Hydraulic Joint Locking for Quiet, Low-Wear Prosthetic Motion
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Solution Overview
Problem
Existing prosthetic and orthotic joint mechanisms are noisy, heavy, and prone to wear due to their reliance on ratchets, cams, sprags, or other braking systems, which fail to effectively allow free movement in one direction while locking in the reverse direction.
Innovation Solution
A hydraulic locking mechanism with two chambers connected by fluid pathways and valves, which allows the joint to freely move in one direction while locking in the opposite direction, and automatically unlocks when the joint is unloaded, using a sense piston and magnetic or ball detent mechanisms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional braking systems are used to lock joints, then locking function is achieved, but the device becomes noisy, heavy, and prone to wear
Solution Approach 1:
The patent replaces traditional mechanical braking systems with a hydraulic locking mechanism. The hydraulic system uses fluid pressure and check valves to achieve locking without the noise, weight, and wear associated with mechanical brakes. The hydraulic fluid transmits force through sealed chambers and valves, eliminating direct mechanical contact and friction-based locking.
Solution Approach 2:
The patent employs a hydraulic system with two chambers connected by fluid pathways containing check valves. Hydraulic fluid flows through these pathways to control joint movement, allowing free motion in one direction while locking in the opposite direction. This hydraulic approach provides reliable locking without the harmful effects of mechanical braking systems.
2Ease of operation
If joint locking mechanism is added to prosthetic devices, then motion control is improved, but device complexity increases
Solution Approach 1:
The hydraulic locking mechanism serves multiple functions within a single integrated system. It provides both free motion allowance in the desired direction and automatic locking in the opposite direction, while also damping oscillations. The check valves and hydraulic chambers work together to achieve these functions without requiring separate mechanisms for each function.
Solution Approach 2:
The hydraulic system automatically controls joint motion without requiring external control inputs. The check valves automatically open to allow fluid flow in the permitted direction and close to lock in the opposite direction. The system self-regulates based on the direction and magnitude of applied forces, eliminating the need for complex control systems.
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 hydraulic locking mechanism enables prosthetic or orthotic joints to function smoothly and efficiently, reducing noise, weight, and wear, while allowing for adaptive movement patterns, such as those required for walking, running, and navigating inclines.
Implementation Method 1
a first hydraulic system that has two chambers that are connected by one or more fluid pathways... When the valves are partially closed, resistance to articulation of the joint occurs. When the valves are totally closed, articulation of the joint is stopped, and the joint is locked.
Implementation Method 2
a magnetic latch that can be positioned adjacent to the sense piston... a magnetically latched position
Data Source
AI summary
Technology is described to provide a locking device to control movement of a prosthetic limb. The technology may include a hydraulic damper having a movable damper wall in a hydraulic housing of the hydraulic damper, and the movable damper wall may form a first chamber and second chamber in the hydraulic damper. A first fluid channel may be coupled to the first chamber. In addition, a latch may be in fluid communication with the first fluid channel. A poppet valve can be configured to set the latch in an open position when pressure is reduced in the first chamber and to stop fluid movement when pressure is increased in the first chamber. A second fluid channel between the second chamber and the latch may enable fluid to flow between the second chamber and the latch.