Digital PID Controller Tuning With Low-Compute Adaptive Feedback
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Solution Overview
Problem
Existing methods for automatic tuning of PID controllers in industrial processes are computationally intensive and lack universality, particularly when dealing with complex systems or systems with significant sensor-actuator delays.
Innovation Solution
The proposed method uses nine tuning equations derived by reverse engineering a PID controller to perform adaptive tuning of PID parameters Kp, Ki, and Kd separately in time, with additional limiting coefficients to ensure smooth attenuation and prevent abrupt parameter modifications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If fuzzy logic mechanism is used for automatic tuning of PID controller parameters, then the solution quality is high, but the computational load becomes very high
Solution Approach 1:
The patent segments the tuning process into distinct phases: initial parameter selection based on system characteristics, followed by iterative refinement using simplified calculation formulas. This segmentation allows achieving high tuning accuracy while maintaining low computational load during runtime, as the complex fuzzy logic setup is performed only once during initialization rather than continuously
Solution Approach 2:
The patent performs preliminary action by pre-determining the initial PID parameters and tuning characteristics during the setup phase before actual control operations begin. This preliminary configuration includes selecting appropriate initial values for Kp, Ki, Kd based on system type, which eliminates the need for continuous complex computations during runtime while maintaining high tuning quality
2Measurement precision
If fuzzy logic mechanism with specific rule set is used for automatic tuning, then the solution quality is high, but the universality is lost
Solution Approach 1:
The patent employs parameter changes by providing multiple sets of initial parameters and tuning characteristics that can be selected based on the specific system type (e.g., temperature control, pressure control, level control). This allows the same basic tuning algorithm to be universally applied across different systems while achieving high accuracy by adjusting the parameters according to system characteristics
Solution Approach 2:
The patent achieves universality by designing a tuning algorithm that can handle various control systems through a unified approach. The method provides a common framework with system-specific parameter selections, enabling the same core algorithm to serve multiple functions across different industrial processes without requiring separate fuzzy logic rule sets for each application
3Measurement precision
If manual parameterization is performed with significant sensor-actuator delay, then the tuning accuracy can be high, but the complexity and experience requirement increase significantly
Solution Approach 1:
The patent implements self-service by enabling the system to automatically determine optimal PID parameters through iterative testing and evaluation. The algorithm autonomously performs tuning operations by systematically adjusting parameters, measuring system response, and refining values without requiring manual intervention or expert knowledge, thereby simplifying the parameterization process while maintaining high accuracy even with sensor-actuator delays
Data Source
AI summary
The aim of the invention is rapid automatic tuning the parameters of a digital proportional-integral-derivative (PID) controller by analog feedback of an actual value for automation of technological processes with programmable logic controllers (PLCs).The proposed invention is based on the use of nine tuning equations derived by reverse engineering of a PID controller.Adjusting the PID controller parameters Kp, Ki and Kd is performed in a closed control loop with negative feedback separately in time, i.e. independently of each other in iteration steps k for Kp, m for Ki and n for Kd (see FIG. 1).The adaptive tuning method is compact, independent of other methods and algorithms, mathematically balanced (i.e. minimal computational resource requirements), and easy to implement.Setting up a PID controller by this method does not require a preliminary evaluation of a controlled system and the creation of its mathematical model. This implies its universal applicability.