← Paper Digest

RL and sim-to-real

Reinforcement learning in simulation and transfer to real robots.

Start here: seminal papers

End-to-End Training of Deep Visuomotor Policies★ Must read

Sergey Levine, Chelsea Finn, Trevor Darrell, Pieter Abbeel

April 2015

Train a 92,000-parameter CNN that maps raw camera images straight to PR2 motor torques, using guided policy search to turn policy learning into supervised learning. End-to-end training beats policies built on separately trained vision on all four real tasks, e.g. 88.9% vs 55.6% success at screwing on a bottle cap.

Embed to Control: A Locally Linear Latent Dynamics Model for Control from Raw ImagesSeminal

Manuel Watter, Jost Tobias Springenberg, Joschka Boedecker, Martin Riedmiller

June 2015

E2C trains a variational autoencoder whose latent dynamics are forced to be locally linear, so iLQR or AICO can plan directly on embeddings of raw images. It swings up a pendulum from 48x48 pixels in 90% of trials and balances a cart-pole and controls a three-link arm from images in 93% and 90%, where autoencoder baselines never succeed.

Continuous control with deep reinforcement learningSeminal

Timothy P. Lillicrap, Jonathan J. Hunt, Alexander Pritzel et al.

September 2015

DDPG adds DQN's replay buffer and target networks, plus batch normalization, to a deterministic actor-critic so it can learn continuous control. With one set of hyperparameters it solves more than 20 simulated physics tasks, often from raw pixels, nearly all within 2.5 million steps, and sometimes beats an iLQG planner that has the true dynamics.

Deep Reinforcement Learning for Robotic Manipulation with Asynchronous Off-Policy UpdatesSeminal

Shixiang Gu, Ethan Holly, Timothy Lillicrap, Sergey Levine

October 2016

Asynchronous NAF trains one deep Q-function from a replay buffer that several robots fill in parallel. Two 7-DoF arms learn to pull open a door from scratch, without demonstrations, in about 2.5 hours, and the final policy succeeds in 20 of 20 trials.

Deep Visual Foresight for Planning Robot MotionSeminal

Chelsea Finn, Sergey Levine

October 2016

Train an action-conditioned video prediction model on 50,000 unlabeled robot pushes, then push objects by choosing actions whose predicted pixel motion carries a user-chosen pixel to its goal. On objects not seen in training it ends 2.52 pixels from the goal on average, against 3.19 for the best calibrated servoing baseline.

CAD2RL: Real Single-Image Flight without a Single Real ImageSeminal

Fereshteh Sadeghi, Sergey Levine

November 2016

Train a quadrotor's collision-avoidance policy from single RGB images entirely in CAD hallways with randomized textures and lighting, then fly it in real buildings. In a realistic scanned hallway it flies 1.2 km without a collision in about 40% of runs, and in real flights it collides 6 times over 164 m versus 13 for a free-space-prediction baseline.

Domain Randomization for Transferring Deep Neural Networks from Simulation to the Real World★ Must read

Josh Tobin, Rachel Fong, Alex Ray et al.

March 2017

Train an object localizer only on simulated images with random non-realistic textures, lighting, camera poses and distractors. In the real world it localizes objects to about 1.5 cm and lets a Fetch robot pick targets out of clutter in 38 of 40 trials.

Safe Model-based Reinforcement Learning with Stability GuaranteesSeminal

Felix Berkenkamp, Matteo Turchetta, Angela P. Schoellig, Andreas Krause

May 2017

Model-based RL that improves a neural network policy using a Gaussian-process dynamics model and only collects data inside a region of attraction certified by a Lyapunov function. On a simulated inverted pendulum, the certified safe region grows from a small initial set over 50 data points and the pendulum never falls.

Deep reinforcement learning from human preferences★ Must read

Paul Christiano, Jan Leike, Tom B. Brown et al.

June 2017

A human picks the better of two short clips of the agent, a neural reward model is fit to those choices, and RL optimizes that learned reward. With 700 comparisons it nearly matches RL on the true reward across eight MuJoCo tasks, and it learns a Hopper backflip from 900 comparisons in under an hour.

Hindsight Experience ReplaySeminal

Marcin Andrychowicz, Filip Wolski, Alex Ray et al.

July 2017

Replay each failed episode as if its goal had been the state the agent actually reached, so sparse binary rewards still give a learning signal. On a simulated Fetch arm, DDPG with HER solves pushing, sliding and pick-and-place where plain DDPG solves none, and the pick-and-place policy succeeds 5/5 on the real robot.

Emergence of Locomotion Behaviours in Rich EnvironmentsSeminal

Nicolas Heess, Dhruva TB, Srinivasan Sriram et al.

July 2017

They train simulated walker, quadruped and humanoid bodies with a distributed PPO on procedurally generated obstacle courses, rewarding mostly forward velocity. Running, jumping, crouching and turning emerge without behaviour-specific reward shaping, and the Planar Walker learns to clear hurdles nearly as tall as its own body.

Proximal Policy Optimization Algorithms★ Must read

John Schulman, Filip Wolski, Prafulla Dhariwal et al.

July 2017

PPO replaces TRPO's constrained update with a clipped probability-ratio objective that can be optimized for several epochs of minibatch SGD on the same batch. With clipping at 0.2 it scores 0.82 (normalized) on 7 MuJoCo tasks, vs at most 0.74 for KL-penalty variants and -0.39 with no clipping.

Using Simulation and Domain Adaptation to Improve Efficiency of Deep Robotic GraspingSeminal

Konstantinos Bousmalis, Alex Irpan, Paul Wohlhart et al.

September 2017

Train a monocular-RGB grasp-success CNN on 8 million simulated grasps of random procedural shapes plus real data, with GraspGAN making the rendered images look real and a domain-adversarial loss aligning features. With 2% of the real data it matches the all-real model (68.51% vs 67.65%), and with no real labels it reaches 63.40%.

Learning Complex Dexterous Manipulation with Deep Reinforcement Learning and Demonstrations★ Must read

Aravind Rajeswaran, Vikash Kumar, Abhishek Gupta et al.

September 2017

Model-free RL learns four dexterous tasks on a simulated 24-DoF hand, and DAPG adds 25 VR demonstrations per task to policy gradient. With only a sparse success reward it reaches 90% success in 3-6 robot hours, against 16-98 hours for RL from scratch with shaped rewards.

Overcoming Exploration in Reinforcement Learning with DemonstrationsSeminal

Ashvin Nair, Bob McGrew, Marcin Andrychowicz et al.

September 2017

Add 100 VR demonstrations to DDPG with Hindsight Experience Replay through a critic-filtered behavior-cloning loss and resets to demonstration states. A simulated Fetch arm learns to stack 6 blocks (32% success), while behavior cloning and HER alone already get 0% on 4 blocks.

Sim-to-Real Transfer of Robotic Control with Dynamics RandomizationSeminal

Xue Bin Peng, Marcin Andrychowicz, Wojciech Zaremba, Pieter Abbeel

October 2017

Train a recurrent puck-pushing policy in MuJoCo with 95 dynamics parameters randomized each episode, then run it on a real Fetch arm with no real-world training. The LSTM policy succeeds 0.89 of the time on the real robot versus 0.91 in simulation.

Asymmetric Actor Critic for Image-Based Robot LearningSeminal

Lerrel Pinto, Marcin Andrychowicz, Peter Welinder et al.

October 2017

Train an image-based policy in simulation with a critic that sees the full simulator state while the actor sees only RGBD images. With domain randomization, the policy transfers to a real Fetch robot with no real-world training data and succeeds 5/5 on picking, pushing and block moving.

Soft Actor-Critic: Off-Policy Maximum Entropy Deep Reinforcement Learning with a Stochastic Actor★ Must read

Tuomas Haarnoja, Aurick Zhou, Pieter Abbeel, Sergey Levine

January 2018

Soft actor-critic (SAC) is an off-policy actor-critic that trains a stochastic policy to maximize reward plus entropy. On six continuous-control benchmarks it matches DDPG, PPO, SQL and TD3 on the easier tasks and beats them on the hardest, including the 21-action-dimension rllab Humanoid, where DDPG makes no progress.

Multi-Goal Reinforcement Learning: Challenging Robotics Environments and Request for ResearchSeminal

Matthias Plappert, Marcin Andrychowicz, Alex Ray et al.

February 2018

OpenAI adds 13 goal-conditioned, sparse-reward MuJoCo tasks to Gym for a Fetch arm and a Shadow Dexterous Hand, and benchmarks DDPG with and without Hindsight Experience Replay. DDPG+HER with sparse rewards does best, while plain DDPG often learns nothing on the hand tasks.

Addressing Function Approximation Error in Actor-Critic MethodsSeminal

Scott Fujimoto, Herke van Hoof, David Meger

February 2018

TD3 curbs value overestimation in DDPG with three changes, a target that takes the minimum of two critics, less frequent actor updates and noise on the target action. Across seven MuJoCo tasks it matches or beats DDPG, PPO, TRPO, ACKTR and SAC, and on Ant it reaches a return of 4372 where no baseline exceeds 1822.

Learning Synergies between Pushing and Grasping with Self-supervised Deep Reinforcement LearningSeminal

Andy Zeng, Shuran Song, Stefan Welker et al.

March 2018

VPG trains two fully convolutional Q-networks, one for pushing and one for grasping, by trial and error, so pushes are learned for how much they help later grasps. On challenging real-world block arrangements it reaches 83.3% grasp success versus 43.5% for a grasping-only policy, after about 5.5 hours of robot training.

World ModelsSeminal

David Ha, Jürgen Schmidhuber

March 2018

A VAE compresses each frame, an MDN-RNN predicts the next latent, and a linear controller with under 1,100 parameters is evolved on top. It scores 906 ± 21 on CarRacing-v0, and a VizDoom policy trained only inside the learned model survives 1092 ± 556 steps in the real game (750 counts as solved).

DeepMimic: Example-Guided Deep Reinforcement Learning of Physics-Based Character Skills★ Must read

Xue Bin Peng, Pieter Abbeel, Sergey Levine, Michiel van de Panne

April 2018

DeepMimic trains physically simulated characters with RL to imitate motion clips, rewarding closeness to the reference pose plus an optional task goal. One recipe learns 24 humanoid skills, from walking to backflips, and adding a task reward raises target-strike success from 19% (imitation only) to 99%.

Sim-to-Real: Learning Agile Locomotion For Quadruped RobotsSeminal

Jie Tan, Tingnan Zhang, Erwin Coumans et al.

April 2018

Trains Minitaur quadruped gaits with PPO in PyBullet and narrows the sim-to-real gap with a measured actuator model, simulated latency, randomization and a compact observation space. The learned gallop and trot run on the real robot without fine-tuning, as fast as expert-tuned gaits with 35% and 23% less power.

Deep Reinforcement Learning in a Handful of Trials using Probabilistic Dynamics ModelsSeminal

Kurtland Chua, Roberto Calandra, Rowan McAllister, Sergey Levine

May 2018

PETS models the dynamics with an ensemble of probabilistic neural networks and plans through it with sampled particle trajectories and MPC. It reaches model-free asymptotic performance on four MuJoCo tasks in under 100 trials, with 8x fewer samples than SAC and 125x fewer than PPO on half-cheetah.

QT-Opt: Scalable Deep Reinforcement Learning for Vision-Based Robotic Manipulation★ Must read

Dmitry Kalashnikov, Alex Irpan, Peter Pastor et al.

June 2018

Off-policy Q-learning on 580k real grasp attempts from 7 robots, choosing actions by optimizing the Q-function instead of training an actor. The closed-loop, RGB-only policy grasps 96% of unseen objects, against 78% for a prior self-supervised grasping method.

Learning Dexterous In-Hand Manipulation★ Must read

OpenAI, Marcin Andrychowicz, Bowen Baker et al.

August 2018

An LSTM policy trained with RL entirely in heavily randomized simulation reorients a block in a real Shadow Dexterous Hand, sensing the block with motion capture or three cameras. It reaches a median of 13 consecutive goal orientations on the real hand (11.5 with vision), versus 0 for the same policy trained without randomization.

Closing the Sim-to-Real Loop: Adapting Simulation Randomization with Real World ExperienceSeminal

Yevgen Chebotar, Ankur Handa, Viktor Makoviychuk et al.

October 2018

SimOpt alternates RL training in a GPU simulator with updates to the distribution of simulation parameters, so that simulated roll-outs of the policy match a few real-robot roll-outs. After two updates with 3 real roll-outs each, a Yumi swings a peg on a rope into a hole in 90% of 20 trials; after one update, a Panda opens a drawer in all 20 trials.

Dexterous Manipulation with Deep Reinforcement Learning: Efficient, General, and Low-CostSeminal

Henry Zhu, Abhishek Gupta, Aravind Rajeswaran et al.

October 2018

Train neural-network policies for low-cost 3- and 4-fingered hands with model-free RL directly on the real robot, with no simulator. Valve turning, box flipping and door opening are learned in 7.4, 4.1 and 15.6 hours, and 20 human demonstrations cut valve and box training to 3.0 and 1.5 hours.

Learning Latent Dynamics for Planning from PixelsSeminal

Danijar Hafner, Timothy Lillicrap, Ian Fischer et al.

November 2018

PlaNet learns a latent dynamics model from 64x64 images and picks every action by planning in that latent space, with no policy or value network. On six DeepMind control suite tasks it comes close to D4PG's final scores, and beats D4PG by 26% on cheetah, while using 1,000 episodes instead of 100,000.

Residual Reinforcement Learning for Robot ControlSeminal

Tobias Johannink, Shikhar Bahl, Ashvin Nair et al.

December 2018

Add an RL policy on top of a hand-engineered feedback controller and train only that residual, directly on a real Sawyer arm. When the blocks in an insertion task are randomly tilted, residual RL succeeds in 15/20 trials versus 2/20 for the hand-engineered controller, after about three hours of real-world training.

Learning to Walk via Deep Reinforcement LearningSeminal

Tuomas Haarnoja, Sehoon Ha, Aurick Zhou et al.

December 2018

Soft actor-critic with its temperature tuned automatically toward a target entropy, used to teach a Minitaur quadruped to walk from scratch on the real robot. A gait emerges in about two hours (about 400 rollouts) and handles a slope, wooden blocks and steps it never trained on.

Learning agile and dynamic motor skills for legged robots★ Must read

Jemin Hwangbo, Joonho Lee, Alexey Dosovitskiy et al.

January 2019

Train ANYmal's controllers with RL in a simulator that uses a neural network, fitted to real robot data, to model the robot's series-elastic actuators, then deploy the policies directly on the robot. The learned locomotion policy tracks commands more accurately and with less torque than the best model-based controller, reaches 1.5 m/s (25% above the previous record), and gets the robot up after a fall.

Variable Impedance Control in End-Effector Space: An Action Space for Reinforcement Learning in Contact-Rich TasksSeminal

Roberto Martín-Martín, Michelle A. Lee, Rachel Gardner et al.

June 2019

An RL policy outputs both end-effector pose targets and the stiffness of an impedance controller (VICES), compared against joint-space and fixed-impedance action spaces on path following, door opening and wiping. VICES earns the highest wiping reward at a 28 N mean force, transfers from a simulated Panda to a Sawyer, and wipes a real whiteboard in 8 of 10 trials.

Deep Dynamics Models for Learning Dexterous ManipulationSeminal

Anusha Nagabandi, Kurt Konoglie, Sergey Levine, Vikash Kumar

September 2019

PDDM learns an ensemble of neural-network dynamics models and plans through them with a smoothed, reward-weighted MPC optimizer. On a real 24-DoF Shadow Hand it learns to rotate two Baoding balls from 4 hours of purely real-world data, with about 100% success on 90° turns.

RLBench: The Robot Learning Benchmark & Learning EnvironmentSeminal

Stephen James, Zicong Ma, David Rovick Arrojo, Andrew J. Davison

September 2019

RLBench is a simulated benchmark of 100 hand-designed manipulation tasks for a Franka Panda, each with unlimited motion-planned demonstrations and text descriptions. The paper proposes a few-shot challenge on 10 held-out tasks but reports no baseline results.

Solving Rubik's Cube with a Robot HandSeminal

OpenAI, Ilge Akkaya, Marcin Andrychowicz et al.

October 2019

A Shadow Hand policy and a vision state estimator are trained only in simulation with automatic domain randomization (ADR), which keeps widening the randomization ranges as the model improves. On the real hand the best policy completes a 43-move fair scramble in 20% of trials and half of it in 60%.

Meta-World: A Benchmark and Evaluation for Multi-Task and Meta Reinforcement LearningSeminal

Tianhe Yu, Deirdre Quillen, Zhanpeng He et al.

October 2019

Meta-World is an open-source MuJoCo benchmark of 50 distinct Sawyer manipulation tasks with randomized object and goal positions, built to test multi-task and meta-RL on broad task distributions. Seven existing algorithms struggle on it; the best multi-task method reaches 68.3% success on 10 tasks and 38.5% on 50, and no meta-RL method solves more than 39.9% of held-out tasks.

Dream to Control: Learning Behaviors by Latent ImaginationSeminal

Danijar Hafner, Timothy Lillicrap, Jimmy Ba, Mohammad Norouzi

December 2019

Dreamer learns a latent world model from pixels and trains an actor and a value model purely on imagined rollouts, backpropagating value gradients through the learned dynamics. On 20 DeepMind Control tasks it averages 823 after 5 million steps, above D4PG's 786 after 100 million.

robosuite: A Modular Simulation Framework and Benchmark for Robot LearningSeminal

Yuke Zhu, Josiah Wong, Ajay Mandlekar et al.

September 2020

A modular MuJoCo framework that builds robot-learning tasks from interchangeable robots, grippers, controllers and objects, with nine standardized manipulation benchmarks. Soft Actor-Critic baselines solve three of the nine tasks and learn faster with operational-space control than with joint-velocity control.

Generation of GelSight Tactile Images for Sim2Real LearningSeminal

Daniel Fernandes Gomes, Paolo Paoletti, Shan Luo

January 2021

They simulate a GelSight optical tactile sensor in Gazebo by turning a depth-camera image into a smoothed elastomer heightmap and shading it with Phong's model. A classifier trained only on generated images, with texture augmentation, recognises 21 real objects with 76.19% test accuracy.

Sim-to-Real for Robotic Tactile Sensing via Physics-Based Simulation and Learned Latent ProjectionsSeminal

Yashraj Narang, Balakumar Sundaralingam, Miles Macklin et al.

March 2021

A finite-element model of the BioTac fingertip in GPU-based Isaac Gym matches a validated ANSYS model at 75x the speed. Small networks that project between learned latent spaces of simulated skin deformation and real electrode signals then predict real BioTac output for unseen objects and recover contact patches from real signals.

Tactile-RL for Insertion: Generalization to Objects of Unknown GeometrySeminal

Siyuan Dong, Devesh K. Jha, Diego Romeres et al.

April 2021

An RL policy learns on a real robot to correct peg-in-hole misalignment from two GelSlim tactile sensors, using a curriculum of increasingly constrained environments and marker-flow input. Trained on 4 objects, it inserts 4 unseen everyday objects with over 85% average success.

AMP: Adversarial Motion Priors for Stylized Physics-Based Character Control★ Must read

Xue Bin Peng, Ze Ma, Pieter Abbeel et al.

April 2021

AMP replaces hand-designed motion-tracking rewards with a discriminator trained on unstructured mocap clips, whose score is added as a style reward to a simple task reward in RL. With a 56-clip locomotion dataset, a simulated humanoid picks walking, jogging or running gaits on its own and reaches 0.90 normalized return on target heading, versus 0.46 and 0.63 with walk-only or run-only data.

Blind Bipedal Stair Traversal via Sim-to-Real Reinforcement LearningSeminal

Jonah Siekmann, Kevin Green, John Warila et al.

May 2021

An LSTM policy trained with PPO in simulation on randomized staircases lets the Cassie biped climb and descend real stairs blind, using only proprioception and the existing flat-ground reward. On an outdoor staircase it succeeded in 8 of 10 ascents and 10 of 10 descents.

Tactile Sim-to-Real Policy Transfer via Real-to-Sim Image TranslationSeminal

Alex Church, John Lloyd, Raia Hadsell, Nathan F. Lepora

June 2021

Train tactile RL policies in PyBullet on simulated depth images of a TacTip sensor, then run them on a real robot by translating real tactile images into simulated ones with a pix2pix GAN. Zero-shot transfer works on 4 of 5 tasks, including 100 consecutive successful ball-rolling trials.

Habitat 2.0: Training Home Assistants to Rearrange their HabitatSeminal

Andrew Szot, Alex Clegg, Eric Undersander et al.

June 2021

Habitat 2.0 is a physics-enabled home simulator with an interactive apartment dataset (ReplicaCAD) and a rearrangement benchmark for a Fetch robot, running at 25,734 steps per second on one 8-GPU node (850x real-time). On its tasks, flat RL fails at long-horizon rearrangement, a hierarchy of RL skills does better, and sense-plan-act is more brittle.

RMA: Rapid Motor Adaptation for Legged Robots★ Must read

Ashish Kumar, Zipeng Fu, Deepak Pathak, Jitendra Malik

July 2021

RMA trains a quadruped walking policy and an online adaptation module entirely in simulation; the module infers a latent environment code from the last 0.5 s of joint states and actions, so a Unitree A1 adapts in fractions of a second with no real-world fine-tuning. It carries 12 kg, its own body weight, and reaches 73.5% success in simulation versus 62.4% for domain randomization.

Isaac Gym: High Performance GPU-Based Physics Simulation For Robot LearningSeminal

Viktor Makoviychuk, Lukasz Wawrzyniak, Yunrong Guo et al.

August 2021

Isaac Gym keeps the whole RL loop on one GPU, with physics, observations, rewards and PPO training all on the device, and simulator state exposed as PyTorch tensors that never pass through the CPU. On a single A100 it trains Shadow Hand cube reorientation to 20 consecutive successes in under 1 hour; OpenAI needed 30 hours on 6144 CPU cores plus 8 V100 GPUs.

Learning to Walk in Minutes Using Massively Parallel Deep Reinforcement Learning★ Must read

Nikita Rudin, David Hoeller, Philipp Reist, Marco Hutter

September 2021

Run simulation and PPO training for thousands of quadrupeds in parallel on a single GPU, with a game-inspired terrain curriculum. A rough-terrain ANYmal policy trains in under 20 minutes (flat terrain in under 4) and transfers to the real robot.

A System for General In-Hand Object Re-Orientation★ Must read

Tao Chen, Jie Xu, Pulkit Agrawal

November 2021

Model-free RL with teacher-student distillation trains a simulated Shadow Hand to reorient objects to any 3D orientation, palm up or palm down, without knowing their shape. On more than 2000 EGAD objects it succeeds 96% of the time palm up and over 80% palm down in mid-air.

Concurrent Training of a Control Policy and a State Estimator for Dynamic and Robust Legged LocomotionSeminal

Gwanghyeon Ji, Juhyeok Mun, Hyeongjun Kim, Jemin Hwangbo

February 2022

Train a quadruped's locomotion policy and a neural state estimator together in one PPO loop, with the estimator supplying base velocity, foot height and contact probability to the policy. On a real Mini Cheetah it runs at up to 3.75 m/s on flat ground and 3.54 m/s on a slippery plate with friction 0.22.

Rapid Locomotion via Reinforcement LearningSeminal

Gabriel B. Margolis, Ge Yang, Kartik Paigwar et al.

May 2022

One RL policy trained in simulation, with an adaptive curriculum over velocity commands and teacher-student online system identification, runs the MIT Mini Cheetah at up to 3.9 m/s and spins it at 5.7 rad/s, deployed zero-shot.

MyoSuite -- A contact-rich simulation suite for musculoskeletal motor controlSeminal

Vittorio Caggiano, Huawei Wang, Guillaume Durandau et al.

May 2022

MyoSuite converts validated OpenSim models of the finger, elbow and hand into MuJoCo and builds 204 contact-rich RL tasks on them, from posing to key turning, pen twirling and Baoding balls, with sarcopenia, fatigue, tendon-transfer and exoskeleton variants. The converted models match OpenSim muscle forces within 4.1% RMS error while simulating 60x to 4000x faster.

Towards Human-Level Bimanual Dexterous Manipulation with Reinforcement LearningSeminal

Yuanpei Chen, Tianhao Wu, Shengjie Wang et al.

June 2022

Bi-DexHands is an Isaac Gym benchmark of 20 two-Shadow-Hand tasks matched to the ages at which children learn them, running at 30,000+ FPS on one RTX 3090. PPO solves most single tasks, but multi-task PPO averages 8.9 reward over all 20 tasks against 32.5 for per-task PPO, and meta RL barely beats a random policy.

DayDreamer: World Models for Physical Robot LearningSeminal

Philipp Wu, Alejandro Escontrela, Danijar Hafner et al.

June 2022

Runs the Dreamer world-model RL algorithm online on four real robots, with no simulator and one set of hyperparameters. A Unitree A1 learns to roll over, stand up and walk in about 1 hour, and two arms learn visual pick-and-place from sparse rewards at close to human pick rates.

In-Hand Object Rotation via Rapid Motor Adaptation★ Must read

Haozhi Qi, Ashish Kumar, Roberto Calandra et al.

October 2022

Train a fingertip-only object-rotation policy in simulation on cylinders, plus a module that infers object properties from 1.5 s of joint history. Deployed without fine-tuning on an Allegro hand, it rotates over 30 real objects of 4.5-7.5 cm and 5-200 g, averaging 23.96 rad per 30 s on heavy objects.

DeXtreme: Transfer of Agile In-hand Manipulation from Simulation to RealitySeminal

Ankur Handa, Arthur Allshire, Viktor Makoviychuk et al.

October 2022

Train an in-hand cube reorientation policy for a low-cost Allegro Hand entirely in Isaac Gym with automatic domain randomisation, and feed it cube poses from a vision model trained only on synthetic images. Over 10 real trials the best policy averages 27.8 consecutive successes (best run 112), using three RGB cameras and no markers.

Visual Dexterity: In-Hand Reorientation of Novel and Complex Object ShapesSeminal

Tao Chen, Megha Tippur, Siyang Wu et al.

November 2022

One RL policy trained in simulation uses a single depth camera to reorient new, complex objects to any orientation with a downward-facing, low-cost open-source hand, median time under 7 s. On a table, 55% of trials on unseen shapes end within 0.4 rad; in the air, an unseen duck is dropped 56% of the time.

Walk These Ways: Tuning Robot Control for Generalization with Multiplicity of BehaviorSeminal

Gabriel B. Margolis, Pulkit Agrawal

December 2022

Train one quadruped policy on flat ground only that can walk in many styles (gait, step frequency, body height and pitch, stance width, footswing height), so a human operator can retune it on the spot for stairs, curbs, a 22 cm bar or shoves instead of retraining. On unseen simulated platform terrain, trotting survives 0.88 of the episode vs 0.83 for a gait-free baseline.

Orbit: A Unified Simulation Framework for Interactive Robot Learning EnvironmentsSeminal

Mayank Mittal, Calvin Yu, Qinxi Yu et al.

January 2023

An open-source framework on NVIDIA Isaac Sim for building robot learning environments with GPU-parallel rigid and deformable physics and photo-realistic rendering. It ships with 16 robots, 10 motion generators and over 20 tasks, and simulates about 10x faster than CPU-based frameworks on rigid-body tasks and 3x faster on cloth.

Learning Agile Soccer Skills for a Bipedal Robot with Deep Reinforcement LearningSeminal

Tuomas Haarnoja, Ben Moran, Guy Lever et al.

April 2023

A 20-joint Robotis OP3 miniature humanoid learns 1v1 soccer with deep RL in simulation and plays on real robots zero-shot. Compared with the robot's scripted controllers it walks 181% faster, turns 302% faster, gets up in 63% less time and kicks 34% faster.

Eureka: Human-Level Reward Design via Coding Large Language ModelsSeminal

Yecheng Jason Ma, William Liang, Guanzhi Wang et al.

October 2023

GPT-4 writes RL reward functions as code from the environment's source, then rewrites them over several rounds using training statistics as feedback. Across 29 IsaacGym tasks the rewards beat expert human rewards on 83% of tasks, and with a curriculum they teach a simulated Shadow Hand to spin a pen.

Reinforcement Learning for Versatile, Dynamic, and Robust Bipedal Locomotion ControlSeminal

Zhongyu Li, Xue Bin Peng, Pieter Abbeel et al.

January 2024

One RL recipe trains walking, running and jumping controllers for the Cassie biped, using a policy that reads both a 2-second and a 4-step history of the robot's inputs and outputs, trained across many commanded tasks. Transferred zero-shot, Cassie ran 400 m in 2 min 34 s, 100 m in 27.06 s, and jumped 1.4 m forward and onto a 0.44 m platform.

Reconciling Reality through Simulation: A Real-to-Sim-to-Real Approach for Robust ManipulationSeminal

Marcel Torne, Anthony Simeonov, Zechu Li et al.

March 2024

RialTo scans a real scene into an articulated simulation, carries about 15 real demos into it, fine-tunes the imitation policy there with sparse-reward RL, and distills it back to a point-cloud policy. On real tasks it averages 91%, 77% and 75% success under pose randomization, distractors and disturbances, against 25%, 11% and 5% for imitation learning.

TacSL: A Library for Visuotactile Sensor Simulation and LearningSeminal

Iretiayo Akinola, Jie Xu, Jan Carius et al.

August 2024

TacSL simulates GelSight tactile images and contact force fields on the GPU inside Isaac Simulator, over 200x faster than prior tactile simulators, and adds a policy-learning toolkit with a new RL method (AACD). Tactile policies trained in simulation transfer zero-shot to a real robot, succeeding 91.4% of the time on peg placement and 82.7% on peg insertion.

SplatSim: Zero-Shot Sim2Real Transfer of RGB Manipulation Policies Using Gaussian SplattingSeminal

Mohammad Nomaan Qureshi, Sparsh Garg, Francisco Yandun et al.

September 2024

SplatSim swaps a simulator's mesh renderer for a Gaussian Splat of the real scene, moving each robot link and object's Gaussians to follow the PyBullet state. RGB diffusion policies trained only on these renderings transfer zero-shot to a real UR5 with 86.25% average success over four tasks, against 97.5% for policies trained on real data.

Precise and Dexterous Robotic Manipulation via Human-in-the-Loop Reinforcement LearningSeminal

Jianlan Luo, Charles Xu, Jeffrey Wu, Sergey Levine

October 2024

HIL-SERL trains vision-based manipulation policies with RL directly on real robots, starting from 20-30 demonstrations and taking corrections from a human with a SpaceMouse during training. It reaches 100% success on all 13 tasks, against 49.7% for an HG-DAgger baseline given the same human data, with 1.8x faster cycle times.

ASAP: Aligning Simulation and Real-World Physics for Learning Agile Humanoid Whole-Body SkillsSeminal

Tairan He, Jiawei Gao, Wenli Xiao et al.

February 2025

ASAP learns a residual "delta action" model from real humanoid rollouts so the simulator reproduces real dynamics, then fine-tunes motion-tracking policies inside it. On a Unitree G1 this cuts global tracking error from 61.2 to 50.2 mm on a kick and from 159 to 112 mm on an unseen motion.

Recent

TactileLab: Sim-to-Real Dexterous Robot Manipulation with Efficient Shear-Sensitive Tactile Simulation

Yijiong Lin, Wenhao He, Toby Jack et al.

November 2026

TactileLab adds simulated tactile flow, a dense shear field computed from rigid-body contact motion in IsaacLab, so RL policies can feel tangential contact at scale. Trained only in simulation, a LEAP Hand policy using contact depth plus flow makes 1.95 real in-hand rotations in 30 s, against 0.82 with proprioception alone.

Semantics-to-Contact: A Stagewise Framework for Robust Contact-Rich Manipulation

Guanren Qiao, Ruixiang Ouyang, Sheng Xu et al.

November 2026

S2C uses a vision-language model to bring the robot near the contact point, then learns the final force-aware insertion with human-in-the-loop residual RL on the real robot, trained on wrist images with randomized backgrounds. Under new tablecloths and lighting it averages 69-84% success on six tasks, while HIL-SERL and HIL-ConRFT mostly fail.

Perceptive Humanoid Motion from Simulation

Siyuan Hu, Abulikemu Abuduweili, Yue Meng et al.

November 2026

HALO trains a Unitree G1 humanoid only on synthetic vision-language-motion data rendered in 1,000 procedurally generated rooms. Zero-shot, it sits, crouches, crawls, sidesteps through doors and pushes boxes in six unseen real homes, succeeding in 91% of 360 trials.

Reinforcement Learning Enables Scaling Generalist Robot Policy Improvement

Michal Korniak, Marco Bagatella, Ralf Römer et al.

November 2026

They post-train the pi0.5 VLA online with RL on up to 144 simulated pick tasks at once and test on held-out scenes and objects. With critic-based recipes the gains grow with the number of training tasks, up to +58 points on unseen scenes and +39 on unseen objects, while filtered fine-tuning generalizes much less.

Playing Soccer Like Humans Do: Learning Versatile and Agile Humanoid Soccer via Latent Motion Priors

Haoyu Shao, Yunshen Wang, Jingze Zhang et al.

November 2026

SoccerBot trains one skill-conditioned RL policy that moves, dribbles, traps and kicks a ball on a Unitree G1, acting as a residual on a latent motion prior distilled from human soccer motion capture. In simulation it kicks successfully 97.0% of the time and dribbles 89.9%, and it transfers zero-shot to the real robot with motion-capture ball tracking.

TwinBridge: Digital Twin-Driven Policy and Reward Transfer for Real-World Reinforcement Learning in Laboratory Robotics

Shu'ang Sun, Yibo Qiu, Haoliang Ye et al.

November 2026

TwinBridge builds Gaussian-splatting digital twins of lab benches, pretrains a policy in them, and distills simulator-derived progress labels into a visual reward model for human-in-the-loop RL on the real robot. Across five lab tasks it reaches 98% mean autonomous success with at most 25 minutes of real-world interaction per task.

GSBR: Geometric Support Behavior Regularization for Online RL

Charles Xu, Jacob Berg, Liyiming Ke, Sergey Levine

November 2026

GSBR fine-tunes a frozen imitation-learned base policy with online RL, penalizing actions only by how far they fall outside the base policy's estimated support. Across 19 simulated tasks on four benchmarks it raises average success from 33% for the base policy to 95%, with about 23% higher normalized throughput than the next-best RL method.

DexHOT: Learning Hand-Object Configuration Transfer for Dexterous Manipulation

Zhewei Gui, Anthony Bolton, Jiyao Zhang et al.

November 2026

One RL policy for a 22-DoF hand learns to move between grasps that fix both the finger joints and the object's pose in the hand, then chains these short moves into longer tasks. It succeeds on 61.5% of 200 real-robot transfers and 27 of 30 demonstration-guided task trials.

HLO-AMP: Hierarchical Loco-Manipulation from Object-Aware Motion Priors

Jean-Pierre Sleiman, Bilal Hammoud, He Li et al.

November 2026

A Unitree G1 learns bimanual box pick-and-place from a low-level controller trained to imitate human motion capture with the box in the simulation, steered by a high-level RL policy. One deployed policy carries boxes up to 7 kg and recovers from drops. In simulation it succeeds 80.7% of the time, vs 50.3% for a whole-body controller trained without the object.

Play2Perfect: What Matters in Dexterous Play Pretraining for Precise Assembly?

Tyler Ga Wei Lum, Kushal Kedia, C. Karen Liu, Jeannette Bohg

June 2026

Pretrain one dexterous-hand RL policy by playing with a thousand random objects in simulation, then finetune it on sparse-reward assembly. Play2Perfect learns 33x faster than RL from scratch and transfers zero-shot to 0.5 mm insertions on a real robot.

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