Variable-Stiffness Mechanism Eliminates Prismatic Joints
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Solution Overview
Problem
Existing variable-stiffness mechanisms in robotics, particularly those using variable-levers, are complex due to the use of prismatic joints, leading to inefficiencies and high energy consumption.
Innovation Solution
A variable-stiffness mechanism utilizing racks, pinion gears, spring elements, and a pulley system, where the pinion gears act as a variable pivot point, allowing for adjustable stiffness without prismatic joints, enabling efficient energy use and continuous rotation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If variable-levers are used to achieve variable stiffness, then energy consumption is reduced, but device complexity increases due to prismatic joints
Solution Approach 1:
The patent extracts and eliminates the prismatic joint from the variable-lever mechanism, replacing it with a gear-to-rack mesh that achieves the same variable stiffness function without the complexity and energy consumption issues of traditional prismatic joints
Solution Approach 2:
The patent substitutes the mechanical prismatic joint with a gear-to-rack mesh system, using rotational motion of the pinion gear combined with linear motion of the rack to achieve variable stiffness, thereby replacing a complex mechanical joint with a simpler gear-based mechanism
2Adaptability or versatility
If prismatic joints are used to adjust the lever in variable-levers, then variable stiffness is achieved, but device complexity and energy consumption increase
Solution Approach 1:
The patent implements a dynamic adjustment mechanism where the pinion gear can rotate to different angular positions, dynamically changing the effective lever arm length and thus the stiffness characteristic of the mechanism without requiring complex prismatic joints
Solution Approach 2:
The patent changes the geometric parameter of the lever mechanism by rotating the pinion gear to different angular positions, which modifies the effective moment arm and achieves variable stiffness through parameter change rather than through complex joint adjustment
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 mechanism provides a wide range of adjustable stiffness with reduced energy consumption and load on actuators, preventing breakage by allowing tasks beyond critical load thresholds.
Implementation Method 1
a first spring element and a second spring element, wherein the first spring element and the second spring element couple to the first rack and the second rack, respectively
Implementation Method 2
a first pinion gear and a second pinion gear, wherein the first rack and the second rack are coupled with the first pinion gear and the second pinion gear by a first gear-to-rack mesh and a second gear-to-rack mesh, respectively
Data Source
AI summary
A variable-stiffness mechanism may include racks, pinion gears, spring elements, a cable, and a pulley. The variable-stiffness mechanism may be based on a variable-lever principal using the racks as a lever and the pinion gears as a variable pivot point. The pinion gears may be fixed in position relative to the pulley and coupled together by a gear-to-gear mesh. Alternatively, the pinion gears may be configured to translate relative to the pulley using a central drive rack and drive motor.