Capturing switchover transients in a dual-circuit hydraulic redundancy test requires high-speed synchronised data acquisition across both circuits and a controlled failure injection mechanism. Here's the implementation approach, described conceptually.
Dual-Circuit Synchronised DAQ Architecture
The core of the system is a synchronised data acquisition controller that samples both hydraulic circuits independently but simultaneously, typically at a sample rate around 1000 Hz. Each circuit (Circuit A and Circuit B) has its own pressure and flow sensors, and its own dedicated sampling thread, so that neither circuit's readings can be delayed or distorted by activity on the other.
When recording starts, the controller launches one thread per circuit. Each thread runs a tight sampling loop: at every sample interval it reads the pressure sensor and flow sensor for its circuit, timestamps the reading relative to the recording start time, and appends the values to that circuit's dataset. Because each circuit's thread runs independently, a slowdown or anomaly in one circuit's sampling never affects the other's timing. When recording stops, both threads are joined cleanly so the dataset is complete and synchronised across circuits.
Controlled Failure Injection
Alongside the DAQ, a failure injector provides repeatable, controlled ways to simulate a circuit failure on demand. It is tied to a specific circuit's valve controller and supports at least two failure modes.
The first is a gradual pressure loss, simulating a developing leak. The injector reads the circuit's initial pressure, then ramps the commanded pressure down smoothly over a configurable ramp time (for example, half a second) until it reaches a target residual pressure, updating the setpoint in small steps so the decline is realistic rather than instantaneous.
The second mode is an instantaneous failure, simulating something like a sudden line rupture. Here the injector immediately commands an emergency vent on the circuit, producing a near-instant pressure collapse rather than a ramp. Both modes record metadata (failure type, circuit identifier, and injection timing) so the event can be precisely correlated against the DAQ timeline afterward.
Switchover Transient Analysis
Once a test run is complete, the recorded data is analysed to characterise how the test article behaved around the moment of failure injection. The analysis looks at a window of time just before and after the failure event, typically a couple of seconds, and extracts the test article's output values within that window.
It first establishes a pre-failure baseline by averaging the last several output readings before the failure was injected. It then scans the post-failure readings to find the recovery time: the point at which the output returns to within five percent of that baseline value. If the output never recovers within the analysis window, recovery is reported as not achieved.
The analysis also computes the maximum deviation observed during the transient, expressed as a percentage of the baseline value, which indicates how severe the disturbance was at its worst point. Together, the recovery time and maximum deviation give engineers a quantified picture of switchover quality: not just whether the system survived the failure, but precisely how much it deviated and how quickly it stabilised.
The Neometrix Dual Power Hydraulic Test Rig implements this synchronised dual-circuit DAQ and controlled failure injection architecture for redundant hydraulic system qualification testing.
Link: https://neometrixgroup.com/products/dual-power-hydraulic-test-rig
Top comments (0)