def __init__(self,
name,
masscenter=None,
mass=None,
frame=None,
central_inertia=None):
self.name = name
self.loads = []
if frame is None:
frame = ReferenceFrame(name + '_frame')
if masscenter is None:
masscenter = Point(name + '_masscenter')
if central_inertia is None and mass is None:
ixx = Symbol(name + '_ixx')
iyy = Symbol(name + '_iyy')
izz = Symbol(name + '_izz')
izx = Symbol(name + '_izx')
ixy = Symbol(name + '_ixy')
iyz = Symbol(name + '_iyz')
_inertia = (inertia(frame, ixx, iyy, izz, ixy, iyz,
izx), masscenter)
else:
_inertia = (central_inertia, masscenter)
if mass is None:
_mass = Symbol(name + '_mass')
else:
_mass = mass
masscenter.set_vel(frame, 0)
# If user passes masscenter and mass then a particle is created
# otherwise a rigidbody. As a result a body may or may not have inertia.
if central_inertia is None and mass is not None:
self.frame = frame
self.masscenter = masscenter
Particle.__init__(self, name, masscenter, _mass)
else:
RigidBody.__init__(self, name, masscenter, frame, _mass, _inertia)
def __init__(self, name, masscenter=None, mass=None, frame=None,
central_inertia=None):
self.name = name
self.loads = []
if frame is None:
frame = ReferenceFrame(name + '_frame')
if masscenter is None:
masscenter = Point(name + '_masscenter')
if central_inertia is None and mass is None:
ixx = Symbol(name + '_ixx')
iyy = Symbol(name + '_iyy')
izz = Symbol(name + '_izz')
izx = Symbol(name + '_izx')
ixy = Symbol(name + '_ixy')
iyz = Symbol(name + '_iyz')
_inertia = (inertia(frame, ixx, iyy, izz, ixy, iyz, izx),
masscenter)
else:
_inertia = (central_inertia, masscenter)
if mass is None:
_mass = Symbol(name + '_mass')
else:
_mass = mass
masscenter.set_vel(frame, 0)
# If user passes masscenter and mass then a particle is created
# otherwise a rigidbody. As a result a body may or may not have inertia.
if central_inertia is None and mass is not None:
self.frame = frame
self.masscenter = masscenter
Particle.__init__(self, name, masscenter, _mass)
else:
RigidBody.__init__(self, name, masscenter, frame, _mass, _inertia)
def __init__(self, name, mass=None, J_G=None, rho_G=None, J_diag=False):
"""
Define a rigid body and introduce symbols for convenience.
Origin point have no velocities in the body frame!
INPUTS:
name: string (can be one character), make sure this string is unique between all bodies
OPTIONAL INPUTS:
mass : scalar, body mass
J_G : 3x3 array or 3-array defining the coordinates of the inertia tensor in the body frame at the COG
rho_G: array-like of length 3 defining the coordinates of the COG in the body frame
J_diag: if true, the inertial tensor J_G is initialized as diagonal
"""
# YAMS Body creates a default "origin", "masscenter", and "frame"
YAMSBody.__init__(self, name)
# --- Mass
if mass is None:
mass = Symbol('M_' + name)
# --- Inertia, creating a dyadic using our frame and G
if J_G is not None:
if len(list(J_G)) == 3:
ixx = J_G[0]
iyy = J_G[1]
izz = J_G[2]
ixy, iyz, izx = 0, 0, 0
else:
J_G = ensureMat(J_G, 3, 3)
ixx = J_G[0, 0]
iyy = J_G[1, 1]
izz = J_G[2, 2]
izx = J_G[2, 0]
ixy = J_G[0, 1]
iyz = J_G[1, 2]
else:
ixx = Symbol('J_xx_' + name)
iyy = Symbol('J_yy_' + name)
izz = Symbol('J_zz_' + name)
izx = Symbol('J_zx_' + name)
ixy = Symbol('J_xy_' + name)
iyz = Symbol('J_yz_' + name)
if J_diag:
ixy, iyz, izx = 0, 0, 0
#inertia: dyadic : (inertia(frame, *list), point)
_inertia = (inertia(self.frame, ixx, iyy, izz, ixy, iyz,
izx), self.masscenter)
# --- Position of COG in body frame
if rho_G is None:
rho_G = symbols('x_G_' + name + ', y_G_' + name + ', z_G_' + name)
self.setGcoord(rho_G)
self.masscenter.set_vel(self.frame, 0 * self.frame.x)
# Init Sympy Rigid Body
SympyRigidBody.__init__(self, name, self.masscenter, self.frame, mass,
_inertia)
