diff --git a/examples/interfaces/playstation.py b/examples/interfaces/playstation.py
index fb7db5c..78a96f6 100644
--- a/examples/interfaces/playstation.py
+++ b/examples/interfaces/playstation.py
@@ -8,16 +8,20 @@ $ python playstation.py --controller ps          # to use any PS game controller
 $ python playstation.py --controller ps3         # to use PS3 game controller
 $ python playstation.py --controller ps4         # to use PS4 game controller
 ```
+
+Note that these game controllers are blocking by default, thus set `use_thread` to True to avoid to be blocked.
 """
 
 import time
-from itertools import count
 import argparse
 
 from pyrobolearn.tools.interfaces.controllers.playstation import *
 
+
 # create parser to select the game controller
 parser = argparse.ArgumentParser()
+parser.add_argument('-t', '--use_thread', help='If we should run the PlayStation controller in a thread.', type=bool,
+                    default=True)
 parser.add_argument('-c', '--controller', help='The Playstation game controller to use (ps, ps3, or ps4)', type=str,
                     choices=['ps', 'ps3', 'ps4'], default='ps')
 args = parser.parse_args()
@@ -25,25 +29,25 @@ args = parser.parse_args()
 
 # load corresponding Playstation controller interface
 if args.controller == 'ps':
-    controller = PSControllerInterface(verbose=False)
+    controller = PSControllerInterface(use_thread=args.use_thread, verbose=False)
 if args.controller == 'ps3':
-    controller = PS3ControllerInterface(verbose=False)
+    controller = PS3ControllerInterface(use_thread=args.use_thread, verbose=False)
 elif args.controller == 'ps4':
-    controller = PS4ControllerInterface(verbose=False)
+    controller = PS4ControllerInterface(use_thread=args.use_thread, verbose=False)
 else:
     raise NotImplementedError("Unknown game controller")
 
 
 # run controller
 print('Running controller...')
-for _ in count():
+while True:
 
     # run one step with the interface
-    controller.run()  # same as `step()` if we are not using threads
+    controller.step()  # same as `step()` if we are not using threads
 
     # get the last update and print it
-    b = controller.X
-    print("X: {}".format(b))  # , controller[b]))
+    b = controller.last_updated_button
+    print("Last updated button: {} with value: {}".format(b, controller[b]))
 
     # sleep a bit
     time.sleep(0.01)
diff --git a/examples/interfaces/robots/quadcopter_controller.py b/examples/interfaces/robots/quadcopter_controller.py
new file mode 100644
index 0000000..2274649
--- /dev/null
+++ b/examples/interfaces/robots/quadcopter_controller.py
@@ -0,0 +1,85 @@
+#!/usr/bin/env python
+"""Control a quadcopter in the air using an Xbox or Playstation game controller.
+
+how to run:
+```
+$ python quadcopter_controller.py --help                    # for help
+$ python quadcopter_controller.py --controller keyboard     # to use the keyboard
+$ python quadcopter_controller.py --controller xbox         # to use Xbox game controller
+$ python quadcopter_controller.py --controller ps          # to use PS game controller
+```
+
+Mapping of the keyboard interface:
+- `top arrow`: move forward
+- `bottom arrow`: move backward
+- `left arrow`: move sideways to the left
+- `right arrow`: move sideways to the right
+- `ctrl + top arrow`: ascend
+- `ctrl + bottom arrow`: descend
+- `ctrl + left arrow`: turn to the right
+- `ctrl + right arrow`: turn to the left
+- `space`: switch between first-person and third-person view
+
+Mapping between the controller and the quadcopter:
+- left joystick: use to move the quadcopter
+- right joystick: use to ascend/descend and turn
+- south button (X on PlayStation and A on Xbox): change between the first-person and third-person view.
+- east button (circle on PlayStation and B on Xbox): increase the speed
+- west button (square on PlayStation and X on Xbox): decrease the speed
+"""
+
+# import numpy as np
+from itertools import count
+import argparse
+
+import pyrobolearn as prl
+
+
+# create parser to select the game controller
+parser = argparse.ArgumentParser()
+parser.add_argument('-c', '--controller', help='the controller to use', type=str,
+                    choices=['keyboard', 'xbox', 'ps'], default='keyboard')
+args = parser.parse_args()
+
+
+# load corresponding interface
+if args.controller == 'keyboard':  # keyboard interface
+    from pyrobolearn.tools.interfaces.mouse_keyboard.mousekeyboard import MouseKeyboardInterface as Controller
+    from pyrobolearn.tools.bridges.mouse_keyboard.bridge_mousekeyboard_quadcopter \
+        import BridgeMouseKeyboardQuadcopter as Bridge
+elif args.controller == 'xbox':  # Xbox interface
+    from pyrobolearn.tools.interfaces.controllers.xbox import XboxControllerInterface as Controller
+    from pyrobolearn.tools.bridges.controllers.robots.bridge_controller_quadcopter import BridgeControllerQuadcopter \
+        as Bridge
+elif args.controller == 'ps':  # PS interface
+    from pyrobolearn.tools.interfaces.controllers.playstation import PSControllerInterface as Controller
+    from pyrobolearn.tools.bridges.controllers.robots.bridge_controller_quadcopter import BridgeControllerQuadcopter \
+        as Bridge
+else:
+    raise NotImplementedError("Unknown game controller")
+
+
+# create simulator
+sim = prl.simulators.Bullet()
+
+# create basic world (with a floor and gravity enabled by default)
+world = prl.worlds.BasicWorld(sim)
+
+# load quadcopter
+robot = prl.robots.Quadcopter(sim, position=[0., 0., 2.])
+world.load_robot(robot)
+
+# load interface that accepts input events
+controller = Controller(use_thread=True, verbose=False)
+
+# load bridge that connects the interface/controller with the quadcopter
+# The bridge is the one that maps the input events from the interface to commands sent to the quadcopter
+bridge = Bridge(quadcopter=robot, interface=controller)
+
+# run simulator
+for t in count():
+    # perform a step with the bridge and interface
+    bridge.step(update_interface=True)
+
+    # perform one step in the world
+    world.step(sleep_dt=1. / 240)
diff --git a/examples/interfaces/robots/quadcopter_speech.py b/examples/interfaces/robots/quadcopter_speech.py
new file mode 100644
index 0000000..c77dae6
--- /dev/null
+++ b/examples/interfaces/robots/quadcopter_speech.py
@@ -0,0 +1,41 @@
+#!/usr/bin/env python
+"""Control a quadcopter in the air using speech.
+
+Try to say:
+- turn right/left
+- move/go higher/lower/forward/backward/right/left
+- go faster/slower
+- anything else will ask the robot to hover
+"""
+
+from itertools import count
+
+import pyrobolearn as prl
+from pyrobolearn.tools.bridges.audio.robots.bridge_speech_quadcopter import BridgeSpeechRecognizerQuadcopter
+
+
+# create simulator
+sim = prl.simulators.Bullet()
+
+# create basic world (with a floor and gravity enabled by default)
+world = prl.worlds.BasicWorld(sim)
+
+# load quadcopter
+robot = prl.robots.Quadcopter(sim, position=[0., 0., 2.])
+world.load_robot(robot)
+
+# load bridge that connects the speech interface with the quadcopter
+# Note that it will create automatically the Speech Recognizer interface inside the bridge
+bridge = BridgeSpeechRecognizerQuadcopter(robot=robot, interface=None, verbose=True)
+
+
+# run simulator
+for t in count():
+    # perform a step with the bridge and interface
+    bridge.step(update_interface=True)
+
+    # ask the world camera to follow the wheeled robot
+    world.follow(robot, distance=2)
+
+    # perform one step in the world
+    world.step(sleep_dt=1. / 240)
diff --git a/examples/interfaces/robots/wheeled_controller.py b/examples/interfaces/robots/wheeled_controller.py
new file mode 100644
index 0000000..2ec9f2e
--- /dev/null
+++ b/examples/interfaces/robots/wheeled_controller.py
@@ -0,0 +1,79 @@
+#!/usr/bin/env python
+"""Control a wheeled robot using a keyboard, an Xbox or Playstation game controller.
+
+how to run:
+```
+$ python wheeled_controller.py --help                    # for help
+$ python wheeled_controller.py --controller keyboard     # to use the keyboard
+$ python wheeled_controller.py --controller xbox         # to use Xbox game controller
+$ python wheeled_controller.py --controller ps           # to use PS game controller
+```
+
+Mapping of the keyboard interface:
+* `top arrow`: move forward
+* `bottom arrow`: move backward
+* `left arrow`: turn/steer to the left
+* `right arrow`: turn/steer to the right
+
+Mapping between the controller and the wheeled robot:
+- left joystick: velocity of the wheeled robot
+- east button (circle on PlayStation and B on Xbox): increase the speed
+- west button (square on PlayStation and X on Xbox): decrease the speed
+"""
+
+# import numpy as np
+from itertools import count
+import argparse
+
+import pyrobolearn as prl
+
+
+# create parser to select the game controller
+parser = argparse.ArgumentParser()
+parser.add_argument('-c', '--controller', help='the controller to use', type=str,
+                    choices=['keyboard', 'xbox', 'ps'], default='keyboard')
+args = parser.parse_args()
+
+
+# load corresponding interface
+if args.controller == 'keyboard':  # keyboard interface
+    from pyrobolearn.tools.interfaces.mouse_keyboard.mousekeyboard import MouseKeyboardInterface as Controller
+    from pyrobolearn.tools.bridges.mouse_keyboard.bridge_mousekeyboard_wheeled \
+        import BridgeMouseKeyboardDifferentialWheeledRobot as Bridge
+elif args.controller == 'xbox':  # Xbox interface
+    from pyrobolearn.tools.interfaces.controllers.xbox import XboxControllerInterface as Controller
+    from pyrobolearn.tools.bridges.controllers.robots.bridge_controller_wheeled import BridgeControllerWheeledRobot \
+        as Bridge
+elif args.controller == 'ps':  # PS interface
+    from pyrobolearn.tools.interfaces.controllers.playstation import PSControllerInterface as Controller
+    from pyrobolearn.tools.bridges.controllers.robots.bridge_controller_wheeled import \
+        BridgeControllerWheeledRobot as Bridge
+else:
+    raise NotImplementedError("Unknown game controller")
+
+
+# create simulator
+sim = prl.simulators.Bullet()
+
+# create basic world (with a floor and gravity enabled by default)
+world = prl.worlds.BasicWorld(sim)
+
+# load quadcopter
+robot = prl.robots.Epuck(sim, position=[0., 0.])
+world.load_robot(robot)
+
+# load interface that accepts input events
+controller = Controller(use_thread=True, verbose=False)
+
+# load bridge that connects the interface/controller with the quadcopter
+# The bridge is the one that maps the input events from the interface to commands sent to the quadcopter
+bridge = Bridge(robot=robot, interface=controller)
+
+
+# run simulator
+for t in count():
+    # perform a step with the bridge and interface
+    bridge.step(update_interface=True)
+
+    # perform one step in the world
+    world.step(sleep_dt=1. / 240)
diff --git a/examples/interfaces/robots/wheeled_speech.py b/examples/interfaces/robots/wheeled_speech.py
new file mode 100644
index 0000000..b320eff
--- /dev/null
+++ b/examples/interfaces/robots/wheeled_speech.py
@@ -0,0 +1,41 @@
+#!/usr/bin/env python
+"""Control a wheeled robot in the air using speech.
+
+Try to say:
+- turn right/left
+- move/go forward/backward
+- go faster/slower
+- anything else will ask the robot to hover
+"""
+
+from itertools import count
+
+import pyrobolearn as prl
+from pyrobolearn.tools.bridges.audio.robots.bridge_speech_wheeled import BridgeSpeechRecognizerDifferentialWheeledRobot
+
+
+# create simulator
+sim = prl.simulators.Bullet()
+
+# create basic world (with a floor and gravity enabled by default)
+world = prl.worlds.BasicWorld(sim)
+
+# load wheeled robot
+robot = prl.robots.Epuck(sim, position=[0., 0.])
+world.load_robot(robot)
+
+# load bridge that connects the speech interface with the wheeled robot
+# Note that it will create automatically the Speech Recognizer interface inside the bridge
+bridge = BridgeSpeechRecognizerDifferentialWheeledRobot(robot=robot, interface=None, verbose=True)
+
+
+# run simulator
+for t in count():
+    # perform a step with the bridge and interface
+    bridge.step(update_interface=True)
+
+    # ask the world camera to follow the wheeled robot
+    world.follow(robot, distance=2)
+
+    # perform one step in the world
+    world.step(sleep_dt=1. / 240)
diff --git a/examples/interfaces/speech.py b/examples/interfaces/speech.py
index 51b51d4..a47ec2a 100644
--- a/examples/interfaces/speech.py
+++ b/examples/interfaces/speech.py
@@ -33,4 +33,4 @@ interface = SpeechTranslatorInterface(verbose=True, from_lang=args.lang, target_
 
 # run the interface
 while True:
-    data = interface.run()
+    data = interface.step()
diff --git a/examples/interfaces/webcam.py b/examples/interfaces/webcam.py
index 3ad2c6d..e839fe0 100644
--- a/examples/interfaces/webcam.py
+++ b/examples/interfaces/webcam.py
@@ -33,7 +33,7 @@ else:
     plt.ion()   # interactive mode on
 
     while True:
-        # if don't use thread call `step` or `run` (note that `run` returns the frame but not
+        # perform a `step` with the interface
         interface.step()
 
         # get the frame and plot it with matplotlib
diff --git a/examples/interfaces/xbox.py b/examples/interfaces/xbox.py
index f32d3a5..03a8ca8 100644
--- a/examples/interfaces/xbox.py
+++ b/examples/interfaces/xbox.py
@@ -1,35 +1,50 @@
 #!/usr/bin/env python
 """Load the Xbox game controller interface
+
+How to run:
+```
+$ python xbox.py --help                         # for help
+$ python xbox.py --controller xbox              # to use any Xbox game controller (by default)
+$ python xbox.py --controller xbox-360          # to use Xbox 360 game controller
+$ python xbox.py --controller xbox-one          # to use Xbox One game controller
+```
+
+Note that these game controllers are blocking by default, thus set `use_thread` to True to avoid to be blocked.
 """
 
 import time
-from itertools import count
 import argparse
 
-from pyrobolearn.tools.interfaces.controllers.xbox import Xbox360ControllerInterface, XboxOneControllerInterface
+from pyrobolearn.tools.interfaces.controllers.xbox import XboxControllerInterface, XboxOneControllerInterface, \
+    Xbox360ControllerInterface
+
 
 # create parser to select the game controller
 parser = argparse.ArgumentParser()
-parser.add_argument('-c', '--controller', help='The Xbox game controller to use (xbox one or xbox 360)', type=str,
-                    choices=['360', 'one'], default='one')
+parser.add_argument('-t', '--use_thread', help='If we should run the Xbox controller in a thread.', type=bool,
+                    default=True)
+parser.add_argument('-c', '--controller', help='The Xbox game controller to use.', type=str,
+                    choices=['xbox', 'xbox-360', 'xbox-one'], default='xbox')
 args = parser.parse_args()
 
 
 # load corresponding Xbox controller interface
-if args.controller == '360':
-    controller = Xbox360ControllerInterface(verbose=True)
-elif args.controller == 'one':
-    controller = XboxOneControllerInterface(verbose=True)
+if args.controller == 'xbox':
+    controller = XboxControllerInterface(use_thread=args.use_thread, verbose=False)
+elif args.controller == 'xbox-360':
+    controller = Xbox360ControllerInterface(use_thread=args.use_thread, verbose=False)
+elif args.controller == 'xbox-one':
+    controller = XboxOneControllerInterface(use_thread=args.use_thread, verbose=False)
 else:
     raise NotImplementedError("Unknown game controller")
 
 
 # run controller
 print('Running controller...')
-for _ in count():
+while True:
 
     # run one step with the interface
-    controller.run()  # same as `step()` if we are not using threads
+    controller.step()
 
     # get the last update and print it
     b = controller.last_updated_button
diff --git a/examples/robots/quadcopter_controller.py b/examples/robots/quadcopter_controller.py
index c1dde02..2274649 100644
--- a/examples/robots/quadcopter_controller.py
+++ b/examples/robots/quadcopter_controller.py
@@ -19,6 +19,13 @@ Mapping of the keyboard interface:
 - `ctrl + left arrow`: turn to the right
 - `ctrl + right arrow`: turn to the left
 - `space`: switch between first-person and third-person view
+
+Mapping between the controller and the quadcopter:
+- left joystick: use to move the quadcopter
+- right joystick: use to ascend/descend and turn
+- south button (X on PlayStation and A on Xbox): change between the first-person and third-person view.
+- east button (circle on PlayStation and B on Xbox): increase the speed
+- west button (square on PlayStation and X on Xbox): decrease the speed
 """
 
 # import numpy as np
@@ -63,7 +70,7 @@ robot = prl.robots.Quadcopter(sim, position=[0., 0., 2.])
 world.load_robot(robot)
 
 # load interface that accepts input events
-controller = Controller()
+controller = Controller(use_thread=True, verbose=False)
 
 # load bridge that connects the interface/controller with the quadcopter
 # The bridge is the one that maps the input events from the interface to commands sent to the quadcopter
diff --git a/examples/robots/visualize_robot.py b/examples/robots/visualize_robot.py
index b63138f..2f93b6c 100644
--- a/examples/robots/visualize_robot.py
+++ b/examples/robots/visualize_robot.py
@@ -36,8 +36,7 @@ import pyrobolearn as prl
 # create parser to select the robot
 robots = ['coman', 'hyq2max']  # prl.robots.implemented_robots
 parser = argparse.ArgumentParser()
-parser.add_argument('-r', '--robot', help='the robot to load in the world', type=str,
-                    choices=robots, default='hyq2max')
+parser.add_argument('-r', '--robot', help='the robot to load in the world', type=str, choices=robots, default='hyq2max')
 args = parser.parse_args()
 
 
@@ -57,7 +56,8 @@ for _ in range(100):
 # change visualization
 robot.change_transparency()
 robot.draw_link_coms()
-robot.draw_link_frames()
+robot.draw_link_frames(robot.legs[0])
+robot.draw_joint_frames(robot.legs[0])
 robot.draw_bounding_boxes(link_ids=-1)
 
 robot.draw_friction_cone(floor_id=world.floor_id)
diff --git a/examples/robots/wheeled_controller.py b/examples/robots/wheeled_controller.py
new file mode 100644
index 0000000..2ec9f2e
--- /dev/null
+++ b/examples/robots/wheeled_controller.py
@@ -0,0 +1,79 @@
+#!/usr/bin/env python
+"""Control a wheeled robot using a keyboard, an Xbox or Playstation game controller.
+
+how to run:
+```
+$ python wheeled_controller.py --help                    # for help
+$ python wheeled_controller.py --controller keyboard     # to use the keyboard
+$ python wheeled_controller.py --controller xbox         # to use Xbox game controller
+$ python wheeled_controller.py --controller ps           # to use PS game controller
+```
+
+Mapping of the keyboard interface:
+* `top arrow`: move forward
+* `bottom arrow`: move backward
+* `left arrow`: turn/steer to the left
+* `right arrow`: turn/steer to the right
+
+Mapping between the controller and the wheeled robot:
+- left joystick: velocity of the wheeled robot
+- east button (circle on PlayStation and B on Xbox): increase the speed
+- west button (square on PlayStation and X on Xbox): decrease the speed
+"""
+
+# import numpy as np
+from itertools import count
+import argparse
+
+import pyrobolearn as prl
+
+
+# create parser to select the game controller
+parser = argparse.ArgumentParser()
+parser.add_argument('-c', '--controller', help='the controller to use', type=str,
+                    choices=['keyboard', 'xbox', 'ps'], default='keyboard')
+args = parser.parse_args()
+
+
+# load corresponding interface
+if args.controller == 'keyboard':  # keyboard interface
+    from pyrobolearn.tools.interfaces.mouse_keyboard.mousekeyboard import MouseKeyboardInterface as Controller
+    from pyrobolearn.tools.bridges.mouse_keyboard.bridge_mousekeyboard_wheeled \
+        import BridgeMouseKeyboardDifferentialWheeledRobot as Bridge
+elif args.controller == 'xbox':  # Xbox interface
+    from pyrobolearn.tools.interfaces.controllers.xbox import XboxControllerInterface as Controller
+    from pyrobolearn.tools.bridges.controllers.robots.bridge_controller_wheeled import BridgeControllerWheeledRobot \
+        as Bridge
+elif args.controller == 'ps':  # PS interface
+    from pyrobolearn.tools.interfaces.controllers.playstation import PSControllerInterface as Controller
+    from pyrobolearn.tools.bridges.controllers.robots.bridge_controller_wheeled import \
+        BridgeControllerWheeledRobot as Bridge
+else:
+    raise NotImplementedError("Unknown game controller")
+
+
+# create simulator
+sim = prl.simulators.Bullet()
+
+# create basic world (with a floor and gravity enabled by default)
+world = prl.worlds.BasicWorld(sim)
+
+# load quadcopter
+robot = prl.robots.Epuck(sim, position=[0., 0.])
+world.load_robot(robot)
+
+# load interface that accepts input events
+controller = Controller(use_thread=True, verbose=False)
+
+# load bridge that connects the interface/controller with the quadcopter
+# The bridge is the one that maps the input events from the interface to commands sent to the quadcopter
+bridge = Bridge(robot=robot, interface=controller)
+
+
+# run simulator
+for t in count():
+    # perform a step with the bridge and interface
+    bridge.step(update_interface=True)
+
+    # perform one step in the world
+    world.step(sleep_dt=1. / 240)
diff --git a/pyrobolearn/tools/bridges/audio/robots/bridge_speech_quadcopter.py b/pyrobolearn/tools/bridges/audio/robots/bridge_speech_quadcopter.py
new file mode 100644
index 0000000..81e96d1
--- /dev/null
+++ b/pyrobolearn/tools/bridges/audio/robots/bridge_speech_quadcopter.py
@@ -0,0 +1,89 @@
+#!/usr/bin/env python
+"""Bridges between speech interface and quadcopter
+"""
+
+from pyrobolearn.robots import Quadcopter
+from pyrobolearn.tools.interfaces.audio.speech import SpeechRecognizerInterface
+from pyrobolearn.tools.bridges.bridge import Bridge
+
+
+__author__ = "Brian Delhaisse"
+__copyright__ = "Copyright 2018, PyRoboLearn"
+__credits__ = ["Brian Delhaisse"]
+__license__ = "GNU GPLv3"
+__version__ = "1.0.0"
+__maintainer__ = "Brian Delhaisse"
+__email__ = "briandelhaisse@gmail.com"
+__status__ = "Development"
+
+
+class BridgeSpeechRecognizerQuadcopter(Bridge):
+    r"""Bridge Speech Wheeled Robot
+
+    Bridge between the speech recognizer interface and a wheeled robot. You can give oral orders to the robot.
+    """
+
+    def __init__(self, robot, interface=None, speed=10., priority=None, verbose=False, *args, **kwargs):
+        """
+        Initialize the bridge between the speech recognizer interface and the quadcopter robot.
+
+        Args:
+            robot (Quadcopter): quadcopter robot instance.
+            interface (SpeechRecognizerInterface, None): speech recognizer interface. If None, it will instantiate it
+                here, and launch it in a thread.
+            speed (float): initial speed of the quadcopter robot.
+            priority (int): priority of the bridge.
+            verbose (bool): If True, print information on the standard output.
+        """
+        # check the robot
+        if not isinstance(quadcopter, Quadcopter):
+            raise TypeError("Expecting the given 'quadcopter' to be an instance of `Quadcopter`, but got instead: "
+                            "{}".format(type(robot)))
+        self.robot = robot
+        self.speed = speed
+
+        if interface is None:
+            interface = SpeechRecognizerInterface(use_thread=True, verbose=verbose)
+        if not isinstance(interface, SpeechRecognizerInterface):
+            raise TypeError("Expecting the given 'interface' to be an instance of `SpeechRecognizerInterface`, but "
+                            "got instead: {}".format(type(interface)))
+
+        super(BridgeSpeechRecognizerQuadcopter, self).__init__(interface, priority=priority, verbose=verbose)
+
+    def step(self, update_interface=False):
+        """Perform a step with the bridge."""
+        # update interface
+        if update_interface:
+            self.interface()
+
+        # get the data
+        data = self.interface.data
+
+        if self.verbose and data is not None:
+            print("Bridge: the data = {}".format(data))
+
+        # split the data
+        data = data.split()
+
+        if data[-1] == 'higher':
+            self.robot.ascend(speed=self.speed)
+        elif data[-1] == 'lower':
+            self.robot.descend(speed=self.speed)
+        elif data[-1] == 'forward':
+            self.robot.move_forward(speed=self.speed)
+        elif data[-1] == 'backward':
+            self.robot.move_backward(speed=self.speed)
+        elif data == 'turn right':
+            self.robot.turn_right(speed=self.speed)
+        elif data == 'turn left':
+            self.robot.turn_left(speed=self.speed)
+        elif data[-1] == 'right':
+            self.robot.move_right(speed=self.speed)
+        elif data[-1] == 'left':
+            self.robot.move_left(speed=self.speed)
+        elif data[-1] == 'faster':
+            self.speed *= 2.
+        elif data[-1] == 'slower':
+            self.speed /= 2.
+        else:
+            self.robot.hover()
diff --git a/pyrobolearn/tools/bridges/audio/robots/bridge_speech_rotatory_uav.py b/pyrobolearn/tools/bridges/audio/robots/bridge_speech_rotatory_uav.py
deleted file mode 100644
index 1f23788..0000000
--- a/pyrobolearn/tools/bridges/audio/robots/bridge_speech_rotatory_uav.py
+++ /dev/null
@@ -1,63 +0,0 @@
-#!/usr/bin/env python
-"""Bridges between audio interface and rotatory wing robots
-"""
-
-from pyrobolearn.robots import RotaryWingUAV
-from pyrobolearn.tools.interfaces.audio.audio import SpeechRecognizerInterface
-from pyrobolearn.tools.bridges.bridge import Bridge
-
-
-__author__ = "Brian Delhaisse"
-__copyright__ = "Copyright 2018, PyRoboLearn"
-__credits__ = ["Brian Delhaisse"]
-__license__ = "GNU GPLv3"
-__version__ = "1.0.0"
-__maintainer__ = "Brian Delhaisse"
-__email__ = "briandelhaisse@gmail.com"
-__status__ = "Development"
-
-
-class BridgeSpeechRecognizerRotatoryUAV(Bridge):
-    r"""Bridge Speech Wheeled Robot
-
-    Bridge between the speech recognizer interface and a wheeled robot. You can give oral orders to the robot.
-    """
-
-    def __init__(self, interface, uav_robot, init_speed=1.):
-        if not isinstance(interface, SpeechRecognizerInterface):
-            raise TypeError("Expecting a speech recognizer interface")
-        if not isinstance(uav_robot, RotaryWingUAV):
-            raise TypeError("Expecting a wheeled robot")
-        super(BridgeSpeechRecognizerRotatoryUAV, self).__init__(interface)
-        self.robot = uav_robot
-        self.speed = init_speed
-
-    def step(self):
-        data = self.interface.data
-        data = data.split()
-        # print('data: {}'.format(data))
-        if data[0] == 'stop' or data[0] == 'stay':
-            self.robot.stop()
-        elif data[-1] == 'higher':
-            pass
-        elif data[-1] == 'lower':
-            pass
-        elif data[-1] == 'forward':
-            pass
-        elif data[-1] == 'backward':
-            pass
-        elif data == 'turn right':
-            pass
-        elif data == 'turn left':
-            pass
-        elif data[-1] == 'right':
-            pass
-        elif data[-1] == 'left':
-            pass
-        elif data[-1] == 'faster':
-            self.speed *= 2.
-        elif data[-1] == 'slower':
-            self.speed /= 2.
-        elif data:
-            pass
-            # print('I do not know the meaning of {}'.format(data))
diff --git a/pyrobolearn/tools/bridges/audio/robots/bridge_speech_wheeled.py b/pyrobolearn/tools/bridges/audio/robots/bridge_speech_wheeled.py
index 717dca9..0b1288d 100644
--- a/pyrobolearn/tools/bridges/audio/robots/bridge_speech_wheeled.py
+++ b/pyrobolearn/tools/bridges/audio/robots/bridge_speech_wheeled.py
@@ -1,13 +1,14 @@
 #!/usr/bin/env python
-"""Bridges between audio interface and wheeled robots
+"""Bridges between speech interface and wheeled robots
 """
 
 import numpy as np
 
-from pyrobolearn.robots import WheeledRobot, AckermannWheeledRobot
-from pyrobolearn.tools.interfaces.audio.audio import SpeechRecognizerInterface
+from pyrobolearn.robots import WheeledRobot, DifferentialWheeledRobot, AckermannWheeledRobot
+from pyrobolearn.tools.interfaces.audio.speech import SpeechRecognizerInterface
 from pyrobolearn.tools.bridges.bridge import Bridge
 
+
 __author__ = "Brian Delhaisse"
 __copyright__ = "Copyright 2018, PyRoboLearn"
 __credits__ = ["Brian Delhaisse"]
@@ -24,71 +25,137 @@ class BridgeSpeechRecognizerWheeledRobot(Bridge):
     Bridge between the speech recognizer interface and a wheeled robot. You can give oral orders to the robot.
     """
 
-    def __init__(self, interface, wheeled_robot, init_speed=1.):
-        if not isinstance(interface, SpeechRecognizerInterface):
-            raise TypeError("Expecting a speech recognizer interface")
-        if not isinstance(wheeled_robot, WheeledRobot):
-            raise TypeError("Expecting a wheeled robot")
-        super(BridgeSpeechRecognizerWheeledRobot, self).__init__(interface)
-        self.robot = wheeled_robot
-        self.speed = init_speed
+    def __init__(self, robot, interface=None, speed=1., priority=None, verbose=False):
+        """
+        Initialize the bridge between the speech recognizer interface and the wheeled robot.
 
-    def step(self):
+        Args:
+            robot (WheeledRobot): wheeled robot instance.
+            interface (SpeechRecognizerInterface, None): speech recognizer interface. If None, it will instantiate it
+                here, and launch it in a thread.
+            speed (float): initial speed of the wheeled robot.
+            priority (int): priority of the bridge.
+            verbose (bool): If True, print information on the standard output.
+        """
+        # check the robot
+        if not isinstance(robot, WheeledRobot):
+            raise TypeError("Expecting a wheeled robot, instead got: {}".format(robot))
+        self.robot = robot
+        self.speed = speed
+
+        # check the interface
+        if interface is None:
+            interface = SpeechRecognizerInterface(use_thread=True, verbose=verbose)
+        if not isinstance(interface, SpeechRecognizerInterface):
+            raise TypeError("Expecting a speech recognizer interface, instead got: {}".format(type(interface)))
+
+        super(BridgeSpeechRecognizerWheeledRobot, self).__init__(interface, priority=priority, verbose=verbose)
+
+    def step(self, update_interface=False):
+        """Perform a step with the bridge."""
+        # update interface
+        if update_interface:
+            self.interface()
+
+
+class BridgeSpeechRecognizerDifferentialWheeledRobot(BridgeSpeechRecognizerWheeledRobot):
+    r"""Bridge between Speech Recognizer and Differential Wheeled Robot
+
+    Bridge between the speech recognizer interface and a differential wheeled robot. You can give oral
+    orders to the robot.
+    """
+
+    def __init__(self, robot, interface=None, speed=1., priority=None, verbose=False):
+        """
+       Initialize the bridge between the speech recognizer interface and the wheeled robot.
+
+       Args:
+           robot (DifferentialWheeledRobot): wheeled robot instance.
+           interface (SpeechRecognizerInterface, None): speech recognizer interface. If None, it will instantiate it
+                here, and launch it in a thread.
+           speed (float): initial speed of the wheeled robot.
+           verbose (bool): If True, print information on the standard output.
+       """
+        if not isinstance(robot, DifferentialWheeledRobot):
+            raise TypeError("Expecting a wheeled robot of type Ackermann steering, instead got: {}".format(robot))
+
+        super(BridgeSpeechRecognizerDifferentialWheeledRobot, self).__init__(robot=robot, interface=interface,
+                                                                             speed=speed, priority=priority,
+                                                                             verbose=verbose)
+
+    def step(self, update_interface=False):
+        """Perform a step with the bridge."""
+        super(BridgeSpeechRecognizerDifferentialWheeledRobot, self).step(update_interface=update_interface)
+
+        # get the data from the interface
         data = self.interface.data
-        #print('data: {}'.format(data))
-        if data == 'stop':
-            self.robot.stop()
-        elif data == 'move forward':
+
+        if self.verbose and data is not None:
+            print("Bridge: the data = {}".format(data))
+
+        if data == 'move forward':
             self.robot.drive_forward(self.speed)
         elif data == 'move backward':
             self.robot.drive_backward(self.speed)
         elif data == 'turn right':
-            pass
+            self.robot.turn_right(1)
         elif data == 'turn left':
-            pass
+            self.robot.turn_left(1)
         elif data == 'faster':
             self.speed *= 2.
         elif data == 'slower':
             self.speed /= 2.
-        elif data:
-            pass
-            #print('I do not know the meaning of {}'.format(data))
+        else:
+            self.robot.stop()
 
 
-class BridgeSpeechRecognizerAckermannWheeledRobot(Bridge):
+class BridgeSpeechRecognizerAckermannWheeledRobot(BridgeSpeechRecognizerWheeledRobot):
     r"""Bridge Speech Ackermann Wheeled Robot
 
     Bridge between the speech recognizer interface and a wheeled robot (with ackermann steering). You can give oral
     orders to the robot.
     """
 
-    def __init__(self, interface, wheeled_robot, init_speed=1.):
-        if not isinstance(interface, SpeechRecognizerInterface):
-            raise TypeError("Expecting a speech recognizer interface")
-        if not isinstance(wheeled_robot, AckermannWheeledRobot):
-            raise TypeError("Expecting a wheeled robot of type Ackermann steering")
-        super(BridgeSpeechRecognizerAckermannWheeledRobot, self).__init__(interface)
-        self.robot = wheeled_robot
-        self.speed = init_speed
+    def __init__(self, robot, interface=None, speed=1., priority=None, verbose=False):
+        """
+       Initialize the bridge between the speech recognizer interface and the wheeled robot.
+
+       Args:
+           robot (AckermannWheeledRobot): wheeled robot instance.
+           interface (SpeechRecognizerInterface, None): speech recognizer interface. If None, it will instantiate it
+               here, and launch it in a thread.
+           speed (float): initial speed of the wheeled robot.
+           verbose (bool): If True, print information on the standard output.
+       """
+        if not isinstance(robot, AckermannWheeledRobot):
+            raise TypeError("Expecting a wheeled robot of type Ackermann steering, instead got: {}".format(robot))
+
+        super(BridgeSpeechRecognizerAckermannWheeledRobot, self).__init__(robot=robot, interface=interface,
+                                                                          speed=speed, priority=priority,
+                                                                          verbose=verbose)
         self.steering_angle = 0.
 
-    def step(self):
+    def step(self, update_interface=False):
+        """Perform a step with the bridge."""
+        super(BridgeSpeechRecognizerAckermannWheeledRobot, self).step(update_interface=update_interface)
+
+        # get the data from the interface
         data = self.interface.data
-        #print('data: {}'.format(data))
-        if data == 'stop':
-            self.robot.stop()
-        elif data == 'move forward':
+
+        if self.verbose and data is not None:
+            print("Bridge: the data = {}".format(data))
+
+        if data == 'move forward':
             self.robot.drive_forward(self.speed)
         elif data == 'move backward':
             self.robot.drive_backward(self.speed)
         elif data == 'turn right':
-            self.robot.set_steering(np.deg2rad(-20))
+            self.robot.steer(np.deg2rad(-20))
         elif data == 'turn left':
-            self.robot.set_steering(np.deg2rad(20))
+            self.robot.steer(np.deg2rad(20))
         elif data == 'faster':
             self.speed *= 2.
         elif data == 'slower':
             self.speed /= 2.
-        elif data:
-            pass
-            #print('I do not know the meaning of {}'.format(data))
\ No newline at end of file
+        else:
+            self.robot.stop()
diff --git a/pyrobolearn/tools/bridges/controllers/robots/bridge_controller_quadcopter.py b/pyrobolearn/tools/bridges/controllers/robots/bridge_controller_quadcopter.py
index 50d0104..dee6525 100644
--- a/pyrobolearn/tools/bridges/controllers/robots/bridge_controller_quadcopter.py
+++ b/pyrobolearn/tools/bridges/controllers/robots/bridge_controller_quadcopter.py
@@ -67,16 +67,15 @@ class BridgeControllerQuadcopter(Bridge):
                             "got: {}".format(type(interface)))
 
         # call superclass
-        super(BridgeControllerQuadcopter, self).__init__(interface, priority)
+        super(BridgeControllerQuadcopter, self).__init__(interface, priority=priority, verbose=verbose)
 
         # camera
         self.camera = camera
-        self.verbose = verbose
         self.fpv = first_person_view
         self.camera_pitch = self.camera.pitch
 
         # joystick threshold (to remove noise)
-        self.threshold = 0.05
+        self.threshold = 0.1
 
     ##############
     # Properties #
@@ -144,8 +143,8 @@ class BridgeControllerQuadcopter(Bridge):
 
     def check_events(self):
         # move the quadcopter
-        left_joystick = self.interface.LJ   # (x,y)
-        right_joystick = self.interface.RJ  # (x,y)
+        left_joystick = self.interface.LJ[::-1]   # (y,x)
+        right_joystick = self.interface.RJ[::-1]  # (y,x)
         south_button = self.interface.BTN_SOUTH
         east_button = self.interface.BTN_EAST
         west_button = self.interface.BTN_WEST
diff --git a/pyrobolearn/tools/bridges/controllers/robots/bridge_controller_wheeled.py b/pyrobolearn/tools/bridges/controllers/robots/bridge_controller_wheeled.py
index a4861e5..c62f4c7 100644
--- a/pyrobolearn/tools/bridges/controllers/robots/bridge_controller_wheeled.py
+++ b/pyrobolearn/tools/bridges/controllers/robots/bridge_controller_wheeled.py
@@ -63,16 +63,15 @@ class BridgeControllerWheeledRobot(Bridge):
             raise TypeError
 
         # call superclass
-        super(BridgeControllerWheeledRobot, self).__init__(interface, priority)
+        super(BridgeControllerWheeledRobot, self).__init__(interface, priority=priority, verbose=verbose)
 
         # camera
         self.camera = camera
-        self.verbose = verbose
         self.fpv = first_person_view
         self.camera_pitch = self.camera.pitch
 
         # joystick threshold (to remove noise)
-        self.threshold = 0.05
+        self.threshold = 0.1
 
     ##############
     # Properties #
@@ -139,28 +138,27 @@ class BridgeControllerWheeledRobot(Bridge):
         self.fpv = not self.fpv
 
     def check_key_events(self):
-        left_joystick = self.interface.LJ  # (x,y)
-        # south_button = self.interface.BTN_SOUTH
-        # east_button = self.interface.BTN_EAST
-        # west_button = self.interface.BTN_WEST
+        left_joystick = self.interface.LJ[::-1]  # (y,x)
+        south_button = self.interface.BTN_SOUTH
+        east_button = self.interface.BTN_EAST
+        west_button = self.interface.BTN_WEST
 
         # change camera view
         # if south_button:
         #     self.change_camera_view()
 
         # change speed
-        # if east_button:
-        #     self.speed += 1
-        # if west_button:
-        #     self.speed -= 1
+        if east_button:
+            self.speed += 1
+        if west_button:
+            self.speed -= 1
 
         # move robot
-        # if np.linalg.norm(left_joystick) > self.threshold:
-        #     # print(left_joystick)
-        #     self.robot.move(velocity=self.speed * left_joystick)
-        # else:
-        #     self.robot.move(velocity=[0., 0.])
-        print(left_joystick[0])
+        if np.linalg.norm(left_joystick) > self.threshold:
+            # print(left_joystick)
+            self.robot.move(velocity=self.speed * left_joystick)
+        else:
+            self.robot.move(velocity=[0., 0.])
 
 
 class BridgeControllerDifferentialWheeledRobot(BridgeControllerWheeledRobot):
@@ -199,7 +197,7 @@ class BridgeControllerDifferentialWheeledRobot(BridgeControllerWheeledRobot):
 
     def check_key_events(self):
         super(BridgeControllerDifferentialWheeledRobot, self).check_key_events()
-        directional_pad = self.interface.Dpad  # (x,y)
+        directional_pad = self.interface.Dpad[::-1]  # (y,x)
 
         # move robot
         if directional_pad[0] != 0:
diff --git a/pyrobolearn/tools/bridges/mouse_keyboard/bridge_mousekeyboard_wheeled.py b/pyrobolearn/tools/bridges/mouse_keyboard/bridge_mousekeyboard_wheeled.py
index 443c6c5..58959ff 100644
--- a/pyrobolearn/tools/bridges/mouse_keyboard/bridge_mousekeyboard_wheeled.py
+++ b/pyrobolearn/tools/bridges/mouse_keyboard/bridge_mousekeyboard_wheeled.py
@@ -45,6 +45,8 @@ class BridgeMouseKeyboardWheeledRobot(Bridge):
         * `left arrow`: turn/steer to the left
         * `right arrow`: turn/steer to the right
         * `space`: switch between first-person and third-person view.  # TODO
+        * `shift`: increase speed
+        * `ctrl`: decrease speed
         * predefined in simulator:
             * `w`: show the wireframe (collision shapes)
             * `s`: show the reference system
@@ -143,8 +145,8 @@ class BridgeMouseKeyboardWheeledRobot(Bridge):
         pitch, yaw = get_rpy_from_quaternion(self.robot.orientation)[1:]
         if self.fpv:  # first-person view
             target_pos = self.robot.position + 2 * np.array([np.cos(yaw) * np.cos(pitch),
-                                                                  np.sin(yaw) * np.cos(pitch),
-                                                                  np.sin(pitch)])
+                                                             np.sin(yaw) * np.cos(pitch),
+                                                             np.sin(pitch)])
             self.camera.reset(distance=2, pitch=-pitch, yaw=yaw - np.pi / 2, target_position=target_pos)
         else:  # third-person view
             self.camera.follow(body_id=self.robot.id, distance=2, yaw=yaw - np.pi / 2, pitch=self.camera_pitch)
@@ -154,7 +156,16 @@ class BridgeMouseKeyboardWheeledRobot(Bridge):
         self.fpv = not self.fpv
 
     def check_key_events(self):
-        pass
+        key, pressed, down = self.interface.key, self.interface.key_pressed, self.interface.key_down
+
+        # change camera view
+        # if key.space in pressed:
+        #     self.change_camera_view()
+
+        if key.shift in pressed:
+            self.speed += 1
+        if key.ctrl in pressed:
+            self.speed -= 1
 
 
 class BridgeMouseKeyboardDifferentialWheeledRobot(BridgeMouseKeyboardWheeledRobot):
@@ -199,21 +210,18 @@ class BridgeMouseKeyboardDifferentialWheeledRobot(BridgeMouseKeyboardWheeledRobo
                                                                           verbose=verbose)
 
     def check_key_events(self):
+        super(BridgeMouseKeyboardDifferentialWheeledRobot, self).check_key_events()
         key, pressed, down = self.interface.key, self.interface.key_pressed, self.interface.key_down
 
-        # change camera view
-        # if key.space in pressed:
-        #     self.change_camera_view()
-
         # move the robot
         if key.top_arrow in down:
             self.robot.drive(speed=self.speed)
         elif key.bottom_arrow in down:
             self.robot.drive(speed=-self.speed)
         elif key.left_arrow in down:
-            self.robot.turn(speed=self.speed)
+            self.robot.turn(speed=self.speed/10.)
         elif key.right_arrow in down:
-            self.robot.turn(speed=-self.speed)
+            self.robot.turn(speed=-self.speed/10.)
         else:
             self.robot.drive(speed=0)
 
@@ -261,10 +269,6 @@ class BridgeMouseKeyboardAckermannWheeledRobot(BridgeMouseKeyboardWheeledRobot):
     def check_key_events(self):
         key, pressed, down = self.interface.key, self.interface.key_pressed, self.interface.key_down
 
-        # change camera view
-        # if key.space in pressed:
-        #     self.change_camera_view()
-
         # move the robot
         if key.top_arrow in down:
             self.robot.drive(speed=self.speed)
diff --git a/pyrobolearn/tools/interfaces/audio/speech.py b/pyrobolearn/tools/interfaces/audio/speech.py
index cda2107..9766cb0 100644
--- a/pyrobolearn/tools/interfaces/audio/speech.py
+++ b/pyrobolearn/tools/interfaces/audio/speech.py
@@ -329,8 +329,8 @@ if __name__ == '__main__':
 
     print("Available languages are: {}".format(SpeechRecognizerInterface.available_languages))
 
-    # interface = SpeechRecognizerInterface(verbose=True, lang='english')
-    interface = SpeechTranslatorInterface(verbose=True, from_lang='french', target_lang='english')
+    interface = SpeechRecognizerInterface(use_thread=True, verbose=True, lang='english')
+    # interface = SpeechTranslatorInterface(verbose=True, from_lang='french', target_lang='english')
 
     while True:
         data = interface.run()
diff --git a/pyrobolearn/tools/interfaces/controllers/playstation.py b/pyrobolearn/tools/interfaces/controllers/playstation.py
index d9d8759..db81e7a 100755
--- a/pyrobolearn/tools/interfaces/controllers/playstation.py
+++ b/pyrobolearn/tools/interfaces/controllers/playstation.py
@@ -402,7 +402,7 @@ class PS4ControllerInterface(PSControllerInterface):
 # Tests
 if __name__ == '__main__':
     # create controller
-    controller = PSControllerInterface(use_thread=True, sleep_dt=0.01)
+    controller = PSControllerInterface(use_thread=True)
     print(controller.map)
     print(controller.buttons)
 
diff --git a/pyrobolearn/tools/interfaces/controllers/xbox.py b/pyrobolearn/tools/interfaces/controllers/xbox.py
index 8ca648d..442eb34 100644
--- a/pyrobolearn/tools/interfaces/controllers/xbox.py
+++ b/pyrobolearn/tools/interfaces/controllers/xbox.py
@@ -398,12 +398,15 @@ if __name__ == '__main__':
     import time
     from itertools import count
 
+    # set variable
+    use_thread = True
+
     # create interface
-    xbox = XboxOneControllerInterface()
+    xbox = XboxControllerInterface(use_thread=use_thread)
 
     for _ in count():
         # run one step with the interface
-        xbox.run()  # same as `step()` if we are not using threads
+        xbox.step()  # same as `step()` if we are not using threads
 
         # get the last update and print it
         b = xbox.last_updated_button
diff --git a/pyrobolearn/tools/interfaces/interface.py b/pyrobolearn/tools/interfaces/interface.py
index bd14621..fbd097a 100644
--- a/pyrobolearn/tools/interfaces/interface.py
+++ b/pyrobolearn/tools/interfaces/interface.py
@@ -103,7 +103,7 @@ class Interface(object):
     # @thread_loop
     def run(self, *args, **kwargs):
         """
-        Code to be run by the interface. This needs to be implemented by the user
+        Code to be run by the interface. This needs to be implemented by the user.
         """
         pass
 
diff --git a/pyrobolearn/tools/interfaces/mouse_keyboard/mousekeyboard.py b/pyrobolearn/tools/interfaces/mouse_keyboard/mousekeyboard.py
index 0913924..46be688 100644
--- a/pyrobolearn/tools/interfaces/mouse_keyboard/mousekeyboard.py
+++ b/pyrobolearn/tools/interfaces/mouse_keyboard/mousekeyboard.py
@@ -71,7 +71,7 @@ class MouseKeyboardInterface(InputInterface):
         triggered, 4 if it has been released.
     """
 
-    def __init__(self, simulator=None, verbose=False):
+    def __init__(self, simulator=None, verbose=False, *args, **kwargs):
         """
         Initialize the Mouse-Keyboard Interface. This interface is a little bit special in the sense that we use
         the simulator to provide the mouse and keyboard events instead of using an external library.
@@ -223,12 +223,12 @@ class MouseKeyboardInterface(InputInterface):
 
 # Tests
 if __name__ == '__main__':
-    from pyrobolearn.simulators import BulletSim
     import time
     from itertools import count
+    from pyrobolearn.simulators import Bullet
 
     # create simulator
-    sim = BulletSim()
+    sim = Bullet()
 
     # create interface
     interface = MouseKeyboardInterface(sim, verbose=True)