Project 1' PHANToM Premium with GHOST SDK

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Project 1. PHANToM Premium with GHOST SDK

• Jaeyoung Cheon
• VRPM Lab, Dept. of CSE, POSTECH
• 2006. 4. 3

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Introduction

• PHANToM
• GHOST SDK
• The characteristics of GHOST SDK
• Real-Time issues
• Prototypical Application
• Simple Codes
• The simple program

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1. PHANToM

• And..
• Impedance Type
• Pen-based Interaction
• Serial Linkage

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2. GHOST SDK

• GHOST (General Haptic Open Software Toolkit)
• is commercial product.
• works with MSVC 6.0 only because of STL problem.
• requires PHANToM Device Driver 4.08 version.
• The characteristics
• Object-oriented Toolkit
• Scene graph based
• Easy manipulation
• Automatic force computation in the scene graph
• Using SCP (Surface Contact Point) for force
  computation
• Special support for VRML Version 2.0

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2. GHOST SDK (ctd.)

• Real-Time issues
• Real time requirements
• At a periodic rate of 1kHz, the servo loop
  function has, at most, 1 millisecond to finish
  operations before the next servo loop begins.
• The GHOST SDK imposes a limit on the amount of
  processor time that may be used by a single
  iteration of the servo loop.
• Information sharing
• Multiple, successive calls to access the state of
  a scene node are not guaranteed to occur within
  the same iteration of the simulation loop.
• It can be resolved by using graphic callback.
• Callback mechanisms should be used to get
  information concerning the haptic scene.

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2. GHOST SDK (ctd.)

• Prototypical Application
• Create a haptic environment through the
  specification of a haptic scene graph
• Start the haptic simulation process (the servo
  control loop)
• Perform application-specific (core) functions
• Communicate with the haptic simulation process as
  needed
• Perform clean-up operations when the application
  ends

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2. GHOST SDK (ctd.)
Scene

• Simple Code
• main()
• gstScene scene new gstScene
• gstSeparator root new gstSeparator
• gstSphere sphere new gstSphere
• sphere-gtsetRadius(20)
• gstPHANToM phantom new gstPHANToM("PHANTOM
  name")
• root-gtaddChild(phantom)
• root-gtaddChild(sphere)
• scene-gtsetRoot(root)
• scene-gtstartServoLoop()
• ghostGLUTManager glutManager
  ghostGLUTManagerCreateInstance(argc, argv,
  "Hello GhostGL")
• glutManager-gtloadScene(myScene)
• glutKeyboardFunc(keypress)
• glutManager-gtstartMainloop()

root
sphere
PHANToM
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2. GHOST SDK (ctd.)

• Simple Code (Low Level APIs)
• main()
• int pid gstInitializePhantom("Default
  PHANToM")
• gstIsPhantomResetNeeded(pid)
• gstResetPhantomEncoders(pid)
• gstEnablePhantomForces(pid)
• gstInitServoScheduler()
• gstStartServoScheduling(servoLoopCallBackFunction
  , NULL)
• // application loop here (ex. graphic loop)
• GST_SCHEDULER_CALLBACK servoloopCallBAckFunction
  (void pUserData)
• gstUpdatePhantom(pid)
• gstGetPhantomPosition(pid, pPos)
• calcForce_sphere()
• gstSetPhantomForce(pid, pForce)

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3. The simple program

• Collision Detection
• Distance lt Radius
• Force Rendering
• Force Stiffness (HIP-Center)