| 摘要 |
The invention provides a fluid controller for controlling a machine, e.g. for steering a vehicle. The controller comprises a housing defining an inlet port connected to the source and an outlet port connected to the pressure operated device. The flow rate is controlled by movement of a valve member within the housing, and a processor provides a reference which is indicative of a desired position of the valve member relative to the housing. The fluid controller comprises a fault detection system based on an observer. The observer calculates a theoretically correct position of the valve member relative to the housing for a given reference, and compares this position to an obtained position of the valve member relative to the housing. The difference between the positions is compared with a threshold value. In order to dynamically change the sensitivity of the system, the threshold value is scaled based on a gradient of the reference.
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