Variable Compliance Metallic Wheel Torque Measurement
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Solution Overview
Problem
Non-pneumatic tires face challenges in adjusting flexibility and measuring torque effectively, especially in environments like planetary surfaces where traditional pneumatic tires are unsuitable, and existing solutions for torque measurement are bulky and costly.
Innovation Solution
A non-pneumatic wheel design with a mechanism to adjust radial stiffness using a leaf spring element and a torque sensor integrated into the drive train, allowing for motorized counter-rotation of hub disks to vary flexibility and measure torque during operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a continuous rotation electrical connection (slip ring) combined with a torque sensor is used to measure torque, then torque measurement capability is achieved, but device volume, mass, and cost increase substantially
Solution Approach 1:
The patent merges the torque sensor functionality directly into the hub structure by integrating a potentiometer with a rotating element that is mechanically coupled to the wheel rotation. This eliminates the need for separate slip rings and external torque sensors, thereby reducing device volume, mass, and complexity while maintaining torque measurement capability.
Solution Approach 2:
The hub structure serves dual functions: it acts as both the rotational support for the wheel and as the torque sensing mechanism. The potentiometer integrated into the hub automatically measures torque through the rotation of its element, which is driven by the wheel's rotation, eliminating the need for separate measurement systems.
2Reliability
If elastic materials are used for deformable spokes in non-pneumatic wheels, then shock absorption capability is improved, but durability deteriorates due to puncturing and material failure
Solution Approach 1:
The patent changes the material parameter from elastic rubber to metallic material for the spokes. This parameter change maintains the deformable characteristic necessary for shock absorption while dramatically improving durability and resistance to puncturing, making the wheel suitable for harsh environments including planetary surfaces.
Solution Approach 2:
The patent employs composite construction where metallic spokes are integrated with a polymeric tire body. This composite approach combines the durability and structural strength of metal with the elastic shock-absorbing properties of polymer, achieving both reliability and durability simultaneously.
3Adaptability or versatility
If radial stiffness of non-pneumatic wheels is adjusted to adapt to road conditions, then adaptability is improved, but device complexity increases due to additional adjustment mechanisms
Solution Approach 1:
The patent implements a dynamic stiffness adjustment mechanism where the hub disks can be motorized to counter-rotate, thereby actively varying the radial stiffness of the wheel. This dynamic capability allows the wheel to adapt to different road conditions and loads, improving versatility while keeping the mechanism integrated within the existing hub structure to minimize added complexity.
Solution Approach 2:
The hub structure serves multiple functions: it supports the wheel rotation, provides torque measurement through the integrated potentiometer, enables radial stiffness adjustment through counter-rotation capability, and supports the deformable spokes. This multi-functionality reduces the need for separate dedicated components, thereby limiting the increase in device complexity.
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 provides durable and adaptable wheel stiffness regulation and accurate torque measurement, enhancing safety and performance of unmanned vehicles on rough terrain or planetary surfaces.
Implementation Method 1
a non-pneumatic wheel design with a mechanism to adjust radial stiffness using a leaf spring element
Implementation Method 2
a torque sensor integrated into the drive train, allowing for motorized counter-rotation of hub disks to vary flexibility and measure torque during operation
Data Source
AI summary
A variable compliance non-pneumatic wheel which comprises a stationary tubular body (32) attached to the vehicle chassis. A tubular member is freely rotatable relative to the stationary tubular body and has a series of peripheral mounting rods (12, 13) on sides of the wheel. A plurality of interconnected and freely rotating caterpillar-like tiles (5), which are in contact with the ground during wheel operation, are coupled to the outer periphery of the wheel. A plurality of connecting spring members, (3, 4, 6, 7, 8, 9, 10, 11), each connecting a specific mounting rod on a side of the hub (1, 2) are configured to connect the tiles (5) to the hub. The tubular member is split in two parts (1, 2) which are each free to rotate relative to one another. Each part carries approximately half number of mounting rods and connecting springs on a respective side of the wheel.