Exoskeleton Gait Trajectory With Foot Roll for Stable Faster Walking
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Solution Overview
Problem
Existing exoskeletons for individuals with mobility issues lack the ability to perform an autonomous, stable, and anthropomorphic gait over a variety of terrains, often resulting in slow and unstable movement due to underactuation and difficulty in rolling the foot, leading to reduced gait speed and stability, especially on uneven surfaces.
Innovation Solution
A method for generating exoskeleton trajectories that includes a neural network-based approach to create periodic elementary trajectories with distinct phases of pure rotation and translation, ensuring each foot performs a specific movement pattern to enhance natural gait, incorporating conditions for stability and anthropomorphic movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the support foot is kept constantly in flat contact with the ground, then stability is maintained, but gait speed becomes extremely slow and step length is limited to less than 30 cm
Solution Approach 1:
The patent applies dynamics by transitioning from static flat-foot contact to dynamic rolling motion. The foot structure enables sequential contact points (heel to toe) during the gait cycle, allowing the center of pressure to move dynamically across the foot surface. This dynamic approach increases gait speed and step length while maintaining stability through controlled rolling motion rather than static support.
2Adaptability or versatility
If the foot structure includes a break to enable rolling, then more natural gait is achieved, but the system enters underactuation and loses static equilibrium when the center of pressure reaches the support polygon limit
Solution Approach 1:
The patent implements feedback control to monitor the center of pressure position and adjust actuator commands in real-time. When the center of pressure approaches the support polygon limit during rolling motion, the control system detects this condition and modulates the actuation to maintain balance. This feedback mechanism allows the system to operate in dynamic gait while reliably preventing loss of equilibrium.
3Device complexity
If conventional trajectory generation methods are used, then computational simplicity is maintained, but the foot roll is insufficient and gait remains unnatural
Solution Approach 1:
The patent applies preliminary action by pre-defining a desired foot roll trajectory and center of pressure path before execution. The control system calculates the sequence of actuator commands needed to achieve the rolling motion in advance, breaking down the complex rolling task into predetermined phases (heel contact, mid-stance roll, toe contact). This approach enables natural foot roll while maintaining manageable computational complexity through structured trajectory planning.
Data Source
AI summary
The present invention relates to a method for generating a trajectory of an exoskeleton (1) provided with two legs each having a foot, the method comprising the implementation by data-processing means (11a) of a server (10a), of steps of:(a) obtaining at least one n-tuple of gait parameters defining a given gait of the exoskeleton (1);(b) generating at least one periodic elementary trajectory of the exoskeleton (1) for said n-tuple of gait parameters, such that said periodic elementary trajectory comprises in sequence a first trajectory portion and a second trajectory portion, such that in the first trajectory portion each foot performs a pure rotation, and in the second portion only one foot performs a translation.