Application of a Dynamic Tip-Over Stability Margin to a Turntable Ladder Model

To ensure structural stability of fire service turntable ladders, the working range and actuator velocities are usually limited based on static calculations with conservative safety factors. Considering dynamic effects through an online stability measure may potentially allow for a more efficient limitation of ladder movements in future, aiming to enhance the performance of turntable ladders. Within this work, a rigid body model of a turntable ladder is derived enabling the elevation and extraction of the ladder parts as well as the outrigger lifting off the ground in case of vanishing contact force. The dynamic equations are derived using the Lagrange formalism. Subsequently, the dynamic stability measure NTOPv3 from Bennett (2019) is applied to assess a margin for the tip-over stability of the manipulator. Two exemplary trajectories are analyzed to examine the respective stability measure. These simulations reveal that initiating an emergency stop based on the stability measure prevents a possible tip-over. Therefore, the NTOPv3 measure is shown to be a useful tool for determining the position and velocities limits of the manipulator actuators of the turntable ladder.