Fluid Cylinder State Estimation Using Piston Position Sensing
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Solution Overview
Problem
The existing methods for determining the system state of a fluid cylinder, such as those used in gearboxes, require multiple expensive sensors, which increase manufacturing costs and are difficult to adapt to various actuator types, limiting their effectiveness and versatility.
Innovation Solution
A method that estimates system states, including chamber pressures, temperatures, and actuation forces, by detecting the position of the piston using a Kalman filter or extended Kalman filter, eliminating the need for multiple sensors and allowing easy adaptation to different actuators, with the system state estimation improved by using a scheduling signal and tuning contraction and friction parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple pressure sensors and temperature sensors are used to determine system states, then measurement precision is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent replaces multiple physical sensors (pressure sensors, temperature sensors) with a model-based estimation system that uses a single position sensor combined with thermodynamic and fluid dynamic models to calculate system states. This substitutes mechanical sensing infrastructure with computational modeling, reducing component quantity while maintaining measurement capability.
Solution Approach 2:
The patent creates virtual copies of sensor measurements through mathematical modeling. Instead of physically measuring pressure and temperature directly, the system computes these parameters as virtual representations based on position data and established physical laws, eliminating the need for corresponding physical sensors.
2Measurement precision
If multiple expensive sensors are used for determining chamber pressure and temperature, then measurement precision is improved, but manufacturing cost increases
Solution Approach 1:
The patent replaces expensive, durable sensors with a computationally-based solution that uses inexpensive position sensing combined with free or low-cost mathematical models. The 'expensive' sensor components are eliminated in favor of computational resources, dramatically reducing manufacturing cost while maintaining the ability to determine chamber pressure and temperature.
Solution Approach 2:
The patent substitutes mechanical sensing infrastructure (pressure sensors, temperature sensors) with a computational approach using thermodynamic and fluid dynamic models. This replacement eliminates the need for expensive physical sensors while providing continuous estimation of the same physical parameters.
3Measurement precision
If specialized pressure sensors and temperature sensors are used, then measurement precision is improved, but adaptability to different actuator types decreases
Solution Approach 1:
The patent creates a universal estimation framework that can determine system states across different actuator types (hydraulic cylinders, pneumatic cylinders, motors) using the same fundamental approach. The model-based methodology adapts to different actuator configurations through parameter adjustments rather than requiring specialized sensing hardware for each actuator type.
Solution Approach 2:
The patent achieves adaptability by changing model parameters (such as fluid properties, cylinder dimensions, valve characteristics) rather than changing the fundamental sensing approach. This allows the same position-sensor-based methodology to accurately estimate system states across diverse actuator configurations by simply adjusting the input parameters to match the specific actuator being controlled.
Data Source
AI summary
A method for determining a system state of a fluid cylinder (2) of an actuator system (1) is provided. The method comprises the steps: detecting a position of a piston (7) of the fluid cylinder (2); and estimating at least one system state from the detected position of the piston (7.