demo-buggy.py

from joy.decl import *
from joy import Plan, JoyApp, StickFilter

# Create Buggy Plan, print "Buggy started" to terminal, and zero wheels
class Buggy( Plan ):
  def __init__(self,*arg,**kw):
    Plan.__init__(self,*arg,**kw)

  def onStart( self ):
    progress("Buggy started")
  
  def onStop( self ):
    progress("Stopping")

    r = self.app.robot.at
    r.lwheel.set_speed(0)
    r.rwheel.set_speed(0)    

# Watch for joystick movements, use these to set left/right wheel speed, and print wheel speed to terminal
  def behavior( self ):
    oncePer = self.app.onceEvery(0.5)
    while True:   
      yield
      sf = self.app.sf
      lspeed = sf.getValue('joy0axis1')
      rspeed = sf.getValue('joy0axis4')
      r = self.app.robot.at
      r.lwheel.set_speed(lspeed*200)
      r.rwheel.set_speed(rspeed*200)

      if oncePer():
        progress("Buggy: left wheel %6f right wheel %6f"
          % (lspeed,rspeed))

# Create BuggyApp JoyApp, a cluster that has two modules    
class BuggyApp( JoyApp ):
  def __init__(self,robot=dict(count=2),*arg,**kw):
    JoyApp.__init__(self,robot=robot,*arg,**kw)

#Create StickFilter Plan, tell it to watch for two joysticks, and to process their signals through the low-pass filter 20x/sec
  def onStart(self):
    sf = StickFilter(self,dt=0.05)
    sf.setLowpass( 'joy0axis1',10)
    sf.setLowpass( 'joy0axis4',10)
    sf.start()
    self.sf = sf
    self.ma = Buggy(self) 

#Create onEvent Plan (the top-level event handler), tell it to watch for joystick motion and pass it to StickFilter Plan.
  def onEvent(self,evt):
    if evt.type == JOYAXISMOTION:
      self.sf.push(evt)
    # The dead-man switch: if the joystick button is held down the robot goes, otherwise it does not
    elif evt.type==JOYBUTTONDOWN and evt.joy==0 and evt.button==0:
      self.ma.stop()
    elif evt.type==JOYBUTTONUP and evt.joy==0 and evt.button==0:
      self.ma.start()
    # Prevent robot-position events from printing to terminal, but print everything else
    elif evt.type==CKBOTPOSITION:
      return
    JoyApp.onEvent(self,evt)

#Stop in an orderly fashion
  def onStop(self):
    self.ma.onStop()

#Boilerplate and housekeeping      
if __name__=="__main__":
  app = BuggyApp()
  app.run()