The advancement of mobile robot technology has made path planning a necessary condition for autonomous navigation, but traditional algorithms have issues with efficiency and reliability in dynamic and unstructured environments. This study proposes a Dynamic Hybrid A* (DHA*)–Adaptive Dynamic Window Approach (ADA-DWA) fusion algorithm for efficient and reliable path planning in dynamic unstructured environments. This paper improves the A* algorithm by introducing a dynamic hybrid heuristic function, optimizing the selection of key nodes, and enhancing the neighborhood search strategy, and collaboratively optimizes the search efficiency and path smoothness through curvature optimization. On this basis, the local planning layer introduces a self-adjusting weight-adaptive system in the DWA framework to dynamically optimize the speed, sampling distribution, and trajectory evaluation metrics, achieving a balance between obstacle avoidance and environmental adaptability. The proposed fusion algorithm’s comprehensive advantages over traditional methods in key operational indicators, including path optimality, computational efficiency, and obstacle avoidance capability, have been widely verified through numerical simulations and physical platforms. This method successfully resolves the inherent trade-off between efficiency and reliability in complex robot navigation scenarios, providing enhanced operational robustness for practical applications ranging from industrial logistics to field robots.

We present a topology-optimization methodology for designing single-sided, tri-state electrode patterns (+V, 0, electrode-free) that maximize shear-mode purity in lithium niobate (LiNbO₃) wafers. The framework combines a complex-Hermitian adjoint sensitivity formulation based on Wirtinger calculus with a coarse–fine design-mesh decomposition and Heaviside projection, and treats the bottom-face electrical boundary condition as an explicit design variable. Applying the method to five crystal cuts (X, Y, Z, 41°Y, 128°Y) over 3.30–4.10 MHz under grounded and single-sided configurations, we find that the optimal boundary condition is jointly determined by crystal cut and frequency through the rotated piezoelectric tensor and that topology optimization improves purity by up to 28.8 percentage points when the baseline is poorly matched but can be counterproductive when it is already optimal (Z-cut). We distil these behaviors into a three-regime taxonomy that predicts, a priori, when optimization is worthwhile. The result is a reusable design methodology, together with per-cut design rules, for shear-mode LiNbO₃ transducers.

Z-cut lithium niobate single crystal demonstrates considerable promise for contact-based ultrasonic nondestructive testing and structural health monitoring (SHM) transducers due to its high piezoelectric coefficients, strong electromechanical coupling capability, and environmentally friendly lead-free composition. As a simulation-based theoretical exploration, this study systematically investigates the impact of gap spacing and electrode width in concentric ring configurations on the resonant characteristics and pulse-echo response of ultrasonic transducers by establishing a parametrized finite element model. Numerical simulations reveal that electrode geometry plays a critical role in determining both the effective electromechanical coupling coefficient and echo signal strength. Optimizing the electrode ring width achieved an effective electromechanical coupling coefficient ($k_{\mathit{eff}}$) of 35.2%, while systematic enlargement of the electrode gap further enhanced this value to 50.8%. The study also demonstrates that optimized ring width and adjusted electrode spacing increased the echo signal’s peak-to-peak amplitude ($V_{pp}$) by factors of 4.94 and 2.03, respectively, compared to the poorest-performing configuration within each parameter group. This study establishes that precise design of concentric electrode configurations serves as an effective strategy for tuning lithium niobate ultrasonic transducer characteristics, providing critical design guidelines for developing high-performance ultrasonic transducers for solid medium coupling.