Capacitive Finger Clutch for Zero-Force Actuation in Surgical Robots
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional user interface devices for surgical robotic systems require significant actuation force to disengage the clutch, leading to unintentional movements of the robotic actuator due to the need to counteract return spring forces, resulting in imprecise surgical maneuvers.
Innovation Solution
A user interface device with a radially-symmetric gripping surface and a capacitive finger clutch that allows for zero-force actuation, using a capacitive sensor to detect finger touch and generate a clutch signal to pause the robotic system's motion, thereby reducing unintentional movements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a conventional clutch button with return spring is used, then the clutch can be actuated to disconnect input from the surgical robotic system, but the surgeon must apply significant force to counteract the return spring force, causing unintentional movement of the end effector
Solution Approach 1:
The patent replaces the mechanical return spring system with a magnetic field-based system. A magnet is positioned such that its magnetic field naturally holds the clutch button in the engaged position without requiring a spring. When the button is pressed, the magnetic holding force releases, allowing the button to return to the engaged position passively. This eliminates the need for the surgeon to overcome spring force, preventing unintentional end effector movement while maintaining reliable clutch actuation.
Solution Approach 2:
The patent changes the physical parameter of force interaction by replacing elastic force (spring) with magnetic force. The magnet is positioned at a specific distance from the clutch button to create an optimal magnetic field strength that provides sufficient holding force without requiring counteracting pressure from the user. This parameter change allows the clutch to be actuated with minimal force while maintaining reliable engagement.
2Ease of operation
If a return spring is used to reset the clutch button, then the clutch can be easily reset after actuation, but the spring force may cause the grip to be pushed downward, resulting in unintentional movement of the robotic actuator
Solution Approach 1:
The patent substitutes the mechanical return spring with a magnetic field-based reset mechanism. A magnet is positioned to create a magnetic field that passively pulls the clutch button back to the engaged position after actuation. This magnetic reset force is distributed and does not create concentrated downward pressure on the grip, eliminating the risk of unintentional end effector movement while ensuring reliable clutch reset functionality.
3Reliability
If the surgeon applies downward pressure on the clutch button to actuate it, then the clutch can be engaged to pause motion, but the pressure may simultaneously push the grip downward, causing imprecise surgical maneuvers
Solution Approach 1:
The patent replaces the mechanical pressure-based actuation system with a magnetic field-based system. The magnet is positioned to create a magnetic field that holds the clutch button in the engaged position. The button can be actuated by a simple pressing motion that does not require overcoming spring force, and the magnetic field ensures reliable engagement without transmitting excessive force to the grip, thereby maintaining surgical precision.
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
The solution effectively reduces the likelihood of unintentional movements of the robotic actuator, enhancing the precision and control of surgical maneuvers by allowing the user to pause the system without applying force, thus improving surgical precision.
Implementation Method 1
The capacitive sensor may include a conductive pad extending around the central axis. The conductive pad is part of an electrode structure mounted at the end of the housing whose capacitance changes in response to the user touch.
Data Source
AI summary
User interface devices for manipulating a robotic surgical tool in a surgical robotic system are described. A user interface device can include a device housing having a gripping surface symmetrically disposed about a central axis. The gripping surface can include a surface of revolution about the central axis. A tracking sensor can be mounted within the device housing to generate spatial state signals in response to movement of the device housing. The spatial state signals can be used to control motion of robotic system actuators. A finger clutch can be disposed at an end of the device housing, and can generate a clutch signal in response to a touch by a user. The clutch signal can be used to pause the motion of the robotic system actuators. Other embodiments are also described and claimed.