MIT 6.821: Underactuated Robotics
Spring 2024, Lecture 10
Follow live at https://slides.com/d/QGK95tc/live
(or later at https://slides.com/russtedrake/spring24-lec10)
Image credit: Boston Dynamics
Explicit LQR + input constraints for the double integrator
99 regions for horizon N=8.
def optimize_double_integrator(N):
# Discrete-time approximation of the double integrator.
dt = 0.01
A = np.eye(2) + dt * np.mat("0 1; 0 0")
B = dt * np.mat("0; 1")
prog = MathematicalProgram()
# Create decision variables
u = prog.NewContinuousVariables(1, N-1, "u")
x = prog.NewContinuousVariables(2, N, "x")
# Add constraints
x0 = [-2, 0]
prog.AddBoundingBoxConstraint(x0, x0, x[:, 0])
for n in range(N - 1):
prog.AddConstraint(eq(x[:, n + 1], A.dot(x[:, n]) + B.dot(u[:, n])))
prog.AddBoundingBoxConstraint(-1, 1, u[:, n])
prog.AddQuadraticCost(u[0,n]**2, True)
xf = [0, 0]
prog.AddBoundingBoxConstraint(xf, xf, x[:, N - 1])
result = Solve(prog)