Sensor Output Estimation for Variable Displacement Hydraulic Pumps
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Solution Overview
Problem
Hydraulic machines often shut down or reduce performance due to failures in pressure or displacement sensors, leading to lost productivity while waiting for sensor replacement, as existing systems require all sensors to be operational for full functionality.
Innovation Solution
A system that includes a prime mover, torque sensor, pressure sensor, displacement sensor, and a controller that estimates the output of a variable displacement hydraulic pump by determining input torque, output torque, and inertia torque loss, allowing the machine to continue operating even with a failed sensor by generating an estimated output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the system requires all sensors to be operational for full functionality, then measurement precision is maintained, but productivity is lost during sensor failures
Solution Approach 1:
The system creates a virtual copy of the failed sensor's output by using a mathematical model that replicates the sensor's function. The model uses alternative measurements (torque sensor, pressure sensor, displacement sensor) to generate an estimated output that copies what the failed sensor would have provided, allowing the system to continue operating with full functionality despite the sensor failure.
Solution Approach 2:
The system introduces a mathematical model as an intermediary between the physical sensors and the control system. When a sensor fails, the model acts as a mediator that translates available sensor data into the missing information, bridging the gap caused by the sensor failure and maintaining system operation without requiring direct input from all original sensors.
2Reliability
If the system shuts down upon sensor failure to prevent uncontrolled operation, then reliability is maintained, but loss of time occurs during sensor replacement
Solution Approach 1:
The system prepares for potential sensor failures by having a mathematical model ready and configured to take over immediately when a sensor fails. This pre-arranged backup mechanism cushions against the impact of sensor failures, allowing continuous operation without shutdown while maintaining system safety through the model's monitoring and estimation capabilities.
Solution Approach 2:
The system dynamically changes operational parameters by switching from direct sensor readings to model-based estimations when sensor failures occur. The controller detects sensor failures and adjusts the data source parameters, transitioning smoothly between actual sensor outputs and estimated values, thereby maintaining reliable operation without interruption for sensor replacement.
3Measurement precision
If the system uses multiple sensors for monitoring, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The mathematical model serves multiple functions: it estimates the output of failed sensors, monitors system state, and provides backup measurements. By making the model multi-functional, the system reduces the need for additional dedicated backup sensors, thereby maintaining measurement precision without proportionally increasing device complexity with redundant sensing hardware.
Data Source
AI summary
A system for determining an estimated output from a variable displacement hydraulic pump includes a prime mover, and torque, pressure, and displacement sensors. A controller determines the output torque from the prime mover, determines an input torque to the variable displacement hydraulic pump based upon the output torque, determines an output from one of the pressure sensor and the displacement sensor, and determines an inertia torque loss based upon the angular acceleration of the prime mover. The controller further determines a failure of another of the pressure sensor and the displacement sensor and determines an estimated output from the another of the pressure sensor and the displacement sensor based upon the input torque to the variable displacement hydraulic pump, the output from the one of the pressure sensor and the displacement sensor, and the inertia torque loss.