As a key component of a drip irrigation system, the performance of the drip irrigation emitters is mainly determined by the flow channel structures and structural parameters. In this study, a novel type of circular water-retaining labyrinth channel (CWRLC) structure emitter was proposed, inspired by the effect of roundabouts that make vehicles slow down and turn. Using the single-factor experiment method, the influence of the hydraulic performance of CWRLC emitters was researched under different circular radii. The internal flow characteristics and energy dissipation mechanism were analyzed by a computational fluid dynamics (CFD) simulation. It can be seen from the analysis that the energy dissipation abilities of the flow channel depend on the proportion of low-speed vortex areas. The larger the proportion of low-speed vortex areas, the smaller the flow index of the CWRLC emitter. Quadrate water-retaining labyrinth channel (QWRLC) and stellate water-retaining labyrinth channel (SWRLC) structures were obtained by structural improvements for increasing the proportion of low-speed vortex areas. The simulation results showed that the flow indexes of two improved structural emitters were significantly decreased. CWRLC, QWRLC, SWRLC, and widely used tooth labyrinth channel (TLC) emitters were manufactured by using technologies of electrical discharge machining (EDM) and injection molding (IM). The physical test results showed that the SWRLC emitter achieved the best hydraulic performance compared with the other three emitters. Therefore, the SWRLC emitter has a broad prospect of application in water-saving irrigation.

The global path planner is an important part of the navigation system for autonomous differential drive mobile robots (DDMRs). Aiming at the problems such as long calculation time, large number of search nodes, and poor smoothness of path when A* is applied to global path planning, this study proposes an improved bidirectional search Gaussian-A* (BSGA*) algorithm. First, the Gaussian function is introduced to realize the dynamic weighting of the heuristic function, which reduces the calculation time. Secondly, the bidirectional search (BS) structure is adopted to solve the problem of nodes’ repeated search when there are large obstacles between the starting point and the target point. Finally, a multi-layer turning point filter strategy is proposed to further smooth the path. In order to verify the performance of the improved BSGA* algorithm, experiments are carried out in simulation environments with the size of 15 × 15 and 30 × 30, respectively, and compared with the five common global path planning algorithms including ant colony optimization (ACO), D* lite algorithm, and genetic algorithm (GA). The results show that the improved BSGA* algorithm has the lowest calculation time and generates the shortest and smoothest path in the same environment. Finally, the program of the improved BSGA* algorithm is embedded into the LEO ROS mobile robot and two different real environments were built for experimental verification. By comparing with the A* algorithm, Dijkstra algorithm, ACO, D* lite algorithm, and GA, the results show that the improved BSGA* algorithm not only outperforms the above five algorithms in terms of calculation time, length, and total turning angle of the generated paths, but also consumes the least time when DDMR drives along the generated paths.

Drip irrigation system performance is largely governed by emitter hydraulic characteristics. This study systematically compares the hydraulic performance of a novel cylindrical asteroid-shaped channel emitter against a conventional toothed labyrinth design. Standardized specimens were produced using precision molds and integrated into drip tapes at 300 mm spacing. To comprehensively analyze flow behavior, pressure–discharge relationships, flow indices, and internal flow fields, a combination of physical experiments and CFD simulations was employed. Experimental results showed that across 20–200 kPa, the cylindrical asteroid-shaped emitter delivered flow rates 24–28% higher than the labyrinth type while maintaining a lower flow index, demonstrating enhanced hydraulic stability. Flow field analysis at 100 kPa revealed that the divergent asteroid geometry generates more intense and sustained turbulent kinetic energy throughout the channel units, resulting in superior energy dissipation. The cylindrical asteroid-shaped unit achieved a pressure drop of 17.5 kPa, exceeding the 15.3 kPa observed in the labyrinth channel, with outlet velocities of 1.6 m/s versus 1.76 m/s. Additionally, the flow pattern promotes comprehensive wall scouring through large-scale vortices, indicating improved resistance to clogging. These findings validate the design superiority of the cylindrical asteroid-shaped emitter and offer a theoretical reference for developing high-uniformity, water-saving irrigation devices.

How suspended grains traverse energy-dissipating micro-passages determines whether sediment-laden water can be used without rapid emitter deterioration. A novel cylindrical asteroid-shaped drip emitter was investigated through laboratory anti-clogging tests and two-way coupled computational fluid dynamics–discrete element method (CFD–DEM) simulations. The laboratory tests comprised 20 intermittent irrigation cycles at five pressures ranging from 60 to 140 kPa, with relative discharge used to characterize hydraulic performance. The simulations tracked particle motion, wall collisions, and mass transmission over a 0.20 s observation window to examine the effects of operating pressure, injected particle mass, and flow-path radius. Numerical cases isolated hydraulic forcing and, at 100 kPa, changes in solids dose and cavity radius. Measured discharge retention occupied a narrow 96.45–97.83% interval, whereas the fraction of particulate mass leaving the domain spanned 81.3–92.7%. Despite representing different responses, both indices followed pressure in a closely associated manner (Pearson r = 0.975, p = 0.0046). Stronger forcing extended the high-speed portion of individual trajectories and brought the final wall contacts forward in time, although contact totals did not follow a monotonic sequence. Changing the dose between 1.0 and 2.0 × 10⁻⁶ kg altered the selected upper-speed statistics by only +1.8% and −2.1% but reshaped the contact histories. Expanding the radius from 0.65 to 0.85 mm produced much larger reductions of 28.1% and 91.3%; the latter record then showed sustained near-stagnation with relatively few impacts. Thus, low collision frequency cannot independently demonstrate effective sediment passage. Combining effluent mass balance with trajectory and contact information provides a mechanistic basis for diagnosing retention in irrigation microchannels.