Using WTB2S-2 sensor in Robocon Competition

The theme of Robocon 2017’s competition is “The Landing Disc” and true to such, this year we have to build robots that land discs onto the poles set up in the game field. Each team will be given 50 discs to try and land either the most discs or at least one disc on each pole within 3 minutes. It is precisely because of these restrictions, a 3 minute game and 50 discs, that we will need an efficient shooting and loading mechanism. There was also a restriction on the weight of the robot. Because we would like our shooting to be as quick as possible, we decided on implementing multiple shooting mechanisms - this puts us dangerously on the weight limit.

The game field

Nevertheless, to ease and speed up the loading process, we wanted it to be automatic - in a sense that the discs will be automatically loaded into the shooter until a stop signal is sent. Thus, we needed a sensor to sense when the disc is at the correct height before moving it along. We needed one that was fast and sensitive enough to react to time critical changes and light enough so that our robot wouldn’t exceed the weight limit. Initially we were using a laser that weighed around 350g and was at least 10 times the size of the WTB2S-2 sensor. It functioned well for accurate distance measurements but it was inefficiently large and possessed redundant features for the function it is currently serving. This was why we chose the WTB2S-2 sensor.

There are multiple approaches to making a shooter. A spinning motor, for example, provides precise force but takes up a large space (because it spins) and relies on encoders to identify its position.

The WTB2S-2

By HKUST Robotics team