class Satellite(RigidBody):
d = 3 # Cartesian Embedding dimension
D = 9 #=3 euler coordinate dimension
#angular_dims = range(3)
n = 12
def __init__(self, mass=1, l=1):
self.body_graph = BodyGraph()
self.body_graph.add_extended_nd(0, m=12, moments=(1 / 2, 1 / 2,
1 / 2)) #main body
self.body_graph.add_extended_nd(1, m=3, moments=(1, 1, 1 / 8))
self.body_graph.add_joint(0,
torch.tensor([1., 0, 0]),
1,
torch.tensor([0., 0, 0]),
rotation_axis=(torch.tensor([1., 0, 0]),
torch.tensor([0, 0, 1.])))
self.body_graph.add_extended_nd(2, m=3, moments=(1, 1, 1 / 8))
self.body_graph.add_joint(0,
torch.tensor([0., -1, 0]),
2,
torch.tensor([0., 0, 0]),
rotation_axis=(torch.tensor([0., -1, 0]),
torch.tensor([0, 0, 1.])))
# self.body_graph.add_extended_nd(3,m=3,moments=(1,1,1/8))
# self.body_graph.add_joint(2,torch.tensor([1.,1,1]),3,torch.tensor([0.,0,0]),
# rotation_axis=(torch.tensor([1.,1,1])/np.sqrt(3),torch.tensor([0,0,1.])))
def sample_initial_conditions(self, N):
bodyX = torch.randn(N, 2, self.n, self.d)
return project_onto_constraints(self.body_graph, bodyX)
def potential(self, x):
""" Gravity potential """
return 0
class Rotor(RigidBody):
d = 3 # Cartesian Embedding dimension
D = 6 #=3 euler + 3 com Total body coordinate dimension
angular_dims = range(3, 6) #slice(3,None)
n = 4
dt = 0.05
integration_time = 5.
def __init__(self, mass=.1, obj='rotor'): #,moments=(1,2,3)):
verts, tris = read_obj(obj + '.obj')
_, com, covar = compute_moments(torch.from_numpy(verts[tris]))
verts -= com.numpy()[None, :] # set com as 0
# verts*=100
eigs, Q = np.linalg.eigh(covar.numpy())
#print(compute_moments(torch.from_numpy((verts@Q)[tris])))
moments = torch.diag(covar)
self.obj = (verts, tris)
self.body_graph = BodyGraph()
self.body_graph.add_extended_nd(0, mass, moments, d=3)
def sample_initial_conditions(self, N):
comEulers = (2 * torch.randn(N, 2, 6)).clamp(max=3, min=-3)
comEulers[:, :, :3] *= .1
bodyX = comEuler2bodyX(comEulers)
#bodyX = torch.randn(N,2,4,3)
#bodyX = project_onto_constraints(self.body_graph,bodyX)
return bodyX
# comEulers = (.75*torch.randn(N,2,6)).clamp(max=1.5,min=-1.5)
# comEulers[:,0,3:]*=.05
# comEulers[:,1,3:]*=1
# # comEulers[:,1,5]*=500
# comEulers[:,:,:3]*=.005
# comEulers[:,1,5]*=4
# #comEulers[]
# bodyX = comEuler2bodyX(comEulers)
# #bodyX = torch.randn(N,2,4,3) + torch.randn(N,1,1,1)
# #bodyX = project_onto_constraints(self.body_graph,bodyX)
# return bodyX
#return
def potential(self, x):
return 0.
def body2globalCoords(self, comEulers):
""" input: (bs,2,6) output: (bs,2,4,3) """
return comEuler2bodyX(comEulers)
def global2bodyCoords(self, bodyX):
""" input: (bs,2,4,3) output: (bs,2,6)"""
comEuler = bodyX2comEuler(bodyX)
#unwrap euler angles for continuous trajectories
unwrapped_angles = torch.from_numpy(
np.unwrap(comEuler[:, 0, 3:], axis=0))
comEuler[:, 0, 3:] = unwrapped_angles.to(bodyX.device, bodyX.dtype)
return comEuler
@property
def animator(self):
return RigidAnimation
def __init__(self, mass=.1, obj='gyro'):
verts,tris = read_obj(obj+'.obj')
verts[:,2] -= verts[:,2].min() # set bottom as 0
_,com,covar = compute_moments(torch.from_numpy(verts[tris]))
print(torch.diag(torch.diag(covar).sum()*torch.eye(3)-covar),torch.diag(covar))
self.obj = (verts,tris,com.numpy())
self.body_graph = BodyGraph()
self.body_graph.add_extended_nd(0,m=mass,moments=100*torch.diag(covar))
self.body_graph.add_joint(0,-com,pos2=torch.tensor([0.,0.,0.]))
def __init__(self, mass=.1, obj='rotor'): #,moments=(1,2,3)):
verts, tris = read_obj(obj + '.obj')
_, com, covar = compute_moments(torch.from_numpy(verts[tris]))
verts -= com.numpy()[None, :] # set com as 0
# verts*=100
eigs, Q = np.linalg.eigh(covar.numpy())
#print(compute_moments(torch.from_numpy((verts@Q)[tris])))
moments = torch.diag(covar)
self.obj = (verts, tris)
self.body_graph = BodyGraph()
self.body_graph.add_extended_nd(0, mass, moments, d=3)
def __init__(self, bobs=2, m=1, l=1,k=10):
self.body_graph = BodyGraph()#nx.Graph()
self.arg_string = f"n{bobs}m{m or 'r'}l{l}"
with FixedNumpySeed(0):
ms = [.6+.8*np.random.rand() for _ in range(bobs)] if m is None else bobs*[m]
self.ms = copy.deepcopy(ms)
ls = bobs*[l]
self.ks = torch.tensor((bobs-1)*[k]).float()
self.locs = torch.zeros(bobs,3)
self.locs[:,0] = 1*torch.arange(bobs).float()
for i in range(bobs):
self.body_graph.add_extended_nd(i, m=ms.pop(), d=0,tether=(self.locs[i],ls.pop()))
self.n = bobs
self.D = 2*self.n # Spherical coordinates, phi, theta per bob
self.angular_dims = range(self.D)
def __init__(self, mass=1, l=1):
self.body_graph = BodyGraph()
self.body_graph.add_extended_nd(0, m=12, moments=(1 / 2, 1 / 2,
1 / 2)) #main body
self.body_graph.add_extended_nd(1, m=3, moments=(1, 1, 1 / 8))
self.body_graph.add_joint(0,
torch.tensor([1., 0, 0]),
1,
torch.tensor([0., 0, 0]),
rotation_axis=(torch.tensor([1., 0, 0]),
torch.tensor([0, 0, 1.])))
self.body_graph.add_extended_nd(2, m=3, moments=(1, 1, 1 / 8))
self.body_graph.add_joint(0,
torch.tensor([0., -1, 0]),
2,
torch.tensor([0., 0, 0]),
rotation_axis=(torch.tensor([0., -1, 0]),
torch.tensor([0, 0, 1.])))
def __init__(self, links=2, beams=False, m=None, l=None):
self.body_graph = BodyGraph() #nx.Graph()
self.arg_string = f"n{links}{'b' if beams else ''}m{m or 'r'}l{l or 'r'}"
assert not beams, "beams temporarily not supported"
with FixedNumpySeed(0):
ms = [.6 + .8 * np.random.rand()
for _ in range(links)] if m is None else links * [m]
ls = [.6 + .8 * np.random.rand()
for _ in range(links)] if l is None else links * [l]
self.ms = copy.deepcopy(ms)
self.body_graph.add_extended_nd(0,
m=ms.pop(),
d=0,
tether=(torch.zeros(2), ls.pop()))
for i in range(1, links):
self.body_graph.add_extended_nd(i, m=ms.pop(), d=0)
self.body_graph.add_edge(i - 1, i, l=ls.pop())
self.D = self.n = links
self.angular_dims = range(links)
def __init__(self, links=2, beams=False, m=1, l=1):
self.body_graph = BodyGraph() #nx.Graph()
self.arg_string = f"n{links}{'b' if beams else ''}m{m}l{l}"
beam_moments = torch.tensor([m * l * l / 12])
if beams:
self.body_graph.add_extended_nd(0, m=m, moments=beam_moments, d=1)
self.body_graph.add_joint(0, torch.tensor([l / 2]))
for i in range(1, links):
self.body_graph.add_extended_nd(i,
m=m,
moments=beam_moments,
d=1)
self.body_graph.add_joint(i - 1, torch.tensor([-l / 2]), i,
torch.tensor([l / 2]))
else:
self.body_graph.add_node(0, m=m, tether=torch.zeros(2), l=l)
for i in range(1, links):
self.body_graph.add_node(i, m=m)
self.body_graph.add_edge(i - 1, i, l=l)
def __init__(self, mass=3, l=1, q=.3, magnets=2):
with FixedNumpySeed(0):
mass = np.random.rand() * .8 + 2.4 if mass is None else mass
self.ms = [mass]
self.arg_string = f"m{mass or 'r'}l{l}q{q}mn{magnets}"
self.body_graph = BodyGraph()
self.body_graph.add_extended_nd(0,
m=mass,
d=0,
tether=(torch.zeros(3), l))
self.q = q # magnetic moment magnitude
theta = torch.linspace(0, 2 * np.pi, magnets + 1)[:-1]
self.magnet_positions = torch.stack(
[
0.1 * theta.cos(), 0.1 * theta.sin(),
-(1.05) * l * torch.ones_like(theta)
],
dim=-1,
)
self.magnet_dipoles = q * torch.stack(
[0 * theta, 0 * theta,
torch.ones_like(theta)], dim=-1) # +z direction
class CoupledPendulum(MagnetPendulum):
d=3
def __init__(self, bobs=2, m=1, l=1,k=10):
self.body_graph = BodyGraph()#nx.Graph()
self.arg_string = f"n{bobs}m{m or 'r'}l{l}"
with FixedNumpySeed(0):
ms = [.6+.8*np.random.rand() for _ in range(bobs)] if m is None else bobs*[m]
self.ms = copy.deepcopy(ms)
ls = bobs*[l]
self.ks = torch.tensor((bobs-1)*[k]).float()
self.locs = torch.zeros(bobs,3)
self.locs[:,0] = 1*torch.arange(bobs).float()
for i in range(bobs):
self.body_graph.add_extended_nd(i, m=ms.pop(), d=0,tether=(self.locs[i],ls.pop()))
self.n = bobs
self.D = 2*self.n # Spherical coordinates, phi, theta per bob
self.angular_dims = range(self.D)
def sample_initial_conditions(self, bs):
n = len(self.body_graph.nodes)
angles_and_angvel = .3*torch.randn(bs, 2, 2*n) # (bs,2,n)
angles_and_angvel[:,0,1::2] += np.pi/2
angles_and_angvel[:,0,::2] += np.pi
z = self.body2globalCoords(angles_and_angvel) #(bs,2,n,d)
#z[:,0] += self.locs.to(z.device,z.dtype)
#z[:,0] += .2*torch.randn(bs,n,3)
#z[:,1,-1] = 1.0*torch.randn(bs,3)
#z[:,1] = .5*z[:,1] + .4*torch.randn(bs,n,3)
try: return project_onto_constraints(self.body_graph,z,tol=1e-5)
except OverflowError: return self.sample_initial_conditions(bs)
# def sample_initial_conditions(self, bs):
# n = len(self.body_graph.nodes)
# angles_and_angvel = .5*torch.randn(bs, 2, 2*n) # (bs,2,n)
# angles_and_angvel[:,0,:] += np.pi/2
# angles_and_angvel[:,0,::2] -= np.pi
# z = self.body2globalCoords(angles_and_angvel) #(bs,2,n,d)
# #z[:,0] += self.locs.to(z.device,z.dtype)
# #z[:,0] += .2*torch.randn(bs,n,3)
# z[:,1,-1] = 2*torch.randn(bs,3)
# #z[:,1] = .5*z[:,1] + .4*torch.randn(bs,n,3)
# try: return project_onto_constraints(self.body_graph,z,tol=1e-5)
# except OverflowError: return self.sample_initial_conditions(bs)
def global2bodyCoords(self, global_pos_vel):
""" input (bs,2,n,3) output (bs,2,dangular=2n) """
xyz = copy.deepcopy(global_pos_vel)
xyz[:,0] -= self.locs.to(xyz.device,xyz.dtype)
return super().global2bodyCoords(xyz)
def body2globalCoords(self, angles_omega):
""" input (bs,2,dangular=2n) output (bs,2,n,3) """
xyz = super().body2globalCoords(angles_omega)
xyz[:,0]+=self.locs.to(xyz.device,xyz.dtype)
return xyz # (bs,2,n,3)
def potential(self, x):
"""inputs [x (bs,n,d)] Gravity potential
outputs [V (bs,)] """
gpe = 9.81*(self.M @ x)[..., 2].sum(1)
l0s = ((self.locs[1:]-self.locs[:-1])**2).sum(-1).sqrt().to(x.device,x.dtype)
xdist = ((x[:,1:,:]-x[:,:-1,:])**2).sum(-1).sqrt()
spring_energy = (.5*self.ks.to(x.device,x.dtype)*(xdist-l0s)**2).sum(1)
return gpe+spring_energy
@property
def animator(self):
return CoupledPendulumAnimation
class MagnetPendulum(RigidBody):
d = 3
n = 1
D = 2
angular_dims = range(2)
dt = 0.05
integration_time = 5.
def __init__(self, mass=3, l=1, q=.3, magnets=2):
with FixedNumpySeed(0):
mass = np.random.rand() * .8 + 2.4 if mass is None else mass
self.ms = [mass]
self.arg_string = f"m{mass or 'r'}l{l}q{q}mn{magnets}"
self.body_graph = BodyGraph()
self.body_graph.add_extended_nd(0,
m=mass,
d=0,
tether=(torch.zeros(3), l))
self.q = q # magnetic moment magnitude
theta = torch.linspace(0, 2 * np.pi, magnets + 1)[:-1]
self.magnet_positions = torch.stack(
[
0.1 * theta.cos(), 0.1 * theta.sin(),
-(1.05) * l * torch.ones_like(theta)
],
dim=-1,
)
self.magnet_dipoles = q * torch.stack(
[0 * theta, 0 * theta,
torch.ones_like(theta)], dim=-1) # +z direction
# self.magnet_positions = torch.tensor([0.,0., -1.1*l])[None]
# self.magnet_dipoles = q*torch.tensor([0.,0.,1.])[None]
def sample_initial_conditions(self, N):
# phi =torch.rand(N)*2*np.pi
# phid = .1*torch.randn(N)
# theta = (4/5)*np.pi + .1*torch.randn(N)
# thetad = 0.00*torch.randn(N)
angles_omega = torch.zeros(N, 2, 2)
angles_omega[:, 0, 0] = np.pi + .3 * torch.randn(N)
angles_omega[:, 1, 0] = .05 * torch.randn(N)
angles_omega[:, 0, 1] = np.pi / 2 + .2 * torch.randn(N)
angles_omega[:, 1, 1] = .4 * torch.randn(N)
xv = self.body2globalCoords(angles_omega)
return xv
# def sample_initial_conditions(self,N):
# angles_vel = torch.randn(N,2,2,1)
# return self.body2globalCoords(angles_vel)
def global2bodyCoords(self, global_pos_vel):
""" input (bs,2,1,3) output (bs,2,dangular=2n) """
bsT, _, n, d = global_pos_vel.shape
x, y, z = global_pos_vel[:, 0, :, :].permute(2, 0, 1)
xd, yd, zd = global_pos_vel[:, 1, :, :].permute(2, 0, 1)
x, z, xd, zd = z, -x, zd, -xd # Rotate coordinate system by 90 about y
phi = torch.atan2(y, x)
rz = (x**2 + y**2).sqrt()
r = (rz**2 + z**2).sqrt()
theta = torch.atan2(rz, z)
phid = (x * yd - y * xd) / rz**2
thetad = ((xd * x * z + yd * y * z) / rz - rz * zd) / r**2
angles = torch.stack([phi, theta], dim=-1)
angles = torch.from_numpy(np.unwrap(angles.numpy(),
axis=0)).to(r.device, r.dtype)
anglesd = torch.stack([phid, thetad], dim=-1)
angles_omega = torch.stack([angles, anglesd], dim=1)
return angles_omega.reshape(bsT, 2, 2 * n)
def body2globalCoords(self, angles_omega):
""" input (bs,2,dangular=2) output (bs,2,1,3) """
bs, _, n2 = angles_omega.shape
n = n2 // 2
euler_angles = torch.zeros(n * bs,
2,
3,
device=angles_omega.device,
dtype=angles_omega.dtype)
euler_angles[:, :, :2] = angles_omega.reshape(bs, 2, n, 2).permute(
2, 0, 1, 3).reshape(n * bs, 2, 2)
# To treat z axis of ZXZ euler angles as spherical coordinates
# simply set (alpha,beta,gamma) = (phi+pi/2,theta,0)
euler_angles[:, 0, 0] += np.pi / 2
zhat_p = euler2frame(euler_angles)[:, :, 2]
#zhat_p = -euler2frame(euler_angles)[:,:,0]
zhat_p[:, :, [0, 2]] = zhat_p[:, :, [2, 0]]
zhat_p[:, :, 0] *= -1 # rotate coordinates by -90 about y
return zhat_p.reshape(n, bs, 2, 3).permute(1, 2, 0, 3) # (bs,2,n,3)
def potential(self, x):
""" Gravity potential """
gpe = 9.81 * (self.M @ x)[..., :, 2].sum(
-1) # (self.M @ x)[..., 2].sum(1)
ri = self.magnet_positions.to(x.device, x.dtype)
mi = self.magnet_dipoles[None].to(x.device, x.dtype) # (1,magnets,d)
r0 = x.squeeze(-2) # (bs,1,d) -> (bs,d)
m0 = (self.q * r0 / (r0**2).sum(-1, keepdims=True))[:, None] #(bs,1,d)
r0i = (ri[None] - r0[:, None]) # (bs,magnets,d)
m0dotr0i = (m0 * r0i).sum(
-1) #([email protected](-1,-2)).squeeze(-1) # (bs,magnets)
midotr0i = (mi * r0i).sum(-1)
m0dotmi = (m0 * mi).sum(-1)
r0inorm2 = (r0i * r0i).sum(-1)
dipole_energy = ((-3 * m0dotr0i * midotr0i - r0inorm2 * m0dotmi) /
(4 * np.pi * r0inorm2**(5 / 2))).sum(-1) # (bs,)
return gpe + dipole_energy #(bs,)
def __str__(self):
return f"{self.__class__}{self.arg_string}"
def __repr__(self):
return str(self)
@property
def animator(self):
return MagnetPendulumAnimation
class Gyroscope(RigidBody):
d=3 # Cartesian Embedding dimension
D=3 #=3 euler coordinate dimension
angular_dims = range(3)
n=4
dt=0.02
integration_time = 2
def __init__(self, mass=.1, obj='gyro'):
verts,tris = read_obj(obj+'.obj')
verts[:,2] -= verts[:,2].min() # set bottom as 0
_,com,covar = compute_moments(torch.from_numpy(verts[tris]))
print(torch.diag(torch.diag(covar).sum()*torch.eye(3)-covar),torch.diag(covar))
self.obj = (verts,tris,com.numpy())
self.body_graph = BodyGraph()
self.body_graph.add_extended_nd(0,m=mass,moments=100*torch.diag(covar))
self.body_graph.add_joint(0,-com,pos2=torch.tensor([0.,0.,0.]))
def sample_initial_conditions(self,N):
# comEulers = torch.randn(N,2,6)
# comEulers[:,1,:3]=0
# comEulers[:,0,:3]=torch.tensor([0.,0.,1.])+.3*torch.randn(3)
# comEulers[:,0,3:] = 1*torch.randn(3)
# comEulers[:,1,3:] *=0#2#.5
# comEulers[:,1,5] = 5
# bodyX = comEuler2bodyX(comEulers)
# try: return project_onto_constraints(self.body_graph,bodyX,tol=1e-5)
# except OverflowError: return self.sample_initial_conditions(N)
eulers = (torch.rand(N,2,3)-.5)*3
#eulers[:,0,1]*=.2
eulers[:,1,0]*=3
eulers[:,1,1]*=.2
eulers[:,1,2] = (torch.randint(2,size=(N,)).float()*2-1)*(torch.randn(N)+7)*1.5
return self.body2globalCoords(eulers)
def body2globalCoords(self,eulers):
""" input: (bs,2,3) output: (bs,2,4,3) """
coms = torch.zeros_like(eulers)
comEulers = torch.cat([coms,eulers],dim=-1)
bodyX = comEuler2bodyX(comEulers)
# need to offset x,v so that joint is stationary
# pos joint =
body_attachment = self.body_graph.nodes[0]['joint'][0].to(eulers.device,eulers.dtype)
ct = torch.cat([1-body_attachment.sum()[None],body_attachment])
global_coords_attachment_point = (bodyX*ct[:,None]).sum(-2,keepdims=True) #(bs,2,3)
return bodyX-global_coords_attachment_point
def global2bodyCoords(self,bodyX):
""" input: (bs,2,4,3) output: (bs,2,3)"""
eulers = bodyX2comEuler(bodyX)[...,3:] # unwrap the euler angles
eulers[:,0,:] = torch.from_numpy(np.unwrap(eulers[:,0,:].numpy(),axis=0)).to(bodyX.device,bodyX.dtype)
# print(eulers[:,0])
# assert False
return eulers
def potential(self, x):
""" Gravity potential """
return 9.81*(self.M @ x)[..., 2].sum(1)
@property
def animator(self):
return RigidAnimation
class ChainPendulum(RigidBody):
d = 2
dt = .03
integration_time = 3
def __init__(self, links=2, beams=False, m=None, l=None):
self.body_graph = BodyGraph() #nx.Graph()
self.arg_string = f"n{links}{'b' if beams else ''}m{m or 'r'}l{l or 'r'}"
assert not beams, "beams temporarily not supported"
with FixedNumpySeed(0):
ms = [.6 + .8 * np.random.rand()
for _ in range(links)] if m is None else links * [m]
ls = [.6 + .8 * np.random.rand()
for _ in range(links)] if l is None else links * [l]
self.ms = copy.deepcopy(ms)
self.body_graph.add_extended_nd(0,
m=ms.pop(),
d=0,
tether=(torch.zeros(2), ls.pop()))
for i in range(1, links):
self.body_graph.add_extended_nd(i, m=ms.pop(), d=0)
self.body_graph.add_edge(i - 1, i, l=ls.pop())
self.D = self.n = links
self.angular_dims = range(links)
def body2globalCoords(self, angles_omega):
d = 2
n = len(self.body_graph.nodes)
N = angles_omega.shape[0]
pvs = torch.zeros(N,
2,
n,
d,
device=angles_omega.device,
dtype=angles_omega.dtype)
global_position_velocity = torch.zeros(N,
2,
d,
device=angles_omega.device,
dtype=angles_omega.dtype)
length = self.body_graph.nodes[0]["tether"][1]
global_position_velocity[:, 0, :] = self.body_graph.nodes[0]["tether"][
0][None]
global_position_velocity += self.joint2cartesian(
length, angles_omega[..., 0])
pvs[:, :, 0] = global_position_velocity
for (_, j), length in nx.get_edge_attributes(self.body_graph,
"l").items():
global_position_velocity += self.joint2cartesian(
length, angles_omega[..., j])
pvs[:, :, j] = global_position_velocity
return pvs
def joint2cartesian(self, length, angle_omega):
position_vel = torch.zeros(angle_omega.shape[0],
2,
2,
device=angle_omega.device,
dtype=angle_omega.dtype)
position_vel[:, 0, 0] = length * angle_omega[:, 0].sin()
position_vel[:, 1,
0] = length * angle_omega[:, 0].cos() * angle_omega[:, 1]
position_vel[:, 0, 1] = -length * angle_omega[:, 0].cos()
position_vel[:, 1,
1] = length * angle_omega[:, 0].sin() * angle_omega[:, 1]
return position_vel
def cartesian2angle(self, rel_pos_vel):
x, y = rel_pos_vel[:, 0].T
vx, vy = rel_pos_vel[:, 1].T
angle = torch.atan2(x, -y)
omega = torch.where(angle < 1e-2, vx / (-y), vy / x)
angle_unwrapped = torch.from_numpy(np.unwrap(angle.numpy(),
axis=0)).to(
x.device, x.dtype)
return torch.stack([angle_unwrapped, omega], dim=1)
def global2bodyCoords(self, global_pos_vel):
N, _, n, d = global_pos_vel.shape
*bsT2, n, d = global_pos_vel.shape
angles_omega = torch.zeros(*bsT2,
n,
device=global_pos_vel.device,
dtype=global_pos_vel.dtype)
start_position_velocity = torch.zeros(*bsT2,
d,
device=angles_omega.device,
dtype=angles_omega.dtype)
start_position_velocity[
..., 0, :] = self.body_graph.nodes[0]["tether"][0][None]
rel_pos_vel = global_pos_vel[..., 0, :] - start_position_velocity
angles_omega[..., 0] += self.cartesian2angle(rel_pos_vel)
start_position_velocity += rel_pos_vel
for (_, j), length in nx.get_edge_attributes(self.body_graph,
"l").items():
rel_pos_vel = global_pos_vel[..., j, :] - start_position_velocity
angles_omega[..., j] += self.cartesian2angle(rel_pos_vel)
start_position_velocity += rel_pos_vel
return angles_omega
def sample_initial_conditions(self, N):
n = len(self.body_graph.nodes)
angles_and_angvel = torch.randn(N, 2, n) # (N,2,n)
z = self.body2globalCoords(angles_and_angvel)
#z = torch.randn(N,2,n,2)
z[:, 0] += .2 * torch.randn(N, n, 2)
z[:, 1] = (.5 * z[:, 1] + .4 * torch.randn(N, n, 2)) * 3
try:
return project_onto_constraints(self.body_graph, z, tol=1e-5)
except OverflowError:
return self.sample_initial_conditions(N)
# return
def potential(self, x):
""" Gravity potential """
return 9.81 * (self.M @ x)[..., 1].sum(1)
def __str__(self):
return f"{self.__class__}{self.arg_string}"
def __repr__(self):
return str(self)
@property
def animator(self):
return PendulumAnimation