach of soft sensors for multifunctional perception under extreme conditions.
The interaction between High Voltage Direct Current (HVDC) transmission lines and turbogenerator units will cause the damage of the generator shafting and the electrical system by exchanging energy at one or more lower synchronous frequencies, resulting in the damage or even breakage of the generator shafting, seriously affecting the safe operation of the power system. To solve this problem, the Supplementary Subsynchronous Damping Controller (SSDC) is an effective method to suppress the secondary synchronous oscillation of turbogenerator units connected to rectifier side caused by HVDC. This paper combines the first standard model parameters of IEEE subsynchronous oscillation with CIGRE HVDC transmission system, and builds a HVDC transmission test system for Subsynchronous Oscillations(SSO) research in PSCAD. Based on signal test method, a narrow band SSDC is designed, and the damping in each synchronization frequency band is greatly increased. When the proportional coefficient is appropriate, the electrical damping is positive. The effectiveness of the designed SSDC is also verified by time domain simulation.
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