Hydraulic Actuation System Pressure Sensor Fault Handling
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Solution Overview
Problem
Hydraulic actuation systems in machinery often become inoperative due to pressure sensor malfunctions, leading to loss of control over fluid flow and inability to manage loads effectively.
Innovation Solution
A method is implemented to detect and manage malfunctions in pressure sensors by regulating the pressure source and valve system to generate fluid flow based on assumed pressure differences, allowing the system to continue operating by closing specific orifices and adjusting fluid flow demands, even if one of the pressure sensors fails.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If pressure sensors are used to control fluid flow in hydraulic actuation systems, then control precision is improved, but system reliability deteriorates due to sensor malfunctions
Solution Approach 1:
The system changes operational parameters by detecting sensor malfunctions and switching from precision control mode to fail-safe mode. When a sensor malfunction is detected, the controller changes the pressure control strategy to prioritize safety over precision, allowing continued operation with modified control parameters that ensure system safety despite degraded sensing capability
Solution Approach 2:
The system converts the harmful effect of sensor malfunction into a beneficial outcome by implementing a malfunction detection mechanism that triggers a safe operational mode. The malfunction signal, which would normally cause system shutdown, is instead used to activate a fail-safe control strategy that maintains operational reliability through alternative control methods
2Reliability
If the system shuts down upon sensor malfunction to ensure safety, then system reliability is improved, but productivity deteriorates due to loss of operational capability
Solution Approach 1:
The system dynamically adjusts its operational state based on sensor status. Instead of a static shutdown response, the controller implements dynamic mode switching between normal operation and fail-safe operation. This dynamic adaptation allows the system to maintain productivity by continuing operation in a degraded but safe manner, adjusting control strategies in real-time according to the malfunction condition
3Quantity of substance
If all orifices remain open during sensor malfunction, then fluid flow capability is maintained, but control precision deteriorates due to inability to regulate pressure accurately
Solution Approach 1:
The system extracts and isolates the malfunctioning sensor from the control loop, removing its influence on control decisions. By detecting the malfunction and excluding the faulty sensor data from pressure regulation calculations, the system maintains fluid flow capability through open orifices while preventing the degraded sensor from compromising overall control precision
Data Source
AI summary
A method for operating a hydraulic actuation system during a pressure sensor malfunction is provided. The hydraulic actuation system includes a pump, a reservoir, a first work-port and a second work-port, a valve system with individual orifices, a pressure sensor system, and a controller for regulating the hydraulic actuation system based on fluid flow demand and on determined pressure differences. The method includes detecting a malfunction of a pressure sensor for the first work-port, closing second and third orifices, and regulating the pump to generate fluid flow corresponding to maximum pressure generated by the pump. The method also includes assigning a value for the difference between pump pressure and the pressure of the subject work-port that is equivalent to a value within an attainable range for difference between the two pressures. Furthermore, the method includes regulating a first orifice and a fourth orifice in response to the fluid flow demand.