Robot Arm Shape Scanner With Non-Resonant MEMS Mirror Control

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Solution Overview

Problem

Existing robot systems with shape-measuring devices attached to robot arms face challenges due to the size increase and complexity of circuits required for resonantly driven MEMS mirrors, which are affected by temperature changes, leading to increased device size and safety concerns.

Innovation Solution

A non-resonantly driven optical scanner with a sinusoidal driving signal frequency within 100 Hz to 4 kHz, eliminating the need for temperature compensation circuits and allowing for stable operation, combined with a failure detection system using semiconductor-manufactured distortion sensors, and an automatic transport device that can move without tracks for enhanced safety and reduced equipment costs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a resonantly driven MEMS mirror is used for shape measurement, then measurement precision is improved, but device complexity and size increase due to temperature compensation circuits

Engineering Contradiction:
Improveshape measurement precisionVSAvoidcircuit complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent extracts and removes the temperature compensation circuit from the device configuration. By using a non-resonantly driven optical scanner instead of a resonantly driven MEMS mirror, the system eliminates the need for temperature compensation circuits that would otherwise be required to maintain resonance frequency stability, thereby reducing device complexity while maintaining measurement capability

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

Instead of using resonant driving with temperature compensation (the conventional approach), the patent inverts the approach by using non-resonant driving without temperature compensation. This reversal of the driving method fundamentally changes the system architecture, eliminating the need for complex temperature compensation circuits

Inventive Principle:
Principle #13The other way round (Inversion)

2Measurement precision

If a resonantly driven MEMS mirror is used, then measurement precision is improved, but device size increases due to temperature compensation circuits

Engineering Contradiction:
Improveshape measurement precisionVSAvoiddevice size
Core Design Contradiction:
Measurement precisionVSVolume of moving object

Solution Approach 1:

The patent extracts and removes the temperature compensation circuit from the device configuration. By using a non-resonantly driven optical scanner instead of a resonantly driven MEMS mirror, the system eliminates the need for temperature compensation circuits that would otherwise be required to maintain resonance frequency stability, thereby reducing device complexity while maintaining measurement capability

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

Instead of using resonant driving with temperature compensation (the conventional approach), the patent inverts the approach by using non-resonant driving without temperature compensation. This reversal of the driving method fundamentally changes the system architecture, eliminating the need for complex temperature compensation circuits

Inventive Principle:
Principle #13The other way round (Inversion)

3Productivity

If the optical scanner is driven at high frequency, then measurement speed is improved, but safety risk increases due to high intensity light exposure

Engineering Contradiction:
Improvemeasurement speedVSAvoidlight exposure hazard
Core Design Contradiction:
ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent implements a feedback mechanism where a sensor detects the actual driving frequency of the optical scanner and feeds this information back to the control unit. The control unit compares the detected frequency with the target frequency and adjusts the driving signal accordingly. This feedback control enables safe operation by ensuring the scanner operates at the intended frequency where safety protocols are effective, preventing dangerous high-intensity light exposure while maintaining measurement productivity

Inventive Principle:
Principle #23Feedback

4Manufacturing precision

If a track-based transport system is used for the robot arm, then positioning precision is improved, but equipment complexity and cost increase

Engineering Contradiction:
Improvepositioning precisionVSAvoidguiding rail complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent extracts and removes the guiding rails (tracks) from the transport system. By using a guideless transport mechanism with sensors to detect position and guide the robot arm, the system eliminates the need for complex physical guiding infrastructure, thereby reducing equipment complexity and cost while maintaining the capability to perform positioning work

Inventive Principle:
Principle #2Taking out (Extraction)

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 configuration reduces the size and complexity of the shape measurement device, enhances safety by preventing high-intensity light exposure, and allows for efficient and accurate shape measurement while enabling the robot arm to perform tasks over a wide range without the need for guiding rails, improving work efficiency and safety.

Implementation Method 1

an optical scanner 512 that scans the target by reflecting light from the light source device 511

Methodology Applied
Scientific EffectLight reflection: Reflection

Implementation Method 2

a distortion sensor 5126 that detects a driving frequency of the optical scanner 512

Methodology Applied
Scientific EffectDistortion detection: Piezoresistive Effect

Data Source

PatentEP3474099B1Robot system
Publication Date: 2023.03.15 SEIKO EPSON CORP
  • EP3474099B1 patent drawingFigure 1
  • EP3474099B1 patent drawingFigure 2
  • EP3474099B1 patent drawingFigure 3

AI summary

A robot system including: one or two robot arms which perform work on a target; a shape measurement device which is disposed on the robot arm and measures a shape of the target; and a controller which controls the robot arm based on the shape measurement device, in which the shape measurement device includes a projection device which projects striped pattern light onto the target, an image capturing unit which captures the image of the pattern light, and a processor which calculates the shape of the target based on the captured image by the image capturing device, and in which the projection device includes a light source device which emits linear laser, an optical scanner which generates the pattern light by reflecting the laser from the light source device and by scanning the target, and a scanner driver which outputs a driving signal to drive the optical scanner non-resonantly.