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Anh Duc Tran

Robot learning · 2025

Reinforcement Learning for Quadruped Walking

Training a four-legged robot to walk smoothly across different terrain in simulation, then deploying the learned controller on a real Unitree Go1.

Reinforcement learning · Isaac Lab · Locomotion · Sim-to-real

UMass course project

Stable walking on rough terrain (blind policy).

The project

Goal
Build a stable walking controller that works across different terrain and can transfer to a real robot.
Approach
Train policies in simulation across varied terrain, using rewards that encourage smoother, symmetric walking.
Outcome
Stable walking on flat and rough terrain, followed by deployment on a Unitree Go1.
Flat terrain without depth camera

Flat terrain

Baseline walking without depth sensing.

Rough terrain with depth camera

Rough terrain

Harder surfaces where gait quality and balance matter more.

Flat terrain with depth camera

Depth perception

Depth observations give information about upcoming terrain that a blind policy cannot see.

Teaching the robot to walk

The controller is learned with reinforcement learning in Isaac Lab. Many parallel simulated robots train at once on GPU. Rewards push for velocity tracking, a steady body height, and smooth actuation so the robot does not default to bouncing or “pronking.”

Why terrain matters

Training only on flat ground often produces irregular jumping gaits. Adding structured terrain during training encourages more natural, symmetric walking.

Without terrain shaping

Irregular jumping / less stable gait.

With terrain shaping

More symmetric, steadier walking.

From simulation to the Go1

After training in simulation, the policy was transferred to a physical Unitree Go1 Edu.

Simulation

Real robot — Unitree Go1

Technical details

Training used diverse terrains (flat, rough, rails, waves). Reward design emphasized velocity tracking, base height, and smooth actuation. Depth-camera trials explored stairs and obstacle navigation on top of the blind policy.

Paper (PDF)