RL, Sim-to-Real & Locomotion

Reinforcement learning (RL) is trial-and-error training of a robot controller, usually in simulation before transfer to hardware. In 2021 an ANYmal quadruped learned to walk on flat ground in under four minutes on one GPU Rudin et al. 2021.

Domain overview: 8 articles. Basics first, then locomotion and the methods behind it.

Related: RL Fine-Tuning of Policies, Model-Based Robot Learning, Control. Further reading: Evolution of Humanoid Locomotion Control (Gu et al. 2026)

  1. RL for Robotics

    Sample efficiency decides which RL algorithm a robot can use.

  2. Why RL Won Locomotion but Not Manipulation

    Walking is cheap to simulate; contact-rich manipulation is not.

  3. Massively Parallel Sim RL

    GPU-parallel simulation with Isaac Lab, Newton, MJX and Brax.

  4. Sim-to-Real Transfer

    Domain randomization, distillation, system identification and real-to-sim reconstruction.

  5. Legged Locomotion Lineage

    How learned gaits became the default for legged robots.

  6. Humanoid Whole-Body Control

    How humanoids track retargeted human motion.

  7. Reward Design and the MPC Debate

    Hand-tuned and language-model rewards, and the MPC debate.

  8. Offline Reinforcement Learning for Robotics

    CQL and TD3+BC, and when behavior cloning is the stronger baseline.