Exoskeleton for Legs: A Modern Marvel

Imagine a device that boosts your leg power and helps you move better. That's exactly what an electrically actuated lower limb exoskeleton (LLE) does. This clever contraption is made up of three main parts: the mechanical structure, the actuation system that makes it move, and the sensors that help it understand your body's movements. The LLE can be in two states: Non-anthropomorphic state (NAS) and anthropomorphic state (AS), depending on how your joints are positioned. To figure out your human motion intention (HMI), the LLE uses fuzzy logic to spot different phases in your gait. It also creates a continuous joint trajectory using a kinematic model, which is like a blueprint of how the LLE should move.

To make sure the LLE follows your movements closely and stays stable, a hybrid dual-mode control strategy is used. This means two methods work together: adaptive impedance control (AIC) for a stable stance phase, and active disturbance rejection control with fast terminal sliding mode control (ADRC-FTSMC) for a swift and precise swing phase. A special smoothing method is also applied during the transition to tackle any torque discontinuity. Prototype experiments were conducted to check how well the LLE tracks movements and assists with power. The results? The LLE performed exceptionally well, thanks to its innovative HMI methodology and the hybrid control strategy.

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