Ultra Wide Band System - Trilateration

One of the most important building blocks for the drone referee is a method for positioning. At all times, the drone state, namely the set {X,Y,Z,Yaw}, should be known in order to perform the refereeing duties. Of the drone state, Z and the Yaw are measured by either the drone sensor suite or other programs as they are required for the low-level control of the drone. However, in order to localize w.r.t. the field and to find X and Y, a solution has to be found. To this end, several concepts were composed. Of those concepts, trilateration using Ultra Wide Band Anchors (UWB) was realized. First, the rejected concepts are shortly listed, followed by a detailed explanation of the UWB system.

Concepts

The positioning system must provide an accurate enough signal at a high enough sample rate for position control. As ball out of pitch detection is to be detected using image processing, an accuracy of 0.5 meters was chosen as minimum accuracy for the positioning system. This means that a circle with a radius of half a meter designate the position of the drone. For the sample rate a minimum of 10 measurements per second was chosen. However, as most of the technologies listed here are very new or still in development, this information could not be obtained for all of them. The following concepts will be discussed:

• Trilateration using a Laser Range Extender
• Trilateration using ultra-wideband beacons
• Positioning using Bluetooth beacons
• Positioning using image processing