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README.md

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Overview

To better represent vehicle dynamics during extreme maneuvers and enable off-roading applications, it is necessary to model vehicle pitch and improve the representation of vehicle roll. The 24 DOF model, which considers the suspension at each corner, offers the same benefits as the 18 DOF model, but it can also predict vehicle heave and pitch motions. The chassis model now includes 6 DOF at the vehicle lumped Centre of Mass (C.M) (compared to 4 in the 18 DOF model), and 1 additional DOF at the four corners of the vehicle for vertical suspension travel. The body is again modeled as rigid, with body-fixed coordinates attached to the C.M and aligned in the principal directions. This model assumes the same engine, torque converter, powertrain and TMeasy tires as the 11 DOF and 18 DOF models and takes the same normalized inputs - Throttle $\in [0,1]$, Braking $\in [0,1]$ and Steering $\in [-1,1]$ where $-1$ is a full left turn. See chapter 2 here for more details.

Where do I set model parameters?

Model parameters are set through JSON files which are then used in the construct solver function. Examples of these JSON files are available for 2 different vehicles in data/json/HMMWV and data/json/Sedan. Examples of use are available in demos.

How do I provide driver-inputs?

Driver Inputs can be provided at run-time during the simualtion or before the beginning of the simulation. For examples on provided driver inputs at run-time, see demos/HMMWV/demo_hmmwv_hi_step.cpp.
These inputs can also be provided before the simulation begins through text files. See data/input/acc.txt for an example. Here, the first column is the time, second column is steering, third column is throttle and the last column is braking. The solver then computes the steering, throttle and braking inputs at a given time through linear-interpolation. See demos/HMMWV/demo_hmmwv_hi for more details.

How do I run the demos?

See here for a general description of how to run the demos. For the 11 DOF model, the demos are placed in the demos folder. The demos are built in the build folder. The demos require command line arguments specifying the input controls for the vehicles. For a description of how to create these control input files, or how to use the default control input files provided, see here.