CS221: LittleDog Robot Project

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CS221 LittleDogRobot Project

• Zico Kolter, Lawson Wong

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LittleDog Robot
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LittleDog Robot
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LittleDog Robot Simulator
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Getting the Simulator

• LittleDog simulator and code available
  at/afs/ir/class/cs221/code/LittleDog
• Get latest version! (10/12/07)?
• Ignore compilation warnings
• make ./main -path
• Should build program, execute footsteps read from
  actions.path

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Important Files/Directories

• main.cpp your code here
• SDSlowWalk.h,cpp walking controller (dont
  edit for milestone, can edit for final
  submission)?
• Classifier.h,cpp where you build classifier
  to classify feasible actions
• simulator/ internal simulator code (dont
  edit)?
• tergen/ terrain generation executable

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Foot Numbers and Reference Configuration
Foot Numbers
Default Axes
Y
0
2
X
Z (up)?
1
3
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Initializing the simulator

• SDLittleDog littleDogSDSlowWalk
  walkControllerSDSimulator simulatorlittleDog
  .setSimulated(true)littleDog.setController(walk
  Controller)walkController.setLittleDog(littleDo
  g)littleDog.initializeSimulator()simulator
  littleDog.getSimulator()

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Getting/Setting Simulator State

• SDSimulator simulatorSDSimulatorState
  state// get current statesimulator.getState(s
  tate)// set current statesimulator.setState(s
  tate)

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The bduVec3f class

• bduVec3f vector// vector.n is a
  float3vector.n0vector.n1vector.n2

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Getting Foot Positions

• SDSimulator simulatorbduVec3f globalFeet4,
  localFeet4// get global positions of the
  feetsimulator-gtgetGlobalFootPositions(globalFeet
  )// get positions of feet relative to
  bodysimulator-gtgetLocalFootPositions(localFeet)
  

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Taking a Step

• SDSimulator simulatorSDWalkController
  walkControllerdouble globalStepX,
  globalStepYint movingFootbduVec localStep
• // tell the controller to take a
  stepwalkController.setStepPosition(movingFoot,
  globalStepX,
  globalStepY)// get local position for a
  global stepsimulator-gtgetLocalStepPosition(global
  StepX,
  globalStepY,
  localStep)

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Executing the simulation

• SDLittleDog littledogSDSimulatorState
  statebool pauseUI...// set desired footstep
  and get start state...// execute
  simulationlittleDog.runTrial(state, pauseUI)

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Useful Functions

• SDSimulator simulatorSDLittleDog
  littleDogdouble height, x, ybool
  show3DDisplay// get the height of a point on
  the terrainheight simulator-gtgetPointHeight(x,y
  )// turn on/off 3D visualizationlittleDog.setS
  imUI(show3DDisplay)

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Advice

• For the milestone the robots state is entirely
  comprised of its foot locations
• Dont try to interpret SDSimulatorState
• Use getState(), setState(), then use
  getGlobalFootPositions() to find feet
• To find whether a step is feasible, simulate the
  step, then check to see if the resulting foot
  position is close (say within 1cm) of the desired
  position

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Advice

• Drawing terrain is slow, press t to turn on/off
  terrain display
• Move simulator view with mouse
• When executing with UI paused, press Ctrl-p to
  unpause
• If you want to implement more advanced
  functionality, all the code is there
• Look in the simulator/.h files

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Tergen Program

• tergen/ directory
• ./tergen ltrandom seedgt ltdifficulty levelgt

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Difficulty 0 (Flat Terrain)?
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Difficulty 1
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Difficulty 2
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Difficulty 3
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Good Luck!