Error analysis of cooperative positioning system using two-way ranging measurements

In the cooperative positioning system (CPS), members of a group communicate each other and share their information to localize their position. The advantage of this system is that all the elements in the CPS can obtain their position collaboratively even if only a few members of the group get their position from GPS. This paper presents a low-cost CPS using two-way ranging (TWR) measurements and GPS. Using chirp spread spectrum ultra wideband (CSS-UWB) modulation scheme, precise TWR measurements with less than 1m error can be obtained and they are used to solve the position of members that cannot acquire GPS signal. This paper also analyzes the error propagation in the CPS. From the ranging covariance matrix, the location covariance matrix is derived to analyze the position error propagation. Simulations with various scenarios show that the geometry of members is the most important factor in the error propagation.