Substrate Transfer End Effector Speed Control for Bounce-Free Pickup

Solution Overview

Problem

The existing substrate transport devices face challenges in achieving a balance between transportation speed and position accuracy, as high speeds destabilize the substrate during transport, while low speeds increase the time required for transportation, leading to inefficiencies and inaccuracies.

Innovation Solution

A substrate transport device and method that control the lifting speed of the end effector, setting an upper limit value to reduce the amplitude of acceleration or jerk during the transition period when the end effector receives the substrate, thereby stabilizing the micro oscillation and preventing bounce, which improves position accuracy and efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the moving speed of the end effector is increased to reduce transportation time, then productivity is improved, but the position accuracy of the substrate deteriorates due to destabilization during transportation

Engineering Contradiction:

Improvetransportation efficiencyVSAvoidposition accuracy

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The patent applies dynamics by making the lifting speed variable rather than constant. The controller dynamically adjusts the lifting speed based on the operational phase: using a first (higher) lifting speed during the approach phase (before substrate contact) and a second (lower) lifting speed during the transition phase (after substrate contact). This dynamic speed adjustment resolves the contradiction by allowing high speed for efficiency when appropriate, while switching to low speed for precision when the substrate is being handled.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent segments the lifting process into two distinct phases with different speed requirements: (1) the approach phase where the end effector moves toward the substrate, and (2) the transition phase where the end effector contacts and receives the substrate. By segmenting the process and applying different speed controls to each phase, the system achieves both high productivity during approach and high position accuracy during substrate reception.

Inventive Principle:

Principle #1Segmentation

2Manufacturing precision

If the moving speed of the end effector is decreased to stabilize substrate position, then position accuracy is improved, but the time taken for transportation increases reducing productivity

Engineering Contradiction:

Improveposition accuracyVSAvoidtransportation efficiency

Core Design Contradiction:

Manufacturing precisionVSProductivity

Solution Approach 1:

The system uses dynamic speed adjustment where the lifting speed is not uniformly low but is instead optimized for each phase. During the approach phase, higher speed maintains productivity, while during the transition phase, lower speed ensures position accuracy. This dynamic approach eliminates the need to maintain low speed throughout the entire process.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent implements periodic action by applying different speed regimes at different time periods of the lifting cycle. The controller switches between a first lifting speed (higher) and a second lifting speed (lower) based on whether the system is in the approach period or transition period, thereby achieving both efficiency and precision without continuous speed reduction.

Inventive Principle:

Principle #19Periodic action

3Productivity

If the lifting speed is increased during the transition period, then transportation efficiency is improved, but the amplitude of acceleration or jerk increases causing substrate bounce and position instability

Engineering Contradiction:

Improvetransportation efficiencyVSAvoidsubstrate position stability

Core Design Contradiction:

ProductivityVSStability of the object's composition

Solution Approach 1:

The patent applies dynamics by making the lifting speed variable rather than constant. The controller dynamically adjusts the lifting speed based on the operational phase: using a first (higher) lifting speed during the approach phase (before substrate contact) and a second (lower) lifting speed during the transition phase (after substrate contact). This dynamic speed adjustment resolves the contradiction by allowing high speed for efficiency when appropriate, while switching to low speed for precision when the substrate is being handled.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The controller applies preliminary anti-action by preemptively reducing the lifting speed before the transition period begins. By detecting when the end effector contacts the substrate and immediately lowering the speed, the system prevents excessive acceleration and jerk that would cause substrate bounce, thereby maintaining stability during the critical transition phase.

Inventive Principle:

Principle #9Preliminary anti-action

Data Source

PatentUS11559889B2Substrate transport device and substrate transporting method

Publication Date: 2023.01.24 ULVAC INC

AI summary

A substrate transport device includes an arm, an end effector coupled to the arm, a driver configured to lift the arm so that the end effector receives a substrate, and a controller configured to control an output of the driver to set a lifting speed of the arm. A difference in height between the end effector and the arm is a position difference. A period from when the end effector contacts the substrate until the end effector completes reception of the substrate is a transition period. The controller sets an upper limit value of the lifting speed that decreases an amplitude of one of acceleration or jerk of the position difference in the transition period as compared to before the transition period to an upper limit value of the lifting speed for the transition period.