Drive the Maxxum Tractor#

This tutorial shows how to start a session with the Maxxum and how to use each control of the tractor. At the end, you drive on a field and compare the values of the HUD with the values of this page.

Before You Start#

Build the packaged game, see Build the Game. The tutorial First Drive gives a shorter introduction.
Use a keyboard and a mouse. The key names of this page are those of a keyboard with the US layout.
Do all commands in the repository root.

CAUTION

Start only one instance of the game at a time. Two instances can use all the memory of the GPU.

Start the game without options.
```
Packaged/Linux/Acres.sh
```
Expected Result

The menu shows the buttons "New Simulation", "Replay Simulation", "Run Optimizer", "Pilot" and "Quit".
Select "New Simulation". This session type writes a session log.

Note

The button "Pilot" starts a free drive without sensors and without a session log.
Select the tab "Vehicle". Make sure that the setting "Vehicle" shows "Case IH Maxxum 150 (Tractor Tab)".
Set "Start Position" to "ICSC Garage".
Select the tab "Tractor". Change the settings of the tractor if necessary, for example "Starting Gear".
Select "Start".

Expected Result

The Maxxum is in front of the ICSC garage. The box "Controls" shows the primary keys for 12 seconds.

The page Menu Settings lists all settings of the menu.

Start a Session from the Command Line#

Start the game with the option -VehicleDemo. The Maxxum is the default vehicle.

Packaged/Linux/Acres.sh -VehicleDemo

Expected Result

The Maxxum is in front of the ICSC garage. The log of the game contains these lines (shortened).

ACRES_SPAWN place=spawn-icsc-garage u=474.60 v=592.20 x_m=-38.71 y_m=140.51 z_m=1.94
  yaw_deg=-90.0 nudge_m=0.0
ACRES_VEHICLE_READY agent=maxxum index=0 trailer=0 mass_kg=5820.0 implement=none
  surface=mapped physics_hz=120 ... front_lead=0.015 diff_lock=0 model=maxxum_150
  implement_model=none governor_droop_rpm=100 ...

Hold W for 5 seconds. Then release W and hold S until the Maxxum stops.

Expected Result

The Maxxum moves north. In gear 10, the speed is 13 km/h and the engine speed is 2270 rpm. The Maxxum stops in approximately 1 second.

Press Esc to stop the game. Add options to change the start. The table shows the options that this tutorial uses.

Packaged/Linux/Acres.sh -VehicleDemo -VehicleGear=8 -VehicleDiffLock=rear \
  -SessionLog -VehicleOutput=/tmp/acres-drive

Name	Type	Unit	Default	Description
`-VehicleDemo`	switch		off	Starts a session with a vehicle and without the menu.
`-Vehicle=`	string		`maxxum`	The vehicle: `maxxum` or `polaris`.
`-SpawnAt=`	string		`spawn-icsc-garage`	The identifier or the name of a start position.
`-VehicleSpawnU=`, `-VehicleSpawnV=`	number	survey cell		The start position on the survey grid. One cell is 1.524 m.
`-VehicleSpawnYaw=`	number	deg		The start direction. -90 points north and 0 points east.
`-VehicleGear=`	integer		10	The gear at the start, 1 to 16.
`-VehicleDiffLock=`	string		`off`	The differential lock at the start: `off`, `rear` or `all`.
`-Vehicle2WD`	switch		off	Disengages the front-wheel drive.
`-Implement=`	string		`none`	The implement. See Attach and Operate Implements.
`-SessionLog`	switch		off	Writes the session log `tractor.csv`.
`-VehicleOutput=`	path		`Saved/Vehicle`	The session folder.

The page Command-Line Options gives all options.

Controls#

The game reads the keys directly. The file Config/DefaultInput.ini contains no key bindings for the vehicle. Hold Tab in the game to see all keys of the current vehicle and implement.

Drive#

Key	Function	Details
`W`	Pedal	Full command while you hold the key. The command sets the engine speed of the governor.
`S` or `Space`	Brake	Full brake on the four wheels while you hold the key. The brake also opens the clutch.
`A` and `D`	Steer left and right	The command is full lock. The front wheels move at 40°/s to a maximum of 38°.
`[` and `]`	Gear down and up	16 gears. The start gear is 10.
`V`	Forward or reverse	The key operates only when the speed is below 0.9 km/h.
`L`	Differential lock	The sequence is: off, rear, front and rear, off.
`=` and `-`	Hand throttle	One step is 5 %. The keys `Num +` and `Num -` do the same.
`P`	Park brake	On or off. The park brake applies the full brake.
`R`	Reset	Puts the vehicle at its start position. The fuel and energy values start again.

The clutch is automatic. It engages when the command is above zero and the brake is off. It opens when you release W and the hand throttle is zero. The Maxxum then coasts, because the model has no engine braking.

Surface#

These keys replace the surface of the map with one surface for all wheels.

Key	Surface
`1`	Asphalt
`2`	Concrete
`3`	Gravel
`4`	Dry soil
`5`	Wet soil
`6`	Mud with 12 cm of standing water
`0`	The surface of the map (default)

Views#

Key	Function	Details
Mouse	Turn the view	In the chase view, the camera moves around the tractor. In the cab view, you look around.
Mouse wheel	Zoom	Chase view only. The distance range is 4 m to 30 m.
`C`	Cab view or chase view	The key also puts the camera in its start direction.
`F2`	Next vehicle	Only in a session with more than one vehicle.

HUD, Recording and Session#

Key	Function	Details
`Tab`	All keys	Shows the key list while you hold the key.
`I`	Work panels	Shows or hides the implement panel and the panel "Energy". The default is on.
`F1`	Engineering panel	Replaces the HUD with the debug panel. Press the key again to go back.
`F6`	Sensor recording	Starts or stops a recording. See Collect Data.
`F12`	Screenshot	Writes an image of the view.
`Esc`	Pause or quit	A menu session shows "Paused" with "Resume", "End Simulation" and "Quit". A command-line session stops.

Farm and Weather#

Key	Function	Details
`J`	Rain	Starts or stops rain. See Set Soil and Weather.
`K`	Fast clock	Changes the clock of the weather and the farm between 1 and 600 times real time.
`N`	Sow the field again	Only when the vehicle does not move.
`F5`	Save the farm state	Writes the farm state into the session folder.
`F9`	Load the farm state	Only when the vehicle does not move.
`H` and `U`	Harvester on or off, unload	Only in a session with the option `-FarmHarvester`.

Implement#

The keys Q, E, O, F, T, Y, G, B, the arrow keys, Page Up, Page Down, Home and End operate the implement. The tutorial Attach and Operate Implements gives these keys.

HUD and Panels#

The HUD has these parts.

Position	Content
Top left	The help box. It shows the primary keys for the first 12 seconds, then hints.
Top right	The clock and the weather. Status lines below it, for example "Diff Lock".
Right, below the clock	The work panels: the implement panel (with an implement) and the panel "Energy".
Bottom left	The map of the tile with the vehicle position. The field number shows above the map when the vehicle goes into a field.
Bottom right	The speed in km/h, the gear and the engine speed with a bar.

The gear shows as F and the gear number, or R and the gear number in reverse. The last 8 % of the engine speed bar are red.

The panel "Energy" has these lines.

Line	Content
Title	The fuel power in kW.
Fuel	The fuel rate in L/h, the fuel for each hectare and the fuel that the session used.
Engine	The engine speed, the brake power of the engine and the hand throttle.
Slip	The mean slip of the front wheels and of the rear wheels, and the tractive efficiency (TE).
Soil	The soil class below the rear wheels, its saturation and its cone index. Only on soil.
Ruts	The sinkage of the front and the rear wheels, and the surface wetness. Only on soil.
Bar	The fuel power in seven groups: engine, PTO, hydraulics, driveline, tyres, soil and traction.

The page Energy and Fuel gives the terms of the bar.

The engineering panel (F1) shows the values of the physics step as text.

Line	Content
1	The time and the number of the physics step.
3	The speed, the engine speed, the surface, the implement, the payload and the draft.
5	The gear, MFD or 2WD, and the differential lock.
6 to 9	For each wheel (FL, FR, RL, RR): the load in kN, the slip, the sinkage in cm and the ground pressure in kPa.

Drive on a Field#

This procedure drives the Maxxum on field F21, a field with silt loam. The start position is on the field and the tractor points north. The values are those of one session with the shipped configuration. Your values can be different by a small quantity.

Start a session on the field with a session log.
```
Packaged/Linux/Acres.sh -VehicleDemo -VehicleSpawnU=480 -VehicleSpawnV=405 \
  -VehicleSpawnYaw=-90 -SessionLog -VehicleOutput=/tmp/acres-drive
```
Expected Result

The Maxxum is on the field. The HUD shows 0 km/h, the gear F10 and an engine speed of 796 rpm. The panel "Energy" shows a fuel rate of 1.0 L/h. The line "Soil" shows "Silt loam", 44 % saturated and a cone index of 2.4 MPa.
Press [ two times to select gear 8.

Expected Result

The HUD shows the gear F8.
Hold W for 10 seconds.

Expected Result

The speed increases to 9 km/h in 1 second. The engine speed is 2260 rpm. The panel "Energy" shows 7.6 L/h, an engine power of 17 kW and a fuel power of 76 kW. The line "Slip" shows 1.2 % for the front wheels, 0.3 % for the rear wheels and a TE of 0.10.
Hold W and press F1. Read the lines of the wheels. Then press F1 again.

Expected Result

The front wheels show a load of 11.4 kN and a pressure of 79 kPa. The rear wheels show 17.0 kN and 82 kPa. All wheels show a sinkage of 1.1 cm.
Release W and do not brake for 4 seconds.

Expected Result

The fuel rate goes to 0.0 L/h, because the clutch is open and the governor gives no fuel. The Maxxum coasts. The speed decreases from 8.7 km/h to 3.3 km/h in 4 seconds.
Hold S until the Maxxum stops.

Expected Result

The Maxxum stops in less than 0.5 seconds.
Press P to apply the park brake. Then press = ten times.

Expected Result

The line "Engine" shows "hand 50 %". The engine speed increases to 1546 rpm and the fuel rate is 3.0 L/h. The Maxxum does not move, because the brake keeps the clutch open.
Press - ten times. Then press P to release the park brake.

Expected Result

The engine speed decreases slowly to the idle speed of 796 rpm. The fuel rate is 0.0 L/h until the engine is at the idle speed.
Press ] three times to select gear 11. Press L one time.

Expected Result

The HUD shows the gear F11. The status line "Diff Lock" shows "rear".
Hold W for 8 seconds. Then release W and hold S.

Expected Result

The speed increases to 16 km/h in 2 seconds. The engine speed is 2256 rpm and the fuel rate is 8.7 L/h. With the full brake, the Maxxum stops from 15.7 km/h in approximately 1 second.
Press L two times to release the differential lock. Press [ three times, then press V.

Expected Result

The status line "Diff Lock" goes away. The gear shows R8.
Hold W for 5 seconds. Then release W and hold S until the Maxxum stops.

Expected Result

The Maxxum moves rearward at 9 km/h. The engine speed is 2262 rpm.
Press V to select forward. Press [ two times to select gear 6.
Hold W and A together for 20 seconds. Then release the keys and hold S.

Expected Result

The front wheels turn to the left lock in 1 second. The Maxxum moves at 5 km/h in a circle with a diameter of 8 m. The line "Slip" shows approximately 9 % for the front wheels and 7 % for the rear wheels. The fuel rate is 8.2 L/h.
Press Esc to stop the session.

Expected Result

The folder /tmp/acres-drive contains tractor.csv with one row for each physics step and session-summary.json.

The speeds agree with the gear table of Maxxum 150 Dynamics: 8.4 km/h for gear 8 and 15.4 km/h for gear 11 at 2200 rpm. The engine speed is above 2200 rpm because the load is low. The governor decreases the engine speed by 100 rpm from no load to full load.

The radius of the circle at the rear axle is 4.0 m. The steering geometry gives 3.4 m without slip. The difference comes from the slip of the tyres. The front axle moves on a larger circle than the rear axle. The rigid front-wheel drive turns the front tyres too slowly for that circle, thus their slip is negative (-10 % in the session log).

Read the Session Log#

The session log contains the values of the HUD for each physics step. The page Session Log gives all columns.

HUD Value	Column of `tractor.csv`
Speed	`speed_mps`
Engine speed	`rpm`
Gear, direction	`gear`, `direction`
Fuel rate	`fuel_lph`
Fuel power, engine power	`fuel_power_kw`, `brake_power_kw`
Slip of a wheel	`fl_slip`, `fr_slip`, `rl_slip`, `rr_slip`
Tractive efficiency	`tractive_eff`
Sinkage of a wheel	`fl_sinkage_m` to `rr_sinkage_m`
Soil class, saturation, cone index	`soil_class`, `soil_saturation`, `cone_index_kpa`
Hand throttle, park brake, differential lock	`hand_throttle`, `park_brake`, `diff_lock`

Next Steps#

Attach and Operate Implements: add an implement and use the hitch and the PTO.
Set Soil and Weather: change the soil water and the weather, then do this drive again.
Maxxum 150 Dynamics: the model of the engine, the driveline and the steering.
Tyre and Soil: the model of the sinkage, the slip and the ruts.
Replay: drive a session again from its session log.