Haptic Rendering with Voxel Mapping for Stable Surgical Feedback
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Solution Overview
Problem
Current haptic rendering technologies in robotic systems, particularly in computer-aided surgery, face challenges in providing precise and stable haptic feedback to surgeons, limiting their ability to accurately interact with virtual environments without causing damage to anatomical structures.
Innovation Solution
The method involves defining primary and secondary proxy positions and a haptic interaction point (HIP) to generate forces based on penetration depth, using a combination of spring and damping torques to stabilize the haptic device, and employing polygonal and voxel-based rendering techniques to enhance haptic stability and accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If haptic rendering is used to provide force feedback to surgeons, then interaction safety with virtual environments is improved, but haptic stability and accuracy deteriorate
Solution Approach 1:
The patent implements dynamic haptic rendering by adjusting force feedback parameters in real-time based on the surgical instrument's position and motion state. The system dynamically modifies spring constants and damping coefficients according to the penetration depth and velocity, enabling stable haptic feedback that adapts to changing surgical conditions while maintaining interaction safety.
Solution Approach 2:
The system employs closed-loop feedback mechanisms where the haptic force applied to the surgeon is continuously adjusted based on real-time measurement of the virtual instrument's penetration depth into virtual anatomical structures. This feedback loop ensures that the force feedback remains stable and accurate while preventing harmful penetration, thereby resolving the contradiction between safety and stability.
2Measurement precision
If haptic rendering algorithm computes forces based on penetration depth, then interaction accuracy is improved, but system complexity increases
Solution Approach 1:
The patent segments the haptic rendering computation into distinct modular components: penetration depth calculation, force magnitude determination, and force direction computation. Each module handles a specific aspect of the haptic feedback, making the overall system more manageable and easier to implement while maintaining high interaction accuracy through precise penetration depth measurement.
Solution Approach 2:
The system performs preliminary calculations of penetration depth and predefined force parameters before actual haptic feedback is applied. By pre-computing the penetration depth based on the virtual instrument's position relative to virtual anatomical boundaries, the system simplifies the real-time force computation while maintaining high interaction accuracy.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach improves haptic stability and accuracy, allowing surgeons to interact safely with virtual environments, preventing unintended penetration and enhancing the precision of surgical procedures by providing controlled and responsive force feedback.
Implementation Method 1
Haptic rendering is the process of computing and applying forces in response to user interactions with virtual objects
Implementation Method 2
a unique kinematic structure with two constant force springs which provide gravity compensation so that the manipulator effectively floats
Implementation Method 3
The present invention relates to a spring-damper system
Data Source
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AI summary
A method is disclosed for mapping a location in haptic space. The method comprises the steps of: a) defining a voxel space comprising a plurality of voxel elements; b) defining a polygonal space comprising a plurality of polygonal rendering elements; c) generating a data structure of each of the voxel elements and its respective polygonal rendering elements; d) locating a point in haptic space; e) mapping that point to a corresponding voxel element; and f) selecting, in the data structure, at least one polygonal rendering element.