diff --git a/class/boids/controls/AbsoluteControls.lua b/class/boids/controls/AbsoluteControls.lua
index 69cd5cd..373dec2 100644
--- a/class/boids/controls/AbsoluteControls.lua
+++ b/class/boids/controls/AbsoluteControls.lua
@@ -1,56 +1,58 @@
 --[[
 
 * Absolute control scheme
 
 Cellulo acts like a mouse
 
 ]]--
 
 local global = require "global"
 
 local AbsoluteControls = (class "boids.controls.Controls"):subclass("AbsoluteControls")
 
 local CELLULO_ABSOLUTE_SPEED = 0.04
 
 local CELLULO_MAX_HAPTIC_FORCE = 20
 local CELLULO_HAPTIC_FACTOR = 10
 
 function AbsoluteControls.static:applyMovement(boid, dt)
     -- move continuously
     local kidnapped = boid:getCellulo():getKidnapped()
     if kidnapped then
         boid.ox, boid.oy, boid.oa = nil, nil, nil
     end
 
     if not kidnapped then
         if boid.ox and boid.oy and boid.oa then
             
             local da = boid:getCellulo():getTheta() - boid.oa
             da = math.atan2(math.sin(da), math.cos(da))
             local angle = boid:getAngle()
             angle = angle - da -- no need for dt?
             boid:setAngle(angle)
             
             local dx, dy = boid:getCellulo():getX() - boid.ox, boid:getCellulo():getY() - boid.oy
             local x, y, z = boid:getCollider():getPosition()
             dx, dy = util.rotateVector(dx, dy, -global.camera:getAngle())
             x, z = x + dx * CELLULO_ABSOLUTE_SPEED, z + dy * CELLULO_ABSOLUTE_SPEED
             boid:setPosition(x, y, z)
             boid:getCollider():setPosition(x, y, z)
         end
 
         -- set origin
         boid.ox, boid.oy, boid.oa = boid:getCellulo():getX(), boid:getCellulo():getY(), boid:getCellulo():getTheta()
     end
 end
 
 function AbsoluteControls.static:applyHapticFeedback(boid, dt, dir)
     dir:mul(CELLULO_HAPTIC_FACTOR)
     if dir:length() > CELLULO_MAX_HAPTIC_FORCE then
         dir:normalize()
         dir:mul(CELLULO_MAX_HAPTIC_FORCE)
     end
     local dx, dy, dz = dir:unpack()
     dx, dz = util.rotateVector(dx, dz, global.camera:getAngle())
     boid:getCellulo():setGoalVelocity(dx, dz, 0)
-end
\ No newline at end of file
+end
+
+return AbsoluteControls
\ No newline at end of file
diff --git a/class/boids/controls/Controls.lua b/class/boids/controls/Controls.lua
index cd69f87..2db71ca 100644
--- a/class/boids/controls/Controls.lua
+++ b/class/boids/controls/Controls.lua
@@ -1,5 +1,7 @@
 local Controls = lib "class" ("Controls")
 
 function Controls.static:applyMovement(boid, dt) end
 
-function Controls.static:applyHapticFeedback(boid, dt) end
\ No newline at end of file
+function Controls.static:applyHapticFeedback(boid, dt) end
+
+return Controls
\ No newline at end of file
diff --git a/class/boids/controls/HybridControls.lua b/class/boids/controls/HybridControls.lua
index 449ef3d..e786eea 100644
--- a/class/boids/controls/HybridControls.lua
+++ b/class/boids/controls/HybridControls.lua
@@ -1,60 +1,62 @@
 --[[
 
 * Hybrid control scheme
 
 Cellulo acts like a joystick position-wise, and goes back to the center when it's released.
 Rotation-wise, it acts like the absolute control scheme.
 
 ]]--
 
 local global = require "global"
 
 local HybridControls = (class "boids.controls.Controls"):subclass("HybridControls")
 
 local CELLULO_RELATIVE_SPEED = 5
 local CELLULO_RELATIVE_ROTATION_SPEED = 2
 
 local CELLULO_MAX_HAPTIC_FORCE = 20
 local CELLULO_HAPTIC_FACTOR = 10
 
 local CELLULO_RELATIVE_TARGET = { x = 0, y = 0 }
 
 function HybridControls.static:applyMovement(boid, dt)
     -- move like the cellulo was a joystick thumb, origin of the paper acting as neutral
     if not kidnapped then
         -- relative position
         local x, y, z = boid:getCollider():getPosition()
         local dx, dy = boid:getCelluloPlane():normalizedRelative(boid:getCellulo():getX(), boid:getCellulo():getY())
         dx, dy = util.rotateVector(dx, dy, -global.camera:getAngle())
         x, z = x + dx * CELLULO_RELATIVE_SPEED * dt, z + dy * CELLULO_RELATIVE_SPEED * dt
         boid:setPosition(x, y, z)
         boid:getCollider():setPosition(x, y, z)
         
         -- absolute rotation
         local da = boid:getCellulo():getTheta() - boid.oa
         da = math.atan2(math.sin(da), math.cos(da))
         local angle = boid:getAngle()
         angle = angle - da -- no need for dt?
         boid:setAngle(angle)
 
         -- force cellulo back to center (haptic)
         local tx, ty = boid:getCelluloPlane():normalizedRelativeToAbsolute(CELLULO_RELATIVE_TARGET.x, CELLULO_RELATIVE_TARGET.y)
         boid:getCellulo():setGoalPosition(tx, ty, 100)
     end
 end
 
 function HybridControls.static:applyHapticFeedback(boid, dt, dir)
     if dir:length() > 1 then
         dir:mul(CELLULO_HAPTIC_FACTOR)
         if dir:length() > CELLULO_MAX_HAPTIC_FORCE then
             dir:normalize()
             dir:mul(CELLULO_MAX_HAPTIC_FORCE)
         end
         dir:div(CELLULO_MAX_HAPTIC_FORCE)
         local dx, dy, dz = dir:unpack()
         dx, dz = util.rotateVector(dx, dz, global.camera:getAngle())
         dx, dz = dx / 2, dz / 2
         dx, dz = boid:getCelluloPlane():normalizedRelativeToAbsolute(dx, dz)
         boid:getCellulo():setGoalPosition(dx, dz, 100)
     end
-end
\ No newline at end of file
+end
+
+return HybridControls
\ No newline at end of file
diff --git a/class/boids/controls/RelativeControls.lua b/class/boids/controls/RelativeControls.lua
index 4fc31ca..aad5f0c 100644
--- a/class/boids/controls/RelativeControls.lua
+++ b/class/boids/controls/RelativeControls.lua
@@ -1,50 +1,52 @@
 --[[
 
 * Relative control scheme
 
 Cellulo acts like a joystick
 
 ]]--
 
 local global = require "global"
 
 local RelativeControls = (class "boids.controls.Controls"):subclass("RelativeControls")
 
 local CELLULO_RELATIVE_SPEED = 5
 local CELLULO_RELATIVE_ROTATION_SPEED = 2
 
 local CELLULO_MAX_HAPTIC_FORCE = 20
 local CELLULO_HAPTIC_FACTOR = 10
 
 function RelativeControls.static:applyMovement(boid, dt)
     -- move like the cellulo was a joystick thumb, origin of the paper acting as neutral
     if not kidnapped then
         local x, y, z = boid:getCollider():getPosition()
         local dx, dy = boid:getCelluloPlane():normalizedRelative(boid:getCellulo():getX(), boid:getCellulo():getY())
         dx, dy = util.rotateVector(dx, dy, -global.camera:getAngle())
         x, z = x + dx * CELLULO_RELATIVE_SPEED * dt, z + dy * CELLULO_RELATIVE_SPEED * dt
         local angle = boid:getAngle()
         local da = boid:getCellulo():getAngle()
         if da > math.pi then da = -2*math.pi + da end
         angle = angle + (-da) * CELLULO_RELATIVE_ROTATION_SPEED * dt
         boid:setPosition(x, y, z)
         boid:getCollider():setPosition(x, y, z)
         boid:setAngle(angle)
     end
 end
 
 function RelativeControls.static:applyHapticFeedback(boid, dt, dir)
     if dir:length() > 1 then
         dir:mul(CELLULO_HAPTIC_FACTOR)
         if dir:length() > CELLULO_MAX_HAPTIC_FORCE then
             dir:normalize()
             dir:mul(CELLULO_MAX_HAPTIC_FORCE)
         end
         dir:div(CELLULO_MAX_HAPTIC_FORCE)
         local dx, dy, dz = dir:unpack()
         dx, dz = util.rotateVector(dx, dz, global.camera:getAngle())
         dx, dz = dx / 2, dz / 2
         dx, dz = boid:getCelluloPlane():normalizedRelativeToAbsolute(dx, dz)
         boid:getCellulo():setGoalPose(dx, dz, 0, 100, 10)
     end
-end
\ No newline at end of file
+end
+
+return RelativeControls
\ No newline at end of file