Fluidic Actuator Position Control Using a Hose Pressure Model

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Solution Overview

Problem

Existing fluidic actuator systems in industrial automation face challenges in precise position control, especially when using longer hoses between the pressurized fluid provision device and the actuator, as they require pressure sensors on the actuator for accurate pressure measurement, which increases complexity and cost.

Innovation Solution

A system model is developed that accounts for physical properties of the hose arrangement, actuator, and pressurized fluid provision device, allowing for model-based position control without pressure sensors on the actuator, by calculating actuator pressure from measurement pressure using a hose model, enabling precise control even with longer hoses.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If pressure sensors are installed on the actuator for accurate pressure measurement, then position control precision is improved, but device complexity and cost increase

Engineering Contradiction:

Improvepressure measurement precisionVSAvoidsystem complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent introduces a hose model as an intermediary computational element that mediates between the easily measurable pressure at the fluid provision device and the difficult-to-measure pressure at the actuator. The hose model accounts for pressure losses and dynamics in the hose, enabling accurate actuator pressure calculation without direct sensing at the actuator location.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent replaces the mechanical sensing approach (pressure sensors on the actuator) with a computational/model-based approach. Instead of physically measuring pressure at the actuator, the system uses a mathematical hose model to calculate the pressure based on measurements from the fluid provision device, substituting mechanical measurement with computational estimation.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Reliability

If pressure sensors are installed on the actuator, then position control quality is improved, but installation cost and operational cost increase

Engineering Contradiction:

Improveposition control qualityVSAvoidinstallation cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The hose model serves as a computational intermediary that enables high-quality position control without the need for additional physical sensors at the actuator. This intermediary model captures the hydraulic dynamics and pressure losses, providing accurate pressure information for control purposes while avoiding the costs associated with sensor installation and maintenance.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent creates a virtual copy or mathematical representation of the hose's pressure characteristics through the hose model. This virtual model replicates the pressure behavior that would be measured by physical sensors, allowing the control system to use this copied information instead of actual sensor data from the actuator location.

Inventive Principle:

Principle #26Copying

3Adaptability or versatility

If longer hoses are used between the fluid provision device and actuator, then system flexibility is improved, but position control precision deteriorates due to pressure measurement errors

Engineering Contradiction:

Improvesystem flexibilityVSAvoidactuator pressure measurement precision

Core Design Contradiction:

Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The patent implements a feedback mechanism where the hose model continuously calculates the actuator pressure based on the measured pressure at the fluid provision device and the known hose characteristics. This feedback loop compensates for pressure losses and dynamics in longer hoses, maintaining measurement precision despite increased hose length that would otherwise degrade control accuracy.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent substitutes direct mechanical pressure measurement at the actuator with a computational model that accounts for hose effects. This substitution allows the system to use longer hoses for greater flexibility while maintaining pressure measurement precision through mathematical compensation rather than relying on physical sensors that would be affected by hose length.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentUS11454261B2System and method including a fluidic actuator and a pressurized fluid provision device

Publication Date: 2022.09.27 FESTO AG & CO KG

AI summary

A system, including: a fluidic actuator which can be acted upon by a pressurized fluid and has an actuator member, a pressurized fluid provision device which is adapted to carry out a position control of the actuator member and, within the position control, to act upon the fluidic actuator with the pressurized fluid in order to move the actuator member into a prescribed position, and a hose arrangement, including at least one hose via which the fluidic actuator is fluidically connected to the pressurized fluid provision device, wherein the pressurized fluid provision device is adapted to carry out the position control taking into account a system model describing the hose arrangement, the actuator and/or the pressurized fluid provision device.