Exoskeleton Trajectory Control for Natural Walking on Varied Terrain
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Solution Overview
Problem
Existing exoskeleton technologies fail to provide users with musculoskeletal disorders, especially those with complete or partial paralysis, with a natural walking pattern and smooth motion, as they cannot account for muscle activity, stride length, step height, and pace adjustments, and are limited in navigating various surfaces and obstacles.
Innovation Solution
The development of a walking assistance device with an exoskeleton that uses motion capture systems to measure and process Cartesian coordinates of a person without a musculoskeletal disorder, allowing for the calculation of time-dependent parameters and interpolation coefficients to generate desired trajectories in the sagittal plane, enabling users to walk naturally on different surfaces and adjust stride parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If motion capture system with Cartesian coordinates and time-dependent parameters is used, then walking pattern naturalness and motion smoothness are improved, but device complexity increases
Solution Approach 1:
The patent uses motion capture systems to record and store Cartesian coordinates of body points during natural walking. These recorded trajectories are then copied and applied to control the exoskeleton joints, allowing the device to reproduce natural walking patterns without requiring complex real-time biomechanical modeling.
Solution Approach 2:
The patent performs preliminary motion capture and trajectory calculation before actual exoskeleton operation. Time-dependent parameters and interpolation coefficients are pre-calculated and stored, enabling smooth real-time control without complex computations during walking, thus improving naturalness while managing device complexity.
2Device complexity
If exoskeleton is limited to predetermined motion modes, then device complexity is reduced, but adaptability to different surfaces and obstacles deteriorates
Solution Approach 1:
The patent implements a dynamic trajectory generation system that can adapt to different walking conditions (horizontal surfaces, inclined surfaces, stair flights, obstacles). The controller modifies Cartesian coordinates and time-dependent parameters in real-time based on detected terrain and desired walking pattern, enabling versatility without requiring completely different mechanical structures for each mode.
3Measurement precision
If force sensors on clamping elements are used for control, then muscle force detection is improved, but usability for users with complete paralysis deteriorates
Solution Approach 1:
The patent replaces force-based control (which requires muscle activation) with a motion-based control system using motion capture and pre-calculated trajectories. The exoskeleton follows predetermined Cartesian coordinate paths that define natural walking motion, eliminating the need for users to generate muscle forces while maintaining accurate and natural movement patterns.
4Device complexity
If step parameters (stride length, step height, pace) are fixed, then control simplicity is improved, but walking pattern adaptability deteriorates
Solution Approach 1:
The patent implements a parameter adaptation system that modifies stride length, step height, and pace based on user characteristics, terrain conditions, and desired walking speed. The controller adjusts the Cartesian coordinates and time-dependent parameters of the trajectories dynamically, allowing flexible adaptation of walking patterns while maintaining a unified control architecture that doesn't significantly increase system complexity.
Data Source
AI summary
A method for setting desired trajectories of movement of an exoskeleton for enabling movement in a user with a musculoskeletal disorder, a device for assisting walking in the user, and a method for controlling said device. Walking in the user can be enabled in predetermined modes of movement. The device has a part worn by the user including a motorized lower limb exoskeleton equipped with a control device, embodied in an on-board controller of the exoskeleton, and a non-worn part which includes an external computer for a specialized assistant and a system for determining the parameters of desired trajectories of movement of the exoskeleton in a Cartesian coordinate system. Control signals for exoskeleton actuators are generated taking into consideration the mass and inertial properties of body segments of the user and of elements of the exoskeleton, as well as requirements regarding the quality of control.