Components#

This page describes each component of the system overview and gives the page that explains it.

Simulators#

Component	Description	Read More
The game	The full simulator in Unreal Engine 5.8. It has the farm, both vehicles, the implements, the weather, the traffic and all sensors. Its physics step is 1/120 s.	Architecture
ACRES Core	The simulator without Unreal. It has the Polaris on the same terrain, soil and crops, with a ray-cast LiDAR. It runs a batch of environments on all CPU cores.	Headless Core Runs
Engine-free models	The C++ files with the mathematics of the models. The game and ACRES Core compile the same files.	Conventions

Component	Description	Read More
Maxxum	The Case IH Maxxum 150 tractor: engine, governor, 16 gears, four-wheel drive, steering, brakes and suspension.	Maxxum 150 Dynamics
Implements	Eight implements for the Maxxum, with tool forces, the hitch, the PTO and the hydraulics.	Implement Catalog
Polaris	The Polaris Ranger of the Purdue lab: engine, CVT, gear lever, drive modes, steering and brakes.	Polaris Ranger Dynamics
Drive-by-wire	The Dataspeed drive-by-wire of the Polaris with the ULC speed controller and its timeouts.	Drive-by-Wire and ULC

Component	Description	Read More
The ACRE scene	The surveyed tile: terrain, 59 fields, roads, lanes, buildings and trees.	The ACRE Scene
Tyre and soil	Sinkage, slip, traction, rolling resistance and ruts on a library of soil classes.	Tyre and Soil
Energy and fuel	The fuel map of the engine and an energy ledger for each physics step.	Energy and Fuel
Crops and ground classes	Crops that grow, the damage from wheels, the harvest, and the class of each ground surface.	Crops and Ground Classes
Soil water	Rain, infiltration, overland flow and drainage on a grid. Wet soil changes the traction.	Soil Water
Weather	Sun, clouds, temperature, wind, fog and rain, with the clock of the session.	Weather
Farm traffic	Tractors, cars and workers that move on the farm.	Farm Traffic and Workers

Component	Description	Read More
Camera	A rendered image with a model of the lens and the sensor.	Camera
LiDAR	Rays that the GPU traces against the scene, with returns, intensity and noise.	LiDAR
INS and GNSS	Position, velocity and attitude with fix states and error models.	INS and GNSS
Wheel and CAN signals	Wheel speeds, steering angle and the J1939 CAN bus of the Maxxum.	Wheel and CAN Signals
Render tiers	The quality level of the main view, and the pinned profile that the sensors use.	Platforms and GPU Tiers

Component	Description	Read More
Menu and command line	The two methods to configure and start a session.	Command-Line Options
Vehicle bridge	A JSON socket for the commands and reports of one vehicle.	Vehicle Bridge
Simulator control channel	A JSON socket for pause, lockstep steps, resets, conditions and recording.	Simulator Control Channel
Sensor stream	A binary socket with the sensor data of one vehicle.	Sensor Stream
`acres_sim`	The ROS 2 bridge. It publishes the topics of the real vehicle and offers the simulator services.	Nodes and Launch Files
`acres_core_sim`	The Core server. It puts ACRES Core behind the same three sockets.	Nodes and Launch Files
`acres_interfaces`	The messages and services of the simulator.	Messages
Lockstep	The mode in which the simulation advances only on step requests.	Lockstep Stepping
DDS loopback fence	The settings that keep ROS 2 traffic on the workstation.	Build the ROS 2 Workspace

Component	Description	Read More
Configuration files	The JSON files with the parameters of the vehicles, sensors, soils and weather.	Configuration Files
Map products	The grids and layers of the ACRE tile.	Map Products
Session log	The files that the game writes for each session, with the sensor episodes.	Session Log
Episode log	An MCAP file with the states of all agents at the physics rate.	Episode Log
ROS 2 bag	A recording of the ROS 2 topics of the bridge.	Collect Data
Replay	The game follows a session log or shows an episode log.	Replay

Component	Description	Read More
Tasks	The benchmark tasks. The first task is field scouting.	Tasks
Learning stack	The package `acres_learn`: environments, training, evaluation and the deployment program.	Learning
Calibration	The tools that fit the models to the logs of the real Polaris and to the weather record.	Calibrate against Real Logs
Field-day kit	The test scripts that the lab runs on the real Polaris.	Field-Day Kit