Lower-Leg Exoskeleton Toe Pogo Spring Force Transmission
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Solution Overview
Problem
Conventional leg exoskeletons have a sloppy interface with the user's foot, leading to nonstandard gait and limited mobility due to force transmission primarily at the heel, which restricts actions like squatting.
Innovation Solution
A lower-leg exoskeleton system with a shoe/orthosis design that transmits force directly through the sole of the footwear, using semi-compliant and dynamically adjustable structures, with inflatable actuators and smart materials to maintain rigidity and comfort, and quick-connect attachment points for ease of use.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If force transmission is effected via a contact point at the heel, then the exoskeleton can provide strength assistance, but it leads to nonstandard gait and limited mobility
Solution Approach 1:
The patent extracts the force transmission function from the heel contact point and relocates it to the toe region. The toe pogo spring mechanism separates the force transmission path from the traditional heel strike, allowing the heel to remain in natural contact with the ground while force is transmitted through the toe region during the push-off phase of gait.
Solution Approach 2:
The patent inverts the conventional approach by placing the active force transmission element (pogo spring) at the toe rather than the heel. This reversal allows the exoskeleton to push the user forward during toe-off, mimicking natural gait mechanics where the toe is the primary propulsion point, rather than relying on heel strike.
2Force
If the exoskeleton interface with the foot is rigid, then force transmission is efficient, but it reduces comfort and adaptability to different gaits
Solution Approach 1:
The patent employs a dynamic interface through the toe pogo spring mechanism that adjusts its stiffness characteristics during the gait cycle. The spring compresses and rebounds, providing rigid force transmission during the push-off phase while allowing compliance during other phases of gait, thus adapting to different movement patterns and terrain conditions.
Solution Approach 2:
The patent changes the mechanical parameters of the foot interface by using a spring-based system rather than a rigid connection. The pogo spring's stiffness, compression distance, and rebound characteristics can be adjusted to optimize force transmission efficiency while maintaining comfort and adaptability to varying gait requirements.
3Ease of operation
If the exoskeleton uses a simple attachment system, then ease of use is improved, but reliability of force transmission decreases
Solution Approach 1:
The toe pogo spring mechanism is designed to be self-aligning and self-adjusting during gait. The spring naturally centers itself during compression and rebound, automatically maintaining proper alignment for force transmission without requiring complex adjustment mechanisms or frequent user intervention, thus achieving both ease of use and reliability.
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 system provides efficient power output and control, enhancing user comfort and range of motion by distributing the load evenly across the ground and compensating for gait changes, allowing for more natural movement and improved strength assistance.
Implementation Method 1
an inflatable actuator configured to provide a moment about a user's ankle
Implementation Method 2
semi-compliant and dynamically adjustable structures, with inflatable actuators and smart materials to maintain rigidity and comfort
Data Source
AI summary
A lower-leg exoskeleton that includes an actuator configured to be worn about a portion a leg of a user that is below the knee of the user; and a foot structure coupled to a first actuator end of the actuator, the foot structure configured to surround a portion of the foot of the user. The foot structure includes one or more sidewalls configured to extend around the foot of the user and including one or more sidewall attachment points for connecting to a base portion, and a base portion configured to reside at a base of the foot of the user and including one or more base attachment points coupling with the one or more sidewall attachment points.