Robotic Bone Cutting With Density-Adaptive Depth Control
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Solution Overview
Problem
Existing robotic systems struggle to efficiently remove material from non-homogeneous workpieces, such as bone, due to varying density distributions, which can lead to inaccurate cuts and inefficiencies.
Innovation Solution
A surgical system comprising a robotic manipulator, a tool configured to remove material, a navigation system with trackers for the tool and workpiece, and controllers that determine the tool's pose relative to the workpiece, adjust cutting depths based on detected density, and control the manipulator to facilitate precise material removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a constant feed rate is used for non-homogeneous workpieces, then the system operation is simple, but cutting accuracy deteriorates due to varying material density
Solution Approach 1:
The patent implements dynamic adjustment of cutting parameters (feed rate, rotational speed, cutting depth) based on real-time detection of workpiece density variations. The controller continuously modifies these parameters during the cutting process to match the local material properties, transforming the static constant-parameter approach into a dynamic adaptive system that maintains cutting accuracy across heterogeneous materials.
Solution Approach 2:
The system changes physical parameters (feed rate, rotational speed, cutting depth) in response to detected density variations. By monitoring material removal characteristics and adjusting cutting parameters accordingly, the system adapts to local material properties, ensuring consistent cutting accuracy throughout the non-homogeneous workpiece.
2Ease of operation
If a uniform tool path is applied to non-homogeneous workpieces, then the system operation is simple, but heat generation increases and cutting accuracy deteriorates
Solution Approach 1:
The patent applies local quality by adjusting cutting parameters according to local material density. Different regions of the workpiece receive customized cutting parameters - denser regions receive shallower cuts and lower feed rates to reduce heat generation, while less dense regions can tolerate higher parameters. This localized adaptation prevents excessive heat buildup in critical areas.
Solution Approach 2:
The cutting depth and feed rate are dynamically adjusted during the cutting process based on real-time density detection. The system transitions from a static uniform tool path to a dynamic adaptive path that modulates cutting intensity according to local material properties, thereby controlling heat generation in real-time.
3Ease of operation
If a constant rotational speed is used for non-homogeneous workpieces, then the system operation is simple, but cutting efficiency deteriorates and heat generation increases
Solution Approach 1:
The rotational speed is adjusted as a variable parameter based on detected material density. Denser materials receive lower rotational speeds to maintain cutting accuracy and control heat, while less dense materials receive higher speeds to maximize material removal efficiency. This parameter adaptation resolves the conflict between simplicity and efficiency.
4Manufacturing precision
If cutting parameters are optimized for dense materials, then cutting accuracy is maintained, but procedure time increases
Solution Approach 1:
The system applies different cutting parameters to different regions of the workpiece based on local density. Dense regions receive conservative parameters (lower feed rate, shallower cuts) to maintain accuracy, while less dense regions receive aggressive parameters (higher feed rate, deeper cuts) to accelerate material removal. This spatial differentiation maintains accuracy where needed while maximizing efficiency where possible.
Solution Approach 2:
The cutting parameters are dynamically adjusted during the procedure based on real-time density detection. The system transitions from a static parameter set optimized for dense materials to a dynamic parameter strategy that adapts to local material properties, thereby reducing procedure time without sacrificing accuracy in critical regions.
Data Source
AI summary
A surgical system and method involve a manipulator including a plurality of links and joints and a tool coupled to the manipulator. A navigation system includes a localizer, a first tracker coupled to the robotic manipulator or the tool, and a second tracker coupled to a workpiece. Controller(s) determine, from the navigation system, a pose of the tool relative to the workpiece. The controller(s) control the robotic manipulator to facilitate removal of a first portion from the workpiece with the tool and sense interaction between the tool and the workpiece during removal of the first portion to detect a density of the workpiece. The controller(s) control the robotic manipulator to facilitate removal of a second portion from the workpiece with the tool, wherein a cutting depth for the second portion is based, at least in part, on the detected density.