Substrate Transfer Robot Control With Independent Withdrawn Posture
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Solution Overview
Problem
Conventional robot control devices for substrate transfer are susceptible to inaccuracies in substrate transfer due to changes in the access standby position, which is influenced by the teaching position, leading to potential collisions and improper substrate handling.
Innovation Solution
A robot control device that defines the position and posture of the end effector using independent variables for the holding and withdrawn positions and postures, ensuring that the values of these variables are not influenced by each other, thereby stabilizing the transfer process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If the access standby position is generated based on the teaching position, then the robot can automatically determine the standby position, but the withdrawn position and posture may be improperly set when the teaching position changes
Solution Approach 1:
The patent segments the position and posture control into independent components. The withdrawn position is determined independently from the teaching position by setting the posture to a predetermined state (minimum turn posture) rather than deriving it from the teaching position. This segmentation prevents error propagation while maintaining automation.
Solution Approach 2:
The patent extracts the posture determination from the teaching position dependency. By separating the position calculation (which uses teaching position) from the posture calculation (which uses predetermined minimum turn posture), it removes the harmful coupling that caused reliability issues when teaching positions changed.
2Adaptability or versatility
If the access standby position changes with teaching position, then the robot adapts to different teaching positions, but collisions may occur due to improper withdrawn position
Solution Approach 1:
The patent applies preliminary anti-action by pre-setting the withdrawn posture to a predetermined minimum turn posture that avoids collisions. This predetermined posture acts as a preventive measure against collision hazards that would otherwise occur when teaching positions change and cause improper withdrawn position calculation.
Solution Approach 2:
The patent converts the constraint of fixed withdrawn posture into a benefit by using the predetermined minimum turn posture to ensure safe operation. What could be seen as a limitation (fixed posture) actually prevents collisions and ensures reliable substrate transfer across different teaching positions.
3Ease of operation
If the end effector position and posture are defined by N variables, then the robot has flexible control, but the variables may be interdependent causing transfer inaccuracies
Solution Approach 1:
The patent segments the N variables into two independent sets: position variables (derived from teaching position) and posture variables (set to predetermined minimum turn posture). This segmentation breaks the harmful interdependence while preserving the flexibility to control the end effector through the position variables.
Data Source
AI summary
A robot control device configured to control operation of a robot configured to transfer a substrate while holding the substrate. The robot includes a robotic arm having at least one joint axis, and an end effector provided to a tip end of the robotic arm and configured to hold the substrate. A position and a posture of the end effector are defined by values of N variables. A value of at least one of the N variables that define a holding position and a holding posture of the end effector for holding the substrate placed on the installation position by the end effector is independent from a value of the corresponding variable among the N variables that define a withdrawn position and a withdrawn posture of the end effector after retreating the end effector in the holding position and the holding posture from the installation position.