Actuator Control System Using Biological Muscle Model

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Solution Overview

Problem

Current actuator technologies for prosthetics and robotics lack the ability to mimic the complex, nonlinear behavior of biological muscle actuation, particularly in terms of force generation and energy storage, which is crucial for natural movement and efficiency.

Innovation Solution

The development of an actuator control system that utilizes a mathematical model of biological muscle actuation, specifically modeling titin as a filament winding around actin, incorporating a contractile element, viscous damping, and a spring in series and parallel configurations, to generate forces and control movements similar to biological muscles.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If traditional motorized actuators are used, then the device can perform basic movement functions, but it cannot mimic the complex nonlinear behavior of biological muscle actuation

Engineering Contradiction:
Improveability to mimic biological muscle actuationVSAvoidcontrol algorithm complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent applies the copying principle by creating a mathematical model that replicates the nonlinear behavior of biological muscle actuation. The control algorithm copies the force-velocity relationship, energy storage characteristics, and titin filament winding dynamics of real muscles, allowing the actuator to mimic biological movement patterns without requiring complex mechanical structures.

Inventive Principle:
Principle #26Copying

Solution Approach 2:

The patent utilizes parameter changes by dynamically adjusting control parameters based on the mathematical model of muscle actuation. The system varies force generation parameters, damping coefficients, and spring constants to replicate different muscle states and movement conditions, enabling adaptive behavior across various operating ranges.

Inventive Principle:
Principle #35Parameter changes

2Adaptability or versatility

If a simple control algorithm is used, then the device is easier to control, but it cannot simulate the nonlinear properties of muscle actuation

Engineering Contradiction:
Improvesimulation of nonlinear muscle propertiesVSAvoidcontrol difficulty
Core Design Contradiction:
Adaptability or versatilityVSEase of operation

Solution Approach 1:

The patent introduces a mathematical model as an intermediary between the simple motorized actuator and the desired complex muscle-like behavior. This intermediary layer translates simple control inputs into sophisticated force generation patterns that mimic muscle actuation, including nonlinear elasticity, viscosity, and energy storage/release mechanisms.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent replaces complex mechanical muscle-mimicking structures with a computational approach. Instead of using intricate mechanical linkages, springs, and dampers to physically replicate muscle behavior, the system uses a mathematical model within the control algorithm to simulate these effects through software-based force generation and damping control.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

3Productivity

If biological muscle modeling is implemented, then movement becomes more natural and efficient, but energy consumption increases due to complex control computations

Engineering Contradiction:
Improvemovement efficiencyVSAvoidenergy consumption
Core Design Contradiction:
ProductivityVSUse of energy by moving object

Solution Approach 1:

The mathematical model of muscle actuation enables the actuator to self-regulate its energy consumption by mimicking the natural efficiency characteristics of biological muscles. The model automatically adjusts force generation and energy storage based on movement requirements, optimizing energy usage without requiring external intervention or complex power management systems.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The system performs preliminary energy storage in the modeled spring element before actual movement is required. By pre-charging the elastic energy storage mechanism through the mathematical model, the actuator can execute movements more efficiently by releasing stored energy rather than continuously consuming power, similar to how biological muscles store and release elastic energy.

Inventive Principle:
Principle #10Preliminary action

4Reliability

If a mathematical model with multiple elements (contractile element, viscous damping, spring) is used, then the actuation behavior becomes more accurate, but the device complexity increases

Engineering Contradiction:
Improveactuation accuracyVSAvoidmathematical model complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies segmentation by dividing the muscle actuation model into distinct functional elements: a contractile element for force generation, a viscous damping element for resistance control, and a spring element for energy storage. Each element is modeled separately with its own mathematical relationships, allowing the complex overall behavior to be constructed from simpler, well-understood components.

Inventive Principle:
Principle #1Segmentation

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

This approach allows for more natural and efficient movement by simulating the nonlinear properties of muscle actuation, enhancing the performance of prosthetics and robotic devices in tasks such as walking and stair ascent, while reducing energy consumption and improving compliance with varying forces.

Implementation Method 1

a spring in series with the contractile element through a pulley and simultaneously in parallel with the contractile element

Methodology Applied
Scientific EffectElasticity: Elasticity

Implementation Method 2

a viscous damping element in parallel with the contractile element

Methodology Applied
Scientific EffectViscous damping: Viscous Damping

Data Source

PatentUS10154915B2Actuator control system and related methods
Publication Date: 2018.12.18 ARIZONA BOARD OF REGENTS ACTING FOR & ON BEHALF OF NORTHERN ARIZONA UNIV
  • US10154915B2 patent drawing
  • US10154915B2 patent drawing
  • US10154915B2 patent drawing

AI summary

An actuator control system includes a motorized joint having first and second members rotatable relative to one another. An actuator is coupled with the motorized joint and is configured to rotate the first member relative to the second member in response to an input including a voltage, a current, or any combination thereof. A controller is coupled with the actuator and is configured to control the input using a control algorithm. The control algorithm controls the input based upon a mathematical model of biological muscle actuation that models titin as a filament which winds around actin during muscle actuation. In implementations the mathematical model includes mathematical representations of a contractile element, a viscous damping element in parallel with the contractile element, and a spring in series with the contractile element through a pulley and simultaneously in parallel with the contractile element.