英文:
Type error in getting context from rootContext
问题
我正在尝试包含具有激活接触标签的机器人的URDF文件，并打算使用DirectCollocation为我的机器人生成最优轨迹。
首先，我尝试使用MultibodyPlant（）创建机器人模型，然后使用SceneGraph（）创建场景图，并认为我使用RegisterAsSourceForSceneGraph（）将机器人模型连接到场景图。当我将context=plant.CreateDefaultContext（）传递给我的SNOPT求解器时，我收到一个错误，指出正在评估时间导数和残差，并被引导到https://drake.mit.edu/troubleshooting.html#system-framework
我修改了我的代码：
sim_time_step = 0.0
builder = DiagramBuilder()
plant, scene_graph = AddMultibodyPlantSceneGraph(
builder, time_step=sim_time_step)
parser = Parser(plant)
parser.AddModelFromFile("robot.urdf")
plant.Finalize()
diagram = builder.Build()
context = diagram.CreateDefaultContext()
plant_context = plant.GetMyContextFromRoot(root_context=context)
当我运行此代码时，现在我收到错误：
TypeError: GetMyContextFromRoot(): 不兼容的函数参数。支持以下参数类型：
1. (self: pydrake.systems.framework.System_ℜfloatℜ, arg0: pydrake.systems.framework.Context_ℜfloatℜ) -> pydrake.systems.framework.Context_ℜfloatℜ;
调用方式为： <pydrake.multibody.plant.MultibodyPlant_ℜfloatℜ object at 0x7fbd2784e370>; kwargs: root_context=<pydrake.systems.framework.Context_ℜfloatℜ object at 0x7fbd27862130>
如何解决这个错误？
英文:
I am trying to include my URDF file with a robot that has contact tags activated, and I intend to use DirectCollocation to generate an optimal trajectory for my robot.
First I tried creating the plant using MultibodyPlant(), then created the scene_graph using SceneGraph() and then thought I connected the plant to the scene_graph using RegisterAsSourceForSceneGraph(). When I passed the context=plant.CreateDefaultContext() to the my SNOPT solver, I got an error saying the time derivatives and residuals are being evaluated, and was directed to https://drake.mit.edu/troubleshooting.html#system-framework
I modified my code to:
sim_time_step = 0.0
builder = DiagramBuilder()
plant, scene_graph = AddMultibodyPlantSceneGraph(
builder, time_step=sim_time_step)
parser = Parser(plant)
parser.AddModelFromFile("robot.urdf")
plant.Finalize()
diagram = builder.Build()
context = diagram.CreateDefaultContext()
plant_context = plant.GetMyContextFromRoot(root_context=context)
When I run this code, now I receive the error:
TypeError: GetMyContextFromRoot(): incompatible function arguments. The following argument types are supported:
1. (self: pydrake.systems.framework.System_𝓣float𝓤, arg0: pydrake.systems.framework.Context_𝓣float𝓤) -> pydrake.systems.framework.Context_𝓣float𝓤
Invoked with: <pydrake.multibody.plant.MultibodyPlant_𝓣float𝓤 object at 0x7fbd2784e370>; kwargs: root_context=<pydrake.systems.framework.Context_𝓣float𝓤 object at 0x7fbd27862130>
How do I get past this error?
答案1
得分: 0
有绑定方面的缺陷。根上下文没有关键字参数。
相反，只需调用
plant_context = plant.GetMyContextFromRoot(context)
（我们需要修复绑定并确保指南与实现匹配。 :") ）
截至#19503，这不应再是一个障碍。导致混淆的缺陷已经得到解决。
英文:
It appears to be a defect in the binding. There is no keyword argument for the root context.
Instead, simply call
plant_context = plant.GetMyContextFromRoot(context)
(And we need to a) fix the bindings and b) make sure the guidance matches the implementation. :") )
As of #19503, this should no longer be a sticking point. The defect that caused the confusion has been resolved.
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