Robot End Effector Transfer with Predictable Redundant Axis Motion
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Solution Overview
Problem
Existing methods for transferring a robot end effector between poses result in unpredictable axis position changes, leading to safety and operability issues due to unmanaged redundancy and increased computational load.
Innovation Solution
Specifying a uniform course for redundant axes before transfer, either offline or online, allows for controlled axis movements between end effector poses, reducing unexpected changes and optimizing robot safety and efficiency by leveraging redundancy and reducing computational requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the entire workspace is divided into equally sized discrete elements to resolve task redundancy, then computational effort is reduced, but a slight change in end effector poses can lead to significantly different and unexpected axis position curves
Solution Approach 1:
The patent applies preliminary action by pre-defining uniform courses for redundant axes offline before actual robot operations. This pre-planning ensures that when the robot needs to move between poses, the redundant axes follow predetermined, smooth trajectories rather than being recalculated in real-time, thus maintaining predictability while reducing computational effort during operation.
Solution Approach 2:
The patent changes the parameter representation by introducing a uniform course specification for redundant axes. Instead of treating each axis independently during real-time control, the system defines a unified trajectory parameter that governs the behavior of redundant axes across multiple poses, ensuring consistency and predictability while simplifying real-time computations.
2Ease of operation
If task redundancy is resolved using known methods, then axis positions can be determined, but the system complexity increases and safety is compromised due to unexpected axis movements
Solution Approach 1:
The patent reduces system complexity during operation by performing the complex redundancy resolution offline. The uniform courses for redundant axes are calculated in advance and stored, so that during real-time operation, the system simply follows these pre-determined paths rather than performing complex calculations, thus improving ease of operation while maintaining safety.
3Productivity
If computational load is reduced by discretizing workspace, then processing time decreases, but the precision and smoothness of axis position transitions deteriorate
Solution Approach 1:
The patent resolves the precision-speed contradiction by performing high-precision trajectory planning offline in advance. The uniform courses for redundant axes are calculated with high precision during the offline phase, and these pre-computed trajectories are then executed during real-time operation, achieving both high processing speed and high precision without compromising either.
Data Source
Figure 1~3
AI summary
In a method according to the invention for transferring an end effector (14) of a robot between an end effector pose and a further end effector pose, for at least one axis (q1) of the robot the same uniform course (q1(s)) of the position of said axis is specified (S30), more particularly in advance, for the transfer between the one end effector pose and the one further end effector pose and for transfers between the one end effector pose and a group of other further end effector poses, more particularly in dependence on activation of a control operating mode. For at least one further axis (12, 13) of the robot, different courses of the position of said further axis are commanded (S50), more particularly during the transferring, for the transfer between the one end effector pose and the one further end effector pose and the transfer between the one end effector pose and at least one of the other further end effector poses.