X80 WiRobot


An X80 WiRobot has a variety of different sensors, including:

My primary interest is in Computer Vision, so I use the camera but don't really care about the other sensors. The camera sends JPEG images over the wireless LAN. Unfortunately, the resolution is quite low and using JPEG introduces "artefacts" into the images.

It is worth noting that the sonar is accurate to within 1 centimeter from about 12 to 250 cm. This is quite useful, but sonar does have its problems. For instance, it will not register properly if the surface absorbs sound or if the surface is at an angle to the robot so that the sound waves bounce off and head away from the robot.

The infra-red sensors are very noisy and non-linear. They are only useful for very close proximity, e.g. less than 30 cm.

The wheel encoders allow reasonably accurate movements. For instance, you can tell the robot to move forward a specified distance, or to rotate by a given amount, by sending it a command that uses target wheel tick counts. However, there is some play in the wheels and the robot does not always move by exactly the desired amount.

My X80 robots have a tendency to move slightly sideways during rotations and will not travel in a straight line over long distances. This can be quite annoying, but this is why you need to perform localization when using a robot. In fact, odometry (using wheel encoders) is notoriously unreliable for mobile robots. The X80 is no exception!