Dynamic Impedance Control for Human-Robot Collaboration

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Conventional human cooperative robots face challenges in setting appropriate impedance parameters, particularly when work phases are unclear, making it difficult to apply techniques to various tasks and improving maneuverability beyond mere positioning operations.

Innovation Solution

A robot system with a multi-joint arm, an external force acquiring unit, an impedance map storage unit, and an impedance map variable unit that adjusts impedance parameters based on the current position and operation of the arm end, allowing for dynamic impedance control to enhance maneuverability and stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If low damping is set for impedance parameters, then ease of shifting is improved, but positioning stability deteriorates

Engineering Contradiction:

Improveease of shiftingVSAvoidpositioning stability

Core Design Contradiction:

Ease of operationVSStability of the object's composition

Solution Approach 1:

The patent applies dynamics by making the impedance parameters (inertia, damping, stiffness) changeable over time and space. The control device dynamically adjusts these parameters based on the robot arm's current position and operation phase, allowing low damping during shifting phases for ease of movement and high damping during positioning phases for stability.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent directly applies parameter changes by modifying the impedance parameters (particularly damping and inertia) according to the work phase and position. The control device changes these parameters to match the required operation, enabling the system to transition between ease of shifting and positioning stability by adjusting the physical parameters of the robot arm's mechanical impedance.

Inventive Principle:

Principle #35Parameter changes

2Stability of the object's composition

If high damping is set for impedance parameters, then positioning stability is improved, but ease of shifting deteriorates

Engineering Contradiction:

Improvepositioning stabilityVSAvoidease of shifting

Core Design Contradiction:

Stability of the object's compositionVSEase of operation

Solution Approach 1:

The system dynamically switches between high and low damping values based on the operation phase. During positioning operations, high damping is applied to ensure stability and precision. During shifting operations, the damping is reduced to allow easy movement. This dynamic adaptation resolves the contradiction by making the damping characteristic context-dependent rather than fixed.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The control device changes the damping parameter value based on the detected work phase and position information. By adjusting the damping parameter to be high during positioning and low during shifting, the system resolves the contradiction between positioning stability and ease of shifting through parameter adaptation.

Inventive Principle:

Principle #35Parameter changes

3Device complexity

If fixed impedance parameters are used, then control simplicity is maintained, but maneuverability for various work phases deteriorates

Engineering Contradiction:

Improvecontrol simplicityVSAvoidmaneuverability

Core Design Contradiction:

Device complexityVSAdaptability or versatility

Solution Approach 1:

The robot arm's control system performs self-service by automatically detecting its own position and operation phase, then autonomously adjusting the impedance parameters accordingly. The control device monitors the work phase and position information, and based on this self-acquired information, it modifies the impedance parameters without external intervention, enabling adaptive maneuverability while maintaining relatively simple control architecture.

Inventive Principle:

Principle #25Self-service

4Reliability

If work phase discernment is required for parameter adjustment, then appropriate impedance parameters can be set, but system complexity and difficulty of application to various works increases

Engineering Contradiction:

Improveparameter setting accuracyVSAvoidsystem complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The control device uses feedback from position sensors and work phase detection to continuously monitor the robot arm's state. Based on this feedback information, the system automatically adjusts the impedance parameters to match the current operation phase. This feedback mechanism ensures reliable parameter setting while keeping the system adaptable to various works through automatic phase recognition rather than complex manual configuration.

Inventive Principle:

Principle #23Feedback

Data Source

PatentUS8725295B2Robot, robot control apparatus, robot control method, and robot control program

Publication Date: 2014.05.13 PANASONIC HOLDINGS CORP

AI summary

A robot includes a multi-joint robot arm, an external force acquiring unit arranged at the multi-joint robot arm to acquire an external force, and an impedance control unit that causes the multi-joint robot arm to operate as a virtual spring-mass-damper system based on the external force acquired by the external force acquiring unit. The impedance control unit has an impedance map storage unit that defines impedance parameters at each of points of the work region, and an impedance map variable unit that changes the distribution of the impedance parameters in the impedance map storage unit in accordance with the current arm end position or the current arm end velocity of the multi-joint robot arm.