Multi-Legged Robot Touchdown Control on Uneven Terrain

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Solution Overview

Problem

Multi-legged robots face challenges in maintaining stable posture and avoiding obstacles while walking on irregular terrain, particularly when disturbances occur during leg swinging.

Innovation Solution

A method and robot design that includes detecting disturbances, recalculating touchdown positions based on dynamic states, and identifying step obstacle regions to determine stable touchdown positions using terrain information and dynamic calculations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If the robot swings its leg toward a predetermined touchdown position, then the walking speed is improved, but the stability deteriorates when disturbances occur during leg swing

Engineering Contradiction:
Improvewalking speedVSAvoidposture stability
Core Design Contradiction:
SpeedVSStability of the object's composition

Solution Approach 1:

The robot dynamically adjusts the touchdown position based on real-time disturbance detection and dynamic state calculations. Instead of following a fixed predetermined position, the system computes a new touchdown position that accounts for current disturbances and terrain conditions, allowing the robot to maintain stability while continuing to walk at efficient speeds

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The system implements feedback control by detecting disturbances during leg swing, calculating the robot's dynamic state, and using this information to determine an adjusted touchdown position. This closed-loop control ensures that the robot responds to disturbances and maintains stability while preserving walking speed

Inventive Principle:
Principle #23Feedback

2Ease of operation

If the robot lands legs at fixed predetermined positions, then the control simplicity is improved, but the adaptability to irregular terrain deteriorates

Engineering Contradiction:
Improvecontrol simplicityVSAvoidterrain adaptability
Core Design Contradiction:
Ease of operationVSAdaptability or versatility

Solution Approach 1:

The robot performs preliminary identification of step obstacle regions based on terrain information before executing the leg swing. By pre-processing terrain data and identifying hazardous regions, the system can make informed adjustments to the touchdown position while maintaining relatively simple control logic

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system changes the touchdown position parameter based on terrain information and identified obstacle regions. Instead of using a fixed position, the touchdown position is dynamically modified according to terrain characteristics, enabling adaptability to irregular terrain while building upon the simple framework of predetermined positioning

Inventive Principle:
Principle #35Parameter changes

3Stability of the object's composition

If the robot calculates touchdown position based on dynamic state during disturbance, then the stability is improved, but the response time to complete the walking cycle deteriorates

Engineering Contradiction:
Improveposture stabilityVSAvoidwalking cycle time
Core Design Contradiction:
Stability of the object's compositionVSLoss of time

Solution Approach 1:

The system performs partial calculations focused specifically on determining the adjusted touchdown position rather than recalculating the entire walking trajectory. By concentrating computational effort only on the critical touchdown position adjustment, the robot achieves stability improvement while minimizing the time added to the walking cycle

Inventive Principle:
Principle #16Partial or excessive action

4Reliability

If the robot avoids step obstacle regions, then the reliability is improved, but the walking speed deteriorates due to position adjustments

Engineering Contradiction:
Improvefall preventionVSAvoidwalking speed
Core Design Contradiction:
ReliabilityVSSpeed

Solution Approach 1:

The system applies asymmetric adjustment strategies based on the specific terrain conditions and disturbance characteristics. Rather than uniformly slowing down for all terrain variations, the robot selectively adjusts touchdown positions only when necessary to avoid obstacle regions, maintaining higher speeds on safe terrain while ensuring reliability when hazards are detected

Inventive Principle:
Principle #4Asymmetry

Data Source

PatentEP4620631A1Robot having plurality of legs and method for determining touchdown position thereof
Publication Date: 2025.09.24 RAINBOW ROBOTICS INC
  • EP4620631A1 patent drawingFigure 1(a)~1(b)
  • EP4620631A1 patent drawingFigure 2
  • EP4620631A1 patent drawingFigure 3

AI summary

The present invention relates to a method for determining a touchdown position of a robot performed by a computing device, the method comprising the steps of: detecting a disturbance during swing of a first leg of the robot toward a first touchdown position, calculating a second touchdown position based on a dynamic state of the robot in response to the detection of the disturbance, identifying a step obstacle region based on terrain information of the robot and determining whether the second touchdown position belongs to the step obstacle region, and determining a third touchdown position out of the step obstacle region as the touchdown position of the first leg, in a case in which the second touchdown position belongs to the step obstacle region.