Position-Force Control for Human-Like Robot Impedance Adaptation

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Solution Overview

Problem

Conventional robots lack environmental adaptability and flexibility, failing to replicate human-like movements effectively due to constant mechanical impedance, which limits their ability to perform tasks that require time and effort in varying environments.

Innovation Solution

A position/force controller system that uses a function-dependent force/speed distribution conversion block to convert actuator variables into a set of variables representing human-like movements, allowing for adaptable control energy distribution between speed and force, enabling robots to mimic human movements by controlling actuators based on ideal force and speed origins.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If conventional robots use constant mechanical impedance for actuator control, then the control system is simple and stable, but the robot lacks environmental adaptability and cannot replicate human-like movements effectively

Engineering Contradiction:
Improveenvironmental adaptabilityVSAvoidcontrol system complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent applies dynamics by transitioning from constant mechanical impedance to time-varying mechanical impedance that adapts to environmental conditions. The control system dynamically adjusts impedance parameters based on task requirements and environmental feedback, enabling the robot to replicate human-like movements across varying environments while maintaining manageable complexity through structured adaptation mechanisms.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent implements parameter changes by modifying mechanical impedance parameters (mass, damping, stiffness) as variables rather than constants. This allows the control system to adjust these parameters in response to environmental changes and task requirements, achieving environmental adaptability while using systematic parameter adjustment methods to control system complexity.

Inventive Principle:
Principle #35Parameter changes

2Adaptability or versatility

If conventional robots use constant mechanical impedance, then the control structure is straightforward, but the robot cannot adapt to changes in positions, sizes, and mechanical impedances of the environment

Engineering Contradiction:
Improveadaptability to environmental changesVSAvoidcontrol operation simplicity
Core Design Contradiction:
Adaptability or versatilityVSEase of operation

Solution Approach 1:

The patent employs feedback mechanisms where the control system continuously monitors environmental conditions, task progress, and robot state, then adjusts mechanical impedance parameters accordingly. This feedback loop enables adaptation to environmental changes in positions, sizes, and mechanical impedances while maintaining ease of operation through automated adjustment rather than manual reconfiguration.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The control system transitions from static to dynamic operation by continuously adapting mechanical impedance parameters based on real-time environmental feedback. This dynamic adaptation allows the robot to handle varying environmental conditions while the systematic approach to parameter adjustment maintains operational simplicity.

Inventive Principle:
Principle #15Dynamics

3Adaptability or versatility

If conventional robots use fixed control parameters, then the system is stable and easy to implement, but human-like movements with varying force and speed characteristics cannot be reproduced

Engineering Contradiction:
Improveability to reproduce human-like movementsVSAvoidcontrol stability
Core Design Contradiction:
Adaptability or versatilityVSReliability

Solution Approach 1:

The patent achieves stable reproduction of human-like movements by implementing dynamic control parameters that vary over time according to task requirements. The mechanical impedance parameters (mass, damping, stiffness) are adjusted dynamically to match the varying force and speed characteristics of human movements while maintaining overall system stability through controlled adaptation.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent uses parameter changes to reproduce human-like movements by varying mechanical impedance parameters (mass, damping, stiffness) according to the specific movement task. This allows the system to replicate the varying force and speed characteristics of human movements while maintaining reliability through systematic parameter adjustment based on task requirements.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP3045271B1Position/force controller, and position/force control method and program
Publication Date: 2022.04.06 KEIO UNIV
  • EP3045271B1 patent drawingFigure 1
  • EP3045271B1 patent drawingFigure 2
  • EP3045271B1 patent drawingFigure 3

AI summary

Provided is a technique for more appropriately realizing human-like movement by a robot. This position/force controller performs: detecting information relating to a position based on the effect of an actuator; converting by distributing control energy to speed or positional energy and force energy in response to functions realized on the basis of speed (position) and force information corresponding to the information relating to the position and on the basis of information serving as a reference for control; calculating the control amount for speed or position on the basis of the speed or positional energy; calculating the force control amount on the basis of the force energy; and integrating the speed or position control amount and the force control amount and performing a reverse conversion on the speed or position control amount and the force control amount to return the output to the actuator, to determine the input to the actuator.