Пример #1
0
N = Frame('N')
A = Frame('A')
B = Frame('B')
C = Frame('C')

system.set_newtonian(N)
A.rotate_fixed_axis_directed(N, [1, 0, 0], qA, system)
B.rotate_fixed_axis_directed(A, [0, 1, 0], qB, system)
C.rotate_fixed_axis_directed(B, [0, 0, 1], qC, system)

pCcm = 0 * N.x

IC = Dyadic.build(C, Ixx, Iyy, Izz)

w1 = N.getw_(C)
w2 = wx * C.x + wy * C.y + wz * C.z
N.set_w(C, w2)

from pynamics.constraint import Constraint

eq0 = w1 - w2
eq = []
eq.append(eq0.dot(B.x))
eq.append(eq0.dot(B.y))
eq.append(eq0.dot(B.z))

c = Constraint(eq)
c.linearize(0)
system.add_constraint(c)
Пример #2
0
#    for item,value in zip(system.get_state_variables(),result.x):
#        initialvalues[item]=value

pAcm = pOA + lA / 2 * A.x
pBcm = pAB + lB / 2 * B.x
pCcm = pOC + lC / 2 * C.x
pDcm = pCD + lD / 2 * D.x
pEcm = pBtip - .1 * E.y

pE1 = pEcm + lE / 2 * E.x
vE1 = pE1.time_derivative(N, system)

pE2 = pEcm - lE / 2 * E.x
vE2 = pE2.time_derivative(N, system)

wOA = O.getw_(A)
wAB = A.getw_(B)
wOC = O.getw_(C)
wCD = C.getw_(D)
wBD = B.getw_(D)
wOE = O.getw_(E)

BodyO = Body('BodyO', O, pOcm, mO, Dyadic.build(O, I_main, I_main, I_main),
             system)
#BodyA = Body('BodyA',A,pAcm,mA,Dyadic.build(A,I_leg,I_leg,I_leg),system)
#BodyB = Body('BodyB',B,pBcm,mB,Dyadic.build(B,I_leg,I_leg,I_leg),system)
#BodyC = Body('BodyC',C,pCcm,mC,Dyadic.build(C,I_leg,I_leg,I_leg),system)
#BodyD = Body('BodyD',D,pDcm,mD,Dyadic.build(D,I_leg,I_leg,I_leg),system)
BodyE = Body('BodyE', E, pEcm, mE, Dyadic.build(D, I_leg, I_leg, I_leg),
             system)
def init_system(v, drag_direction, time_step):
    import pynamics
    from pynamics.frame import Frame
    from pynamics.variable_types import Differentiable, Constant
    from pynamics.system import System
    from pynamics.body import Body
    from pynamics.dyadic import Dyadic
    from pynamics.output import Output, PointsOutput
    from pynamics.particle import Particle
    import pynamics.integration
    import logging
    import sympy
    import numpy
    import matplotlib.pyplot as plt
    from math import pi
    from scipy import optimize
    from sympy import sin
    import pynamics.tanh as tanh

    from fit_qs import exp_fit
    import fit_qs

    # time_step = tstep
    x = numpy.zeros((7, 1))
    friction_perp = x[0]
    friction_par = x[1]
    given_b = x[2]
    given_k = x[3]
    given_k1 = x[4]
    given_b1 = x[4]
    system = System()
    pynamics.set_system(__name__, system)
    global_q = True

    lO = Constant(7 / 1000, 'lO', system)
    lA = Constant(33 / 1000, 'lA', system)
    lB = Constant(33 / 1000, 'lB', system)
    lC = Constant(33 / 1000, 'lC', system)

    mO = Constant(10 / 1000, 'mA', system)
    mA = Constant(2.89 / 1000, 'mA', system)
    mB = Constant(2.89 / 1000, 'mB', system)
    mC = Constant(2.89 / 1000, 'mC', system)
    k = Constant(0.209, 'k', system)
    k1 = Constant(0.209, 'k1', system)

    friction_perp = Constant(1.2, 'f_perp', system)
    friction_par = Constant(-0.2, 'f_par', system)
    b_damping = Constant(given_b, 'b_damping', system)

    # time_step = 1/00

    if v == 0:
        [
            t, tinitial, tfinal, tstep, qAa1, qAb1, qAc1, qAa2, qAb2, qAc2,
            qAa3, qAb3, qAc3, qBa1, qBb1, qBc1, qBa2, qBb2, qBc2, qBa3, qBb3,
            qBc3, qCa1, qCb1, qCc1, qCa2, qCb2, qCc2, qCa3, qCb3, qCc3
        ] = fit_qs.fit_0_amount(time_step)
    elif v == 10:
        [
            t, tinitial, tfinal, tstep, qAa1, qAb1, qAc1, qAa2, qAb2, qAc2,
            qAa3, qAb3, qAc3, qBa1, qBb1, qBc1, qBa2, qBb2, qBc2, qBa3, qBb3,
            qBc3, qCa1, qCb1, qCc1, qCa2, qCb2, qCc2, qCa3, qCb3, qCc3
        ] = fit_qs.fit_10_amount(time_step)
    elif v == 20:
        [
            t, tinitial, tfinal, tstep, qAa1, qAb1, qAc1, qAa2, qAb2, qAc2,
            qAa3, qAb3, qAc3, qBa1, qBb1, qBc1, qBa2, qBb2, qBc2, qBa3, qBb3,
            qBc3, qCa1, qCb1, qCc1, qCa2, qCb2, qCc2, qCa3, qCb3, qCc3
        ] = fit_qs.fit_20_amount(time_step)
    elif v == 30:
        [
            t, tinitial, tfinal, tstep, qAa1, qAb1, qAc1, qAa2, qAb2, qAc2,
            qAa3, qAb3, qAc3, qBa1, qBb1, qBc1, qBa2, qBb2, qBc2, qBa3, qBb3,
            qBc3, qCa1, qCb1, qCc1, qCa2, qCb2, qCc2, qCa3, qCb3, qCc3
        ] = fit_qs.fit_30_amount(time_step)
    elif v == 40:
        [
            t, tinitial, tfinal, tstep, qAa1, qAb1, qAc1, qAa2, qAb2, qAc2,
            qAa3, qAb3, qAc3, qBa1, qBb1, qBc1, qBa2, qBb2, qBc2, qBa3, qBb3,
            qBc3, qCa1, qCb1, qCc1, qCa2, qCb2, qCc2, qCa3, qCb3, qCc3
        ] = fit_qs.fit_40_amount(time_step)
    elif v == 50:
        [
            t, tinitial, tfinal, tstep, qAa1, qAb1, qAc1, qAa2, qAb2, qAc2,
            qAa3, qAb3, qAc3, qBa1, qBb1, qBc1, qBa2, qBb2, qBc2, qBa3, qBb3,
            qBc3, qCa1, qCb1, qCc1, qCa2, qCb2, qCc2, qCa3, qCb3, qCc3
        ] = fit_qs.fit_50_amount(time_step)

    distance = 200 / 1000

    nums = int(tfinal / tstep)
    array_num = numpy.arange(0, nums)
    array_num1 = numpy.repeat(array_num, nums, axis=0)
    array_num1.shape = (nums, nums)
    error_k = array_num1 / 8000 + numpy.ones((nums, nums))

    fit_t = t
    fit_qA = exp_fit(fit_t, qAa1, qAb1, qAc1, qAa2, qAb2, qAc2, qAa3, qAb3,
                     qAc3)
    fit_qB = exp_fit(fit_t, qBa1, qBb1, qBc1, qBa2, qBb2, qBc2, qBa3, qBb3,
                     qBc3)
    fit_qC = exp_fit(fit_t, qCa1, qCb1, qCc1, qCa2, qCb2, qCc2, qCa3, qCb3,
                     qCc3)
    fit_qAd1 = numpy.diff(fit_qA) / numpy.diff(fit_t)
    fit_qAd = numpy.append(fit_qAd1[0], fit_qAd1)
    fit_qBd1 = numpy.diff(fit_qB) / numpy.diff(fit_t)
    fit_qBd = numpy.append(fit_qBd1[0], fit_qBd1)
    fit_qCd1 = numpy.diff(fit_qC) / numpy.diff(fit_t)
    fit_qCd = numpy.append(fit_qCd1[0], fit_qCd1)

    fit_states1 = numpy.stack(
        (fit_qA, fit_qB, fit_qC, fit_qAd, fit_qBd, fit_qCd), axis=1)
    fit_states1[:, 0:3] = fit_states1[:, 0:3] - fit_states1[0, 0:3]
    fit_states = -drag_direction * numpy.deg2rad(fit_states1)

    # plt.plot(t,fit_states)

    if drag_direction == -1:
        zero_shape = fit_states.shape
        fit_states = numpy.zeros(zero_shape)

    fit_vel = drag_direction * distance / (tfinal)

    if qAa1 == 0:
        fit_vel = 0
    fit_v = numpy.ones(t.shape) * fit_vel

    if qAa1 == 0:
        fit_d = numpy.ones(t.shape) * fit_vel
    else:
        fit_d = drag_direction * numpy.r_[tinitial:distance:tstep *
                                          abs(fit_vel)]

    preload0 = Constant(0 * pi / 180, 'preload0', system)
    preload1 = Constant(0 * pi / 180, 'preload1', system)
    preload2 = Constant(0 * pi / 180, 'preload2', system)
    preload3 = Constant(0 * pi / 180, 'preload3', system)

    Ixx_O = Constant(1, 'Ixx_O', system)
    Iyy_O = Constant(1, 'Iyy_O', system)
    Izz_O = Constant(1, 'Izz_O', system)
    Ixx_A = Constant(1, 'Ixx_A', system)
    Iyy_A = Constant(1, 'Iyy_A', system)
    Izz_A = Constant(1, 'Izz_A', system)
    Ixx_B = Constant(1, 'Ixx_B', system)
    Iyy_B = Constant(1, 'Iyy_B', system)
    Izz_B = Constant(1, 'Izz_B', system)
    Ixx_C = Constant(1, 'Ixx_C', system)
    Iyy_C = Constant(1, 'Iyy_C', system)
    Izz_C = Constant(1, 'Izz_C', system)

    y, y_d, y_dd = Differentiable('y', system)
    qO, qO_d, qO_dd = Differentiable('qO', system)
    qA, qA_d, qA_dd = Differentiable('qA', system)
    qB, qB_d, qB_dd = Differentiable('qB', system)
    qC, qC_d, qC_dd = Differentiable('qC', system)

    initialvalues = {}
    initialvalues[y] = 0 + 1e-14
    initialvalues[y_d] = fit_vel + 1e-14
    initialvalues[qO] = 0 + 1e-14
    initialvalues[qO_d] = 0 + 1e-14
    initialvalues[qA] = fit_states[0, 0] + 1e-14
    initialvalues[qA_d] = fit_states[0, 3] + 1e-14
    initialvalues[qB] = fit_states[0, 1] + 1e-14
    initialvalues[qB_d] = fit_states[0, 4] + 1e-14
    initialvalues[qC] = fit_states[0, 2] + 1e-14
    initialvalues[qC_d] = fit_states[0, 5] + 1e-14

    statevariables = system.get_state_variables()
    ini = [initialvalues[item] for item in statevariables]

    N = Frame('N')
    O = Frame('O')
    A = Frame('A')
    B = Frame('B')
    C = Frame('C')

    drag_direction = drag_direction
    velocity = 200 / tfinal / 1000
    vSoil = drag_direction * velocity * N.y
    nSoil = 1 / vSoil.length() * vSoil

    system.set_newtonian(N)
    if not global_q:
        O.rotate_fixed_axis_directed(N, [0, 0, 1], qO, system)
        A.rotate_fixed_axis_directed(O, [0, 0, 1], qA, system)
        B.rotate_fixed_axis_directed(A, [0, 0, 1], qB, system)
        C.rotate_fixed_axis_directed(B, [0, 0, 1], qC, system)
    else:
        O.rotate_fixed_axis_directed(N, [0, 0, 1], qO, system)
        A.rotate_fixed_axis_directed(N, [0, 0, 1], qA, system)
        B.rotate_fixed_axis_directed(N, [0, 0, 1], qB, system)
        C.rotate_fixed_axis_directed(N, [0, 0, 1], qC, system)

    pNO = 0 * N.x + y * N.y
    pOA = lO * N.x + y * N.y
    pAB = pOA + lA * A.x
    pBC = pAB + lB * B.x
    pCtip = pBC + lC * C.x

    pOcm = pNO + lO / 2 * N.x
    pAcm = pOA + lA / 2 * A.x
    pBcm = pAB + lB / 2 * B.x
    pCcm = pBC + lC / 2 * C.x

    wNO = N.getw_(O)
    wOA = N.getw_(A)
    wAB = A.getw_(B)
    wBC = B.getw_(C)

    IO = Dyadic.build(O, Ixx_O, Iyy_O, Izz_O)
    IA = Dyadic.build(A, Ixx_A, Iyy_A, Izz_A)
    IB = Dyadic.build(B, Ixx_B, Iyy_B, Izz_B)
    IC = Dyadic.build(C, Ixx_C, Iyy_C, Izz_C)

    BodyO = Body('BodyO', O, pOcm, mO, IO, system)
    BodyA = Body('BodyA', A, pAcm, mA, IA, system)
    BodyB = Body('BodyB', B, pBcm, mB, IB, system)
    BodyC = Body('BodyC', C, pCcm, mC, IC, system)
    # BodyC = Particle(pCcm,mC,'ParticleC',system)

    vOcm = pOcm.time_derivative()
    vAcm = pAcm.time_derivative()
    vBcm = pBcm.time_derivative()
    vCcm = pCcm.time_derivative()

    system.add_spring_force1(k1 + 10000 * (qA + abs(qA)),
                             (qA - qO - preload1) * N.z, wOA)
    system.add_spring_force1(k + 10000 * (qB + abs(qB)),
                             (qB - qA - preload2) * N.z, wAB)
    system.add_spring_force1(k + 10000 * (qC + abs(qC)),
                             (qC - qB - preload3) * N.z, wBC)

    #new Method use nJoint
    nvAcm = 1 / vAcm.length() * vAcm
    nvBcm = 1 / vBcm.length() * vBcm
    nvCcm = 1 / vCcm.length() * vCcm

    faperp = friction_perp * nvAcm.dot(A.y) * A.y
    fapar = friction_par * nvAcm.dot(A.x) * A.x
    system.addforce(-(faperp + fapar), vAcm)

    fbperp = friction_perp * nvBcm.dot(B.y) * B.y
    fbpar = friction_par * nvBcm.dot(B.x) * B.x
    system.addforce(-(fbperp + fbpar), vBcm)

    fcperp = friction_perp * nvCcm.dot(C.y) * C.y
    fcpar = friction_par * nvCcm.dot(C.x) * C.x
    system.addforce(-(fcperp + fcpar), vCcm)

    system.addforce(-b_damping * wOA, wOA)
    system.addforce(-b_damping * wAB, wAB)
    system.addforce(-b_damping * wBC, wBC)
    eq = []
    eq_d = [(system.derivative(item)) for item in eq]

    eq_d.append(y_d - fit_vel)
    eq_dd = [(system.derivative(item)) for item in eq_d]

    f, ma = system.getdynamics()
    func1 = system.state_space_post_invert(f, ma, eq_dd)
    points = [pNO, pOA, pAB, pBC, pCtip]
    constants = system.constant_values

    return system, f, ma, func1, points, t, ini, constants, b_damping, k, k1, tstep, fit_states
statevariables = system.get_q(0) + system.get_q(1)
ini = [initialvalues[item] for item in statevariables]

N = Frame('N')
A = Frame('A')

system.set_newtonian(N)
A.rotate_fixed_axis_directed(N, [0, 0, 1], qA, system)

pNA = 0 * N.x
#pAB=pNA+lA*A.x

pAcm = pNA - lA * A.y

wNA = N.getw_(A)

IA = Dyadic.build(A, Ixx_A, Iyy_A, Izz_A)

BodyA = Body('BodyA', A, pAcm, mA, IA, system)

#BodyA = Particle(system,pAcm,mA,'ParticleA')
#ParticleB = Particle(system,pBcm,mB,'ParticleB')
#ParticleC = Particle(system,pCcm,mC,'ParticleC')

#system.addforce(-k*(qA-preload1)*N.z,wNA)
#system.addforce(-k*(qB-preload2)*A.z,wAB)
#system.addforce(-k*(qC-preload3)*B.z,wBC)

system.addforcegravity(-g * N.y)
Пример #5
0
    for item in y:
        plt.plot(*(item.T))
#    for item,value in zip(system.get_state_variables(),result.x):
#        initialvalues[item]=value

pA1cm = pOA + lA / 4 * A1.x
pB1cm = pAB + lB / 4 * B1.x
pC1cm = pOC + lC / 4 * C1.x
pD1cm = pCD + lD / 4 * D1.x

pA2cm = pA1A2 + lA / 4 * A2.x
pB2cm = pB1B2 + lB / 4 * B2.x
pC2cm = pC1C2 + lC / 4 * C2.x
pD2cm = pD1D2 + lD / 4 * D2.x

wOA1 = O.getw_(A1)
wA1A2 = A1.getw_(A2)
wA2B1 = A2.getw_(B1)
wB1B2 = B1.getw_(B2)
wOC1 = O.getw_(C1)
wC1C2 = C1.getw_(C2)
wC2D1 = C2.getw_(D1)
wD1D2 = D1.getw_(D2)
wB2D2 = B2.getw_(D2)

#BodyO = Body('BodyO',O,pOcm,mO,Dyadic.build(O,I_main,I_main,I_main),system)
#BodyA = Body('BodyA',A,pAcm,mA,Dyadic.build(A,I_leg,I_leg,I_leg),system)
#BodyB = Body('BodyB',B,pBcm,mB,Dyadic.build(B,I_leg,I_leg,I_leg),system)
#BodyC = Body('BodyC',C,pCcm,mC,Dyadic.build(C,I_leg,I_leg,I_leg),system)
#BodyD = Body('BodyD',D,pDcm,mD,Dyadic.build(D,I_leg,I_leg,I_leg),system)
Пример #6
0
#Izz_B = Constant('Izz_B',1.98358014762822e-06,system)
#Ixx_C = Constant('Ixx_C',4.39320316677997e-07,system)
#Iyy_C = Constant('Iyy_C',7.9239401855911e-07,system)
#Izz_C = Constant('Izz_C',7.9239401855911e-07,system)
IA = Dyadic.build(A,Ixx_A,Iyy_A,Izz_A)
#IB = Dyadic.build(B,Ixx_B,Iyy_B,Izz_B)
#IC = Dyadic.build(C,Ixx_C,Iyy_C,Izz_C)

BodyA = Body('BodyA',A,pm1,m1,IA,system)
#Particle1 = Particle(system,pm1,m1,'Particle1')
Particle2 = Particle(system,pm2,m2,'Particle2')

s1 = pk1.dot(N.y)*N.y
s2 = pk2.dot(N.y)*N.y
s3 = (q2-q2_command)*A.z
wNA = A.getw_(N)
wNB = B.getw_(N)

#switch1 = 

system.add_spring_force(k,s1,vk1)
system.add_spring_force(k,s2,vk2)
system.add_spring_force(k_controller,s3,wNA)
system.add_spring_force(k_controller,-s3,wNB)

system.addforce(-b*vm1,vm1)

system.addforcegravity(-g*N.y)

#system.addforcegravity(-g*N.y)
#system.addforcegravity(-g*N.y)
Пример #7
0
def Cal_system(initial_states, drag_direction, tinitial, tstep, tfinal,
               fit_vel, f1, f2):

    g_k, g_b_damping, g_b_damping1 = [0.30867935, 1.42946955, 1.08464536]
    system = System()
    pynamics.set_system(__name__, system)

    global_q = True

    lO = Constant(7 / 1000, 'lO', system)
    lA = Constant(33 / 1000, 'lA', system)
    lB = Constant(33 / 1000, 'lB', system)
    lC = Constant(33 / 1000, 'lC', system)

    mO = Constant(10 / 1000, 'mA', system)
    mA = Constant(2.89 / 1000, 'mA', system)
    mB = Constant(2.89 / 1000, 'mB', system)
    mC = Constant(2.89 / 1000, 'mC', system)
    k = Constant(g_k, 'k', system)
    k1 = Constant(0.4, 'k1', system)

    friction_perp = Constant(f1, 'f_perp', system)
    friction_par = Constant(f2, 'f_par', system)
    b_damping = Constant(g_b_damping, 'b_damping', system)
    b_damping1 = Constant(g_b_damping1, 'b_damping1', system)

    preload0 = Constant(0 * pi / 180, 'preload0', system)
    preload1 = Constant(0 * pi / 180, 'preload1', system)
    preload2 = Constant(0 * pi / 180, 'preload2', system)
    preload3 = Constant(0 * pi / 180, 'preload3', system)

    Ixx_O = Constant(1, 'Ixx_O', system)
    Iyy_O = Constant(1, 'Iyy_O', system)
    Izz_O = Constant(1, 'Izz_O', system)
    Ixx_A = Constant(1, 'Ixx_A', system)
    Iyy_A = Constant(1, 'Iyy_A', system)
    Izz_A = Constant(1, 'Izz_A', system)
    Ixx_B = Constant(1, 'Ixx_B', system)
    Iyy_B = Constant(1, 'Iyy_B', system)
    Izz_B = Constant(1, 'Izz_B', system)
    Ixx_C = Constant(1, 'Ixx_C', system)
    Iyy_C = Constant(1, 'Iyy_C', system)
    Izz_C = Constant(1, 'Izz_C', system)

    y, y_d, y_dd = Differentiable('y', system)
    qO, qO_d, qO_dd = Differentiable('qO', system)
    qA, qA_d, qA_dd = Differentiable('qA', system)
    qB, qB_d, qB_dd = Differentiable('qB', system)
    qC, qC_d, qC_dd = Differentiable('qC', system)

    fit_states = initial_states

    initialvalues = {}
    initialvalues[y] = fit_states[0]
    initialvalues[y_d] = fit_states[5]
    initialvalues[qO] = 0
    initialvalues[qO_d] = 0
    initialvalues[qA] = fit_states[2]
    initialvalues[qA_d] = fit_states[7]
    initialvalues[qB] = fit_states[3]
    initialvalues[qB_d] = fit_states[8]
    initialvalues[qC] = fit_states[4]
    initialvalues[qC_d] = fit_states[9]

    statevariables = system.get_state_variables()
    ini = [initialvalues[item] for item in statevariables]

    N = Frame('N')
    O = Frame('O')
    A = Frame('A')
    B = Frame('B')
    C = Frame('C')

    system.set_newtonian(N)
    if not global_q:
        O.rotate_fixed_axis_directed(N, [0, 0, 1], qO, system)
        A.rotate_fixed_axis_directed(O, [0, 0, 1], qA, system)
        B.rotate_fixed_axis_directed(A, [0, 0, 1], qB, system)
        C.rotate_fixed_axis_directed(B, [0, 0, 1], qC, system)
    else:
        O.rotate_fixed_axis_directed(N, [0, 0, 1], qO, system)
        A.rotate_fixed_axis_directed(N, [0, 0, 1], qA, system)
        B.rotate_fixed_axis_directed(N, [0, 0, 1], qB, system)
        C.rotate_fixed_axis_directed(N, [0, 0, 1], qC, system)

    pNO = 0 * N.x + y * N.y
    pOA = lO * N.x + y * N.y
    pAB = pOA + lA * A.x
    pBC = pAB + lB * B.x
    pCtip = pBC + lC * C.x

    pOcm = pNO + lO / 2 * N.x
    pAcm = pOA + lA / 2 * A.x
    pBcm = pAB + lB / 2 * B.x
    pCcm = pBC + lC / 2 * C.x

    wNO = N.getw_(O)
    wOA = N.getw_(A)
    wAB = A.getw_(B)
    wBC = B.getw_(C)

    IO = Dyadic.build(O, Ixx_O, Iyy_O, Izz_O)
    IA = Dyadic.build(A, Ixx_A, Iyy_A, Izz_A)
    IB = Dyadic.build(B, Ixx_B, Iyy_B, Izz_B)
    IC = Dyadic.build(C, Ixx_C, Iyy_C, Izz_C)

    BodyO = Body('BodyO', O, pOcm, mO, IO, system)
    BodyA = Body('BodyA', A, pAcm, mA, IA, system)
    BodyB = Body('BodyB', B, pBcm, mB, IB, system)
    BodyC = Body('BodyC', C, pCcm, mC, IC, system)

    # vOcm = pOcm.time_derivative()
    vAcm = pAcm.time_derivative()
    vBcm = pBcm.time_derivative()
    vCcm = pCcm.time_derivative()

    # system.add_spring_force1(k1+10000*(qA+abs(qA)),(qA-qO-preload1)*N.z,wOA)
    # system.add_spring_force1(k+10000*(qB+abs(qB)),(qB-qA-preload2)*N.z,wAB)
    # system.add_spring_force1(k+10000*(qC+abs(qC)),(qC-qB-preload3)*N.z,wBC)

    system.add_spring_force1(k1, (qA - qO - preload1) * N.z, wOA)
    system.add_spring_force1(k, (qB - qA - preload2) * N.z, wAB)
    system.add_spring_force1(k, (qC - qB - preload3) * N.z, wBC)

    #new Method use nJoint
    nvAcm = 1 / vAcm.length() * vAcm
    nvBcm = 1 / vBcm.length() * vBcm
    nvCcm = 1 / vCcm.length() * vCcm

    vSoil = drag_direction * 1 * N.y
    nSoil = 1 / vSoil.length() * vSoil

    if fit_vel == 0:
        vSoil = 1 * 1 * N.y
        nSoil = 1 / vSoil.length() * vSoil

        faperp = friction_perp * nSoil.dot(A.y) * A.y
        fapar = friction_par * nSoil.dot(A.x) * A.x
        system.addforce(-(faperp + fapar), vAcm)

        fbperp = friction_perp * nSoil.dot(B.y) * B.y
        fbpar = friction_par * nSoil.dot(B.x) * B.x
        system.addforce(-(fbperp + fbpar), vBcm)

        fcperp = friction_perp * nSoil.dot(C.y) * C.y
        fcpar = friction_par * nSoil.dot(C.x) * C.x
        system.addforce(-(fcperp + fcpar), vCcm)
    else:
        faperp = friction_perp * nvAcm.dot(A.y) * A.y
        fapar = friction_par * nvAcm.dot(A.x) * A.x
        system.addforce(-(faperp + fapar), vAcm)

        fbperp = friction_perp * nvBcm.dot(B.y) * B.y
        fbpar = friction_par * nvBcm.dot(B.x) * B.x
        system.addforce(-(fbperp + fbpar), vBcm)

        fcperp = friction_perp * nvCcm.dot(C.y) * C.y
        fcpar = friction_par * nvCcm.dot(C.x) * C.x
        system.addforce(-(fcperp + fcpar), vCcm)

    system.addforce(-b_damping1 * wOA, wOA)
    system.addforce(-b_damping * wAB, wAB)
    system.addforce(-b_damping * wBC, wBC)

    eq = []
    eq_d = [(system.derivative(item)) for item in eq]

    eq_d.append(y_d - fit_vel)
    eq_dd = [(system.derivative(item)) for item in eq_d]

    f, ma = system.getdynamics()
    func1 = system.state_space_post_invert(f, ma, eq_dd)

    points = [pNO, pOA, pAB, pBC, pCtip]

    constants = system.constant_values
    states = pynamics.integration.integrate_odeint(func1,
                                                   ini,
                                                   t,
                                                   args=({
                                                       'constants': constants
                                                   }, ))

    points_output = PointsOutput(points, system, constant_values=constants)
    y = points_output.calc(states)
    final = numpy.asarray(states[-1, :])
    time1 = time.time()
    points_output.animate(fps=30,
                          movie_name=str(time1) + 'video_1.mp4',
                          lw=2,
                          marker='o',
                          color=(1, 0, 0, 1),
                          linestyle='-')
    return final, states, y, system
    state = numpy.array([ini, result.x])
    ini1 = list(result.x)
    y = points.calc(state)
    y = y.reshape((-1, 6, 2))
    plt.figure()
    for item in y:
        plt.plot(*(item.T))
#    for item,value in zip(system.get_state_variables(),result.x):
#        initialvalues[item]=value

pAcm = pOA + lA / 2 * A.x
pBcm = pAB + lB / 2 * B.x
pCcm = pOC + lC / 2 * C.x
pDcm = pCD + lD / 2 * D.x

wOMA = O.getw_(MA)
wOA = O.getw_(A)
wAB = A.getw_(B)
wOMC = O.getw_(MC)
wOC = O.getw_(C)
wCD = C.getw_(D)
wBD = B.getw_(D)

wNMA = N.getw_(MA)
aNMA = wNMA.time_derivative()
wNMC = N.getw_(MC)
aNMC = wNMC.time_derivative()

I_motorA = Dyadic.build(MA, Im, Im, Im)
I_motorC = Dyadic.build(MC, Im, Im, Im)
    y = y.reshape((-1, len(points), 2))
    plt.figure()
    for item in y:
        plt.plot(*(item.T))
#    for item,value in zip(system.get_state_variables(),result.x):
#        initialvalues[item]=value

pA1cm = pOA + lA / 4 * A1.x
pC1cm = pOC + lC / 4 * C1.x
pBcm = pAB + lB / 2 * B.x
pDcm = pCD + lD / 2 * D.x

pA2cm = pA1A2 + lA / 4 * A2.x
pC2cm = pC1C2 + lC / 4 * C2.x

wOMA = O.getw_(MA)
wOMC = O.getw_(MC)

wOA1 = O.getw_(A1)
wA1A2 = A1.getw_(A2)
wA2B = A2.getw_(B)
#wB1B2 = B1.getw_(B2)
wOC1 = O.getw_(C1)
wC1C2 = C1.getw_(C2)
wC2D = C2.getw_(D)
#wD1D2 = D1.getw_(D2)
wBD = B.getw_(D)

wNMA = N.getw_(MA)
aNMA = wNMA.time_derivative()
wNMC = N.getw_(MC)
def Cal_robot(direction, given_l, omega1, t1, t2, ini_states, name1, system,
              video_on, x1):
    time_a = time.time()
    pynamics.set_system(__name__, system)
    given_k, given_b = x1
    global_q = True

    damping_r = 0
    tinitial = 0
    tfinal = (t1 - t2) / omega1
    tstep = 1 / 30
    t = numpy.r_[tinitial:tfinal:tstep]

    tol_1 = 1e-6
    tol_2 = 1e-6
    lO = Constant(27.5 / 1000, 'lO', system)
    lR = Constant(40.5 / 1000, 'lR', system)
    lA = Constant(given_l / 1000, 'lA', system)
    lB = Constant(given_l / 1000, 'lB', system)
    lC = Constant(given_l / 1000, 'lC', system)

    mO = Constant(154.5 / 1000, 'mO', system)
    mR = Constant(9.282 / 1000, 'mR', system)
    mA = Constant(given_l * 2.75 * 0.14450000000000002 / 1000, 'mA', system)
    mB = Constant(given_l * 2.75 * 0.14450000000000002 / 1000, 'mB', system)
    mC = Constant(given_l * 2.75 * 0.14450000000000002 / 1000, 'mC', system)
    k = Constant(given_k, 'k', system)

    friction_perp = Constant(13 / 3, 'f_perp', system)
    friction_par = Constant(-2 / 3, 'f_par', system)
    friction_arm_perp = Constant(5.6, 'fr_perp', system)
    friction_arm_par = Constant(-0.2, 'fr_par', system)
    b_damping = Constant(given_b, 'b_damping', system)

    preload0 = Constant(0 * pi / 180, 'preload0', system)
    preload1 = Constant(0 * pi / 180, 'preload1', system)
    preload2 = Constant(0 * pi / 180, 'preload2', system)
    preload3 = Constant(0 * pi / 180, 'preload3', system)

    Ixx_O = Constant(1, 'Ixx_O', system)
    Iyy_O = Constant(1, 'Iyy_O', system)
    Izz_O = Constant(1, 'Izz_O', system)
    Ixx_R = Constant(1, 'Ixx_R', system)
    Iyy_R = Constant(1, 'Iyy_R', system)
    Izz_R = Constant(1, 'Izz_R', system)
    Ixx_A = Constant(1, 'Ixx_A', system)
    Iyy_A = Constant(1, 'Iyy_A', system)
    Izz_A = Constant(1, 'Izz_A', system)
    Ixx_B = Constant(1, 'Ixx_B', system)
    Iyy_B = Constant(1, 'Iyy_B', system)
    Izz_B = Constant(1, 'Izz_B', system)
    Ixx_C = Constant(1, 'Ixx_C', system)
    Iyy_C = Constant(1, 'Iyy_C', system)
    Izz_C = Constant(1, 'Izz_C', system)

    y, y_d, y_dd = Differentiable('y', system)
    qO, qO_d, qO_dd = Differentiable('qO', system)
    qR, qR_d, qR_dd = Differentiable('qR', system)
    qA, qA_d, qA_dd = Differentiable('qA', system)
    qB, qB_d, qB_dd = Differentiable('qB', system)
    qC, qC_d, qC_dd = Differentiable('qC', system)

    initialvalues = {}
    initialvalues[y] = ini_states[0] + tol_1
    initialvalues[qO] = ini_states[1] + tol_1
    initialvalues[qR] = ini_states[2] + tol_1
    initialvalues[qA] = ini_states[3] + tol_1
    initialvalues[qB] = ini_states[4] + tol_1
    initialvalues[qC] = ini_states[5] + tol_1

    initialvalues[y_d] = ini_states[6] + tol_1
    initialvalues[qO_d] = ini_states[7] + tol_1
    initialvalues[qR_d] = ini_states[8] + tol_1
    initialvalues[qA_d] = ini_states[9] + tol_1
    initialvalues[qB_d] = ini_states[10] + tol_1
    initialvalues[qC_d] = ini_states[11] + tol_1

    statevariables = system.get_state_variables()
    ini = [initialvalues[item] for item in statevariables]
    N = Frame('N')
    O = Frame('O')
    R = Frame('R')
    A = Frame('A')
    B = Frame('B')
    C = Frame('C')

    system.set_newtonian(N)
    if not global_q:
        O.rotate_fixed_axis_directed(N, [0, 0, 1], qO, system)
        R.rotate_fixed_axis_directed(O, [0, 0, 1], qR, system)
        A.rotate_fixed_axis_directed(R, [0, 0, 1], qA, system)
        B.rotate_fixed_axis_directed(A, [0, 0, 1], qB, system)
        C.rotate_fixed_axis_directed(B, [0, 0, 1], qC, system)
    else:
        O.rotate_fixed_axis_directed(N, [0, 0, 1], qO, system)
        R.rotate_fixed_axis_directed(N, [0, 0, 1], qR, system)
        A.rotate_fixed_axis_directed(N, [0, 0, 1], qA, system)
        B.rotate_fixed_axis_directed(N, [0, 0, 1], qB, system)
        C.rotate_fixed_axis_directed(N, [0, 0, 1], qC, system)

    pNO = 0 * N.x + y * N.y
    pOR = pNO + lO * N.x
    pRA = pOR + lR * R.x
    pAB = pRA + lA * A.x
    pBC = pAB + lB * B.x
    pCtip = pBC + lC * C.x

    pOcm = pNO + lO / 2 * N.x
    pRcm = pOR + lR / 2 * R.x
    pAcm = pRA + lA / 2 * A.x
    pBcm = pAB + lB / 2 * B.x
    pCcm = pBC + lC / 2 * C.x

    wNO = N.getw_(O)
    wOR = N.getw_(R)
    wRA = R.getw_(A)
    wAB = A.getw_(B)
    wBC = B.getw_(C)

    IO = Dyadic.build(O, Ixx_O, Iyy_O, Izz_O)
    IR = Dyadic.build(R, Ixx_R, Iyy_R, Izz_R)
    IA = Dyadic.build(A, Ixx_A, Iyy_A, Izz_A)
    IB = Dyadic.build(B, Ixx_B, Iyy_B, Izz_B)
    IC = Dyadic.build(C, Ixx_C, Iyy_C, Izz_C)

    BodyO = Body('BodyO', O, pOcm, mO, IO, system)
    BodyR = Body('BodyR', R, pRcm, mR, IR, system)
    BodyA = Body('BodyA', A, pAcm, mA, IA, system)
    BodyB = Body('BodyB', B, pBcm, mB, IB, system)
    BodyC = Body('BodyC', C, pCcm, mC, IC, system)

    j_tol = 3 * pi / 180
    inv_k = 10
    system.add_spring_force1(k + inv_k * (qA - qR + abs(qA - qR - j_tol)),
                             (qA - qR - preload1) * N.z, wRA)
    system.add_spring_force1(k + inv_k * (qB - qA + abs(qB - qA - j_tol)),
                             (qB - qA - preload2) * N.z, wAB)
    system.add_spring_force1(k + inv_k * (qC - qB + abs(qC - qB - j_tol)),
                             (qC - qB - preload3) * N.z, wBC)

    vOcm = y_d * N.y
    vRcm = pRcm.time_derivative()
    vAcm = pAcm.time_derivative()
    vBcm = pBcm.time_derivative()
    vCcm = pCcm.time_derivative()

    nvRcm = 1 / (vRcm.length() + tol_1) * vRcm
    nvAcm = 1 / (vAcm.length() + tol_1) * vAcm
    nvBcm = 1 / (vBcm.length() + tol_1) * vBcm
    nvCcm = 1 / (vCcm.length() + tol_1) * vCcm

    vSoil = -direction * 1 * N.y
    nSoil = 1 / vSoil.length() * vSoil
    foperp = 8 * nSoil
    system.addforce(-foperp, vOcm)

    frperp = friction_arm_perp * nvRcm.dot(R.y) * R.y
    frpar = friction_arm_par * nvRcm.dot(R.x) * R.x
    system.addforce(-(frperp + frpar), vRcm)

    faperp = friction_perp * nvAcm.dot(A.y) * A.y
    fapar = friction_par * nvAcm.dot(A.x) * A.x
    system.addforce(-(faperp + fapar), vAcm)

    fbperp = friction_perp * nvBcm.dot(B.y) * B.y
    fbpar = friction_par * nvBcm.dot(B.x) * B.x
    system.addforce(-(fbperp + fbpar), vBcm)

    fcperp = friction_perp * nvCcm.dot(C.y) * C.y
    fcpar = friction_par * nvCcm.dot(C.x) * C.x
    system.addforce(-(fcperp + fcpar), vCcm)

    system.addforce(-b_damping * 1 * wRA, wRA)
    system.addforce(-b_damping * 1 * wAB, wAB)
    system.addforce(-b_damping * 1 * wBC, wBC)

    eq = []
    eq_d = [(system.derivative(item)) for item in eq]
    eq_d.append(qR_d - omega1)
    eq_dd = [(system.derivative(item)) for item in eq_d]

    f, ma = system.getdynamics()
    func1 = system.state_space_post_invert(f, ma, eq_dd)
    points = [pNO, pOR, pRA, pAB, pBC, pCtip]

    constants = system.constant_values
    states = pynamics.integration.integrate_odeint(func1,
                                                   ini,
                                                   t,
                                                   args=({
                                                       'constants': constants
                                                   }, ))
    final = numpy.asarray(states[-1, :])

    logger1 = logging.getLogger('pynamics.system')
    logger2 = logging.getLogger('pynamics.integration')
    logger3 = logging.getLogger('pynamics.output')
    logger1.disabled = True
    logger2.disabled = True
    logger3.disabled = True
    points_output = PointsOutput(points, system, constant_values=constants)

    y1 = points_output.calc(states)
    if video_on == 1:
        plt.figure()
        plt.plot(*(y1[::int(len(y1) / 20)].T) * 1000)
        plt.axis('equal')
        plt.axis('equal')
        plt.title("Plate Configuration vs Distance")
        plt.xlabel("Configuration")
        plt.ylabel("Distance (mm)")

        plt.figure()
        plt.plot(t, numpy.rad2deg(states[:, 2]))
        plt.plot(t, numpy.rad2deg(states[:, 8]))
        plt.legend(["qR", "qR_d"])
        plt.hlines(numpy.rad2deg(t1), tinitial, tfinal)
        plt.hlines(numpy.rad2deg(t2), tinitial, tfinal)
        plt.title("Robot Arm angle and velocitues (qR and qR_d) over Time")
        plt.xlabel("Time (s)")
        plt.ylabel("Angles,Velocities (deg, deg/s)")

        plt.figure()
        q_states = numpy.c_[(states[:, 2], states[:, 3], states[:,
                                                                4], states[:,
                                                                           5])]
        plt.plot(t, numpy.rad2deg(q_states))
        plt.title("Joint Angule over Time")
        plt.xlabel("Time (s)")
        plt.ylabel("Joint Angles (deg)")
        plt.legend(["Arm", "Joint 1", "Joint 2", "Joint 3"])

        plt.figure()
        qd_states = numpy.c_[(states[:, 8], states[:,
                                                   9], states[:,
                                                              10], states[:,
                                                                          11])]
        plt.plot(t, numpy.rad2deg(qd_states))
        plt.legend(["qR_d", "qA_d", "qB_d", "qC_d"])
        plt.title("Joint Angular Velocities over Time")
        plt.xlabel("Time (s)")
        plt.ylabel("Joint Angular Velocities (deg/s)")
        plt.legend(["Arm", "Joint 1", "Joint 2", "Joint 3"])

        plt.figure()
        plt.plot(t, states[:, 0], '--')
        plt.plot(t, states[:, 6])
        plt.title("Robot Distance and Velocity over time")
        plt.xlabel("Time (s)")
        plt.ylabel("Distance (mm)")
        plt.legend(["Distance", "Velocity of the robot"])

        points_output.animate(fps=1 / tstep,
                              movie_name=name1,
                              lw=2,
                              marker='o',
                              color=(1, 0, 0, 1),
                              linestyle='-')
    else:
        pass
    return final, states, y1
Пример #11
0
B2.rotate_fixed_axis_directed(B12, [1, 0, 0], qB2, system)
B23.rotate_fixed_axis_directed(B2, [0, 0, 1], -t3, system)

################################################
#Define particles at the center of mass of each body
pNO = 0 * N.x

ParticleA1 = Particle(A1.x + A12.x, m, 'ParticleA1', system)
ParticleA2 = Particle(A2.x + A23.x, m, 'ParticleA2', system)
# ParticleA3 = Particle(A3.x+A34.x,m/2,'ParticleA3',system)
ParticleB1 = Particle(B1.x + B12.x, m, 'ParticleB1', system)
ParticleB2 = Particle(B2.x + B23.x, m, 'ParticleB2', system)

################################################
#Get the relative rotational velocity between frames
wA1 = N.getw_(A1)
wA2 = A12.getw_(A2)
wA3 = A23.getw_(A3)
wB1 = NB1.getw_(B1)
wB2 = B12.getw_(B2)

################################################
#Add damping between joints
system.addforce(-b * wA1, wA1)
system.addforce(-b * wA2, wA2)
system.addforce(-b * wA3, wA3)
system.addforce(-b * wB1, wB1)
system.addforce(-b * wB2, wB2)

#system.addforce(1*A1.x,wA1)
Пример #12
0
statevariables = system.get_state_variables()
ini = [initialvalues[item] for item in statevariables]

N = Frame('N')
#A = Frame('A')
B = Frame('B')
M = Frame('M')

system.set_newtonian(N)
#A.rotate_fixed_axis_directed(N,[0,0,1],qA,system)
B.rotate_fixed_axis_directed(N, [0, 0, 1], qB, system)

pO = 0 * N.x
#wNA = N.getw_(A)
wNB = N.getw_(B)
wNA = G * wNB
aNA = wNA.time_derivative()
#wNB = wB*B.z
#aNB = wB_d*B.z

I_motor = Dyadic.build(B, Im, Im, Im)
I_load = Dyadic.build(B, Il, Il, Il)

#Motor = Body('Motor',A,pO,0,I_motor,system)
Motor = Body('Motor', B, pO, 0, I_motor, system, wNBody=wNA, alNBody=aNA)
Inductor = PseudoParticle(0 * M.x,
                          L,
                          name='Inductor',
                          vCM=i * M.x,
                          aCM=i_d * M.x)
Пример #13
0
ini = [initialvalues[item] for item in statevariables]

A = Frame('A')
B = Frame('B')
C = Frame('C')
D = Frame('D')

system.set_newtonian(A)
B.rotate_fixed_axis_directed(A, [0, 0, 1], H, system)
C.rotate_fixed_axis_directed(B, [1, 0, 0], -L, system)
D.rotate_fixed_axis_directed(C, [0, 1, 0], Q, system)

pNA = 0 * A.x
pAD = pNA + x * A.x + y * A.y
pBcm = pAD + r * C.z
pDA = pBcm - r * D.z

wAD = A.getw_(D)

II = Dyadic.build(B, J, I, J)

BodyD = Body('BodyD', D, pBcm, m, II, system)

#ParticleA = Particle(pAcm,mA,'ParticleA',system)
#ParticleB = Particle(pBcm,mB,'ParticleB',system)
#ParticleC = Particle(pCcm,mC,'ParticleC',system)

system.addforcegravity(-g * A.z)

f, ma = system.getdynamics()
vAB = pAB.time_derivative(N,system)
aAB = vAB.time_derivative(N,system)

vBA = pBA.time_derivative(N,system)
aBA = vBA.time_derivative(N,system)

#constraint1 = pNA-pAN
#constraint1_d = vectorderivative(constraint1,N)
#constraint1_dd = vectorderivative(constraint1_d,N)
#
constraint2 = pAB-pBA
constraint2_d = constraint2.time_derivative(N,system)
constraint2_dd = constraint2_d.time_derivative(N,system)

wNA = N.getw_(A)
wAB = A.getw_(B)

IA = Dyadic.build(A,Ixx_A,Iyy_A,Izz_A)
IB = Dyadic.build(A,Ixx_B,Iyy_B,Izz_B)

Body('BodyA',A,pAcm,mA,IA,system)
Body('BodyB',B,pBcm,mB,IB,system)

system.addforce(-b*wNA,wNA)
system.addforce(-b*wAB,wAB)

system.addforce(-k*qA*N.z,wNA)
system.addforce(-k*qB*A.z,wAB)

#system.addforce(fNAx*N.x+fNAy*N.y,vNA)
Пример #15
0
f1 = Frame()
f2 = Frame()
f3 = Frame()
f4 = Frame()
#f5 = Frame()

system.set_newtonian(f1)
f2.rotate_fixed_axis_directed(f1, [0, 0, 1], q1)
f3.rotate_fixed_axis_directed(f2, [1, 0, 0], q2)
f4.rotate_fixed_axis_directed(f3, [0, 1, 0], q3)

p1 = x * f1.x + y * f1.y + z * f1.z
p2 = -l1 * f4.x
#v1=p1.time_derivative(f1)

wNA = f1.getw_(f2)

particle1 = Particle(p1, mp1)
body1 = Body('body1', f4, p1, mp1, Dyadic.build(f4, 1, 1, 1), system=None)

#system.addforce(-b*v1,v1)
system.addforcegravity(-g * f1.z)
#system.add_spring_force1(k,(q1)*f1.z,wNA)

eq1 = []
#eq1.append(p2.dot(p2))
eq1.append(p2.dot(f1.x))
eq1.append(p2.dot(f1.y))
eq1.append(p2.dot(f1.z))
eq1_d = [system.derivative(item) for item in eq1]
eq1_dd = [system.derivative(item) for item in eq1_d]
# In[15]:

pAcm = pNA - lA / 2 * A.y
pBcm = pAB - lB / 2 * B.y
pCcm = pBC

# ## Calculating Velocity
#
# The angular velocity between frames, and the time derivatives of vectors are extremely useful in calculating the equations of motion and for determining many of the forces that need to be applied to your system (damping, drag, etc).  Thus, it is useful, once kinematics have been defined, to take or find the derivatives of some of those vectors for calculating  linear or angular velocity vectors
#
# ### Angular Velocity
# The following three lines of code computes and returns the angular velocity between frames N and A (${}^N\omega^A$), A and B (${}^A\omega^B$), and B and C (${}^B\omega^C$).  In other cases, if the derivative expression is complex or long,  you can supply pynamics with a given angular velocity between frames to speed up computation time.

# In[16]:

wNA = N.getw_(A)
wAB = A.getw_(B)
wBC = B.getw_(C)

# ### Vector derivatives
# The time derivatives of vectors may also be

# vCtip = pCtip.time_derivative(N,system)

# ### Define Inertias and Bodies
# The next several lines compute the inertia dyadics of each body and define a rigid body on each frame.  In the case of frame C, we represent the mass as a particle located at point pCcm.

# In[17]:

IA = Dyadic.build(A, Ixx_A, Iyy_A, Izz_A)
IB = Dyadic.build(B, Ixx_B, Iyy_B, Izz_B)
Пример #17
0
pCcm = pBC + lC / 2 * C.x

vAcm = pAcm.time_derivative()
vCcm = pCcm.time_derivative()

# ## Calculating Velocity
#
# The angular velocity between frames, and the time derivatives of vectors are extremely useful in calculating the equations of motion and for determining many of the forces that need to be applied to your system (damping, drag, etc).  Thus, it is useful, once kinematics have been defined, to take or find the derivatives of some of those vectors for calculating  linear or angular velocity vectors
#
# ### Angular Velocity
# The following three lines of code computes and returns the angular velocity between frames N and A (${}^N\omega^A$), A and B (${}^A\omega^B$), and B and C (${}^B\omega^C$).  In other cases, if the derivative expression is complex or long,  you can supply pynamics with a given angular velocity between frames to speed up computation time.

# In[16]:

#wNA3 = N.getw_(A3)
wA3B1 = A3.getw_(B1)
wB2C = B2.getw_(C)

# ### Vector derivatives
# The time derivatives of vectors may also be

# vCtip = pCtip.time_derivative(N,system)

# ### Define Inertias and Bodies
# The next several lines compute the inertia dyadics of each body and define a rigid body on each frame.  In the case of frame C, we represent the mass as a particle located at point pCcm.

# In[17]:

IA = Dyadic.build(A3, Ixx_A, Iyy_A, Izz_A)
IB = Dyadic.build(B1, Ixx_B, Iyy_B, Izz_B)
IC = Dyadic.build(C, Ixx_C, Iyy_C, Izz_C)