Hello,
Do you want to get the angle by which the tire-wheel steers? GetSteering
will only give you the normalized steering input (between -1 and 1) that
the driver applies onto the steering wheel at the current time step.
If you would like to get the tire-wheel steer angle, you could do something
like this
// Get the right wheel state
auto state = vehicle.GetWheel(0,
VehicleSide{RIGHT})->GetState();
// Wheel normal (expressed in global frame)
ChVector<> wheel_normal = state.rot.GetYaxis();
// Terrain normal at wheel location (expressed in global frame)
ChVector<> Z_dir = terrain.GetNormal(state.pos);
// Longitudinal (heading) and lateral directions, in the
terrain plane
ChVector<> X_dir = Vcross(wheel_normal, Z_dir);
X_dir.Normalize();
ChVector<> Y_dir = Vcross(Z_dir, X_dir);
// Tire reference coordinate system
ChMatrix33<> rot;
rot.Set_A_axis(X_dir, Y_dir, Z_dir);
ChCoordsys<> tire_csys(state.pos, rot.Get_A_quaternion());
// Express wheel normal in tire frame
ChVector<> n =
tire_csys.TransformDirectionParentToLocal(wheel_normal);
// Wheel normal in the Vehicle frame
ChVector<> n_v =
vehicle.GetTransform().TransformDirectionParentToLocal(wheel_normal);
// Toe-in
auto toe_in_r = std::atan2(n_v.x(), n_v.y());
However, I do not understand what you mean by "steering velocity and
acceleration", do you want to control the lateral velocity and acceleration
of the vehicle?
On Monday, October 23, 2023 at 9:23:40 AM UTC-5 [email protected] wrote:
> Hello,
>
> Thank you so much for providing this wonderful simulator.
> I'm new to Pychrono and I have a question.
>
> I'm trying to modify demo_VEH_SteeringController.py so that the vehicle
> can accept steering velocity and acceleration commands. I want to convert
> these two commands into throttle, brake, and steering input.
> ChPathFillowerDriver has GetSteering to get the driver steering *input,*
> but how can I get the *current actual *steering angle so that I can
> implement a PID controller for the steering?
>
> Or in this simulation, is it assumed that the driver steering input is
> always the same as the actual steering?
>
> Best regards,
> Urara
>
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