Biped Robot Running Gait Control on Rough Terrain

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Solution Overview

Problem

Current biped robots face challenges in achieving a stable running gait on rough terrain due to limitations in mechanical design and control strategies, particularly the ZMP stability criterion, which restricts their adaptability to complex environments.

Innovation Solution

A method utilizing a hybrid inverted pendulum model that switches between SLIP and LIP models for balance control, combined with state machine-based movement planning and trajectory control, allows for dynamic running on rough terrain by stabilizing posture and center of mass during different phases of the gait cycle.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If ZMP stability criterion is used for control, then balance stability is improved, but adaptability to rough terrain deteriorates

Engineering Contradiction:
Improvebalance stabilityVSAvoidadaptability to rough terrain
Core Design Contradiction:
Stability of the object's compositionVSAdaptability or versatility

Solution Approach 1:

The patent transitions from static ZMP stability criterion to dynamic running gait control. The robot dynamically switches between walking and running gaits based on terrain conditions, with the running gait featuring an air phase where both feet are off the ground simultaneously. This dynamic approach allows the robot to maintain balance stability while adapting to rough terrain by adjusting gait parameters in real-time.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The control strategy changes key parameters including switching from single-support phase to double-air phase gait, adjusting foot placement coordinates, and modifying joint angle trajectories. These parameter changes enable the robot to achieve both balance stability and terrain adaptability by optimizing gait characteristics for different terrain conditions.

Inventive Principle:
Principle #35Parameter changes

2Stability of the object's composition

If large foot design is adopted, then balance stability is improved, but adaptability to complex roads deteriorates

Engineering Contradiction:
Improvebalance stabilityVSAvoidadaptability to complex roads
Core Design Contradiction:
Stability of the object's compositionVSAdaptability or versatility

Solution Approach 1:

Instead of relying on large static foot design, the patent employs dynamic gait control where the robot coordinates leg movements and foot placement to achieve balance. The running gait with air phase allows the robot to maintain stability without requiring oversized feet, thereby improving adaptability to complex road surfaces while preserving balance capabilities.

Inventive Principle:
Principle #15Dynamics

3Speed

If running gait is adopted, then moving speed is improved, but dynamic balance control difficulty increases

Engineering Contradiction:
Improvemoving speedVSAvoiddynamic balance control difficulty
Core Design Contradiction:
SpeedVSDevice complexity

Solution Approach 1:

The running gait cycle is segmented into distinct phases: left leg support phase, right leg support phase, and air phase where both legs are simultaneously off the ground. This segmentation allows the control system to manage dynamic balance by focusing on specific phases, reducing overall control complexity while achieving higher speeds.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent implements periodic switching between walking and running gaits, with each gait consisting of periodic cycles of support and air phases. This periodic structure simplifies dynamic balance control by creating predictable, repeating patterns that can be controlled through standardized trajectories and timing, enabling high-speed movement without excessive control complexity.

Inventive Principle:
Principle #19Periodic action

4Speed

If air phase duration is extended, then moving speed is improved, but joint motor performance requirements increase

Engineering Contradiction:
Improvemoving speedVSAvoidjoint motor performance requirements
Core Design Contradiction:
SpeedVSDevice complexity

Solution Approach 1:

The patent implements a partial air phase where both feet are off the ground for a limited duration, rather than extending the air phase to maximum possible length. This partial action approach achieves speed improvement while keeping joint motor performance requirements within practical limits, balancing speed enhancement with hardware feasibility.

Inventive Principle:
Principle #16Partial or excessive action

Data Source

PatentUS11858138B2Method for realizing dynamic running gait of biped robot on rough terrain road
Publication Date: 2024.01.02 ZHEJIANG HUMANOID ROBOT INNOVATION CENTER CO LTD
  • US11858138B2 patent drawing
  • US11858138B2 patent drawing
  • US11858138B2 patent drawing

AI summary

The present disclosure provides a method for realizing a dynamic running gait of a biped robot on a rough terrain road, which sets a state machine for an entire running cycle to perform a balance control and movement trajectory planning of the robot in each state. At the time that the robot switches from the in-air phase into a landing phase, a SLIP model is used to control the posture balance and landing cushion; and when the robot is stable after landing, an LIP model is used to control a center of mass of the robot to a set height. An in-air phase of the robot in running is generated through movement trajectory planning and state switching of a supporting leg and a swinging leg to realize a running of the robot.