Tunable Static Balancer for Intuitive Compliant Grasper Force Feedback
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Solution Overview
Problem
Compliant mechanisms, such as laparoscopic graspers, face challenges in accurately adjusting force compensation and providing intuitive force feedback due to non-linear relationships between actuation force and jaw force, leading to user fatigue and potential damage to delicate objects.
Innovation Solution
A tunable static balancer system with a moveable actuation member, first stiffness elements exerting negative force, and adjustable second stiffness elements, allowing for precise adjustment of force compensation to balance actuation forces across a movement range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If force compensation is introduced to counteract actuation forces in compliant mechanisms, then user fatigue is reduced, but the relationship between actuation force and jaw force becomes non-linear and non-intuitive
Solution Approach 1:
The patent adjusts the stiffness parameter of the balancer spring to change the force compensation characteristics. By tuning the spring stiffness, the system optimizes the balance between reducing actuation force (improving ease of operation) and maintaining an intuitive linear relationship between handle force and jaw force (preserving force feedback intuition).
Solution Approach 2:
The patent designs the balancer mechanism to provide force feedback that reflects the actual jaw interaction forces. The balancer spring is configured so that the force required to actuate the mechanism provides intuitive information about the forces being applied by the jaws, enabling the user to sense and control delicate object manipulation through handle feedback.
2Ease of manufacture
If static balancer with fixed stiffness is used, then manufacturing is simplified, but accurate force compensation across movement range cannot be achieved
Solution Approach 1:
The patent introduces adjustability to the balancer spring stiffness, transforming a fixed static balancer into a tunable system. The spring can be adjusted to different stiffness levels to precisely match the force characteristics of specific compliant mechanisms, enabling accurate force compensation across the full movement range while maintaining relatively simple manufacturing through standardized adjustment mechanisms.
3Volume of moving object
If compliant mechanism is used instead of hinge-based mechanism, then compactness and sterilization ease are improved, but force feedback intuition and adjustable force compensation are lost
Solution Approach 1:
The patent introduces a balancer spring as an intermediary element between the compliant mechanism and the user's hand. This mediator provides the missing force feedback function by mechanically coupling the compliant mechanism's elastic forces to the user's actuation, creating an intuitive force relationship despite the compliant mechanism's inherent non-linearity. The balancer acts as a force translation device that preserves adaptability while maintaining compactness.
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
Enables accurate and intuitive force transfer, reducing user fatigue and preventing damage to objects by allowing precise tuning of the static balancer, ensuring balanced force application throughout the movement range.
Implementation Method 1
at least a member for storing potential energy that is arranged to compensate an actuation force
Implementation Method 2
at least one first stiffness element that exerts a negative force in the axial direction counteracting said positive force
Implementation Method 3
adjustable second stiffness element, wherein said first stiffness element is connected on one end to said moveable part, and on the opposite end to the adjustable second stiffness element
Data Source
AI summary
A tunable static balancer arrangement on a mechanic device, for adjustably compensating a positive force needed to actuate a moveable part of the device from a first position to a second position. The arrangement comprises a moveable actuation member for transferring movement from an input to said moveable part, the actuation member being moveable in a general axial direction, at least one first stiffness element that exerts in at least one position a negative force in the axial direction counteracting at least partially said positive force when the moveable part is moved from the first position to the second position, at least one adjustable second stiffness element, wherein said first stiffness element is connected on one end to said moveable actuation member, and on the opposite end to the adjustable second stiffness element, such that the first stiffness element exerts a positive force on the adjustable second stiffness element, and such that when stiffness of said adjustable second stiffness element is adjusted, the negative force of said first stiffness element in the axial direction is altered. Also provided is a compliant grasper comprising the tunable static balancer arrangement.