Actuator Load Control via Dynamic Signal Filtering

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Solution Overview

Problem

Existing actuators face challenges in applying an appropriate load to workpieces due to the limitations of cushioning members, such as springs, which are difficult to adjust based on the type of workpiece, and are prone to noise interference from commercial power supplies, leading to phase delays and potentially large loads being applied.

Innovation Solution

An actuator system incorporating a linear motion motor, a force sensor, an amplifier, a low-pass filter, and a control device that detects loads using the amplifier's output before contact and the filtered output after contact, allowing for precise load application and minimizing phase delays.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If a low-pass filter is used to reduce noise from the amplifier output, then noise reduction is achieved, but phase delay is caused in the load detection

Engineering Contradiction:

Improvenoise from commercial power supplyVSAvoidphase delay in load detection

Core Design Contradiction:

Object-affected harmful factorsVSLoss of time

Solution Approach 1:

The system performs preliminary action by detecting the load using the amplifier output before contact occurs, and switches to filtered output after contact. This anticipates the need for noise reduction only when necessary, avoiding phase delay during the critical approach phase.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system dynamically switches between two detection modes: using amplifier output for high-speed response during approach, and low-pass filter output for noise reduction during contact. This dynamic adaptation resolves the contradiction by applying the appropriate filtering level based on the operational phase.

Inventive Principle:

Principle #15Dynamics

2Object-affected harmful factors

If a cushioning member with a fixed spring constant is used, then impact reduction is achieved, but the load applied to the workpiece cannot be adjusted according to workpiece type

Engineering Contradiction:

Improveimpact damageVSAvoidload adjustment capability

Core Design Contradiction:

Object-affected harmful factorsVSAdaptability or versatility

Solution Approach 1:

The patent replaces the mechanical cushioning member system with an electronic control system that uses force sensor feedback and dynamic filter switching. This substitution enables programmable load adjustment while maintaining impact protection, providing adaptability across different workpiece types.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The system changes the parameter of load detection by switching between unfiltered and filtered signal processing modes. This allows the same physical system to adapt its detection characteristics based on operational requirements, effectively providing variable cushioning behavior without physical reconfiguration.

Inventive Principle:

Principle #35Parameter changes

3Productivity

If the shaft moves at high speed toward the workpiece, then productivity is improved, but impact damage may occur due to collision

Engineering Contradiction:

Improveshaft movement speedVSAvoidimpact from collision

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The system uses feedback from the force sensor to detect contact between the shaft and workpiece, then dynamically switches to filtered output processing. This feedback mechanism enables high-speed operation by providing rapid contact detection while preventing impact damage through immediate response to load changes.

Inventive Principle:

Principle #23Feedback

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

This solution enables the actuator to apply appropriate loads to workpieces without unnecessary large loads, preventing damage and ensuring accurate load detection, even in the presence of noise interference from commercial power supplies.

Implementation Method 1

a force sensor provided in the connecting member, an output of the force sensor being according to a force applied to the connecting member

Methodology Applied

Scientific EffectForce sensor detection: Piezoelectric Effect

Implementation Method 2

an amplifier that amplifies the output of the force sensor

Methodology Applied

Scientific EffectSignal amplification: Magnetic Amplifier

Implementation Method 3

a low-pass filter that reduces components of frequencies higher than a cut-off frequency, among components of frequencies included in an output from the amplifier

Methodology Applied

Scientific EffectFrequency filtering: Filter (electronic)

Data Source

PatentUS11735991B2Actuator

Publication Date: 2023.08.22 THK CO LTD

AI summary

In an actuator, an unnecessarily large load is prevented from being applied to a shaft and a workpiece. There are included a force sensor, an output of which is according to a force applied to a connecting member connected to the shaft, an amplifier that amplifies the output of the force sensor, and a low-pass filter, and a load applied to the shaft is detected based on an output from the amplifier until the shaft or a member associated with the shaft comes in contact with another member, and thereafter, the load applied to the shaft is detected based on an output from the low-pass filter.