Reaction Torque Actuation for Flexible Fin Swimming Robots
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Solution Overview
Problem
Conventional autonomous underwater vehicles (AUVs) are costly and mechanically complex, making them expensive to build and maintain, while also performing below the capabilities of ocean animals in terms of speed, agility, and efficiency.
Innovation Solution
A robotic system featuring a body with a flexible fin and a rotatable mass that applies a reaction torque to deform the fin, creating a propagating elastic wave for propulsion, simplifying mechanical complexity and reducing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional mechanical actuation systems are used in AUVs, then operational capabilities can be achieved, but device complexity and manufacturing cost increase significantly
Solution Approach 1:
The patent replaces complex mechanical actuation systems with a simplified reaction wheel mechanism. Instead of using traditional motors, linkages, and control systems to deform fins, the invention uses a reaction wheel that exploits conservation of angular momentum. When the reaction wheel accelerates or decelerates, it generates reaction torques that passively deform the flexible fin, eliminating the need for complex mechanical transmission systems while maintaining operational capabilities
Solution Approach 2:
The patent changes the actuation mechanism from direct mechanical force application to angular momentum-based torque generation. By controlling the rotational speed and acceleration of the reaction wheel, the system generates varying reaction torques that deform the fin to different degrees, enabling diverse swimming maneuvers without mechanical complexity
2Adaptability or versatility
If complex mechanical systems are designed for different AUV applications, then mission-specific operational capabilities are achieved, but manufacturing and maintenance costs increase
Solution Approach 1:
The patent creates a universal actuation platform where a single reaction wheel mechanism can perform multiple swimming functions. By controlling the reaction wheel's acceleration patterns, the system can generate different torque profiles that produce various fin deformations, enabling the same hardware to perform tasks ranging from steady cruising to agile maneuvers, eliminating the need for application-specific mechanical designs
Solution Approach 2:
The patent uses a flexible fin with passive elastic properties that can dynamically adapt to different operating conditions. The fin's flexibility allows it to deform in response to reaction torques without requiring active mechanical control, and the same fin can be used for different missions by simply changing the actuation pattern of the reaction wheel rather than changing the physical structure
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 system achieves high performance in speed and agility while reducing mechanical complexity and costs, with the ability to execute various swimming maneuvers efficiently.
Implementation Method 1
The angular acceleration of the first rotatable mass relative to the body creates a reaction torque that rotates the body to deform the at least one flexible fin
Implementation Method 2
The angular acceleration of the first rotatable mass relative to the body creates a reaction torque
Implementation Method 3
creating a propagating elastic wave for propulsion
Implementation Method 4
The predetermined frequency is a resonance frequency of the at least one flexible fin
Data Source
AI summary
Underwater robotic systems are disclosed. In some instances, a robotic system may include a body, a flexible fin, and a rotatable mass associated with the body such that angular acceleration of the rotatable mass causes a reaction torque that rotates the body to deform the flexible fin to create thrust in water.