Disturbance Observer Control for Stable High-Precision Positioning

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Solution Overview

Problem

Conventional control systems for high-precision position/velocity control are unstable and sensitive to manufacturing errors, leading to performance degradation due to external disturbances and uncertainties in the manufacturing process.

Innovation Solution

A robust optimal disturbance observer system is designed using a controller with first and second weight functions, which stabilize the system by minimizing disturbances and accounting for manufacturing uncertainties through linear matrix inequality optimization.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If a conventional trial-and-error method is used to design a controller for high-precision position/velocity control, then the controller can be designed with simple procedures, but the controller is frequently driven unstably because stability is not guaranteed

Engineering Contradiction:

Improvecontroller design procedureVSAvoidcontroller stability

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent transforms the controller design from a trial-and-error parameter tuning approach to a systematic parameter synthesis approach using linear matrix inequalities. By changing the design methodology parameters (from empirical to mathematical optimization), the system achieves guaranteed stability while maintaining design feasibility.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent incorporates stability feedback into the design process itself by using linear matrix inequality conditions that mathematically guarantee stability. This feedback mechanism ensures that any controller designed through this method inherently satisfies stability requirements, eliminating the instability problems of conventional approaches.

Inventive Principle:

Principle #23Feedback

2Ease of manufacture

If existing design methods are used, then the design process can be completed with standard procedures, but tolerances in the manufacturing process are not taken into account, requiring precise manufacturing and causing performance to be greatly influenced by errors

Engineering Contradiction:

Improvedesign processVSAvoiddriving device precision requirement

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent changes the design parameters to include explicit tolerance considerations through linear matrix inequality formulations. This allows the controller to be designed with built-in robustness against manufacturing variations, reducing the stringency of manufacturing precision requirements while maintaining control performance.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent applies beforehand cushioning by designing the controller to anticipate and compensate for manufacturing tolerances and uncertainties before actual manufacturing occurs. The linear matrix inequality framework pre-cushions the system against potential errors, making the control system robust without requiring ultra-precise manufacturing.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Ease of operation

If conventional controllers are used, then the system can operate with standard control mechanisms, but the system is sensitive to external disturbances and manufacturing uncertainties, leading to performance degradation

Engineering Contradiction:

Improvecontrol mechanismVSAvoiddisturbance sensitivity

Core Design Contradiction:

Ease of operationVSObject-affected harmful factors

Solution Approach 1:

The patent modifies the control mechanism parameters through linear matrix inequality optimization to achieve disturbance rejection. By changing the design approach from conventional to LMI-based optimization, the controller gains inherent robustness against external disturbances and uncertainties while maintaining ease of operation.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent implements feedback through the linear matrix inequality design framework that continuously ensures stability and performance bounds are satisfied. This mathematical feedback mechanism guarantees that the controller maintains robust performance against disturbances without requiring complex operational adjustments.

Inventive Principle:

Principle #23Feedback

Data Source

PatentUS11983024B2System comprising robust optimal disturbance observer for high-precision position control performed by electronic device, and control method therefor

Publication Date: 2024.05.14 GANGNEUNG WONJU NAT UNIV IND ACAD COOPERATION GROUP

AI summary

Disclosed is a system comprising: a plant (P) to be controlled; a controller (C); a first weight function (W1); a second weight function (W2); and a disturbance observer, wherein the first weight function (W1) receives a difference value between a disturbance (w) and an output (uDO) of the disturbance observer as an input value, the second weight function (W2) receives a difference value between the output value of the controller (C) and the output (uDO) of the disturbance observer as an input value, the plant (P) to be controlled receives, as an input value, the sum value of the disturbance (w) and the difference value between the output value of the controller (C) and the output (uDO) of the disturbance observer, and the controller (C) receives an output value of the plant (P) to be controlled as an input value.