A plurality of control channels each include a power supply, an interface that receives a manipulation signal, an arithmetic processing portion that calculates and generates an operation command signal for actuators based on the manipulation signal, and a signal determination unit that determines a control signal for finally controlling the operation of the actuators and outputs the control signal. The arithmetic processing portions respectively provided in the plurality of control channels have designs different from one another. Each of the signal determination units determines the control signal by receiving a first operation command signal generated by the arithmetic processing portion of the control channel in which that signal determination unit is provided, and a second operation command signal generated in the arithmetic processing portion of another of the control channels, and comparing the first operation command signal and the second operation command signal, and outputs the control signal.