pydrake_continuous_time_system_simulation_cubic_dynamics.py

1import numpy as np
2import matplotlib.pyplot as plt
3from pydrake.systems.analysis import Simulator
4from pydrake.systems.framework import LeafSystem_
5
6# Define a simple custom system: xdot = -x + x^3
7class SimpleSystem(LeafSystem_):
8    def __init__(self):
9        LeafSystem_.__init__(self, data_type=float)
10        self.DeclareContinuousState(1)  # One state variable
11
12    def DoCalcTimeDerivatives(self, context, derivatives):
13        x = context.get_continuous_state_vector().GetAtIndex(0)
14        xdot = -x + x**3
15        derivatives.get_mutable_vector().SetAtIndex(0, xdot)
16
17# Create the system and a simulator
18system = SimpleSystem()
19simulator = Simulator(system)
20
21# Set the initial conditions
22context = simulator.get_mutable_context()
23context.SetTime(0.0)
24context.get_mutable_continuous_state_vector().SetAtIndex(0, 0.5)
25
26# Run the simulation
27simulator.AdvanceTo(10.0)
28
29# Print the final state
30print(f"Final state at time 10.0: {context.get_continuous_state_vector().GetAtIndex(0)}")