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OmniSafe's Safety-Gymnasium Benchmark for On-Policy Algorithms

The OmniSafe Safety-Gymnasium Benchmark for on-policy algorithms evaluates the effectiveness of OmniSafe's on-policy algorithms across multiple environments from the Safety-Gymnasium task suite. For each supported algorithm and environment, we offer the following:

  • Default hyperparameters used for the benchmark and scripts that enable result replication.
  • Performance comparison with other open-source implementations.
  • Graphs and raw data that can be utilized for research purposes.
  • Detailed logs obtained during training.
  • Suggestions and hints on fine-tuning the algorithm for achieving optimal results.

Supported algorithms are listed below:

First-Order

Second-Order

Saute RL

Simmer

PID-Lagrangian

Early Terminated MDP

Safety-Gymnasium

We highly recommend using Safety-Gymnasium to run the following experiments. To install, in a linux machine, type:

pip install safety_gymnasium

Run the Benchmark

You can set the main function of examples/benchmarks/experiment_grid.py as:

if __name__ == '__main__':
    eg = ExperimentGrid(exp_name='On-Policy-Benchmarks')

    # set up the algorithms.
    base_policy = ['PolicyGradient', 'NaturalPG', 'TRPO', 'PPO']
    naive_lagrange_policy = ['PPOLag', 'TRPOLag', 'RCPO']
    first_order_policy = ['CUP', 'FOCOPS', 'P3O']
    second_order_policy = ['CPO', 'PCPO']
    saute_policy = ['PPOSaute', 'TRPOSaute']
    simmer_policy = ['PPOSimmerPID', 'TRPOSimmerPID']
    pid_policy = ['CPPOPID', 'TRPOPID']
    early_mdp_policy = ['PPOEarlyTerminated', 'TRPOEarlyTerminated']

    eg.add(
        'algo',
        base_policy +
        naive_lagrange_policy +
        first_order_policy +
        second_order_policy +
        saute_policy +
        simmer_policy +
        pid_policy +
        early_mdp_policy
    )

    # you can use wandb to monitor the experiment.
    eg.add('logger_cfgs:use_wandb', [False])
    # you can use tensorboard to monitor the experiment.
    eg.add('logger_cfgs:use_tensorboard', [True])

    # the default configs here are as follows:
    # eg.add('algo_cfgs:steps_per_epoch', [20000])
    # eg.add('train_cfgs:total_steps', [20000 * 500])
    # which can reproduce results of 1e7 steps.

    # if you want to reproduce results of 1e6 steps, using
    # eg.add('algo_cfgs:steps_per_epoch', [2048])
    # eg.add('train_cfgs:total_steps', [2048 * 500])

    # set the device.
    avaliable_gpus = list(range(torch.cuda.device_count()))
    # if you want to use GPU, please set gpu_id like follows:
    # gpu_id = [0, 1, 2, 3]
    # if you want to use CPU, please set gpu_id = None
    # we recommends using CPU to obtain results as consistent
    # as possible with our publicly available results,
    # since the performance of all on-policy algorithms
    # in OmniSafe is tested on CPU.
    gpu_id = None

    if gpu_id and not set(gpu_id).issubset(avaliable_gpus):
        warnings.warn('The GPU ID is not available, use CPU instead.', stacklevel=1)
        gpu_id = None

    # set up the environment.
    eg.add('env_id', [
        'SafetyHopperVelocity-v1',
        'SafetyWalker2dVelocity-v1',
        'SafetySwimmerVelocity-v1',
        'SafetyAntVelocity-v1',
        'SafetyHalfCheetahVelocity-v1',
        'SafetyHumanoidVelocity-v1'
        ])
    eg.add('seed', [0, 5, 10, 15, 20])

    # total experiment num must can be divided by num_pool.
    # meanwhile, users should decide this value according to their machine.
    eg.run(train, num_pool=5, gpu_id=gpu_id)

After that, you can run the following command to run the benchmark:

cd examples/benchmarks
python run_experiment_grid.py

You can also plot the results by running the following command:

cd examples
python analyze_experiment_results.py

For a detailed usage of OmniSafe statistics tool, please refer to this tutorial.

Logs is saved in examples/benchmarks/exp-x and can be monitored with tensorboard or wandb.

tensorboard --logdir examples/benchmarks/exp-x

After the experiment is finished, you can use the following command to generate the video of the trained agent:

cd examples
python evaluate_saved_policy.py

Please note that before you evaluate, set the LOG_DIR in evaluate_saved_policy.py.

For example, if I train PPOLag in SafetyHumanoidVelocity-v1

LOG_DIR = '~/omnisafe/examples/runs/PPOLag-<SafetyHumanoidVelocity-v1>/seed-000'
play = True
save_replay = True
if __name__ == '__main__':
    evaluator = omnisafe.Evaluator(play=play, save_replay=save_replay)
    for item in os.scandir(os.path.join(LOG_DIR, 'torch_save')):
        if item.is_file() and item.name.split('.')[-1] == 'pt':
            evaluator.load_saved(
                save_dir=LOG_DIR, model_name=item.name, camera_name='track', width=256, height=256
            )
            evaluator.render(num_episodes=1)
            evaluator.evaluate(num_episodes=1)

OmniSafe Benchmark

Classic Reinforcement Learning Algorithms

To ascertain the credibility of OmniSafe ’s algorithmic implementation, a comparative assessment was conducted, juxtaposing the performance of classical reinforcement learning algorithms. Such as Policy Gradient, Natural Policy Gradient, TRPO and PPO. The performance table is provided in Table 1. with well-established open-source implementations, specifically Tianshou and Stable-Baselines3.

Table 1:The performance of OmniSafe, which was evaluated in relation to published baselines within the Safety-Gymnasium MuJoCo Velocity environments. Experimental outcomes, comprising mean and standard deviation, were derived from 10 assessment iterations encompassing multiple random seeds. A noteworthy distinction lies in the fact that Stable-Baselines3 employs distinct parameters tailored to each environment, while OmniSafe maintains a consistent parameter set across all environments.

Policy Gradient PPO
Environment OmniSafe (Ours) Tianshou Stable-Baselines3 OmniSafe (Ours) Tianshou Stable-Baselines3
SafetyAntVelocity-v1 2769.45 ± 550.71 145.33 ± 127.55 - ± - 4295.96 ± 658.2 2607.48 ± 1415.78 1780.61 ± 780.65
SafetyHalfCheetahVelocity-v1 2625.44 ± 1079.04 707.56 ± 158.59 - ± - 3507.47 ± 1563.69 6299.27 ± 1692.38 5074.85 ± 2225.47
SafetyHopperVelocity-v1 1884.38 ± 825.13 343.88 ± 51.85 - ± - 2679.98 ± 921.96 1834.7 ± 862.06 838.96 ± 351.10
SafetyHumanoidVelocity-v1 647.52 ± 154.82 438.97 ± 123.68 - ± - 1106.09 ± 607.6 677.43 ± 189.96 762.73 ± 170.22
SafetySwimmerVelocity-v1 47.31 ± 16.19 27.12 ± 7.47 - ± - 113.28 ± 20.22 37.93 ± 8.68 273.86 ± 87.76
SafetyWalker2dVelocity-v1 1665 .00 ± 930.18 373.63 ± 129.2 - ± - 3806.39 ± 1547.48 3748.26 ± 1832.83 3304.35 ± 706.13
NaturalPG TRPO
Environment OmniSafe (Ours) Tianshou Stable-Baselines3 OmniSafe (Ours) Tianshou Stable-Baselines3
SafetyAntVelocity-v1 3793.70 ± 583.66 2062.45 ± 876.43 - ± - 4362.43 ± 640.54 2521.36 ± 1442.10 3233.58 ± 1437.16
SafetyHalfCheetahVelocity-v1 4096.77 ± 1223.70 3430.9 ± 239.38 - ± - 3313.31 ± 1048.78 4255.73 ± 1053.82 7185.06 ± 3650.82
SafetyHopperVelocity-v1 2590.54 ± 631.05 993.63 ± 489.42 - ± - 2698.19 ± 568.80 1346.94 ± 984.09 2467.10 ± 1160.25
SafetyHumanoidVelocity-v1 3838.67 ± 1654.79 810.76 ± 270.69 - ± - 1461.51 ± 602.23 749.42 ± 149.81 2828.18 ± 2256.38
SafetySwimmerVelocity-v1 116.33 ± 5.97 29.75 ± 12.00 - ± - 105.08 ± 31.00 37.21 ± 4.04 258.62 ± 124.91
SafetyWalker2dVelocity-v1 4054.62 ± 1266.76 3372.59 ± 1049.14 - ± - 4099.97 ± 409.05 3372.59 ± 961.74 4227.91 ± 760.93

Safe Reinforcement Learning Algorithms

To demonstrate the high reliability of the algorithms implemented, OmniSafe offers performance insights within the Safety-Gymnasium environment. It should be noted that all data is procured under the constraint of cost_limit=25.00. The results are presented in Table 2 and the training curves are in the following sections (Please click the triangle button to see the training curves).

Performance Table

Table 2: The performance of OmniSafe on-policy algorithms, encompassing both reward and cost, was assessed within the Safety-Gymnasium environments. It is crucial to highlight that all on-policy algorithms underwent evaluation following 1e7 training steps.

Policy Gradient Natural PG TRPO PPO
Environment Reward Cost Reward Cost Reward Cost Reward Cost
SafetyAntVelocity-v1 5292.29 ± 913.44 919.42 ± 158.61 5547.20 ± 807.89 895.56 ± 77.13 6026.79 ± 314.98 933.46 ± 41.28 5977.73 ± 885.65 958.13 ± 134.5
SafetyHalfCheetahVelocity-v1 5188.46 ± 1202.76 896.55 ± 184.7 5878.28 ± 2012.24 847.74 ± 249.02 6490.76 ± 2507.18 734.26 ± 321.88 6921.83 ± 1721.79 919.2 ± 173.08
SafetyHopperVelocity-v1 3218.17 ± 672.88 881.76 ± 198.46 2613.95 ± 866.13 587.78 ± 220.97 2047.35 ± 447.33 448.12 ± 103.87 2337.11 ± 942.06 550.02 ± 237.70
SafetyHumanoidVelocity-v1 7001.78 ± 419.67 834.11 ± 212.43 8055.20 ± 641.67 946.40 ± 9.11 8681.24 ± 3934.08 718.42 ± 323.30 9115.93 ± 596.88 960.44 ± 7.06
SafetySwimmerVelocity-v1 77.05 ± 33.44 107.1 ± 60.58 120.19 ± 7.74 161.78 ± 17.51 124.91 ± 6.13 176.56 ± 15.95 119.77 ± 13.8 165.27 ± 20.15
SafetyWalker2dVelocity-v1 4832.34 ± 685.76 866.59 ± 93.47 5347.35 ± 436.86 914.74 ± 32.61 6096.67 ± 723.06 914.46 ± 27.85 6239.52 ± 879.99 902.68 ± 100.93
SafetyCarGoal1-v0 35.86 ± 1.97 57.46 ± 48.34 36.07 ± 1.25 58.06 ± 10.03 36.60 ± 0.22 55.58 ± 12.68 33.41 ± 2.89 58.06 ± 42.06
SafetyCarButton1-v0 19.76 ± 10.15 353.26 ± 177.08 22.16 ± 4.48 333.98 ± 67.49 21.98 ± 2.06 343.22 ± 24.60 17.51 ± 9.46 373.98 ± 156.64
SafetyCarGoal2-v0 29.43 ± 4.62 179.2 ± 84.86 30.26 ± 0.38 209.62 ± 29.97 32.17 ± 1.24 190.74 ± 21.05 29.88 ± 4.55 194.16 ± 106.2
SafetyCarButton2-v0 18.06 ± 10.53 349.82 ± 187.07 20.85 ± 3.14 313.88 ± 58.20 20.51 ± 3.34 316.42 ± 35.28 21.35 ± 8.22 312.64 ± 138.4
SafetyPointGoal1-v0 26.19 ± 3.44 201.22 ± 80.4 26.92 ± 0.58 57.92 ± 9.97 27.20 ± 0.44 45.88 ± 11.27 25.44 ± 5.43 55.72 ± 35.55
SafetyPointButton1-v0 29.98 ± 5.24 141.74 ± 75.13 31.95 ± 1.53 123.98 ± 32.05 30.61 ± 0.40 134.38 ± 22.06 27.03 ± 6.14 152.48 ± 80.39
SafetyPointGoal2-v0 25.18 ± 3.62 204.96 ± 104.97 26.19 ± 0.84 193.60 ± 18.54 25.61 ± 0.89 202.26 ± 15.15 25.49 ± 2.46 159.28 ± 87.13
SafetyPointButton2-v0 26.88 ± 4.38 153.88 ± 65.54 28.45 ± 1.49 160.40 ± 20.08 28.78 ± 2.05 170.30 ± 30.59 25.91 ± 6.15 166.6 ± 111.21
RCPO TRPOLag PPOLag P3O
Environment Reward Cost Reward Cost Reward Cost Reward Cost
SafetyAntVelocity-v1 3139.52 ± 110.34 12.34 ± 3.11 3041.89 ± 180.77 19.52 ± 20.21 3261.87 ± 80.00 12.05 ± 6.57 2636.62 ± 181.09 20.69 ± 10.23
SafetyHalfCheetahVelocity-v1 2440.97 ± 451.88 9.02 ± 9.34 2884.68 ± 77.47 9.04 ± 11.83 2946.15 ± 306.35 3.44 ± 4.77 2117.84 ± 313.55 27.6 ± 8.36
SafetyHopperVelocity-v1 1428.58 ± 199.87 11.12 ± 12.66 1391.79 ± 269.07 11.22 ± 9.97 961.92 ± 752.87 13.96 ± 19.33 1231.52 ± 465.35 16.33 ± 11.38
SafetyHumanoidVelocity-v1 6286.51 ± 151.03 19.47 ± 7.74 6551.30 ± 58.42 59.56 ± 117.37 6624.46 ± 25.9 5.87 ± 9.46 6342.47 ± 82.45 126.4 ± 193.76
SafetySwimmerVelocity-v1 61.29 ± 18.12 22.60 ± 1.16 81.18 ± 16.33 22.24 ± 3.91 64.74 ± 17.67 28.02 ± 4.09 38.02 ± 34.18 18.4 ± 12.13
SafetyWalker2dVelocity-v1 3064.43 ± 218.83 3.02 ± 1.48 3207.10 ± 7.88 14.98 ± 9.27 2982.27 ± 681.55 13.49 ± 14.55 2713.57 ± 313.2 20.51 ± 14.09
SafetyCarGoal1-v0 18.71 ± 2.72 23.10 ± 12.57 27.04 ± 1.82 26.80 ± 5.64 13.27 ± 9.26 21.72 ± 32.06 -1.10 ± 6.851 50.58 ± 99.24
SafetyCarButton1-v0 -2.04 ± 2.98 43.48 ± 31.52 -0.38 ± 0.85 37.54 ± 31.72 0.33 ± 1.96 55.5 ± 89.64 -2.06 ± 7.2 43.78 ± 98.01
SafetyCarGoal2-v0 2.30 ± 1.76 22.90 ± 16.22 3.65 ± 1.09 39.98 ± 20.29 1.58 ± 2.49 13.82 ± 24.62 -0.07 ± 1.62 43.86 ± 99.58
SafetyCarButton2-v0 -1.35 ± 2.41 42.02 ± 31.77 -1.68 ± 2.55 20.36 ± 13.67 0.76 ± 2.52 47.86 ± 103.27 0.11 ± 0.72 85.94 ± 122.01
SafetyPointGoal1-v0 15.27 ± 4.05 30.56 ± 19.15 18.51 ± 3.83 22.98 ± 8.45 12.96 ± 6.95 25.80 ± 34.99 1.6 ± 3.01 31.1 ± 80.03
SafetyPointButton1-v0 3.65 ± 4.47 26.30 ± 9.22 6.93 ± 1.84 31.16 ± 20.58 4.60 ± 4.73 20.8 ± 35.78 -0.34 ± 1.53 52.86 ± 85.62
SafetyPointGoal2-v0 2.17 ± 1.46 33.82 ± 21.93 4.64 ± 1.43 26.00 ± 4.70 1.98 ± 3.86 41.20 ± 61.03 0.34 ± 2.2 65.84 ± 195.76
SafetyPointButton2-v0 7.18 ± 1.93 45.02 ± 25.28 5.43 ± 3.44 25.10 ± 8.98 0.93 ± 3.69 33.72 ± 58.75 0.33 ± 2.44 28.5 ± 49.79
CUP PCPO FOCOPS CPO
Environment Reward Cost Reward Cost Reward Cost Reward Cost
SafetyAntVelocity-v1 3215.79 ± 346.68 18.25 ± 17.12 2257.07 ± 47.97 10.44 ± 5.22 3184.48 ± 305.59 14.75 ± 6.36 3098.54 ± 78.90 14.12 ± 3.41
SafetyHalfCheetahVelocity-v1 2850.6 ± 244.65 4.27 ± 4.46 1677.93 ± 217.31 19.06 ± 15.26 2965.2 ± 290.43 2.37 ± 3.5 2786.48 ± 173.45 4.70 ± 6.72
SafetyHopperVelocity-v1 1716.08 ± 5.93 7.48 ± 5.535 1551.22 ± 85.16 15.46 ± 9.83 1437.75 ± 446.87 10.13 ± 8.87 1713.71 ± 18.26 13.40 ± 5.82
SafetyHumanoidVelocity-v1 6109.94 ± 497.56 24.69 ± 20.54 5852.25 ± 78.01 0.24 ± 0.48 6489.39 ± 35.1 13.86 ± 39.33 6465.34 ± 79.87 0.18 ± 0.36
SafetySwimmerVelocity-v1 63.83 ± 46.45 21.95 ± 11.04 54.42 ± 38.65 17.34 ± 1.57 53.87 ± 17.9 29.75 ± 7.33 65.30 ± 43.25 18.22 ± 8.01
SafetyWalker2dVelocity-v1 2466.95 ± 1114.13 6.63 ± 8.25 1802.86 ± 714.04 18.82 ± 5.57 3117.05 ± 53.60 8.78 ± 12.38 2074.76 ± 962.45 21.90 ± 9.41
SafetyCarGoal1-v0 6.14 ± 6.97 36.12 ± 89.56 21.56 ± 2.87 38.42 ± 8.36 15.23 ± 10.76 31.66 ± 93.51 25.52 ± 2.65 43.32 ± 14.35
SafetyCarButton1-v0 1.49 ± 2.84 103.24 ± 123.12 0.36 ± 0.85 40.52 ± 21.25 0.21 ± 2.27 31.78 ± 47.03 0.82 ± 1.60 37.86 ± 27.41
SafetyCarGoal2-v0 1.78 ± 4.03 95.4 ± 129.64 1.62 ± 0.56 48.12 ± 31.19 2.09 ± 4.33 31.56 ± 58.93 3.56 ± 0.92 32.66 ± 3.31
SafetyCarButton2-v0 1.49 ± 2.64 173.68 ± 163.77 0.66 ± 0.42 49.72 ± 36.50 1.14 ± 3.18 46.78 ± 57.47 0.17 ± 1.19 48.56 ± 29.34
SafetyPointGoal1-v0 14.42 ± 6.74 19.02 ± 20.08 18.57 ± 1.71 22.98 ± 6.56 14.97 ± 9.01 33.72 ± 42.24 20.46 ± 1.38 28.84 ± 7.76
SafetyPointButton1-v0 3.5 ± 7.07 39.56 ± 54.26 2.66 ± 1.83 49.40 ± 36.76 5.89 ± 7.66 38.24 ± 42.96 4.04 ± 4.54 40.00 ± 4.52
SafetyPointGoal2-v0 1.06 ± 2.67 107.3 ± 204.26 1.06 ± 0.69 51.92 ± 47.40 2.21 ± 4.15 37.92 ± 111.81 2.50 ± 1.25 40.84 ± 23.31
SafetyPointButton2-v0 2.88 ± 3.65 54.24 ± 71.07 1.05 ± 1.27 41.14 ± 12.35 2.43 ± 3.33 17.92 ± 26.1 5.09 ± 1.83 48.92 ± 17.79
PPOSaute TRPOSaute PPOSimmerPID TRPOSimmerPID
Environment Reward Cost Reward Cost Reward Cost Reward Cost
SafetyAntVelocity-v1 2978.74 ± 93.65 16.77 ± 0.92 2507.65 ± 63.97 8.036 ± 0.39 2944.84 ± 60.53 16.20 ± 0.66 3018.95 ± 66.44 16.52 ± 0.23
SafetyHalfCheetahVelocity-v1 2901.40 ± 25.49 16.20 ± 0.60 2521.80 ± 477.29 7.61 ± 0.39 2922.17 ± 24.84 16.14 ± 0.14 2737.79 ± 37.53 16.44 ± 0.21
SafetyHopperVelocity-v1 1650.91 ± 152.65 17.87 ± 1.33 1368.28 ± 576.08 10.38 ± 4.38 1699.94 ± 24.25 17.04 ± 0.41 1608.41 ± 88.23 16.30 ± 0.30
SafetyHumanoidVelocity-v1 6401.00 ± 32.23 17.10 ± 2.41 5759.44 ± 75.73 15.84 ± 1.42 6401.85 ± 57.62 11.06 ± 5.35 6411.32 ± 44.26 13.04 ± 2.68
SafetySwimmerVelocity-v1 35.61 ± 4.37 3.44 ± 1.35 34.72 ± 1.37 10.19 ± 2.32 77.52 ± 40.20 0.98 ± 1.91 51.39 ± 40.09 0.00 ± 0.00
SafetyWalker2dVelocity-v1 2410.89 ± 241.22 18.88 ± 2.38 2548.82 ± 891.65 13.21 ± 6.09 3187.56 ± 32.66 17.10 ± 0.49 3156.99 ± 30.93 17.14 ± 0.54
SafetyCarGoal1-v0 -0.65 ± 2.89 22.90 ± 16.85 1.89 ± 3.52 4.86 ± 3.11 0.81 ± 0.41 17.18 ± 14.30 0.24 ± 0.41 0.90 ± 1.18
SafetyCarButton1-v0 -1.72 ± 0.89 51.88 ± 28.18 -2.03 ± 0.40 6.24 ± 6.14 -0.57 ± 0.63 49.14 ± 37.77 -1.24 ± 0.47 17.26 ± 16.13
SafetyCarGoal2-v0 -0.87 ± 0.79 6.13 ± 4.51 -1.03 ± 1.46 18.07 ± 11.62 -0.96 ± 1.10 3.00 ± 0.83 -0.36 ± 0.09 9.83 ± 13.91
SafetyCarButton2-v0 -1.89 ± 1.86 47.33 ± 28.90 -2.60 ± 0.40 74.57 ± 84.95 -1.31 ± 0.93 52.33 ± 19.96 -0.99 ± 0.63 20.40 ± 12.77
SafetyPointGoal1-v0 1.99 ± 2.87 7.80 ± 2.78 1.02 ± 0.80 7.46 ± 5.26 1.69 ± 3.25 5.34 ± 10.33 1.38 ± 1.91 1.34 ± 1.82
SafetyPointButton1-v0 -1.47 ± 0.98 22.60 ± 13.91 -3.13 ± 3.51 9.04 ± 3.94 -1.97 ± 1.41 12.80 ± 7.84 -1.36 ± 0.37 2.14 ± 1.73
SafetyPointGoal2-v0 -1.85 ± 0.99 21.77 ± 13.56 -1.38 ± 1.16 7.87 ± 2.02 -1.13 ± 0.39 7.03 ± 4.21 -0.54 ± 0.18 26.57 ± 19.13
SafetyPointButton2-v0 -1.38 ± 0.11 12.00 ± 8.60 -2.56 ± 0.67 17.27 ± 10.01 -1.70 ± 0.29 7.90 ± 3.30 -1.66 ± 0.99 6.70 ± 4.74
CPPOPID TRPOPID PPOEarlyTerminated TRPOEarlyTerminated
Environment Reward Cost Reward Cost Reward Cost Reward Cost
SafetyAntVelocity-v1 3213.36 ± 146.78 14.30 ± 7.39 3052.94 ± 139.67 15.22 ± 3.68 2801.53 ± 19.66 0.23 ± 0.09 3052.63 ± 58.41 0.40 ± 0.23
SafetyHalfCheetahVelocity-v1 2837.89 ± 398.52 8.06 ± 9.62 2796.75 ± 190.84 11.16 ± 9.80 2447.25 ± 346.84 3.47 ± 4.90 2555.70 ± 368.17 0.06 ± 0.08
SafetyHopperVelocity-v1 1713.29 ± 10.21 8.96 ± 4.28 1178.59 ± 646.71 18.76 ± 8.93 1643.39 ± 2.58 0.77 ± 0.26 1646.47 ± 49.95 0.42 ± 0.84
SafetyHumanoidVelocity-v1 6579.26 ± 55.70 3.76 ± 3.61 6407.95 ± 254.06 7.38 ± 11.34 6321.45 ± 35.73 0.00 ± 0.00 6332.14 ± 89.86 0.00 ± 0.00
SafetySwimmerVelocity-v1 91.05 ± 62.68 19.12 ± 8.33 69.75 ± 46.52 20.48 ± 9.13 33.02 ± 7.26 24.23 ± 0.54 39.24 ± 5.01 23.20 ± 0.48
SafetyWalker2dVelocity-v1 2183.43 ± 1300.69 14.12 ± 10.28 2707.75 ± 980.56 9.60 ± 8.94 2195.57 ± 1046.29 7.63 ± 10.44 2079.64 ± 1028.73 13.74 ± 15.94
SafetyCarGoal1-v0 10.60 ± 2.51 30.66 ± 7.53 25.49 ± 1.31 28.92 ± 7.66 17.92 ± 1.54 21.60 ± 0.83 22.09 ± 3.07 17.97 ± 1.35
SafetyCarButton1-v0 -1.36 ± 0.68 14.62 ± 9.40 -0.31 ± 0.49 15.24 ± 17.01 4.47 ± 1.12 25.00 ± 0.00 4.34 ± 0.72 25.00 ± 0.00
SafetyCarGoal2-v0 0.13 ± 1.11 23.50 ± 1.22 1.77 ± 1.20 17.43 ± 12.13 6.59 ± 0.58 25.00 ± 0.00 7.12 ± 4.06 23.37 ± 1.35
SafetyCarButton2-v0 -1.59 ± 0.70 39.97 ± 26.91 -2.95 ± 4.03 27.90 ± 6.37 4.86 ± 1.57 25.00 ± 0.00 5.07 ± 1.24 25.00 ± 0.00
SafetyPointGoal1-v0 8.43 ± 3.43 25.74 ± 7.83 19.24 ± 3.94 21.38 ± 6.96 16.03 ± 8.60 19.17 ± 9.42 16.31 ± 6.99 22.10 ± 6.13
SafetyPointButton1-v0 1.18 ± 1.02 29.42 ± 12.10 6.40 ± 1.43 27.90 ± 13.27 7.48 ± 8.47 24.27 ± 3.95 9.52 ± 7.86 25.00 ± 0.00
SafetyPointGoal2-v0 -0.56 ± 0.06 48.43 ± 40.55 1.67 ± 1.43 23.50 ± 11.17 6.09 ± 5.03 25.00 ± 0.00 8.62 ± 7.13 25.00 ± 0.00
SafetyPointButton2-v0 0.42 ± 0.63 28.87 ± 11.27 1.00 ± 1.00 30.00 ± 9.50 6.94 ± 4.47 25.00 ± 0.00 8.35 ± 10.44 25.00 ± 0.00

First Order Algorithms

1e6 Steps Velocity Results

SafetyAntVelocity-v1

SafetyHalfCheetahVelocity-v1

SafetyHopperVelocity-v1

SafetyHumanoidVelocity-v1

SafetyWalker2dVelocity-v1

SafetySwimmerVelocity-v1

Figure 1.1: Training curves in Safety-Gymnasium MuJoCo Velocity environments within 1e6 steps

1e7 Steps Velocity Results

SafetyAntVelocity-v1

SafetyHalfCheetahVelocity-v1

SafetyHopperVelocity-v1

SafetyHumanoidVelocity-v1

SafetyWalker2dVelocity-v1

SafetySwimmerVelocity-v1

Figure 1.2: Training curves in Safety-Gymnasium MuJoCo Velocity environments within 1e7 steps

1e7 Steps Navigation Results

SafetyCarButton1-v0

SafetyCarButton2-v0

SafetyCarGoal1-v0

SafetyCarGoal2-v0

SafetyPointButton1-v0

SafetyPointButton2-v0

SafetyPointGoal1-v0

SafetyPointGoal2-v0

Figure 1.3: Training curves in Safety-Gymnasium MuJoCo Navigation environments within 1e7 steps

Second Order Algorithms

1e6 Steps Velocity Results

SafetyAntVelocity-v1

SafetyHalfCheetahVelocity-v1

SafetyHopperVelocity-v1

SafetyHumanoidVelocity-v1

SafetyWalker2dVelocity-v1

SafetySwimmerVelocity-v1

Figure 2.1: Training curves of second order algorithms in Safety-Gymnasium MuJoCo Velocity environments within 1e6 steps

1e7 Steps Velocity Results

SafetyAntVelocity-v1

SafetyHalfCheetahVelocity-v1

SafetyHopperVelocity-v1

SafetyHumanoidVelocity-v1

SafetyWalker2dVelocity-v1

SafetySwimmerVelocity-v1

Figure 2.2: Training curves of second order algorithms in Safety-Gymnasium MuJoCo Velocity environments within 1e7 steps

1e7 Steps Navigation Results

SafetyCarButton1-v0

SafetyCarButton2-v0

SafetyCarGoal1-v0

SafetyCarGoal2-v0

SafetyPointButton1-v0

SafetyPointButton2-v0

SafetyPointGoal1-v0

SafetyPointGoal2-v0

Figure 2.3: Training curves of second order algorithms in Safety-Gymnasium MuJoCo Navigation environments within 1e7 steps

Saute Algorithms

1e6 Steps Velocity Results

SafetyAntVelocity-v1

SafetyHalfCheetahVelocity-v1

SafetyHopperVelocity-v1

SafetyHumanoidVelocity-v1

SafetyWalker2dVelocity-v1

SafetySwimmerVelocity-v1

Figure 3.1: Training curves of Saute MDP algorithms in Safety-Gymnasium MuJoCo Velocity environments within 1e6 steps

1e7 Steps Velocity Results

SafetyAntVelocity-v1

SafetyHalfCheetahVelocity-v1

SafetyHopperVelocity-v1

SafetyHumanoidVelocity-v1

SafetyWalker2dVelocity-v1

SafetySwimmerVelocity-v1

Figure 3.2: Training curves of Saute MDP algorithms in Safety-Gymnasium MuJoCo Velocity environments within 1e7 steps

1e7 Steps Navigation Results

SafetyCarButton1-v0

SafetyCarButton2-v0

SafetyCarGoal1-v0

SafetyCarGoal2-v0

SafetyPointButton1-v0

SafetyPointButton2-v0

SafetyPointGoal1-v0

SafetyPointGoal2-v0

Figure 3.3: Training curves of Saute MDP algorithms in Safety-Gymnasium MuJoCo Navigation environments within 1e7 steps

Simmer Algorithms

1e6 Steps Velocity Results

SafetyAntVelocity-v1

SafetyHalfCheetahVelocity-v1

SafetyHopperVelocity-v1

SafetyHumanoidVelocity-v1

SafetyWalker2dVelocity-v1

SafetySwimmerVelocity-v1

Figure 4.1: Training curves of Simmer MDP algorithms in Safety-Gymnasium MuJoCo Velocity environments within 1e6 steps

1e7 Steps Velocity Results

SafetyAntVelocity-v1

SafetyHalfCheetahVelocity-v1

SafetyHopperVelocity-v1

SafetyHumanoidVelocity-v1

SafetyWalker2dVelocity-v1

SafetySwimmerVelocity-v1

Figure 4.2: Training curves of Simmer MDP algorithms in Safety-Gymnasium MuJoCo Velocity environments within 1e7 steps

1e7 Steps Navigation Results

SafetyCarButton1-v0

SafetyCarButton2-v0

SafetyCarGoal1-v0

SafetyCarGoal2-v0

SafetyPointButton1-v0

SafetyPointButton2-v0

SafetyPointGoal1-v0

SafetyPointGoal2-v0

Figure 4.3: Training curves of Simmer MDP algorithms in Safety-Gymnasium MuJoCo Navigation environments within 1e7 steps

PID-Lagrangian Algorithms

1e6 Steps Velocity Results

SafetyAntVelocity-v1

SafetyHalfCheetahVelocity-v1

SafetyHopperVelocity-v1

SafetyHumanoidVelocity-v1

SafetyWalker2dVelocity-v1

SafetySwimmerVelocity-v1

Figure 5.1: Training curves of PID-Lagrangian algorithms in Safety-Gymnasium MuJoCo Velocity environments within 1e6 steps

1e7 Steps Velocity Results

SafetyAntVelocity-v1

SafetyHalfCheetahVelocity-v1

SafetyHopperVelocity-v1

SafetyHumanoidVelocity-v1

SafetyWalker2dVelocity-v1

SafetySwimmerVelocity-v1

Figure 5.2: Training curves of PID-Lagrangian algorithms in Safety-Gymnasium MuJoCo Velocity environments within 1e7 steps

1e7 Steps Navigation Results

SafetyCarButton1-v0

SafetyCarButton2-v0

SafetyCarGoal1-v0

SafetyCarGoal2-v0

SafetyPointButton1-v0

SafetyPointButton2-v0

SafetyPointGoal1-v0

SafetyPointGoal2-v0

Figure 5.3: Training curves of PID-Lagrangian algorithms in Safety-Gymnasium MuJoCo Navigation environments within 1e7 steps.

Early Terminated MDP Algorithms

1e6 Steps Velocity Results

SafetyAntVelocity-v1

SafetyHalfCheetahVelocity-v1

SafetyHopperVelocity-v1

SafetyHumanoidVelocity-v1

SafetyWalker2dVelocity-v1

SafetySwimmerVelocity-v1

Figure 6.1: Training curves of early terminated MDP algorithms in Safety-Gymnasium MuJoCo Velocity environments within 1e6 steps.

1e7 Steps Velocity Results

SafetyAntVelocity-v1

SafetyHalfCheetahVelocity-v1

SafetyHopperVelocity-v1

SafetyHumanoidVelocity-v1

SafetyWalker2dVelocity-v1

SafetySwimmerVelocity-v1

Figure 6.2: Training curves of early terminated MDP algorithms in Safety-Gymnasium MuJoCo Velocity environments within 1e7 steps.

1e7 Steps Navigation Results

SafetyCarButton1-v0

SafetyCarButton2-v0

SafetyCarGoal1-v0

SafetyCarGoal2-v0

SafetyPointButton1-v0

SafetyPointButton2-v0

SafetyPointGoal1-v0

SafetyPointGoal2-v0

Figure 6.3: Training curves of early terminated MDP algorithms in Safety-Gymnasium MuJoCo Navigation environments within 1e7 steps.

Experiment Analysis

Hyperparameters

We are continuously improving performance for on-policy algorithms and finding better hyperparameters. So we are happy to receive any advice from users, feel free for opening an issue or pull request.

First-Order Methods Specific Hyperparameters

  • algo_cfgs:kl_early_stop: Whether to use the early stop trick for KL divergence. In first-order methods, this parameter is set to True. If the KL divergence is too large, we will stop the updating iteration.

Second-Order Methods Specific Hyperparameters

  • algo_cfgs:kl_early_stop: Whether to use early stop for KL divergence. In second-order methods, we use line search to find the proper step size. If the KL divergence is too large, we will stop the line search and use the previous step size. So it is not necessary to use the early stop trick for KL divergence in second-order methods. We set kl_early_stop=False in second-order methods.

  • model_cfgs:actor:lr: The learning rate of the policy network. Second-order methods update the policy by directly setting the parameters. So we just set the learning rate of the policy network to None.

You may find that in some environments, Natural PG performs nearly the same as TRPO. This is because, in the Mujoco Velocity environment series, the TRPO search update step size is always 1. Additionally, since all algorithms were tested under the same series of random seeds, there is an occurrence of TRPO and Natural PG training curves overlapping.

Saute RL Methods Specific Hyperparameters

  • saute_gamma: In the experiment we found that saute_gamma impacts the performance of Saute RL methods a lot. We found that 0.999 is a good value for this hyperparameter.

Simmer RL Methods Specific Hyperparameters

  • saute_gamma: Since the Simmer RL methods are based on Saute RL methods, we also set saute_gamma to 0.999.
  • control_cfgs: The controller parameters of the Simmer RL methods. While Simmer uses a PID controller to control the safety budget, and PID is known as a parameter-sensitive controller. So we need to tune the control parameters (Kp, Ki and Kd) for different environments. We have done some experiments to find control parameters generally suitable for all environments, that is:
Parameters Descriptions Values
kp The proportional gain of the PID controller 1.0
ki The derivative gain of the PID controller 0.001
kd The integral gain of the PID controller 0.01
polyak The learning rate for soft update 0.995

PID-Lagrangian Methods Specific Hyperparameters

PID-Lagrangian methods use a PID controller to control the lagrangian multiplier, The pid_kp, pid_kd and pid_ki count for the proportional gain, derivative gain and integral gain of the PID controller respectively. As PID-Lagrangian methods use a PID controller to control the lagrangian multiplier, the hyperparameters of the PID controller are important for the performance of the algorithm.

  • pid_kp: The proportional gain of the PID controller, determines how much the output responds to changes in the ep_costs signal. If the pid_kp is too large, the lagrangian multiplier will oscillate and the performance will be bad. If the pid_kp is too small, the lagrangian multiplier will update slowly and the performance will also be bad.
  • pid_kd: The derivative gain of the PID controller, determines how much the output responds to changes in the ep_costs signal. If the pid_kd is too large, the lagrangian multiplier may be too sensitive to noise or changes in the ep_costs signal, leading to instability or oscillations. If the pid_kd is too small, the lagrangian multiplier may not respond quickly or accurately enough to changes in the ep_costs.
  • pid_ki: The integral gain of the PID controller, determines the controller's ability to eliminate the steady-state error, by integrating the ep_costs signal over time. If the pid_ki is too large, the lagrangian multiplier may become too responsive to errors before.

We have done some experiments to find relatively good pid_kp, pid_ki, and pid_kd for all environments, and we found that the following value is a good value for this hyperparameter.

Parameters Descriptions Values
pid_kp The proportional gain of the PID controller 0.1
pid_ki The derivative gain of the PID controller 0.01
pid_kd The integral gain of the PID controller 0.01

Early Terminated MDP Methods Specific Hyperparameters

  • vector_num_envs: Though vectorized environments can speed up the training process, we found that the early terminated MDP will reset all the environments when one of the agents violates the safety constraint. So we set vector_num_envs to 1 in the early terminated MDP methods.

Lagragian

The lagrangian versions of on-policy algorithms share the same set of lagrangian hyperparameters (Except for PID-Lagrangian). The hyperparameters are listed below:

Hyperparameter Value
cost_limit 25.0
lagrangian_multiplier_init 0.001
lambda_lr 0.035
lambda_optimizer Adam

Some Hints

In our experiments, we found that some hyperparameters are important for the performance of the algorithm:

  • obs_normalize: Whether to normalize the observation.
  • reward_normalize: Whether to normalize the reward.
  • cost_normalize: Whether to normalize the cost.

We have done some experiments to show the effect of these hyperparameters, and we log the best configuration for each algorithm in each environment. You can check it in the omnisafe/configs/on_policy.

In experiments, we found that the obs_normalize=True always performs better than obs_normalize=False in on-policy algorithms. That means the reward would increase quicker while the safety constraint also maintained if we normalize the observation. So we set obs_normalize=True in almost all on-policy algorithms.

Importantly, we found that the reward_normalize=True does not always perform better than reward_normalize=False, especially in the SafetyHopperVelocity-v1 and SafetyWalker2dVelocity environments.

To improve the overall performance stability, we use the following unified setting in all of OmniSafe on-policy algorithms

Hyperparameter Value
obs_normalize True
reward_normalize False
cost_normalize False

Besides, the hyperparameter torch_num_threads in train_cfgs is also important. In a single training session, a larger value for torch_num_threads often means faster training speed. However, we found in experiments that setting torch_num_threads too high can cause resource contention between parallel training sessions, resulting in slower overall experiment speed. In the configs file, we set the default value for torch_num_threads to 16, which ensures faster training speed for a single session. If you need to launch multiple training sessions in parallel, please consider your device configuration. For example, suppose your CPU has 2 physical threads per core and has a total of 32 cores, if you are launching 16 training scripts in parallel, you had better not set torch_num_threads to a value greater than 4.

If you find that other hyperparameters perform better, please feel free to open an issue or pull request.