An improved Near-Field Computer Vision (NFCV) system for intelligent fire robot was proposed that was based on our previous works in this paper, whose aims are to realize falling position prediction of jet trajectory in fire extinguishing. Firstly, previous studies respecting the NFCV system were briefly reviewed and several issues during application testing were analyzed and summarized. The improved work mainly focuses on the segmentation and discrimination of jet trajectory adapted to complex lighting environment and interference scenes. It mainly includes parameters adjustment on the variance threshold and background update rate of the mixed Gaussian background method, jet trajectory discrimination based on length and area proportion parameters, parameterization, and feature extraction of jet trajectory based on superimposed radial centroid method. When compared with previous works, the proposed method reduces the average error of prediction results from 1.36 m to 0.1 m, and the error variance from 1.58 m to 0.13 m. The experimental results suggest that every part plays an important role in improving the functionality and reliability of the NFCV system, especially the background subtraction and radial centroid methods. In general, the improved NFCV system for jet trajectory falling position prediction has great potential for intelligent fire extinguishing by fire-fighting robots.

During the multi-channel confluent water supply process, the pressure control of the main pipe is often held back by such problems as non-linearity, hysteresis and parameter uncertainty, its own unique load dynamic changes, channel switching disturbance and other system characteristics caused by the actual working conditions. Moreover, pressure fluctuations in the main pipe will lead to a reduction in the service life of fire-fighting equipment, an increase in the failure rate, and even an interruption of the fire-fighting water supply. Therefore, a master and auxiliary control strategy is proposed to stabilize the pressure change in the process of multi-channel concentrated water supply switching, by using variable universe fuzzy proportional integral derivative (PID) control as the main controller on the main pipe and traditional PID control as the subsidiary controller on the channel. The control strategy is verified by the co-simulation platforms of LabVIEW and AMESim. Simulation results show that the variable universe fuzzy PID control and the master and auxiliary compound control based on the variable universe fuzzy PID control have advantages in step response, tracking response and anti-interference, respectively. The parameters obtained in the co-simulation are used in the experimental system. The experimental results show that the maximum deviation rate of main pipe pressure can be reduced by about 10% compared with other control methods under different loads. In conclusion, the proposed control strategy has strong anti-interference ability, fast dynamic response speed, high stability and good peak shaving effect.

Transportation efficiency is a problem of particular interest in multi-channel confluent water supply engineering. Transportation efficiency depends not only on the system control strategy but also on the pressure loss (pressure difference between the inlet and outlet) and pressure drop (amplitude of outlet pressure fluctuations) of its structure. In this article, sensitivity analyses of the pressure loss and pressure drop to changes in multi-channel confluent water supply geometry are presented. An experimental set-up was established to validate computational fluid dynamic (CFD) predictions and obtain the boundary conditions for two-channel synchronous switching. The influences of the geometric structure varies by the clustered pipe diameter (40 mm < Dc < 80 mm), main pipe diameter (30 mm < Do < 80 mm), channel pitch (60 mm < L < 400 mm) and number of channels (2 ≤ n ≤ 4); those variables were investigated with the help of CFD simulations. The results showed that configuration “C” can be considered a costless method of decreasing pressure loss (β_C(2.05) < β_A(2.42) < β_B(2.64)) and that the different configurations are insensitive to pressure drop. The variations of the influence of channel pitch and clustered pipe diameter on pressure loss have extremes at L/d = 5 and Dc/d = 2.5, respectively, but the effect on pressure drop is not obvious. The main pipe diameter and the inlet velocity have more significant influences on efficiency. The results can be used to choose the proper geometry of multi-channel confluent water supply to enable energy savings.

Many large-flow fires need sustained and stable water supplies, which are often challenging because of the complex fire ground. To analyze the causes and influencing factors of pressure fluctuation in the process of switching water sources, an experimental setup and a simulation model were established. The basic hydraulics principle is that pressure drop occurs during the switching between two channels. The pressure drop magnitude in the main pipe was studied for various resistance values of the main pipe, switching time of the control valve in the channel, the number of parallel channels, and the diameter of the clustered pipe. The results show that three key parameters affect the magnitude of the pressure drop: a longer switching time, less pipe resistance, and more parallel channels can minimize the pressure drop magnitude of the mine pipe. This study provides fire equipment designer with information about the influence of different variables on the pressure drop magnitude of the main pipe and basic design criteria to minimize these effects. Meanwhile, a simple scheme is proposed to minimize the large pressure fluctuation, and the pressure fluctuation can be decreased and even eliminated to some extent.

Real-time motion control of heavy-duty hydraulic demolition robots is frequently compromised by kinematic singularities and joint stroke constraints, which induce adverse pressure fluctuations and mechanical instability. This paper proposes a computationally efficient, Jacobian-free inverse kinematics solver tailored for a 5-degree-of-freedom (DOF) heavy-duty demolition robotic arm. The proposed approach combines an improved geometric method with a discrete traversal screening mechanism to address the computational overhead and convergence difficulties associated with traditional iterative numerical methods. By incorporating joint boundaries directly into the solution process and selecting configurations based on minimum joint displacement, the method facilitates smoother actuation transitions. The solver was evaluated through numerical simulations and validated on a physical demolition platform. Results indicate a mean execution time of 4.11 ms with a success rate of 98.2%. In singular configurations, the end-effector position error was observed to be lower than that of the conventional Damped Least Squares (DLS) method, with a reduction in average error of approximately 95% near singular configurations. Furthermore, the effective suppression of joint velocity spikes confirms the algorithm’s capability to enhance hydraulic execution stability and operational reliability in unstructured environments.

The multi-channel concentrated water supply system represents a pivotal link in the firefighting water supply chain, and ensuring the efficiency of its water supply is of paramount importance for the smooth progress of firefighting. A mathematical model is established for the steady state and transient conditions of the multi-channel water supply system. The model solution indicates that the number of parallel channels, centrifugal pump operating frequency, valve execution time, and system resistance can affect the output pressure and flow rate of the confluent water supply system. A detailed investigation was performed into the influence laws of different operating parameters on the output characteristics of the multi-channel confluent water supply system, based on the experimental and simulation research platform. Especially under transient conditions, the increase in the operating frequency and valve switching interval will result in a greater value for the main pipe pressure drop/pressure rise. When the load valve opening is below 50%, the influence of the valve switching interval time and channel transported distance on the pressure drop value is reduced. The research results provide a foundation for the smooth switching of multi-channel confluent water supply systems.