Strain-Gauge Actuator Control for Workpiece Load and Impact

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Solution Overview

Problem

Existing actuator systems face challenges in accurately controlling the load applied to a workpiece, as the load is often determined by the spring constant of a cushioning member, making it difficult to adjust for different workpieces and potentially leading to damage during pickup or placement.

Innovation Solution

An actuator system incorporating a shaft, a support part, a linear motion motor, a connecting member with a strain gauge, and a control device that detects strain to adjust the load applied to the workpiece, allowing for precise control of the load and speed to prevent damage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If a cushioning member such as a spring is provided to determine the load applied to the workpiece, then the impact during contact is reduced, but the load applied to the workpiece varies and cannot be accurately controlled or adjusted for different workpieces

Engineering Contradiction:

Improveimpact damageVSAvoidload control precision

Core Design Contradiction:

Object-affected harmful factorsVSMeasurement precision

Solution Approach 1:

A strain gauge is attached to the connecting member to detect the load applied to the workpiece in real-time. The control device receives this feedback signal and adjusts the actuator's output to maintain the load within a predetermined range, enabling precise load control while maintaining the cushioning effect.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The mechanical spring-based load determination system is replaced with an electro-mechanical system comprising a strain gauge and control device. This substitution enables dynamic adjustment and precise control of the load through electronic feedback rather than relying solely on fixed mechanical properties.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Reliability

If the load applied to the workpiece is increased to ensure secure contact, then the workpiece pickup reliability is improved, but the workpiece may be damaged due to excessive load

Engineering Contradiction:

Improveworkpiece pickup reliabilityVSAvoidworkpiece damage

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The strain gauge continuously monitors the load applied to the workpiece and provides feedback to the control device. This enables the system to maintain optimal contact force for reliable pickup while preventing excessive load that could damage the workpiece, by dynamically adjusting the actuator output within a predetermined safe range.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The system dynamically adjusts the load parameter within a predetermined range based on workpiece characteristics and operational requirements. By controlling the load to vary within specific boundaries rather than being fixed or uncontrolled, the system achieves both reliable contact and damage prevention.

Inventive Principle:

Principle #35Parameter changes

3Productivity

If the shaft speed is increased to improve productivity, then the handling efficiency is improved, but the workpiece may be damaged due to high-speed collision

Engineering Contradiction:

Improvehandling efficiencyVSAvoidcollision damage

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The strain gauge detects the load during shaft-workpiece contact and provides feedback to the control device. This enables the system to operate at high speeds while automatically detecting and controlling the impact load, allowing high-speed handling without compromising workpiece safety through real-time load monitoring and adjustment.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The strain gauge and control system provide beforehand protection by detecting load changes during high-speed operation and preparing to adjust the actuator output to prevent excessive impact. This anticipatory control mechanism enables high-speed handling while maintaining workpiece safety.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

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

Enables secure pickup and placement of workpieces by accurately controlling the load and speed, reducing the risk of damage and allowing for adjustment based on the type of workpiece, while also ensuring appropriate contact and suction conditions.

Implementation Method 1

a strain gauge provided in the connecting member to detect strain of the connecting member

Methodology Applied

Scientific EffectStrain detection: Piezoresistive Effect

Implementation Method 2

a linear motion motor including a stator and a mover, movement of the mover in parallel with a central axis of the shaft relative to the stator of the linear motion motor causing the support part and the shaft to move

Methodology Applied

Scientific EffectLinear motor: Linear Motor

Data Source

PatentUS11883952B2Actuator

Publication Date: 2024.01.30 THK CO LTD

AI summary

Provided is an actuator in which a load applied to a shaft and a workpiece is controlled. The actuator includes a support part that rotatably supports the shaft, a linear motion motor that moves the shaft in a direction of a central axis, a connecting member that is at least a part of a member connecting a mover of the linear motion motor and the support part, a strain gauge that detects strain of the connecting member, and a control device that controls the linear motion motor, based on the strain detected by the strain gauge.