An Advanced Reinforcement Learning Control Method for Quadruped Robots in Typical Urban Terrains

Chi Yan1             Hongbo Gao1,2,3*             Xinmiao Wang1             Chao Tang1
Lin Zhou1             Yuehua Li4             Yue Wang5             Ning Wang6

College of Information Science and Technology, University of Science and Technology of China1
Institute of Advanced Technology, University of Science and Technology of China2
School of Electrical and Electronic Engineering, Nanyang Technological University3*
Zhejiang Lab4
College of Control Science and Engineering, Zhejiang University5
School of Information and Security, Chongqing College of Mobile Communication6

Abstract

Quadruped robots, with their exceptional flexibility and stable structure, are highly suitable for traversing the complex unstructured terrains in urban environments. However, the current flexibility and stability of quadruped robots based on reinforcement learning are still not ideal in these terrains. To address this limitation, a large-scale parallel technology-based end-to-end teacher-student learning network framework is proposed, where the Gated Recurrent Unit achieves a potential estimation of the heights surrounding the robot. Meanwhile, by introducing an omnidirectional terrain learning curriculum, the robot can move in any commanded direction, achieving smooth output and tracking of motor joint angles. By utilizing state machines, the model trained from the simulation is deployed in the Unitree Go1 robot via zero-shot learning. Simulation and real-world experiments have demonstrated that this approach significantly enhances the robot's adaptability and mobility across various urban terrains such as gravel, grass, slopes, and steps.

Unitree Go1 trotting

Smooth Floor

Slate Floor

Soft Cushion

Grassland

10° Scree Slope

30° Grassy Slope

Cobblestone Floor

16cm Steps

30° Grassy Slope

move forward and include the measurement process

30° Grassy Slope

move sideways

30° Grassy Slope

move backward

15cm Steps

move forward and include the measurement process

15cm Steps

move sideways

15cm Steps

move backward

23cm Obstacle

move forward and include the measurement process

23cm Obstacle

move sideways

23cm Obstacle

move backward

16cm Obstacle

move forward

16cm Obstacle

move backward and include the measurement process

40° Slope in Isaac Gym

move forward

40° Slope in Isaac Gym

move sideways

40° Slope in Isaac Gym

move backward