Multi-Robot Deposition Control for Collision and Thermal Balancing
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Solution Overview
Problem
Current additive manufacturing processes, such as Laser Powder Bed Fusion, Electron Beam Melting, and Selective Laser Sintering, face limitations including high costs, low deposition rates, and restricted build volumes, while Directed Energy Deposition and Wire Arc Additive Manufacturing struggle with toolpath generation and motion control, leading to increased costs and manufacturing defects.
Innovation Solution
The implementation of a non-continuous deposition process using multiple robotic material-depositing subsystems with controlled motion systems to perform discrete material deposition at specific locations, predicting and resolving potential collisions, and adapting to thermal conditions through agile manipulation of deposition instructions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple robotic material-depositing subsystems are used to increase deposition rates and reduce costs, then productivity and cost-effectiveness improve, but the complexity of toolpath generation and motion control increases
Solution Approach 1:
The patent divides the build space into discrete voxel regions and assigns different material-depositing subsystems to specific voxels or voxel groups. Each subsystem has its own time-ordered list of deposit location instructions, allowing independent control and simplifying the coordination complexity while maintaining high deposition rates through parallel operation.
Solution Approach 2:
The patent introduces a central coordinator that acts as an intermediary between multiple material-depositing subsystems. This coordinator manages the time-ordered lists of deposit instructions, predicts potential collisions between subsystems, and resolves conflicts by adjusting the timing or positioning of deposits, thereby simplifying the overall control architecture.
2Device complexity
If robotic systems are used instead of CNC platforms to reduce capital costs, then device cost decreases, but dynamic accuracy and surface finish quality worsen
Solution Approach 1:
By segmenting the deposition process into discrete voxel-by-voxel operations rather than continuous toolpaths, the patent reduces the impact of robotic positioning errors. The discrete nature of the deposits allows for greater tolerance in robotic motion while maintaining acceptable surface quality, as each deposit is a distinct operation rather than part of a continuous path.
Solution Approach 2:
The patent changes the fundamental parameter of deposition continuity from continuous (as in traditional welding or CNC-based DED) to non-continuous/discrete. This parameter change allows robotic systems to operate at lower dynamic accuracy requirements while achieving comparable or better surface finishes through the discrete, controlled placement of material at each voxel location.
3Productivity
If high deposition rates are achieved in WAAM processes, then productivity increases, but residual stresses and distortion increase
Solution Approach 1:
The patent employs periodic deposition patterns where material is deposited in a systematic sequence through multiple passes. By alternating between different voxel regions and using time-ordered lists that space out deposits temporally and spatially, the process allows heat to dissipate between deposits, reducing thermal gradients and minimizing residual stresses and distortion even at high overall deposition rates.
Solution Approach 2:
The patent applies different deposition strategies to different regions of the build space. Each voxel or voxel group can have customized deposit instructions in its time-ordered list, allowing the process to optimize for minimal thermal stress in critical areas while maintaining high deposition rates in less sensitive regions. This localized control enables high productivity without uniformly increasing residual stresses throughout the entire part.
Data Source
AI summary
In the context of additive manufacturing processes wherein an object is built by layered accumulations of discrete instantaneous deposits of feedstock material at specific locations according to a three-dimensional digital data model, systems and methods are taught for operating multiple independently-moving depositing devices in a shared build space to build the object. In some embodiments, depositing components perform discrete material depositing actions according to sequential lists of deposit location instructions which are dynamically sortable, enabling a control methodology to alleviate collision risks among depositing components and to improve thermal conditions of a workpiece during construction. Further embodiments provide for dynamic apportionment of discrete deposition actions among the available depositing devices for load balancing and fault tolerance.