Control Device Vibration Filtering for Accurate Defect Detection
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Solution Overview
Problem
Existing control devices for driven objects, such as those in printer apparatuses, face challenges in accurately and promptly detecting defects or collisions due to the adverse effects of vibrational components caused by mechanical characteristics, leading to potential misjudgments and delayed recovery actions.
Innovation Solution
A control device is designed with a controller that computes operation amounts and measures control amounts, generating differential signals between an inverse model and actual outputs, and uses filters with specific frequency characteristics to attenuate vibrational components, enabling accurate defect detection and minimizing misjudgments. This includes the use of first and second low-pass filters with distinct cut-off frequencies to correct operation amounts and suppress disturbances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a disturbance observer is used to detect collisions by estimating disturbance torque, then collision detection capability is improved, but vibrational components from mechanical characteristics cause misjudgments and reduce detection accuracy
Solution Approach 1:
The patent extracts and removes the harmful vibrational components from the disturbance observer output through filtering. A low-pass filter is applied to eliminate high-frequency vibrations caused by mechanical characteristics, while a band-pass filter targets specific vibration frequencies. This separation allows the collision detection function to operate without interference from mechanical vibrations.
Solution Approach 2:
The patent introduces filter processing as an intermediary between the disturbance observer and the collision judgment logic. The filter acts as a mediator that processes the raw disturbance torque signal, removing harmful vibrational components before the signal is used for collision detection, thereby improving measurement precision without losing collision detection capability.
2Measurement precision
If filtering is applied to eliminate high-frequency components from disturbance observer output, then vibrational interference is reduced, but detection response time increases due to filtering delay
Solution Approach 1:
The patent dynamically adjusts the cut-off frequency of the low-pass filter based on the operational state of the controlled object. When the object is stationary or moving slowly, a lower cut-off frequency is used for better vibration suppression. When the object moves quickly, the cut-off frequency is increased to reduce detection delay. This dynamic adaptation balances detection accuracy and response time.
Solution Approach 2:
The patent changes the filter parameters (cut-off frequency) according to the operational conditions. By adjusting the filter characteristics in real-time based on speed and load conditions, the system maintains high detection accuracy while minimizing the time delay introduced by filtering.
3Reliability
If the cut-off frequency of the low-pass filter is set low to suppress vibrations, then misjudgment is reduced, but detection delay increases
Solution Approach 1:
The system dynamically adjusts the cut-off frequency based on the current speed of the controlled object. At low speeds, a lower cut-off frequency is used to maximize vibration suppression and reliability. At high speeds, the cut-off frequency is raised to reduce detection delay, maintaining an optimal balance between reliability and speed across different operating conditions.
4Difficulty of detecting and measuring
If inverse model is used to generate differential signals for defect detection, then defect detection capability is improved, but mechanical characteristic variations cause vibrational components that lead to misjudgments
Solution Approach 1:
The patent extracts and removes the vibrational components generated by inverse model calculations through filter processing. By applying low-pass and band-pass filters to the differential signal from the inverse model, the harmful vibrations caused by model-mechanical characteristic mismatches are eliminated, allowing accurate defect detection without misjudgments.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution allows for highly accurate and prompt detection of defects or collisions, reducing the risk of misjudgments and enabling timely recovery actions, thereby improving the reliability of control systems in applications like printer apparatuses.
Implementation Method 1
a filter which is configured to filter the generated differential signal, and which has frequency characteristics of attenuating a vibrational component which is developed due to mechanical characteristics of the controlled object
Data Source
AI summary
There is provided a control device configured to control a drive system including a motor and a driven object. The control device includes a controller configured to compute an operation amount, to measure a control amount of the controlled object, to input a measurement signal of the control amount to an inverse model of a model indicating input-output characteristics of the controlled object, and to generate a differential signal between an output of the inverse model and the operation amount; and a filter configured to filter the generated differential signal, and which has frequency characteristics of attenuating a vibrational component which is developed due to mechanical characteristics of the controlled object, from the differential signal. The controller is configured to make a judgment of whether or not a defect has occurred in the controlled object, based on an output of the filter.