Robot Cable Shape Simulation Using Via Points and Length Feedback
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Solution Overview
Problem
Existing multi-joint robot linear-member simulation methods struggle to accurately represent complex shapes, such as twisted cables, using approximate curves, making it difficult to intuitively correct teaching operations in offline teaching systems.
Innovation Solution
A multi-joint-robot linear-member-shape simulator that determines the shape of a linear member by setting via points and adjusting parameters, allowing for the expression of complex shapes through repetitive shape and length adjustments, using an input unit, shape control function, and length adjustment unit to refine the shape based on initial and adjustment via points.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a cubic curve approximation is used to represent the linear member shape based on two positions and tangent vectors, then the calculation is simple, but the complex shape such as twisted shape cannot be expressed accurately
Solution Approach 1:
The linear member shape is divided into multiple segments between via points, with each segment represented by a cubic curve. This segmentation allows complex shapes to be approximated through multiple simple curve segments, resolving the contradiction between calculation simplicity and shape accuracy.
Solution Approach 2:
The patent introduces via points as additional dimensional constraints beyond the basic two-position cubic curve approach. By specifying positions of intermediate via points, the system gains additional degrees of freedom to accurately represent complex three-dimensional shapes while maintaining the simplicity of cubic curve calculations for each segment.
2Manufacturing precision
If via points are set to express complex linear member shapes, then the shape representation accuracy is improved, but the device complexity increases
Solution Approach 1:
The system segments the linear member into multiple sections defined by via points, allowing complex shapes to be represented through a series of simple cubic curve segments. This reduces the overall computational complexity compared to using a single complex curve while maintaining shape accuracy.
Solution Approach 2:
The patent uses virtual model copying where the linear member shape is represented by a virtual cubic curve model that mirrors the physical member's geometry. This virtual representation simplifies the system by replacing complex physical measurements and adjustments with computational geometry operations.
3Manufacturing precision
If the linear member shape is adjusted to match actual length, then the shape accuracy is improved, but the adjustment time increases due to repetitive cycles
Solution Approach 1:
Via points are predetermined based on expected linear member configurations before actual shape adjustment begins. This preliminary positioning of via points provides a good initial approximation, reducing the number of iterative adjustments needed to achieve final shape accuracy and minimizing adjustment time.
Solution Approach 2:
The system implements feedback by comparing the calculated linear member length from the cubic curve approximation with the actual measured length, then adjusting via point positions accordingly. This feedback loop efficiently converges to the accurate shape by using length discrepancy as the adjustment criterion, reducing unnecessary iterative cycles.
Data Source
AI summary
A multi-joint-robot linear-member-shape simulator receives a position of at least one via point via which the linear member extends between a start-point position and an end-point position, an initial position of an adjustment via point that adjusts a length of the linear member, and an adjustment parameter of the adjustment via point, and repeatedly executes shape control for determining the shape of the linear member and a length adjustment for determining the length of the linear member when the linear member has the determined shape by using the input position of the via point and the input initial position of the adjustment via point as an initial value until a difference between an actual length of the linear member and the determined length thereof becomes smaller than or equal to a permissible value. When the shape control is to be executed, the adjustment parameter is changed.