Sensor-Fault-Tolerant Operation for the Independent Metering Control System

Due to the complex control software based on electronic sensors, an independent metering control system (IMCS) has a higher risk of failures than a traditional electrohydraulic system. Considering the tough requirements of safety and reliability in mobile applications, this article innovatively proposes an active sensor-fault-tolerant controller (SFTC) for IMCSs. It is a model-free controller without any additional sensors. All the faults of the inlet, outlet, and supply pressure sensors are tolerated via analytical redundancy rather than hardware redundancy. The core of the analytical redundancy is to reconfigure the control loops of the normal controller by utilizing the cross-couplings among multivariables. To guarantee the switching stability from the normal controller to the SFTC, in this article, a bumpless transfer strategy based on latent tracking is designed, such that the abrupt output jump of the SFTC is suppressed and a smooth switching is obtained when the fault occurs. The feasibility of the SFTC system was evaluated by implementing the system on the two-ton excavator. The experimental results of boom motions verify the effectiveness of the controller under abrupt and random sensor faults.