Powered Knee Exoskeleton with Passive Hip Constraints
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Solution Overview
Problem
Current exoskeleton systems for spinal cord injured patients often require unnatural gestures for walking, lead to excessive hip rotations and unbalance, and are heavy and bulky, limiting usability and transportability.
Innovation Solution
A bilateral robotic exoskeleton system with a lumbar segment, shank, and thigh segments, featuring passive hip joints that restrict undesirable hip rotations, powered knee joints, and sensors to detect user intention for intuitive gait, along with a modular design for ease of use and transport.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If exoskeleton systems are designed to provide hip control and restrict undesirable hip rotations, then gait speed and step length increase, but device complexity increases
Solution Approach 1:
The exoskeleton is divided into separate functional modules: a lumbar support segment, hip joint mechanisms with passive constraints, knee joints with powered actuators, and ankle-foot units. This segmentation allows hip control through passive mechanical constraints while keeping powered actuators only at the knees, reducing overall system complexity while maintaining gait speed improvements
Solution Approach 2:
Instead of using powered actuators at the hip joint to control hip rotation, the invention inverts the approach by using passive mechanical constraints at the hip while placing powered actuators at the knee joints. This inversion achieves hip control without the complexity of powering the hip joints directly
2Reliability
If exoskeleton systems are designed to be heavy and bulky to provide sufficient support, then patient stability improves, but ease of operation and transportability deteriorate
Solution Approach 1:
The exoskeleton is segmented into lightweight modular components that can be easily assembled and disassembled. The lumbar segment, hip constraints, knee actuators, and ankle-foot units are separate modules that distribute weight across different body regions, improving stability without requiring a single heavy structure
Solution Approach 2:
Passive mechanical constraints at the hip joints act as intermediaries that provide stability and control hip motion without requiring heavy powered actuators. These passive constraints work together with lighter powered knee actuators to achieve overall system stability while maintaining portability
3Reliability
If exoskeleton systems require unnatural gestures to initiate steps, then activation reliability improves, but ease of operation deteriorates
Solution Approach 1:
The system incorporates sensors that detect natural user movements and physiological signals to trigger step initiation. Feedback from pressure sensors, inertial measurement units, and electromyography sensors allows the control system to recognize natural gait intentions and activate the appropriate actuators without requiring unnatural gestures
Solution Approach 2:
The exoskeleton system automatically detects and responds to the user's natural movement intentions through embedded sensors and control algorithms. The system serves itself by autonomously determining when to initiate steps based on detected user intent, eliminating the need for complex manual activation gestures
Data Source
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AI summary
The present invention refers to an exoskeleton system to aid in the walking rehabilitation and assistance process of patients. The system comprises: shank segments, thigh segments, a pair of powered knee joints connecting respectively a shank segment and a thigh segment respectively for the left and right legs. A pair of hip joints connect a lumbar segment with the thigh segments, and a pair of foot sole segments are connected with the shank segments. A system controller is adapted for processing angular velocity sensor readings and for controlling the operation of the powered knee joints based on the angular velocity sensors readings. The system controller is further adapted to detect a user´s hip thrust gesture indicating a user´s intention to initiate a step forward, by detecting an increase in the forward velocity of a hip joint in the direction of walking. The invention provides an intuitive gait experience for users, that closely resembles natural walking.