Load-Adjustable Constant-Force Mechanism for Robotic Glass Cutting

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Solution Overview

Problem

Conventional constant-force compliant mechanisms are restrictive in their ability to maintain consistent force output across varying glass thicknesses and lack the capability to adjust stiffness, limiting their versatility in applications like robotic glass cutting.

Innovation Solution

A load-adjustable constant-force mechanism is introduced, which incorporates a compliant crank-slider mechanism with a rotatable beam that adjusts its output force by rotating about its longitudinal axis, constrained to its initial plane of bending, allowing for precise force control independent of position through positional feedback and digital control of stiffness.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If conventional constant-force compliant mechanisms are used, then force output consistency is maintained, but adaptability to varying loads and positions is limited

Engineering Contradiction:

Improveadaptability to varying loadsVSAvoidforce output consistency

Core Design Contradiction:

Adaptability or versatilityVSForce

Solution Approach 1:

The compliant beam is made rotatable about its longitudinal axis, transforming the static mechanism into a dynamic one. By rotating the beam to different angles, the mechanism can adapt its stiffness and force output characteristics to match varying load requirements while maintaining constant-force properties within each configured state

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The mechanism changes its effective stiffness parameter by rotating the compliant beam to different angular positions. This parameter change allows the same mechanism to operate effectively across a wide range of loads (400% bandwidth) and positions without sacrificing force output consistency within each configured state

Inventive Principle:

Principle #35Parameter changes

2Adaptability or versatility

If conventional constant-force compliant mechanisms are used, then force output is maintained, but stiffness adjustment capability is lacking

Engineering Contradiction:

Improvestiffness adjustment capabilityVSAvoidmechanism structure

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The rotatable compliant beam serves multiple functions: it maintains the constant-force property, enables stiffness adjustment, and provides adaptability to varying positions. This single rotational degree of freedom integrates multiple capabilities that would otherwise require separate mechanisms

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Force

If force control is implemented in robotic systems, then contact pressure control is achieved, but positional precision requirements increase

Engineering Contradiction:

Improvecontact pressure controlVSAvoidpositional precision

Core Design Contradiction:

ForceVSMeasurement precision

Solution Approach 1:

The mechanism incorporates positional feedback to digitally control the beam's rotational position, which in turn controls the force output. This feedback loop transforms force control into positional control, allowing precise force regulation without requiring extremely high positional precision from the robotic system itself

Inventive Principle:

Principle #23Feedback

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 solution enables a 400% increase in force output bandwidth and allows for precise force control across a range of positions, enhancing the versatility and efficiency of robotic systems by transforming force control into positional control, enabling the mechanism to handle varying loads and positions effectively.

Implementation Method 1

A compliant mechanism is a flexible mechanism that derives some or all its motion (mobility) from the deflection of flexible segments, thereby replacing the need for mechanical joints. It transfers an input force or displacement from one point to another through elastic body deformation.

Methodology Applied

Scientific EffectElastic deformation: Elasticity

Implementation Method 2

A torsional spring is disposed at the fixed end of the first link, such that the first link is rotatable about the spring. The torsional spring is biased toward a stable position and upon being unstable, outputs a constant force to return to the stable position.

Methodology Applied

Scientific EffectTorsional spring: Torsion Spring

Data Source

PatentUS10508721B1Load-adjustable constant-force mechanisms

Publication Date: 2019.12.17 UNIV OF SOUTH FLORIDA

AI summary

A compliant crank slider with adjustable constant-force output. Constant-force mechanisms (CFM) are used to maintain a constant output reaction force throughout a large range of compressive motion. The invention improves on existing CFM by introducing a second degree of freedom that adjusts the mechanism's output without changing its kinematic structure. This second degree of freedom is the rotation of a compliant beam about its longitudinal axis as it is constrained to the initial plane of bending. The resulting change in the beam's stiffness allows for adjustment to a specifiable range of constant-force outputs.