Question

我有一个自定义LeafSystem，它具有如下的输入端口和输出端口

template <typename T>
MyLeafSystem<T>::MyLeafSystem() :
    systems::LeafSystem<T>(systems::SystemTypeTag<MyLeafSystem>{}),
    input1_idx(this->DeclareVectorInputPort("input1", systems::BasicVector<T>(1)).get_index()),
    input2_idx(this->DeclareVectorInputPort("input2", systems::BasicVector<T>(1)).get_index()),
    output_idx(this->DeclareVectorOutputPort("output", systems::BasicVector<T>(2), &TorqueCombiner::convert).get_index())
{}

我通过以下方式将其添加到系统中

auto my_leaf_system = builder.AddSystem(std::make_unique<MyLeafSystem<double>>());
// Connect one of the input ports of my_leaf_system
// Connect one of the output port of my_leaf_system
auto diagram = builder.Build();

对于其余端口，我现在想连接修复输入端口。我通过

auto diagram = builder.Build();

std::unique_ptr<systems::Context<double>> diagram_context = diagram->CreateDefaultContext();
Context<double>& context = diagram->GetMutableSubsystemContext(plant, diagram_context.get());

context.FixInputPort(my_leaf_system->get_second_input_port().get_index(), Vector1d::Zero());

但是，当我运行std::logic_error时会抛出FixInputPort

terminate called after throwing an instance of 'std::logic_error'
  what():  System::FixInputPortTypeCheck(): expected value of type drake::geometry::QueryObject<double> for input port 'geometry_query' (index 0) but the actual type was drake::systems::BasicVector<double>. (System ::_::drake/multibody/MultibodyPlant@000055e087146ec0)

奇怪的是

int(my_leaf_system->get_second_input_port().get_index())) == 0

和

int(plant.get_geometry_query_input_port().get_index())) == 0

我的植物添加如下

auto pair = drake::multibody::AddMultibodyPlantSceneGraph(&builder, std::make_unique<drake::multibody::MultibodyPlant<double>>(0));

drake::multibody::MultibodyPlant<double>& plant = pair.plant;
drake::geometry::SceneGraph<double>& scene_graph = pair.scene_graph;

// Make and add the model.
drake::multibody::Parser(&plant, &scene_graph).AddModelFromFile(model_filename);

// Connect scene graph to visualizer
drake::geometry::ConnectDrakeVisualizer(&builder, scene_graph);

plant.Finalize();



auto my_leaf_system = builder.AddSystem(std::make_unique<MyLeafSystem<double>>());
...

Answer 1

您的帖子有几处不一致的地方。对于初学者，该错误消息表示尝试修复多体植物（不是您的叶子系统）的输入端口时会生成错误。而且该输入端口的类型不是向量，因此错误很明显。

怀疑您在某处越过了导线（或指针）。修复派生的叶子系统的向量输入端口应该没问题-这非常普遍。

Answer 2

我犯的错误是

Context<double>& context = diagram->GetMutableSubsystemContext(plant, diagram_context.get());

context.FixInputPort(my_leaf_system->get_second_input_port().get_index(), Vector1d::Zero());

在这里，我将context子系统的plant用于FixInputPort上的my_leaf_system。

正确的代码应该是

Context<double>& my_leaf_system_context = diagram->GetMutableSubsystemContext(*my_leaf_system, diagram_context.get());

my_leaf_system_context.FixInputPort(my_leaf_system->get_mip_input_port().get_index(), Vector1d::Zero());

Thx Russ，谢尔姆！

FixInputPort尝试连接错误的端口

2 个答案: