Exoskeleton Knee Joint Self-Locking With Automatic Friction Control
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Solution Overview
Problem
Existing knee joint exoskeletons face issues with high power consumption, weight, and manual intervention for locking and unlocking, leading to poor user experience and safety concerns.
Innovation Solution
A self-locking mechanism using a rotating outward expanding locking member with friction surfaces and a locking driving member that controls friction force for progressive locking and unlocking, integrated with a control unit and ranging sensor for automatic control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a lead screw and slide mechanism is used for knee joint actuation, then self-locking function is achieved, but weight and size increase significantly
Solution Approach 1:
The patent extracts the heavy lead screw mechanism from the knee joint and replaces it with a lightweight friction-based locking mechanism. The locking member with friction surfaces directly contacts the thigh and shank supports to provide self-locking without requiring complex screw mechanisms, thereby significantly reducing weight while maintaining the self-locking function.
Solution Approach 2:
The patent replaces the mechanical lead screw system with a friction-based locking system. Instead of using threaded mechanical engagement, the invention uses friction surfaces between the locking member and the support structures to achieve locking, substituting a complex mechanical system with a simpler friction-based mechanism that reduces weight and complexity.
2Reliability
If a manual locking mechanism with locking pin and spring is used, then self-locking is achieved, but frequent human control intervention is required
Solution Approach 1:
The patent implements self-service by enabling the knee joint to automatically lock and unlock based on detected walking states. The control unit monitors sensors (such as accelerometers or position sensors) and autonomously activates the locking mechanism when standing still or walking, eliminating the need for manual intervention and allowing the system to serve itself through automatic state recognition and response.
Solution Approach 2:
The patent incorporates feedback through sensors that detect the walking state (standing vs. walking motion) and provide information to the control unit. Based on this feedback, the control unit automatically controls the locking mechanism to engage or disengage, creating a closed-loop system that responds to real-time conditions without human input.
3Speed
If rapid locking is implemented through cable steel rope and locking handle, then locking speed increases, but operation complexity increases
Solution Approach 1:
The patent extracts the complex cable steel rope and manual locking handle mechanism and replaces it with a simplified friction-based locking member actuated by a small motor. This removal of unnecessary components reduces operational complexity while maintaining rapid locking capability through automated control.
Solution Approach 2:
The patent replaces the manual cable and handle mechanical system with an automated motor-driven system. Instead of requiring manual manipulation of cables and handles, a small motor actuates the locking member through a simple transmission mechanism, substituting complex manual mechanical operations with automated electrical-mechanical actuation that is both simpler and faster.
4Reliability
If torsion spring and brake rod mechanism is used for passive knee locking, then locking function is achieved, but friction force control precision decreases
Solution Approach 1:
The patent replaces the passive torsion spring and brake rod mechanism with an active motor-controlled locking system. Instead of relying on passive elastic energy storage and release, a small motor provides precise, controllable friction force through the locking member, enabling accurate control of the locking intensity and timing.
Solution Approach 2:
The patent implements parameter changes by using a motor to dynamically adjust the friction force applied by the locking member. Instead of fixed friction characteristics from springs, the system can vary the normal force between the locking member and support surfaces through motor control, enabling precise regulation of friction force based on detected walking states.
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
Reduces power consumption, weight, and improves safety by enabling automatic and gradual locking and unlocking, mimicking human knee joint movement for enhanced user experience and endurance.
Implementation Method 1
an outer side of the first rotating frame (31) and an outer side of the second rotating frame (32) are correspondingly provided with a first friction surface; the second base (2) has a second compartment... an inner wall of the second compartment encloses the rotating outward expanding locking member and defines a second friction surface matching with the first friction surface
Data Source
AI summary
An exoskeleton joint self-locking mechanism, a knee joint and a bionic rehabilitation robot are provided. The self-locking mechanism comprises a first base, a rotating outward expanding locking member, a second base and a locking driving member; the rotating outward expanding locking member comprises a first rotating frame and a second rotating frame, and outer sides of the first rotating frame and the second rotating frame have a first friction surface; one end of the first rotating frame is pivoted with one end of the second rotating frame; the second base is rotationally mounted on the first base, and an inner wall of the second base defines a second friction surface enclosing the first friction surface; the locking driving member applies/removes a force pushing away from free ends of the first rotating frame and the second rotating frame, to make the first friction surface lock/unlock the second friction surface.