Add real robot devices and scripts to control real robot (#288)

Co-authored-by: Simon Alibert <alibert.sim@gmail.com>

lerobot/common/robot_devices/utils.py

@@ -0,0 +1,19 @@
+class RobotDeviceNotConnectedError(Exception):
+    """Exception raised when the robot device is not connected."""
+
+    def __init__(
+        self, message="This robot device is not connected. Try calling `robot_device.connect()` first."
+    ):
+        self.message = message
+        super().__init__(self.message)
+
+
+class RobotDeviceAlreadyConnectedError(Exception):
+    """Exception raised when the robot device is already connected."""
+
+    def __init__(
+        self,
+        message="This robot device is already connected. Try not calling `robot_device.connect()` twice.",
+    ):
+        self.message = message
+        super().__init__(self.message)