Adjustable Impedance Backpack Suspension for Load Motion Damping
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Solution Overview
Problem
Existing suspended-load backpacks with flexible and low damping suspensions are ineffective under high loads and limited to a narrow range of payload and walking speed, failing to effectively reduce metabolic costs and prevent musculoskeletal injuries.
Innovation Solution
A suspended-load backpack with an adjustable impedance suspension system incorporating an inerter and adjustable stiffness module that filters movements by altering the natural frequency and stiffness, using an inerter to increase inertia and an adjustable stiffness module to adjust the spring constant, thereby damping and filtering movements relative to the ground.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a very flexible and low damping suspension is used, then the maximum reaction forces during load carrying are reduced, but the suspension is subject to excessive displacements under high loads and is limited to a relatively narrow range of payload and walking speed
Solution Approach 1:
The patent applies dynamics by implementing a variable stiffness suspension system that can adapt its mechanical properties in real-time. The adjustable stiffness module allows the suspension to change its stiffness characteristic dynamically, enabling it to handle different payload ranges and walking speeds effectively. This resolves the contradiction by making the suspension adaptive rather than static, allowing it to maintain optimal performance across varying conditions.
Solution Approach 2:
The patent employs parameter changes by modifying the stiffness parameter of the suspension system through the adjustable stiffness module. By changing the stiffness parameter according to different operating conditions (payload and walking speed), the system can reduce reaction forces when needed while avoiding excessive displacements under high loads. This parameter adjustment capability enables the suspension to operate effectively across a broader range of conditions.
2Use of energy by moving object
If a low stiffness suspension is used, then the metabolic costs during movement are reduced, but the effectiveness is limited to a relatively narrow range of payload and walking speed
Solution Approach 1:
The variable stiffness suspension system dynamically adjusts its properties to optimize energy efficiency across different walking conditions. By adapting the stiffness in real-time based on payload and walking speed, the system reduces metabolic costs effectively whether the user is walking slowly with light load or moving faster with heavier payload, thus resolving the limited effectiveness range.
Solution Approach 2:
The adjustable stiffness module changes the stiffness parameter to match different operating conditions. At lower payloads and speeds, the suspension operates with lower stiffness to minimize metabolic costs. When payload or walking speed increases, the stiffness is adjusted upward to maintain effectiveness, thereby extending the operational range while managing energy expenditure.
3Object-affected harmful factors
If a flexible suspension is used, then the movements between the load and the wearer are increased to reduce fluctuations of vertical motion, but excessive displacements occur under high loads
Solution Approach 1:
The variable stiffness suspension dynamically adjusts its characteristics to manage the balance between motion filtering and displacement control. Under normal conditions, the flexible suspension effectively reduces vertical motion fluctuations. When high loads are detected or anticipated, the stiffness is increased to prevent excessive displacements, thus resolving the contradiction through real-time adaptation.
Solution Approach 2:
The adjustable stiffness module changes the suspension stiffness parameter based on load conditions. At lower loads, higher flexibility is maintained to filter vertical motion fluctuations effectively. Under high load conditions, the stiffness parameter is increased to limit displacements, thereby resolving the contradiction between motion reduction and displacement control.
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
Effectively reduces metabolic costs and minimizes musculoskeletal strain across various payloads and walking speeds by filtering and damping movements, enhancing user comfort and safety.
Implementation Method 1
The suspension system also comprises an inerter which is connected in parallel with the adjustable stiffness module and which increases the effective inertia. The forces applied to the two terminals are directly proportional to the relative acceleration between the two terminals.
Implementation Method 2
The adjustable stiffness module adjusts the natural frequency by changing the spring constant of the system.
Data Source
AI summary
A suspended-load backpack comprising a loading chamber suitable for placing therein the loads to be carried; at least one strap; an adjustable impedance suspension system having a first connection portion where it is connected with the strap and a second connection portion where it is connected with the loading chamber and enabling that the movements of the loading chamber perpendicular to the ground caused by the movement of the user, when in use, are filtered; an adjustable stiffness module located on the suspension system, one end of which is connected with the first connection portion and the other end of which is connected with the second connection portion.