Force-fight problem in control of aileron's plane

To reduce or eliminate the force-fight phenomenon of single feedback loop of redundant-channels, the mechanical transmission structure, plate valves, parallel actuating cylinders, spindle and pipelines of the whole control system were modeled and simulated to obtain the bandwidth frequency of the system and the fighting-force caused by the internal asymmetry of the steering-gear. Then the influences of the system's input ratio, the size of valve's dead zone and the gradient of the valve's open area on the system's fighting-force and response speed were studied. Simulation results show that setting the dead zone of the valve which controls the feedback loop smaller is conducive to the decrease of system's fighting-force, and with the increase of the input ratio the fighting-force will be reduced greatly and the bandwidth will be increased and with the reduce of the valve's dead zone, and the increase of the gradient of the valve's open area, the bandwidth frequency increases, but have no influence on the fighting-force. Therefore, increase the input ratio and reduce the valve's dead zone or appropriate increase the gradient of the valve's open area can improve the dynamic and static performance of the system. Finally, a method of setting a variable orifice put forward to reduce system's fighting-force when these structural parameters cannot be changed, and simulation results prove its feasibility.