Compliant Wheel Assembly for Caliper Force Control
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Solution Overview
Problem
Existing calipers face challenges in providing repeatable and controlled measurement force, especially when measuring soft objects, leading to unreliable and non-repeatable measurements due to variations in applied force.
Innovation Solution
A wheel assembly with a rotary bearing member, rotary actuation member, and compliant coupling element is introduced, which allows for controlled force application through rotational displacement, providing tactile or visual feedback to ensure consistent force application and prevent excessive force, thereby improving measurement repeatability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a rigid thumb wheel is used to move the slider assembly, then the structure is simple and easy to manufacture, but the applied force varies and measurement repeatability deteriorates
Solution Approach 1:
The patent transforms the static rigid thumb wheel into a dynamic compliant system where the wheel assembly can deform elastically under applied force. The compliant coupling element allows the wheel to flex and return to its original position, creating a spring-loaded mechanism that automatically maintains consistent contact force with the scale member regardless of variations in user applied force.
Solution Approach 2:
The patent changes the mechanical parameter of the wheel assembly from rigid to compliant by introducing elasticity. This parameter change allows the system to absorb force variations through elastic deformation, converting an unstable force application system into one that maintains constant force through the elastic recovery of the compliant coupling element.
2Reliability
If force sensing features are added to measure and indicate applied force, then measurement repeatability improves, but device complexity and cost increase significantly
Solution Approach 1:
The patent implements passive mechanical feedback through the compliant coupling element. As the user applies force to rotate the wheel, the element deforms and provides tactile resistance that automatically limits the applied force to a safe, consistent level. This feedback mechanism eliminates the need for active sensors while achieving the same goal of force control and measurement repeatability.
Solution Approach 2:
The wheel assembly is designed to self-regulate the applied force through its own compliant structure. The elastic deformation of the coupling element creates inherent force limiting without requiring external sensing or control systems. The system serves itself by using its structural compliance to automatically maintain proper measurement force.
3Measurement precision
If excessive force is applied to measure soft objects, then the measurement range is sufficient, but the object is distorted and measurement accuracy deteriorates
Solution Approach 1:
The patent incorporates the compliant coupling element as a pre-designed cushioning mechanism that limits the maximum force applied to the object before damage or distortion can occur. The elastic element acts as a mechanical fuse or circuit breaker, absorbing excess energy and preventing force transmission beyond a safe threshold, thereby protecting soft measurement objects from distortion.
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 enables more consistent and repeatable measurements by providing intuitive force control, preventing distortion of soft objects and improving user experience, especially for unskilled operators, while being economical and ergonomically convenient.
Implementation Method 1
The compliant coupling element is configured to elastically couple the rotary actuation member to the rotary bearing member. The rotary bearing member and the rotary actuation member may be coaxial. In various implementations, the wheel assembly may be configured such that when the rotary bearing element engages the caliper spar a rotational displacement of the rotary actuation member relative to the rotary bearing member may generate a deformation of the compliant coupling element. The deformation of the compliant coupling element may generate a force which is applied to the rotary bearing member
Data Source
AI summary
A compliant wheel assembly is provided for moving a caliper jaw relative to a caliper spar. The wheel assembly includes a rotary bearing member, a rotary actuation member and a compliant coupling element. The rotary bearing member is coupled to the caliper jaw and may engage the caliper spar. The rotary actuation member is actuated by a user to apply a measuring force. The compliant coupling element is configured to compliantly couple the rotary actuation member to the rotary bearing member. Using the compliant wheel assembly, a user is able to apply a more consistent amount of measurement force than could typically be achieved with a conventional rigid thumb wheel in caliper. In one implementation, a displacement indicator may also be provided that is responsive to the rotational displacement between the rotary bearing and actuation members for indicating an amount of measurement force that is being applied.