三维可视化系统的建立依赖于三维图形平台， 如 OpenGL、VTK、OGRE、OSG等， 传统的方法多采用OpenGL进行底层编程，即对其特有的函数进行定量操作， 需要开发人员熟悉相关函数， 从而造成了开发难度大、 周期长等问题。VTK、 ORGE、OSG等平台使用封装更好的函数简化了开发过程。下面将使用Python与VTK进行机器人上位机监控界面的快速原型开发。

　　完整的上位机程序需要有三维显示模块、机器人信息监测模块（位置/角度/速度/电量/温度/错误信息...）、通信模块（串口/USB/WIFI/蓝牙...）、控制模块等功能模块。三维显示模块主要用于实时显示机器人的姿态（或位置）信息。比如机器人上肢手臂抬起，程序界面中的虚拟机器人也会同时进行同样的动作。三维显示模块也可以用于对机器人进行控制，实现良好的人机交互。比如在三维图像界面中可以点击拾取机器人某一关节，拖拽部件(肢体)控制真实的机器人完成同样的运动。Aldebaran Robotics的图形化编程软件Choregraphe可以完成上述的一些功能对NAO机器人进行控制。

　　对于简单的模型可以自己编写函数进行创建，但这种方法做出来的模型过于简单不够逼真。因此可以先在SolidWorks、Blender、3DMax、Maya、Rhino等三维设计软件中建立好模型，然后导出为通用的三维文件格式，再使用VTK将其读入并进行渲染。

　　在SolidWorks等三维设计软件中设计好机器人的大臂（upperarm）和小臂（forearm），然后创建装配体如下图所示。在将装配体导出为STL文件前需要注意几点：

　　1. 当从外界读入STL类型的模型时，其会按照它内部的坐标位置进行显示，因此它的位置和大小是确定的。为了以后的定位以及移动、旋转等操作的方便，需要先在SolidWorks中创建一个坐标系。如下图所示，坐标系建立在大臂关节中心点。

　　2. 如果将装配体整体输出为一个STL文件，则导入VTK后无法控制零部件进行相对运动。因此，需要将装配体各可动部件分别导出。

　　在SolidWorks的另存为STL对话框中，点开输出选项卡，如下图所示。注意之前提到的几点：如果勾选“在单一文件中保存装配体的所有零部件”则会将整个装配体导出为一个STL文件，否则就是分别命名的两个STL文件；输出坐标系下拉列表中选择之前创建的坐标系1，并勾选“不要转换STL输出数据到正的坐标空间”。

　　下面的Python代码简单实现了一个2自由度机械臂的三维仿真，可以拖动滑块或按键盘上的方向键控制肩关节或肘关节运动。当然程序还存在一些问题有待完善...

#!/usr/bin/env python import vtkimport mathfrom vtk.util.colors import * filenames = ["upperarm.stl","forearm.stl"]dt = 1.0        # degree step in rotationangle = [0, 0]  # shoulder and elbow joint anglerenWin = vtk.vtkRenderWindow()assembly = vtk.vtkAssembly()slider_shoulder = vtk.vtkSliderRepresentation2D()slider_elbow = vtk.vtkSliderRepresentation2D()actor  = list() # the list of links# Customize vtkInteractorStyleTrackballCamera class MyInteractor(vtk.vtkInteractorStyleTrackballCamera):    def __init__(self,parent=None):        self.AddObserver("CharEvent",self.OnCharEvent)        self.AddObserver("KeyPressEvent",self.OnKeyPressEvent)        # Override the default key operations which currently handle trackball or joystick styles is provided    # OnChar is triggered when an ASCII key is pressed. Some basic key presses are handled here     def OnCharEvent(self,obj,event):        pass        def OnKeyPressEvent(self,obj,event):        global angle        # Get the compound key strokes for the event        key = self.GetInteractor().GetKeySym()        # Output the key that was pressed        #print "Pressed: " , key        # Handle an arrow key        if(key == "Left"):            actor[1].RotateY(-dt)                    if(key == "Right"):            actor[1].RotateY(dt)                    if(key == "Up"):            assembly.RotateY(-dt)            angle[0] += dt            if angle[0] >= 360.0:                angle[0] -= 360.0            slider_shoulder.SetValue(angle[0])                    if(key == "Down"):            assembly.RotateY(dt)            angle[0] -= dt            if angle[0] < 0.0:                angle[0] += 360.0              slider_shoulder.SetValue(angle[0])                # Ask each renderer owned by this RenderWindow to render its image and synchronize this process        renWin.Render()        return    def LoadSTL(filename):    reader = vtk.vtkSTLReader()    reader.SetFileName(filename)    mapper = vtk.vtkPolyDataMapper() # maps polygonal data to graphics primitives    mapper.SetInputConnection(reader.GetOutputPort())    actor = vtk.vtkLODActor()     actor.SetMapper(mapper)    return actor   # represents an entity in a rendered scene    def CreateCoordinates():    # create coordinate axes in the render window    axes = vtk.vtkAxesActor()     axes.SetTotalLength(100, 100, 100)  # Set the total length of the axes in 3 dimensions     # Set the type of the shaft to a cylinder:0, line:1, or user defined geometry.     axes.SetShaftType(0)     axes.SetCylinderRadius(0.02)     axes.GetXAxisCaptionActor2D().SetWidth(0.03)     axes.GetYAxisCaptionActor2D().SetWidth(0.03)     axes.GetZAxisCaptionActor2D().SetWidth(0.03)     #axes.SetAxisLabels(0)  # Enable:1/disable:0 drawing the axis labels    #transform = vtk.vtkTransform()     #transform.Translate(0.0, 0.0, 0.0)    #axes.SetUserTransform(transform)    #axes.GetXAxisCaptionActor2D().GetCaptionTextProperty().SetColor(1,0,0)    #axes.GetXAxisCaptionActor2D().GetCaptionTextProperty().BoldOff() # disable text bolding    return axes    def ShoulderSliderCallback(obj,event):    sliderRepres = obj.GetRepresentation()    pos = sliderRepres.GetValue()      assembly.SetOrientation(0,-pos,0)    renWin.Render()def ElbowSliderCallback(obj,event):    sliderRepres = obj.GetRepresentation()    pos = sliderRepres.GetValue()      actor[1].SetOrientation(0,-pos,0)    renWin.Render()        def ConfigSlider(sliderRep, TitleText, Yaxes):    sliderRep.SetMinimumValue(0.0)    sliderRep.SetMaximumValue(360.0)    sliderRep.SetValue(0.0) # Specify the current value for the widget    sliderRep.SetTitleText(TitleText) # Specify the label text for this widget    sliderRep.GetSliderProperty().SetColor(1,0,0) # Change the color of the knob that slides    sliderRep.GetSelectedProperty().SetColor(0,0,1) # Change the color of the knob when the mouse is held on it    sliderRep.GetTubeProperty().SetColor(1,1,0) # Change the color of the bar     sliderRep.GetCapProperty().SetColor(0,1,1) # Change the color of the ends of the bar    #sliderRep.GetTitleProperty().SetColor(1,0,0)  # Change the color of the text displaying the value    # Position the first end point of the slider    sliderRep.GetPoint1Coordinate().SetCoordinateSystemToDisplay()    sliderRep.GetPoint1Coordinate().SetValue(50, Yaxes)     # Position the second end point of the slider    sliderRep.GetPoint2Coordinate().SetCoordinateSystemToDisplay()    sliderRep.GetPoint2Coordinate().SetValue(400, Yaxes)     sliderRep.SetSliderLength(0.02) # Specify the length of the slider shape.The slider length by default is 0.05    sliderRep.SetSliderWidth(0.02) # Set the width of the slider in the directions orthogonal to the slider axis    sliderRep.SetTubeWidth(0.005)    sliderRep.SetEndCapWidth(0.03)    sliderRep.ShowSliderLabelOn() # display the slider text label    sliderRep.SetLabelFormat("%.1f")    sliderWidget = vtk.vtkSliderWidget()    sliderWidget.SetRepresentation(sliderRep)    sliderWidget.SetAnimationModeToAnimate()    return sliderWidgetdef CreateGround():    # create plane source    plane = vtk.vtkPlaneSource()    plane.SetXResolution(50)    plane.SetYResolution(50)    plane.SetCenter(0,0,0)    plane.SetNormal(0,0,1)        # mapper    mapper = vtk.vtkPolyDataMapper()    mapper.SetInputConnection(plane.GetOutputPort())         # actor    actor = vtk.vtkActor()    actor.SetMapper(mapper)    actor.GetProperty().SetRepresentationToWireframe()    #actor.GetProperty().SetOpacity(0.4)  # 1.0 is totally opaque and 0.0 is completely transparent    actor.GetProperty().SetColor(light_grey)        '''    # Load in the texture map. A texture is any unsigned char image.    bmpReader = vtk.vtkBMPReader()      bmpReader.SetFileName("ground_texture.bmp")      texture = vtk.vtkTexture()      texture.SetInputConnection(bmpReader.GetOutputPort())      texture.InterpolateOn()      actor.SetTexture(texture)    '''    transform = vtk.vtkTransform()    transform.Scale(2000,2000, 1)    actor.SetUserTransform(transform)        return actor                def CreateScene():    # Create a rendering window and renderer    ren = vtk.vtkRenderer()    #renWin = vtk.vtkRenderWindow()    renWin.AddRenderer(ren)         # Create a renderwindowinteractor    iren = vtk.vtkRenderWindowInteractor()    iren.SetRenderWindow(renWin)    style = MyInteractor()    style.SetDefaultRenderer(ren)    iren.SetInteractorStyle(style)        for id, file in enumerate(filenames):        actor.append(LoadSTL(file))        #actor[id].GetProperty().SetColor(blue)        r = vtk.vtkMath.Random(.4, 1.0)        g = vtk.vtkMath.Random(.4, 1.0)        b = vtk.vtkMath.Random(.4, 1.0)        actor[id].GetProperty().SetDiffuseColor(r, g, b)        actor[id].GetProperty().SetDiffuse(.8)        actor[id].GetProperty().SetSpecular(.5)        actor[id].GetProperty().SetSpecularColor(1.0,1.0,1.0)        actor[id].GetProperty().SetSpecularPower(30.0)        assembly.AddPart(actor[id])        # Add the actors to the scene        #ren.AddActor(actor[id])            # Also set the origin, position and orientation of assembly in space.    assembly.SetOrigin(0, 0, 0) # This is the point about which all rotations take place     #assembly.AddPosition(0, 0, 0)    #assembly.RotateX(45)    actor[1].SetOrigin(274, 0, 0)  # initial elbow joint position    ren.AddActor(assembly)    # Add coordinates    axes = CreateCoordinates()    ren.AddActor(axes)    # Add ground    ground = CreateGround()    ren.AddActor(ground)    # Add slider to control the robot    sliderWidget_shoulder = ConfigSlider(slider_shoulder,"Shoulder Joint", 80)    sliderWidget_shoulder.SetInteractor(iren)    sliderWidget_shoulder.EnabledOn()    sliderWidget_shoulder.AddObserver("InteractionEvent", ShoulderSliderCallback)    sliderWidget_elbow = ConfigSlider(slider_elbow,"Elbow Joint", 160)    sliderWidget_elbow.SetInteractor(iren)    sliderWidget_elbow.EnabledOn()    sliderWidget_elbow.AddObserver("InteractionEvent", ElbowSliderCallback)    # Set background color    ren.SetBackground(.2, .2, .2)    # Set window size    renWin.SetSize(600, 600)    # Set up the camera to get a particular view of the scene    camera = vtk.vtkCamera()    camera.SetFocalPoint(300, 0, 0)    camera.SetPosition(300, -400, 350)    camera.ComputeViewPlaneNormal()    camera.SetViewUp(0, 1, 0)    camera.Zoom(0.4)    ren.SetActiveCamera(camera)    # Enable user interface interactor    iren.Initialize()    iren.Start()        if __name__ == "__main__":    CreateScene()

　　下面是使用MFC搭建的机器人上位机监控平台，可以实现上述的一些基本功能。这个GIF动画使用开源软件生成，非常好用！

 

 

 

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