Ankle-less Walking Assistant Using Sole Pressure Sensors
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Solution Overview
Problem
Exoskeleton robots with ankle joints face challenges in mechanical design and control algorithms, leading to discomfort and unnatural walking due to excessive weight and restricted freedom, as well as difficulties in accurately measuring ground reaction force.
Innovation Solution
An ankle-less walking assistant apparatus with ground-contact feet fixed to calf links, using pressure sensors to determine gait phases and select control modes for hip and knee drivers, simplifying the control algorithm and removing the need for ankle drivers, thereby enhancing natural walking and reducing wearer discomfort.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If ankle joints and feet are added to exoskeleton robots to sense and process physical interaction with the ground, then measurement precision of ground reaction force is improved, but device complexity and weight increase significantly
Solution Approach 1:
The patent removes the ankle joint and foot module from the exoskeleton robot, extracting the problematic components that caused complexity and weight issues. Instead of using force/torque sensors at the ankle, the invention uses pressure sensors distributed on the sole of the shoe to measure ground reaction force, achieving the measurement function without the complex ankle mechanism.
Solution Approach 2:
The patent replaces the mechanical ankle joint system with a shoe-based pressure sensing system. Instead of using a mechanical force/torque sensor at the ankle joint, the invention uses multiple pressure sensors distributed on the shoe sole to capture ground reaction force information, substituting a complex mechanical sensing system with a simpler distributed sensing approach.
2Reliability
If ankle joints are designed to resist frequency shock from the ground, then reliability is improved, but weight of the robot increases
Solution Approach 1:
The patent removes the heavy ankle joint and foot module that were designed to resist ground shocks. Instead, the shock resistance function is distributed to the entire leg structure and compensated through control algorithms, eliminating the need for heavy localized shock-resistant components at the ankle.
Solution Approach 2:
The patent changes the control parameters and feedback mechanisms to compensate for the removal of the ankle joint. By using pressure sensor data from the shoe sole and implementing advanced control algorithms, the system maintains shock resistance and stability without requiring heavy mechanical ankle components.
3Measurement precision
If force/torque sensors are used to measure ground reaction force, then measurement precision is improved, but device complexity increases due to strong foot module support requirements
Solution Approach 1:
The patent removes the force/torque sensor and complex foot module support structure. Instead, it uses multiple pressure sensors distributed on the shoe sole to measure ground reaction force, achieving accurate measurement without requiring strong foot module support.
Solution Approach 2:
The patent segments the ground reaction force measurement function into multiple pressure sensors distributed across the shoe sole. This segmentation allows the measurement task to be distributed across multiple simple sensors rather than requiring a single complex force/torque sensor and strong foot module support structure.
4Adaptability or versatility
If ankle joints with high degree of freedom are designed, then adaptability to wearer movement is improved, but device complexity and weight increase
Solution Approach 1:
The patent removes the ankle joint entirely, extracting the source of complexity. The adaptability to wearer movement is achieved through the flexible shoe design and control algorithms that respond to pressure sensor feedback, eliminating the need for complex mechanical ankle joints with multiple degrees of freedom.
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 solution allows for more natural and comfortable walking by simplifying the control algorithm, reducing the weight and complexity of the exoskeleton, and improving the accuracy of ground interaction, resulting in enhanced walking assistance performance without complex calculations.
Implementation Method 1
pressure sensors sensing pressure on soles of both feet of a wearer
Data Source
AI summary
An ankle-less walking assistant apparatus includes: a body supporting the back of a wearer; left and right hip joint-drivers extending from both sides of the body; left and right thigh links having first ends connected to the left and right hip joint-drivers, respectively; left and right knee-drivers connected to second ends of the left and right thigh links, respectively; left and right calf links having first ends connected to the left and right knee-drivers, respectively; and ground-contact feet fixed to second ends of the left and right calf links, respectively.