Quadruped Gait Control Using Position-Increment Reinforcement Learning

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Solution Overview

Problem

Existing methods for controlling quadruped robot motions face challenges such as sudden changes in control commands, difficulty in designing reward functions, and limited environmental adaptability, which can lead to motor damage and inefficient gait performance.

Innovation Solution

A method and system that utilize reinforcement learning combined with position increment to control quadruped robot motions, constraining foot sole position changes within each time step to avoid sudden control command changes, and using a preset reward function to guide stable and smooth gait performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If reinforcement learning directly outputs motor position commands, then the quadruped robot can adapt to complex environments, but the motor position changes suddenly causing physical damage to the motor

Engineering Contradiction:
Improveenvironmental adaptabilityVSAvoidmotor safety
Core Design Contradiction:
Adaptability or versatilityVSReliability

Solution Approach 1:

The patent introduces an intermediary mechanism (constraint reward function) between the reinforcement learning output and the motor execution. This intermediary constrains the motor position changes to be within a safe range, preventing sudden large movements that would damage the motor while still allowing the robot to adapt to complex environments through reinforcement learning.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent changes the parameter representation from direct motor position to motor position increment. By outputting the change amount rather than the absolute position, the reinforcement learning system can control the magnitude of movements, ensuring they remain within safe limits while maintaining environmental adaptability.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If constraint reward function of motor torque or velocity is introduced, then motor damage is prevented, but the difficulty of designing reward function and adjusting parameters increases greatly

Engineering Contradiction:
Improvemotor safetyVSAvoidreward function design complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent simplifies the reward function design by changing from constraining motor torque or velocity to constraining motor position increment. This parameter transformation makes the constraint more direct and easier to design, as it directly limits the movement amount without requiring complex torque or velocity models.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentUS12326738B2Method for controlling motions of quadruped robot based on reinforcement learning and position increment
Publication Date: 2025.06.10 SHANDONG UNIV
  • US12326738B2 patent drawing
  • US12326738B2 patent drawing
  • US12326738B2 patent drawing

AI summary

A method for controlling motions of a quadruped robot based on reinforcement learning and position increment, including: acquiring motion environment information, quadruped robot attitude information, and foot sole position information; based on the acquired information, generating foot sole positions of the quadruped robot during motions within all preset time steps, and calculating a change of the foot sole positions in all the time steps; taking a maximum moving distance within a single time step as a constraint, and accumulating the time steps at the same time to obtain a foot sole position trajectory; and controlling the quadruped robot to perform corresponding actions based on the foot sole position track combined with a preset reward function, so as to keep motion balance of the quadruped robot.