我正在尝试从头开始为 acrobot 系统创建 LQR:
file_name = "acrobot.sdf" # from drake/multibody/benchmarks/acrobot/acrobot.sdf
acrobot = MultibodyPlant()
parser = Parser(plant=acrobot)
parser.AddModelFromFile(file_name)
acrobot.AddForceElement(UniformGravityFieldElement([0, 0, -9.81]))
acrobot.Finalize()
acrobot_context = acrobot.CreateDefaultContext()
shoulder = acrobot.GetJointByName("ShoulderJoint")
elbow = acrobot.GetJointByName("ElbowJoint")
shoulder.set_angle(context=acrobot_context, angle=0.0)
elbow.set_angle(context=acrobot_context, angle=0.0)
Q = np.identity(4)
R = np.identity(1)
N = np.zeros([4, 4])
controller = LinearQuadraticRegulator(acrobot, acrobot_context, Q, R)
运行此脚本,我在最后一个字符串处收到错误:
RuntimeError: Vector-valued input port acrobot_actuation must be either fixed or connected to the output of another system.
我修复/连接输入端口的方法都没有最终成功。
PS 我知道存在AcrobotPlant
,但想法是在运行时从 sdf 创建 LQR。
PPS 为什么acrobot.get_num_input_ports()
返回 5 而不是 1?