Gait Device Control via Signal Conditioning and Coordinate Transformation

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Solution Overview

Problem

Existing control systems for gait devices, such as prosthetic and robotic systems, face challenges in processing user signals quickly and accurately, leading to inadequate smooth and continuous control.

Innovation Solution

A method involving the measurement of kinematic and loading states, conditioning through integration, differentiation, filtering, and amplification, followed by coordinate transformation, and input into a reference function to calculate a desired reference command for actuators, enabling precise control of gait devices.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional control systems are used for gait devices, then device operation is achieved, but signal processing speed and accuracy are insufficient, resulting in discontinuous and non-smooth control

Engineering Contradiction:
Improvesignal processing accuracyVSAvoidsignal processing time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The patent applies preliminary action by pre-conditioning the state measurement through filtering, integration, and differentiation operations before the control decision is made. This preprocessing of signals ensures that when the control system processes user signals, they are already optimized for accuracy and speed, eliminating the need for time-consuming real-time corrections during actuation.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent introduces an intermediary conditioning system between the sensor and the actuator. This intermediary layer includes filtering operations that remove noise, integration operations that accumulate signal over time for better accuracy, and differentiation operations that enhance signal changes. This intermediary processing layer resolves the contradiction by improving signal quality without adding significant time delay.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Stability of the object's composition

If conventional control methods are used, then basic control function is achieved, but smooth and continuous control is not provided

Engineering Contradiction:
Improvecontrol continuityVSAvoidcontrol system complexity
Core Design Contradiction:
Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The patent ensures continuity of useful action by continuously conditioning the state measurement through filtering and integration operations. Rather than discrete control updates, the system maintains continuous signal processing that smooths transitions and eliminates abrupt changes in actuator movement, providing stable and continuous control throughout the gait cycle.

Inventive Principle:
Principle #20Continuity of useful action

Solution Approach 2:

The patent applies dynamics by making the control system adaptive through conditional processing. The filtering, integration, and differentiation operations dynamically adjust the signal based on the current state, allowing the system to respond smoothly to changing conditions during gait while maintaining overall control stability without requiring overly complex static control structures.

Inventive Principle:
Principle #15Dynamics

3Measurement precision

If state measurement is used directly without conditioning, then processing is simple, but noise and inaccuracies are present causing sudden jumps and oscillations

Engineering Contradiction:
Improvestate measurement accuracyVSAvoidconditioning process complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent applies preliminary action by pre-conditioning the state measurement through filtering, integration, and differentiation operations before the control decision is made. This preprocessing of signals ensures that when the control system processes user signals, they are already optimized for accuracy and speed, eliminating the need for time-consuming real-time corrections during actuation.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent introduces an intermediary conditioning system between the sensor and the actuator. This intermediary layer includes filtering operations that remove noise, integration operations that accumulate signal over time for better accuracy, and differentiation operations that enhance signal changes. This intermediary processing layer resolves the contradiction by improving signal quality without adding significant time delay.

Inventive Principle:
Principle #24Intermediary (Mediator)

Data Source

PatentEP2814643B1Control systems and methods for gait devices
Publication Date: 2021.03.24 OSSUR ICELAND EHF
  • EP2814643B1 patent drawingFigure 1
  • EP2814643B1 patent drawingFigure 2
  • EP2814643B1 patent drawingFigure 3

AI summary

Methods for controlling gait devices include measuring kinematic and/or loading states of limb or robotic segments; conditioning the resulting state measurement by any combination or order of integration, differentiation, filtering, and amplification; transforming conditioned state measurements by coordinate transformation; optionally conditioning the transformed state measurements a second time in a manner similar to the first conditioning step; and using the transformed or conditioned transformed state measurements as independent variables in a predetermined reference function to calculate a desired reference command for any number of actuators.