Justification of Design Parameters and Control System for Manipulator-Actuated Fire Monitors in Robotic Firefighting Systems

Introduction. Robotic firefighting systems equipped with manipulator-actuated fire monitors (water/foam nozzles) enable remote suppression in hazardous environments while reducing personnel exposure. However, accurate jet aiming and stable operation are challenged by strong, rapidly varying disturbance loads caused by jet recoil, flow-rate changes, hose/line dynamics, and platform motion. These factors must be explicitly considered when justifying manipulator design parameters and selecting a control architecture that maintains pointing accuracy and operational safety.

Methods. A coupled dynamic model of the manipulator–fire–monitor assembly was formulated, incorporating joint friction, actuator limits, and a recoil load model expressed through nozzle operating variables (pressure/flow) and monitor orientation. Design parameter justification was performed by evaluating worst-case combinations of required slewing/positioning maneuvers and recoil disturbances to derive bounds for joint torques, speeds, transmission ratios, stiffness, and admissible mass-inertia properties of the end-effector. The control system was synthesized as a two-layer scheme: a feedforward compensation term based on the estimated recoil moment and desired motion profile, and a feedback loop for tracking and disturbance rejection (computed-torque or robust PID structure with anti-windup and saturation handling). Safety constraints were enforced through bounded acceleration/jerk commands and workspace limitations.

Results. The proposed framework yields parameter maps linking nozzle operating regimes and aiming dynamics to required actuator capabilities and structural margins. Simulation-based verification demonstrates stable tracking under abrupt flow changes and external disturbances, with reduced overshoot and faster settling compared to non-compensated control. The controller maintains bounded pointing error while avoiding actuator saturation across the considered operating envelope.

Conclusions. The presented approach provides a systematic justification of manipulator design parameters and control structure for manipulator-actuated fire monitors. It supports evidence-based sizing and tuning to improve aiming stability, robustness to recoil disturbances, and overall safety of robotic firefighting systems.