Pneumatic Actuator Model-Based Control Across Nonlinear Variants
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
PID controllers fail to achieve optimal closed-loop control quality for pneumatic actuators due to strong nonlinearities, especially when used across different variants, limiting their flexibility and accuracy in process automation.
Innovation Solution
A non-linear model of the pneumatic actuator with adaptable parameters is used for closed-loop control and diagnosis, allowing the automation device to be flexible across various variants with a reduced number of adjustable parameters, typically up to five.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a PID controller is used for closed-loop control of pneumatic actuators, then the controller is easy to implement with a small number of parameters, but the control quality is not optimal due to strong nonlinearities
Solution Approach 1:
The patent transitions from a PID controller with fixed parameters to a model-based controller where parameters are dynamically adjusted based on the actuator's operating state. The non-linear model parameters (such as volume, compressibility factors, and flow coefficients) are adapted to match the specific characteristics of different actuator variants, enabling optimal control across varying operating conditions while maintaining ease of implementation through automated parameter identification.
Solution Approach 2:
The patent implements a dynamic model-based control approach that adapts to the changing non-linear characteristics of pneumatic actuators. The controller uses a non-linear dynamic model that accounts for compressibility effects, variable flow coefficients, and state-dependent parameters, allowing the control strategy to evolve with operating conditions rather than relying on fixed PID gains.
2Adaptability or versatility
If a PID controller is used across different variants of pneumatic actuators, then the controller structure remains simple, but the control quality deteriorates due to inability to adapt to variant-specific nonlinearities
Solution Approach 1:
The patent creates a universal model-based control framework that can accommodate multiple actuator variants through a standardized non-linear model structure. The model parameters are made adaptable to different actuator types (single-acting, double-acting, different sizes, different kinematics) while maintaining the same control algorithm, thus achieving both versatility across variants and optimal control quality for each specific variant.
Solution Approach 2:
The patent enables adaptation to different actuator variants by allowing model parameters to be adjusted or identified for each specific variant. The non-linear model includes parameters such as chamber volumes, compressibility factors, and flow coefficients that can be tailored to match the specific characteristics of each actuator variant, enabling the same controller structure to achieve optimal performance across diverse actuator types.
3Measurement precision
If conventional models with many parameters are used to model different pneumatic actuator variants, then the model accuracy improves, but the device complexity increases
Solution Approach 1:
The patent reduces model complexity by identifying and adapting only the critical non-linear parameters that have the most significant impact on control quality. Rather than requiring complete characterization of all actuator parameters, the approach focuses on key parameters such as chamber volumes, compressibility factors, and flow coefficients that dominate the non-linear behavior, thereby achieving high model accuracy with a reduced parameter set.
Solution Approach 2:
The patent extracts and focuses on the essential non-linear characteristics of pneumatic actuators that are most critical for control accuracy. By identifying and modeling only the dominant non-linear effects (compressibility, variable flow coefficients, state-dependent parameters) rather than attempting to model all possible parameters, the approach achieves high accuracy while maintaining a manageable number of parameters.
Data Source
AI summary
An automation device for industrial automation, for closed-loop controlling and/or diagnosing a pneumatic actuator with an actuator member. The automation device has a model, in particular a non-linear model, of the pneumatic actuator, which has at least one model parameter by means of which the model can be adapted to different variants of the pneumatic actuator, and wherein the automation device is configured to carry out closed-loop control and/or diagnosis of the pneumatic actuator using the model.