"""
Chassis Class
=============
The `Chassis` class represents the physical properties and state of the vehicle's chassis in the simulation.
It includes geometric dimensions, mass, inertia properties, and aerodynamic characteristics.
.. code-block::
#
# |<--rear_axle_to_com-->|<--front_axle_to_com-->|
#
# |.....|
# |---|.....|-------------\ | |
# | / \ \-----------------------|...|--------| ---
# | | | / \
# | | | |
# | | | |
# | | com | |
# | rear_track * | front_track
# | | | |
# | | | |
# | | | |
# | | | \ /
# | \ / /-----------------------|...|--------| ---
# |---|.....|-------------/
# |.....|
#
#
+-------------------+------------------------------------------------------+
| Parameter | Description |
+===================+======================================================+
| front_axle_to_com | distance between the front axle and the vehicle CoM |
+-------------------+------------------------------------------------------+
| rear_axle_to_com | distance between the rear axle and the vehicle CoM |
+-------------------+------------------------------------------------------+
| wheelbase | front_axle_to_com + rear_axle_to_com |
+-------------------+------------------------------------------------------+
| front_track | front track |
+-------------------+------------------------------------------------------+
| rear_track | rear track |
+-------------------+------------------------------------------------------+
| com_height | CoM height |
+-------------------+------------------------------------------------------+
| total_mass | total mass of the chassis |
+-------------------+------------------------------------------------------+
| inertia_x | x-axis vehicle inertia (w.r.t. CoM) |
+-------------------+------------------------------------------------------+
| inertia_y | y-axis vehicle inertia (w.r.t. CoM) |
+-------------------+------------------------------------------------------+
| inertia_z | z-axis vehicle inertia (w.r.t. CoM) |
+-------------------+------------------------------------------------------+
| drag_coefficient | aerodynamics drag coefficient |
+-------------------+------------------------------------------------------+
| lift_coefficient | aerodynamics lift coefficient |
+-------------------+------------------------------------------------------+
"""
from pymycar.files import append_results_to_file
[docs]
class Chassis:
"""
The `Chassis` class represents the physical properties and state of the vehicle's chassis in the simulation.
It includes geometric dimensions, mass, inertia properties, and aerodynamic characteristics.
Attributes
----------
front_axle_to_com : float
The distance between the front axle and the vehicle's center of mass (CoM). (default: 1.48 m)
rear_axle_to_com : float
The distance between the rear axle and the vehicle's center of mass (CoM). (default: 1.12 m)
wheelbase : float
The total distance between the front and rear axles. It is the sum of `front_axle_to_com` and `rear_axle_to_com`.
front_track : float
The width of the chassis at the front axle, representing the distance between the left and right front wheels. (default: 1.71 m)
rear_track : float
The width of the chassis at the rear axle, representing the distance between the left and right rear wheels. (default: 1.62 m)
com_height : float
The height of the center of mass (CoM) from the ground. (default: 0.4 m)
mass : float
The total mass of the chassis. (default: 1400 kg)
inertia_x : float
The moment of inertia about the x-axis (roll axis) of the vehicle, with respect to the CoM. (default: 400 kg·m²)
inertia_y : float
The moment of inertia about the y-axis (pitch axis) of the vehicle, with respect to the CoM. (default: 2000 kg·m²)
inertia_z : float
The moment of inertia about the z-axis (yaw axis) of the vehicle, with respect to the CoM. (default: 1320 kg·m²)
drag_coefficient : float
The drag coefficient used for aerodynamic calculations. (default: 0.34)
lift_coefficient : float
The lift coefficient used for aerodynamic calculations. (default: 0.0)
Methods
-------
__init__(front_axle_to_com, rear_axle_to_com, front_track, rear_track, com_height, mass, inertia_x, inertia_y, inertia_z, drag_coefficient, lift_coefficient)
Initializes the chassis with the specified or default parameters.
update_state(dt)
Updates the chassis's position and orientation based on the velocity and angular velocity for the given time step (`dt`).
save_state()
Saves the current state of the chassis, including CAD data, at the current simulation step.
set_velocity(vx, vy, vz, roll_rate, pitch_rate, yaw_rate)
Sets the chassis's linear and angular velocities, including both translational and rotational components.
print_info()
Prints the current state of the chassis, including its position, orientation, velocity, and angular velocity.
update_chassis_data(**kwargs)
Updates chassis parameters dynamically based on the provided keyword arguments.
save_log_info(logger)
Logs the chassis parameters in a tabular format using the provided logger instance.
"""
def __init__(
self,
front_axle_to_com=None,
rear_axle_to_com=None,
front_track=None,
rear_track=None,
com_height=None,
mass=None,
inertia_x=None,
inertia_y=None,
inertia_z=None,
drag_coefficient=None,
lift_coefficient=None
):
"""
Initializes the chassis with the specified or default parameters.
Parameters
----------
front_axle_to_com : float, optional
The distance between the front axle and the center of mass (CoM) of the vehicle (default: 1.48 m).
rear_axle_to_com : float, optional
The distance between the rear axle and the center of mass (CoM) of the vehicle (default: 1.12 m).
front_track : float, optional
The width of the vehicle at the front axle (default: 1.71 m).
rear_track : float, optional
The width of the vehicle at the rear axle (default: 1.62 m).
com_height : float, optional
The height of the center of mass from the ground (default: 0.4 m).
mass : float, optional
The total mass of the chassis (default: 1400 kg).
inertia_x : float, optional
Moment of inertia about the x-axis (roll axis) relative to the CoM (default: 400 kg·m²).
inertia_y : float, optional
Moment of inertia about the y-axis (pitch axis) relative to the CoM (default: 2000 kg·m²).
inertia_z : float, optional
Moment of inertia about the z-axis (yaw axis) relative to the CoM (default: 1320 kg·m²).
drag_coefficient : float, optional
The drag coefficient used for aerodynamic calculations (default: 0.34).
lift_coefficient : float, optional
The lift coefficient used for aerodynamic calculations (default: 0.0).
"""
# Geometry
self.front_axle_to_com = front_axle_to_com
self.rear_axle_to_com = rear_axle_to_com
# Only calculate wheelbase if both front_axle_to_com and rear_axle_to_com are not None
if front_axle_to_com is not None and rear_axle_to_com is not None:
self.wheelbase = front_axle_to_com + rear_axle_to_com
else:
self.wheelbase = None
self.front_track = front_track
self.rear_track = rear_track
self.com_height = com_height
# Mass
self.mass = mass
# Inertia
self.inertia_x = inertia_x
self.inertia_y = inertia_y
self.inertia_z = inertia_z
# Aerodynamics
self.drag_coefficient = drag_coefficient
self.lift_coefficient = lift_coefficient
self.time = 0.0
# Initial chassis state (position and orientation)
self.x = 0.0
self.y = 0.0
self.z = 0.0
self.roll = 0.0
self.pitch = 0.0
self.yaw = 0.0
# Initial chassis velocity and angular velocity
self.vx = 0.0
self.vy = 0.0
self.vz = 0.0
self.roll_rate = 0.0
self.pitch_rate = 0.0
self.yaw_rate = 0.0
[docs]
def update_state(self, dt):
"""
Updates the chassis's position and orientation based on the velocity and angular velocity for the given time step (`dt`).
Parameters
----------
dt : float
The time step used for updating the chassis's state.
"""
self.x += self.vx * dt
self.y += self.vy * dt
self.z += self.vz * dt
self.roll += self.roll_rate * dt
self.pitch += self.pitch_rate * dt
self.yaw += self.yaw_rate * dt
# def save_state(self):
# """
# Saves the current state of the chassis, including CAD data, at the current simulation step.
# """
# self.set_cad()
# file_name = f"chassis_cad_{self.step}.vtm"
# time_step = self.cad
# time_step.save("solution/"+file_name)
# self.step += 1
[docs]
def set_velocity(self, vx, vy, vz, roll_rate, pitch_rate, yaw_rate):
"""
Sets the chassis's linear and angular velocities, including both translational and rotational components.
Parameters
----------
vx : float
The linear velocity along the x-axis.
vy : float
The linear velocity along the y-axis.
vz : float
The linear velocity along the z-axis.
roll_rate : float
The angular velocity around the x-axis (roll).
pitch_rate : float
The angular velocity around the y-axis (pitch).
yaw_rate : float
The angular velocity around the z-axis (yaw).
"""
self.vx = vx
self.vy = vy
self.vz = vz
self.roll_rate = roll_rate
self.pitch_rate = pitch_rate
self.yaw_rate = yaw_rate
[docs]
def save_state_2_text_file(self, output_file_path):
header = '#time\tx\ty\tz\troll\tpitch\tyaw\tvx\tvy\tvz\troll_rate\tpitch_rate\tyaw_rate'
append_results_to_file(output_file_path, header, self.time, self.x, self.y, self.z,self.roll, self.pitch, self.yaw, self.vx, self.vy, self.vz,self.roll_rate, self.pitch_rate, self.yaw_rate)
[docs]
def print_info(self):
"""
Prints the current state of the chassis, including its position, orientation, velocity, and angular velocity.
"""
print(f"Chassis State:")
print(f"Position (x, y, z): ({self.x}, {self.y}, {self.z})")
print(f"Orientation (roll, pitch, yaw): ({self.roll}, {self.pitch}, {self.yaw})")
print(f"Velocity (vx, vy, vz): ({self.vx}, {self.vy}, {self.vz})")
print(f"Angular Velocity (roll_rate, pitch_rate, yaw_rate): ({self.roll_rate}, {self.pitch_rate}, {self.yaw_rate})")
[docs]
def update_chassis_data(self, **kwargs):
"""
Updates chassis parameters dynamically based on the provided keyword arguments.
Parameters
----------
**kwargs : dict
A dictionary of parameters to update in the chassis model.
"""
for key, value in kwargs.items():
if hasattr(self, key):
setattr(self, key, value)
else:
print(f"Warning: Attribute {key} does not exist in CarChassis.")
[docs]
def save_log_info(self, logger):
"""
Logs the chassis parameters in a tabular format using the provided logger instance.
Parameters
----------
logger : logging.Logger
An instance of a logger object to record the chassis parameters.
"""
data = [
("front_axle_to_com", f"{self.front_axle_to_com}"),
("rear_axle_to_com", f"{self.rear_axle_to_com}"),
("wheelbase", f"{self.front_axle_to_com + self.rear_axle_to_com}"),
("front_track", f"{self.front_track}"),
("rear_track", f"{self.rear_track}"),
("com_height", f"{self.com_height}"),
("total_mass", f"{self.mass}"),
("inertia_x", f"{self.inertia_x}"),
("inertia_y", f"{self.inertia_y}"),
("inertia_z", f"{self.inertia_z}"),
("drag_coefficient", f"{self.drag_coefficient}"),
("lift_coefficient", f"{self.lift_coefficient}"),
]
# Create the table header
logger.info("Chassis Parameters")
logger.info("================================================")
logger.info("+-------------------+--------------------------+")
logger.info("| Parameter | Value |")
logger.info("+===================+==========================+")
# Log each row of the table
for param, value in data:
logger.info(f"| {param:<17} | {value:<24} |")
logger.info("+-------------------+--------------------------+")
# # Visualization
# self.cad = None
# self.type_visualization_cad = "tourist_chassiss"
# self.step = 0
# def set_cad(self):
# if self.type_visualization_cad == "tourist_chassis":
# self.cad = tourist_chassis(
# self.front_axle_to_com,
# self.rear_axle_to_com,
# self.front_track,
# self.rear_track,
# self.com_height,
# self.roll,
# self.pitch,
# self.yaw,
# self.x,
# self.y,
# self.z)
# else:
# self.cad = model_A(
# self.front_axle_to_com,
# self.rear_axle_to_com,
# self.front_track,
# self.rear_track,
# self.com_height,
# self.roll,
# self.pitch,
# self.yaw,
# self.x,
# self.y,
# self.z)
