Lower Limb Assistive Device Test Platform With Dynamic Hip Motion
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Solution Overview
Problem
Current test platforms for robotic lower limb assistive devices lack the ability to simulate complex human movements, such as standing, walking, crouching, and overcoming obstacles, while accurately evaluating the devices' performance and preventing misinterpretation of torque values.
Innovation Solution
A test platform system incorporating a lower limb device, a guide system with a vertical rail and ball screw mechanism, a center of mass plate, and a moving belt, allowing for natural hip and ankle movements with separate degrees of freedom, and capable of simulating transitions between positions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a test platform uses a fixed structure with large motors to carry the entire mass, then it can provide stable support, but it cannot simulate separated hip motions and natural human gait patterns
Solution Approach 1:
The test platform divides the lower limb device into separate functional segments: a hip unit with its own motor for hip motion, and a shank/foot assembly. This segmentation allows independent control of hip movements while reducing the mass that each motor needs to move, enabling natural gait simulation without requiring a single large motor to carry the entire mass.
Solution Approach 2:
The platform transitions from a fixed rigid structure to a dynamic system with movable components. The hip unit can perform rotational movements independently, and the center of mass plate can move vertically along the rail, allowing the system to adapt to different gait phases and simulate natural human movement patterns rather than maintaining a static configuration.
2Ease of operation
If the lower limb device is fixed to the test platform, then stable positioning is achieved, but the device generates excessive torque and cannot perform natural movements
Solution Approach 1:
The invention extracts the hip motion function from the main platform structure and places it in a separate hip unit with its own motor. This allows the hip unit to independently control hip movements without the lower limb device needing to generate torque to move the entire platform mass, enabling natural gait patterns with reduced torque requirements.
Solution Approach 2:
The center of mass plate acts as an intermediary between the fixed platform structure and the movable lower limb device. It allows vertical movement along the rail to accommodate changes in the device's center of mass during gait cycles, providing stability while permitting natural movement without excessive torque generation.
3Adaptability or versatility
If the test platform uses a simple fixed structure, then manufacturing is easier, but it cannot accurately evaluate device performance during complex movements like standing, walking, and overcoming obstacles
Solution Approach 1:
The platform is divided into modular components: a fixed base structure, a vertical rail assembly, a movable center of mass plate, and a hip unit with motor. This segmentation allows each component to be manufactured and tested separately, then assembled to create a system capable of simulating complex movements including standing, walking, and obstacle overcoming.
Solution Approach 2:
The test platform is designed with multi-functional capabilities through its modular architecture. The same basic structure with movable center of mass plate and hip unit can simulate various gait patterns and movement conditions (standing, walking, crouching, obstacle overcoming) by adjusting control parameters, eliminating the need for multiple specialized test rigs.
4Weight of moving object
If the platform carries the entire mass as a whole, then structural stability is maintained, but large motors are required and separated hip motions cannot be achieved
Solution Approach 1:
The mass is segmented into the stationary platform base and the movable lower limb device components. The hip unit motor only needs to move the hip assembly mass, not the entire platform mass, enabling separated hip motions with smaller, more efficient motors while maintaining overall structural stability through the fixed base and rail structure.
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
Enables accurate evaluation of lower limb assistive devices by simulating natural human movements, preventing excessive torque generation, and ensuring compatibility with the devices' natural kinematics and dynamics.
Implementation Method 1
a vertical ball screw connected to a vertical rail element by means of at least one connection plate, wherein the ball screw is passed through a screw housing in the plate mounted on the rail element
Implementation Method 2
a first motor positioned on the vertical ball screw and performing the center of mass plate (CoM) motion
Implementation Method 3
at least one nut acting on the ball screw and converting the rotational movement of the first motor into a linear movement, wherein the center of mass plate is coupled with the nut via at least one ball bearing
Data Source
AI summary
A test platform system for testing lower limb assistive devices includes a lower limb device, a guide system by which the movement of a lower limb device is simulated during its transition between positions, a second motor that performs the movement of the lower limb device, and a moving belt.