test_block_diagram.py 文件源码

python
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项目:simupy 作者: sixpearls 项目源码 文件源码
def test_events():
    # use bouncing ball to test events work

    # simulate in block diagram
    int_opts = block_diagram.DEFAULT_INTEGRATOR_OPTIONS.copy()
    int_opts['rtol'] = 1E-12
    int_opts['atol'] = 1E-15
    int_opts['nsteps'] = 1000
    int_opts['max_step'] = 2**-3
    x = x1, x2 = Array(dynamicsymbols('x_1:3'))
    mu, g = sp.symbols('mu g')
    constants = {mu: 0.8, g: 9.81}
    ic = np.r_[10, 15]
    sys = SwitchedSystem(
        x1, Array([0]),
        state_equations=r_[x2, -g],
        state_update_equation=r_[sp.Abs(x1), -mu*x2],
        state=x,
        constants_values=constants,
        initial_condition=ic
    )
    bd = BlockDiagram(sys)
    res = bd.simulate(5, integrator_options=int_opts)

    # compute actual impact time
    tvar = dynamicsymbols._t
    impact_eq = (x2*tvar - g*tvar**2/2 + x1).subs(
        {x1: ic[0], x2: ic[1], g: 9.81}
    )
    t_impact = sp.solve(impact_eq, tvar)[-1]

    # make sure simulation actually changes velocity sign around impact
    abs_diff_impact = np.abs(res.t - t_impact)
    impact_idx = np.where(abs_diff_impact == np.min(abs_diff_impact))[0]
    assert np.sign(res.x[impact_idx-1, 1]) != np.sign(res.x[impact_idx+1, 1])
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