Unpowered Exoskeleton Rotary Brake Joint Stress
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Solution Overview
Problem
Conventional exoskeleton devices for load carriage and injury prevention are often impractical due to their high cost, complexity, and requirement of electrical power, which limits their use for recreational activities like hiking, where joint pain and musculoskeletal injuries are common issues, especially when carrying low loads.
Innovation Solution
An unpowered exoskeleton device with a rotary braking system, utilizing a hydraulically actuated handbrake and a brake rotor that varies its moment arm with knee joint angle, allowing for controlled joint movement and weight transfer, eliminating the need for electrical power and reducing joint stress during activities like descending slopes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional exoskeleton devices are used for load carriage and injury prevention, then joint protection and load sharing are improved, but device complexity, cost, and weight increase due to power supplies and actuators
Solution Approach 1:
The patent removes the power supply and actuator systems from the exoskeleton device, extracting the active control components that cause complexity and weight issues. The device relies on passive mechanical structures and user-operated brakes to provide joint protection and load sharing functionality without requiring electrical power or complex control systems.
Solution Approach 2:
Instead of using powered actuators to actively control joint movement, the patent inverts the approach by using passive friction brakes that the user manually operates. The brakes work against the direction of unwanted movement (excessive flexion during descent), converting the problem of uncontrolled motion into a controllable friction-based resistance system.
2Force
If powered exoskeleton systems are implemented, then joint support and load carriage capability are improved, but weight and cost increase due to batteries and electronic systems
Solution Approach 1:
The patent extracts all power-related components including batteries, motors, and electronic control systems. The joint support force is achieved through passive mechanical advantage in the linkage design and user-applied friction braking, eliminating the need for heavy powered systems while maintaining adequate support capability for recreational hiking loads.
Solution Approach 2:
The exoskeleton device uses the user's own body movements and applied forces to generate the necessary joint support. The friction brakes are manually operated by the user, converting their own muscular effort into controlled resistance, making the system self-sufficient without external power sources.
3Reliability
If friction brakes are used to control joint movement, then joint stress reduction is improved, but control precision may be limited compared to powered systems
Solution Approach 1:
The patent adjusts the friction brake parameters including pad material, contact pressure, and lever mechanical advantage to optimize the balance between control precision and ease of operation. The variable moment arm design of the linkage system dynamically changes the effective braking force throughout the range of motion, providing better control precision at critical joint angles while maintaining simplicity.
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 unpowered exoskeleton effectively reduces joint stress and prevents injuries by allowing controlled movement and weight distribution, enabling users to carry heavier loads and traverse slopes with reduced risk of musculoskeletal damage, while being lightweight and cost-effective.
Implementation Method 1
The plunger is connected to a small hydraulic hose that in turn connects to a brake caliper fitted over a brake rotor. When fluid is displaced by squeezing the handle, the caliper on the other end of the hydraulic hose clamps onto the brake rotor.
Implementation Method 2
the caliper on the other end of the hydraulic hose clamps onto the brake rotor... the brake rotor is connected to exoskeleton structure on one side of a joint, and the caliper is connected to the structure on the other side of the joint
Data Source
AI summary
An exoskeleton device includes a first brace coupled to a first portion of a wearer of the exoskeleton device and a second brace coupled to a second portion of the wearer. A first joint connects the first and second braces and allows relative movement between the first and second braces. A first brake is controllable between an unactuated state and a plurality of actuated states, and the first brake impedes relative movement between the first and second braces at the first joint while the first brake is in one of the plurality of actuated states. A manual actuator is selectively used by the wearer during relative movement between the first and second braces. Use of the actuator causes the first brake to enter one of the plurality of actuated states such that relative movement between the first and second braces is impeded at the first joint.