Racecar Gym

A gym environment for a miniature, F1Tenth-like racecar using the bullet physics engine with pybullet.

Installation

Warning We now migrated to gymnasium. If you need to use the old gym api, you can either use some of the compatibility wrappers of gymnasium or you can use older versions of this gym. The last version supporting the old gym api is tagged as gym-api:

git checkout gym-api; pip install -e .

You can install racecar_gym with the following commands:

git clone https://github.com/axelbr/racecar_gym.git
cd racecar_gym
pip install -e .

On the first use of this gym, the tracks are downloaded automatically.

Of course, you can download them manually too. Here is how you can do this from the command line:

cd ./models/scenes
VERSION=v1.0.0
wget https://github.com/axelbr/racecar_gym/releases/download/tracks-${VERSION}/all.zip
unzip all.zip

Environments

The observation and action space is a Dict holding the agents and their id's. The observation and action space for a single agent is also a Dict, which is described in more detail below. In general, observations are obtained through sensors and commands are executed by actuators. Vehicles can have multiple sensors and actuators. Those are described in the vehicle configuration (e.g. differential racecar). Agents, which consist of a vehicle and an assigned task, are specified in the scenario file (e.g. austria.yml). In this file, agents are described by the sensors to use (note that they must be available in the vehicle configuration) and the corresponding task. Have a look at tasks.py to see all available tasks.

Example:

world:
  name: austria
agents:
  - id: A
    vehicle:
      name: racecar
      sensors: [lidar, pose, velocity, acceleration]
      actuators: [motor, steering]
      color: blue # default is blue, one of red, green, blue, yellow, magenta or random
    task:
      task_name: maximize_progress
      params: {laps: 1, time_limit: 120.0, terminate_on_collision: False}

This example specifies a scenario on the Austria track. One agent with id A is specified. The agent controls the differential drive racecar defined in differential racecar, identified by its name. The scenario tells the agent to use only the specified sensors (lidar, pose, velocity, acceleration). Optionally, one can also specify a color for the car. The default color is blue. Available colors are listed above.

The task which is assigned to this agent is also identified by name (implementations can be found in tasks.py). Task parameters are passed by the dict params.

Observations

Observations are obtained by (possibly noisy) sensors. Parameters for the sensors as well as the level of noise, can be configured in the corresponding vehicle configuration (e.g. differential racecar). In the scenario specification, one can specify which of the available sensors should be actually used. The observation space is a dictionary where the names of the sensors are the keys which map to the actual measurements. Currently, five sensors are implemented: pose, velocity, acceleration, LiDAR and RGB Camera. Further, the observation space also includes the current simulation time.

Key	Space	Defaults	Description
pose	`Box(6,)`		Holds the position (`x`, `y`, `z`) and the orientation (`roll`, `pitch`, `yaw`) in that order.
velocity	`Box(6,)`		Holds the `x`, `y` and `z` components of the translational and rotational velocity.
acceleration	`Box(6,)`		Holds the `x`, `y` and `z` components of the translational and rotational acceleration.
lidar	`Box(<scans>,)`	`scans: 1080`	Lidar range scans.
rgb_camera	`Box(<height>, <width>, 3)`	`height: 240, width: 320`	RGB image of the front camera.

Actions

The action space for a single agent is a defined by the actuators of the vehicle. By default, differential racecar defines two actuators: motor and steering. The action space is therefore a dictionary with keys motor and steering.

Alternatevely, the agent can control the target speed and steering, but must be defined in the scenario specification. In this case, the action space is a dictionary with keys speed and steering.

Note, that the action space of the car is normalized between -1 and 1. The action space can include the following actuators:

Key	Space	Description
motor	`Box(low=-1, high=1, shape=(1,))`	Throttle command. If negative, the car accelerates backwards.
speed	`Box(low=-1, high=1, shape=(1,))`	Normalized target speed.
steering	`Box(low=-1, high=1, shape=(1,))`	Normalized steering angle.

State

In addition to observations obtained by sensors, the environment passes back the true state of each vehicle in each step (the state is returned as the info dictionary). The state is a dictionary, where the keys are the ids of all agents. Currently, the state looks like this:

Key	Type	Description
wall_collision	`bool`	True if the vehicle collided with the wall.
opponent_collisions	`List[str]`	List of opponent id's which are involved in a collision with the agent.
pose	`NDArray[6]`	Ground truth pose of the vehicle (x, y, z, roll, pitch, yaw).
acceleration	`NDArray[6]`	Ground truth acceleration of the vehicle (x, y, z, roll, pitch, yaw).
velocity	`NDArray[6]`	Ground truth velocity of the vehicle (x, y, z, roll, pitch, yaw).
progress	`float`	Current progress in this lap. Interval: [0, 1]
time	`float`	Simulation time.
checkpoint	`int`	Tracks are subdivided into checkpoints to make sure agents are racing in clockwise direction. Starts at 0.
lap	`int`	Current lap.
rank	`int`	Current rank of the agent, based on lap and progress.
wrong_way	`bool`	Indicates wether the agent goes in the right or wrong direction.
observations	`Dict`	The most recent observations of the agent.

Available API's

racecar_gym currently implements the Gym API and the PettingZoo API.

Gym API

To use the Gym API you can either instantiate environments with the standard keys or by loading custom scenarios. In either case, you have to load the gym_api module from this package:

import gymnasium
import racecar_gym.envs.gym_api

# For predefined environments:
env = gymnasium.make(
    id='SingleAgentAustria-v0',
    render_mode='human'
)

# For custom scenarios:
env = gymnasium.make(
    id='SingleAgentRaceEnv-v0', 
    scenario='path/to/scenario',
    render_mode='rgb_array_follow', # optional
    render_options=dict(width=320, height=240, agent='A') # optional
)

done = False
reset_options = dict(mode='grid')
obs, info = env.reset(options=reset_options)

while not done:
    action = env.action_space.sample()
    obs, rewards, terminated, truncated, states = env.step(action)
    done = terminated or truncated

env.close()

The predefined env-strings are of the form

<Multi|Single>Agent<track>-v0
e.g.: MultiAgentAustria-v0

For further documentation on available gym environments, please refer to the Gym Documentation (under construction) and the examples shown in examples/gym_examples/.

PettingZoo API

For multi-agent races, we also implement the PettingZoo API. To create a PettingZoo environment, you can use the pettingzoo_api module:

from racecar_gym.envs import pettingzoo_api
env = pettingzoo_api.env(scenario='path/to/scenario')

For further documentation on available PettingZoo environments, please refer to the PettingZoo Documentation (under construction) and the examples shown in examples/pettingzoo_examples/.