Robotic Surgical Tool Path Control for Variable Bone Density
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Solution Overview
Problem
Existing robotic systems for removing material from workpieces are inefficient when dealing with non-homogeneous workpieces, as they often require constant feed rates, uniform tool paths, and constant rotational speeds, which can lead to inaccuracies and inefficiencies due to varying densities.
Innovation Solution
A surgical system comprising a robotic manipulator, a surgical tool, a navigation system, and a control system that determines the density distribution of the workpiece, generates a tool path with variable cutting depths, and adjusts operating parameters such as feed rate, cutting speed, and cutting depth based on the density distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a constant feed rate and uniform tool path are used, then the system is simple to operate, but cutting accuracy deteriorates when workpiece density varies
Solution Approach 1:
The system dynamically adjusts the feed rate and tool path parameters in real-time based on the detected density distribution of the workpiece. The control system modifies operational parameters adaptively as the cutting tool encounters different density regions, transforming the static constant feed rate approach into a dynamic responsive system that maintains cutting accuracy across varying material densities.
Solution Approach 2:
The system changes operational parameters (feed rate, rotational speed, cutting depth) based on the detected density distribution. By continuously monitoring workpiece density and adjusting parameters accordingly, the system optimizes cutting performance for each local region, preventing tool deflection in dense areas and maintaining efficiency in less dense areas.
2Manufacturing precision
If a slower feed rate is used for denser material, then cutting accuracy is maintained, but productivity decreases
Solution Approach 1:
The system applies different feed rates and cutting parameters to different local regions of the workpiece based on their specific density characteristics. Rather than using a uniformly slow feed rate throughout, the system locally adapts parameters to match the density of each region being cut, maintaining accuracy where needed while preserving speed in less critical areas.
Solution Approach 2:
The feed rate is dynamically adjusted in real-time based on the detected density distribution. The control system increases feed rate in less dense regions and decreases it in denser regions, creating a dynamic operational profile that optimizes both accuracy and productivity throughout the cutting process.
3Productivity
If a faster feed rate is used for less dense material, then productivity increases, but cutting accuracy may deteriorate
Solution Approach 1:
The system continuously adjusts operational parameters including feed rate and rotational speed based on the detected density distribution. In less dense material regions, the system can safely increase feed rate to improve productivity while maintaining accuracy through real-time parameter optimization tailored to each local density condition.
4Device complexity
If a constant rotational speed is used, then the system is simple to control, but heat generation increases in dense material regions
Solution Approach 1:
The rotational speed parameter is dynamically adjusted based on the detected density distribution of the workpiece. In denser material regions, the system reduces rotational speed to minimize heat generation at the tool-workpiece interface, while in less dense regions, higher rotational speeds can be used without excessive heat buildup.
5Temperature
If a shallower tool path is used for denser material, then heat generation is reduced, but productivity decreases
Solution Approach 1:
The tool path parameters including cutting depth and step-over distance are dynamically adjusted based on the detected density distribution. In dense material regions, the system uses shallower cuts with smaller step-overs to control heat generation, while in less dense regions, deeper cuts and larger step-overs are permitted to maintain higher material removal rates.
Data Source
AI summary
Surgical systems involve a robotic manipulator that moves a surgical tool to remove material from a workpiece and a navigation system to track a pose of the surgical tool relative to the workpiece. A control system determines a non-homogenous density distribution of the workpiece. The control system generates a tool path based on the density distribution. The control system controls the robotic manipulator to move the surgical tool along the tool path to remove the material from the workpiece while accounting for the density distribution. As the surgical tool moves along the tool path, the control system adjusts one or more operating parameters of the surgical tool to account for the density distribution, such as by adjusting the feed rate of the surgical tool, the cutting speed of the surgical tool, and/or the cutting depth of the surgical tool.