Virtual Constraint Haptic Guidance for Surgical Tool Positioning
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Solution Overview
Problem
Surgical systems face challenges in precisely placing a tool at a target position and orientation, particularly in manual mode, where user control is compromised during autonomous movement.
Innovation Solution
A surgical system with a manipulator and control system that uses sensors to measure forces and torques, generates virtual constraints, and provides haptic feedback to guide the user towards a target state through a virtual simulator and constraint solver.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the manipulator moves the tool autonomously to place the tool at the target position and orientation, then the precision of tool placement is improved, but the user's sense of control over the tool deteriorates
Solution Approach 1:
The system dynamically switches between manual and autonomous modes, and within manual mode, dynamically adjusts the strength of haptic guidance forces. The virtual constraints are not static but adapt based on the tool's proximity to the target state and the user's interaction forces, allowing the system to be flexible and responsive to user needs while maintaining precision.
Solution Approach 2:
The system implements haptic feedback through virtual constraints that provide force guidance to the user. The constraint solver calculates constraint forces based on the difference between current and target states, and these forces are fed back to the user through the manipulator, guiding the user's hand movements toward the desired tool position and orientation while maintaining user control.
2Manufacturing precision
If the system provides haptic feedback through virtual constraints to guide the user, then the user's precision in tool placement is improved, but the complexity of the control system increases
Solution Approach 1:
The control system performs multiple functions through integrated modules: the guide handler manages target state acquisition and virtual constraint generation, the constraint solver handles force calculations, and the virtual simulator provides dynamic modeling. These modules work together to provide both guidance and control functions, reducing the need for separate specialized components.
Solution Approach 2:
The virtual simulator acts as an intermediary between the physical manipulator and the user's manual control. It creates a virtual model of the tool's dynamics and applies constraint forces in this virtual environment, then translates these forces back to the physical system. This intermediary layer simplifies the control architecture by separating the complex force calculation logic from the direct actuator control.
3Ease of operation
If the system allows manual mode operation where the user engages the tool, then the user's sense of control is improved, but the precision of tool placement deteriorates
Solution Approach 1:
The system applies partial autonomous action through haptic guidance forces that provide just enough guidance to improve precision without taking full control. The virtual constraints apply forces proportional to the deviation from the target state, providing guidance only when and where needed, while allowing the user to maintain primary control of the tool's movement.
Data Source
AI summary
Systems and methods are provided for guiding movement of a tool. The system includes a tool and a manipulator. A guide handler obtains a target state for the tool and generates virtual constraints based on the target state and a current state of the tool. A constraint solver calculates a constraint force adapted to attract the tool toward the target state or repel the tool away from the target state based on the virtual constraints. A virtual simulator simulates dynamics of the tool in a virtual simulation based on the constraint force and input from one or more sensors, to output a commanded pose. The control system commands the manipulator to move the tool based on the commanded pose to thereby provide haptic feedback to the user that guides the user toward placing the tool at the target state or away from the target state.