Lower Extremity Exoskeleton Layout for Self-Balancing Gait
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Solution Overview
Problem
Existing lower extremity exoskeletons for paraplegic patients require additional support from crutches for balance due to insufficient degrees of freedom (DOF), leading to shoulder and arm aches after prolonged use.
Innovation Solution
A wearable lower extremity exoskeleton with 4 active DOF and 2 passive DOF, including hip adduction/abduction, hip and knee flexion/extension, ankle flexion/extension, and a resilient ankle mechanism, with actuators concentrated around the hip level to enhance balance and reduce lateral weight, mimicking an inverted pendulum motion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If additional actuators and DOFs are added to enable self-balancing, then balance capability is improved, but device complexity and weight increase
Solution Approach 1:
The exoskeleton is divided into modular functional units: active DOF modules (hip adduction/abduction, hip flexion/extension, knee flexion/extension, ankle flexion/extension) and passive DOF modules (hip abduction/adduction, ankle dorsiflexion/plantarflexion). Each module contains specific actuators and linkages that can be independently designed, analyzed, and assembled, making the complex 6-DOF system manageable while achieving self-balancing capability
Solution Approach 2:
The system transitions from static support (2-DOF exoskeleton requiring crutches) to dynamic self-balancing through active control of 6 DOFs. The control system continuously adjusts actuator outputs based on real-time sensor feedback about the user's center of mass position and orientation, enabling active balance maintenance without external support structures
2Ease of operation
If actuators are distributed throughout the lower extremity, then joint actuation is improved, but lateral weight and instability increase
Solution Approach 1:
Multiple actuator functions are consolidated at the hip level. The hip adduction/abduction actuator, hip flexion/extension actuator, and associated linkages are integrated into a compact arrangement around the hip joint. This merging reduces the lateral distribution of mass while maintaining full actuation capability for all lower extremity joints through mechanical advantage and linkage design
3Stability of the object's composition
If crutches are used for balance support, then stability is improved, but shoulder and arm strain increase
Solution Approach 1:
The exoskeleton performs self-balancing through its own active control system rather than relying on the user's upper body muscles. Sensors detect the user's center of mass deviations, and the control system automatically actuates the hip and knee joints to correct balance errors, making the system self-regulating and eliminating the need for crutch-based balance support
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
Enhances self-balancing capability, improves locomotion speed and accuracy, reduces the need for crutches, and alleviates shoulder and arm aches by distributing mass and inertia for improved dynamic behavior.
Implementation Method 1
a resilient ankle mechanism, with actuators concentrated around the hip level
Data Source
AI summary
A wearable lower extremity exoskeleton for regenerating a lower body motion functionality of paraplegic patients is provided. The wearable lower extremity exoskeleton has four active DOF and each DOF provided by an actuator disposed around a hip level and a back and/or a front of a user and provided by articulations.