Method and device for measuring joint stiffness, and a system implemented based on the joint stiffness measured by such a method.

Method for measuring knee joint stiffness by measuring reaction forces at two equilibrium states

This technology is a system and method for deriving joint stiffness through mechanical equilibrium equations by utilizing the difference in load cell measurements based on changes in human joint (knee) angles and geometric parameters such as leg length and the distance to the center of rotation.

Conventional dynamic model-based stiffness measurement methods suffer from low accuracy due to the difficulty of individually measuring human segment mass and the lack of constant values, as well as the inconvenience of requiring separate external force transducers.

This technology uses an actuator to control the knee angle to create two different equilibrium states. It then calculates individual joint stiffness for each user by inputting the load data measured by a load cell in each state, along with leg length and joint angle data, into a system of simultaneous equations.

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Key Features:

• A stiffness measurement device comprising an angle sensor, an actuator, a load cell, and a foot rest, with the origin set at the end of the foot rest.
• A step of measuring the distance from the center of gravity of the leg to the origin and the weight acting on the center of gravity using a load cell in a first equilibrium state.
• A step of moving the center of gravity using an actuator and measuring the distance and acting weight using a load cell in a second equilibrium state.
• A step of measuring knee stiffness using heel reaction force, leg length, and the distances and weights from the two equilibrium states.

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