Introduction
The monoDrive Simulator and Scenario Editor support a robust Application Programming Interface (API) through a JSON messaging interface. The simulation can be completely controlled by sending and receiving messages through TCP/IP from any application that implements the API.
monoDrive provides several example client applications in C++, Python, and LabVIEW that implement the monoDrive API. For more information on the Open Source monoDrive clients, check out the overview here.
Sending a Message
A message to the monoDrive Simulator consists of a binary header followed by the JSON string containing the message meta-data. The first part of the message contains the header flag:
0x6d6f6e6f
followed by a 32-bit integer that states the length of the following JSON.
The JSON in the message is dependent on the type of message being sent and must contain the following fields:
{
"type": <monoDrive message type>,
"reference": <unique ID for this message>,
"message": <JSON of the message>
}
- type: A string that describes the type of message being sent.
- reference: An integer defining the unique ID from this message.
- message: The actual JSON containing all the additional meta-data for the message type.
Message Types
Used to configure a simulator session. This command includes the settings associated with the simulator session following the execution of the command and applies to all future sessions until the command is run again. The pys_materials settings affect the returns from lidar and radar sensors for the list of known materials in the scene.
The following message types are currently defined for sending messages to the simulator:
| Message Type | Definition |
|---|---|
| ClosedLoopConfigCommand_ID | Configures the closed loop simulation |
| ClosedLoopStepCommand_ID | Steps the closed loop simulation |
| EgoControl_ID | Control the ego vehicle |
| GetMap | Get the currently loaded map information |
| GetStartPoints | Retrieves the set of starting locations |
| GetVersion | Gets Current version |
| ImportMap | Replaces the current road network |
| REPLAY_ConfigureSensorsCommand_ID | Configure a sensor or set of sensors in a simulator run |
| REPLAY_ConfigureTrajectoryCommand_ID | Configures the simulation trajectory |
| REPLAY_ReConfigureSensorCommand_ID | Reconfigure a sensor or set of sensors in a simulation run |
| REPLAY_StateStepSimulationCommand_ID | Steps the simulation |
| REPLAY_StepSimulationCommand_ID | Steps the simulation |
| SampleSensorsCommand_ID | Obtain the latest sample from the sensors |
| SimulatorConfig_ID | Configure the Simulator session |
| SpawnVehicleCommand_ID | Spawns the EGO vehicle |
| UpdateStateCommand_ID | Update the state of the ego and other actors in the scene |
| WeatherConfig | Configure the current weather in the scenario |
Receiving a Message
The monoDrive Simulator will send messages out over the simulator port
(default 8999) from either localhost or the IP address of the simulator if
running in a networked mode. If a listen_port is specified in the message,
(e.g. a sensor that should stream data over a specified port), the message will
be sent to the specified port.
Each message will begin with a 16 byte monoDrive header starting with the header flag:
0x6f6e6f6d
and followed by a 32-bit integer specifying the length of the JSON message.
Each JSON message received from the simulator will contain, at a minimum, the following fields:
{
"type": <monoDrive message type>,
"reference": <unique ID for this message>,
"message": <JSON of the message>
}
- type: A string that describes the type of message being sent. This will be the type specified by the message that elicited this response.
- reference: An integer defining the unique ID from this message.
- message: The actual JSON containing all the additional meta-data for the message type.