ROSBuzz_MISTLab/src/test1.bzz

# We need this for 2D vectors
# Make sure you pass the correct include path to "bzzc -I <path1:path2> ..."
include "/home/ubuntu/buzz/src/include/vec2.bzz"

TARGET_ALTITUDE = 10.0
 
# Lennard-Jones parameters
TARGET     = 0.000000100005
EPSILON    = 0.1
 
# Lennard-Jones interaction magnitude
function lj_magnitude(dist, target, epsilon) {
  return -(epsilon / dist) * ((target / dist)^4 - (target / dist)^2)
}
 
# Neighbor data to LJ interaction vector
function lj_vector(rid, data) {
  return math.vec2.newp(lj_magnitude(data.distance, TARGET, EPSILON), data.azimuth)
}
 
# Accumulator of neighbor LJ interactions
function lj_sum(rid, data, accum) {
  return math.vec2.add(data, accum)
}
 
# Calculates and actuates the flocking interaction
function hexagon() {
  statef=hexagon
  # Calculate accumulator
  var accum = neighbors.map(lj_vector).reduce(lj_sum, math.vec2.new(0.0, 0.0))
  if(neighbors.count() > 0)
    math.vec2.scale(accum, 1.0 / neighbors.count())
  # Move according to vector
  print("Robot ", id, "must push ",accum.x, "; ", accum.y)
  uav_goto(accum.x+position.latitude, accum.y+position.longitude, TARGET_ALTITUDE)
}
 
########################################
#
# BARRIER-RELATED FUNCTIONS
#
########################################

#
# Constants
#
BARRIER_VSTIG = 1
ROBOTS = 3 # number of robots in the swarm

#
# Sets a barrier
#
function barrier_set(threshold, transf) {
  statef = function() {
    barrier_wait(threshold, transf);
  }
  barrier = stigmergy.create(BARRIER_VSTIG)
}

#
# Make yourself ready
#
function barrier_ready() {
  barrier.put(id, 1)
}

#
# Executes the barrier
#
function barrier_wait(threshold, transf) {
  barrier.get(id)
  if(barrier.size() >= threshold) {
    barrier = nil
    transf()
  }
}

# flight status

function idle() {
statef=idle
neighbors.listen("cmd",
   function(vid, value, rid) {
      print("Got (", vid, ",", value, ") from robot #", rid)
	if(value==22) {
		statef=takeoff
	} else if(value==21) {
		statef=land
	}
   }
)
}

function takeoff() {
	if( flight.status == 2 and position.altitude >= TARGET_ALTITUDE-TARGET_ALTITUDE/50.0) {
		barrier_set(ROBOTS,hexagon)
		barrier_ready()
	}
	else if( flight.status !=3)
		uav_takeoff(TARGET_ALTITUDE)
}
function land() {
	if( flight.status == 1) {
		barrier_set(ROBOTS,idle)
		barrier_ready()
	}
	else if(flight.status!=0 and flight.status!=4)
		uav_land()
}

# Executed once at init time.
function init() {
	statef=idle
}

# Executed at each time step.
function step() {

	if(flight.rc_cmd==22 and flight.status==1) {
		flight.rc_cmd=0
		statef=takeoff		
		neighbors.broadcast("cmd", 22)
	} else if(flight.rc_cmd==21 and flight.status==2) {
		flight.rc_cmd=0
		statef=land
		neighbors.broadcast("cmd", 21)
	}

statef()
}
 
# Executed once when the robot (or the simulator) is reset.
function reset() {
}
 
# Executed once at the end of experiment.
function destroy() {
}