# Update on Local Positioning System

As we already talked before in a couple of post, we are currently developping a local positioning system for the Crazyflie based on ultra-wide-band radio DWM1000. This is one of our main focus currently so we wanted to post a short update on our progress.

We have assembled and shipped a couple of LPS system already and so far the performance and progress are great. We now think that we have the copter flying as good as we can have it without running sensor fusion and the control loop in the Crazyflie microcontroller. Next step is to integrate algorithms in the Crazyflie.

We are currently working hard at finishing the design to make it ready for production. We will write more updates about that so stay tuned :).

We have shot a short video demonstrating the current state, see after the video for more information about the setup:

To make this video we have installed 6 anchors. 3 are above the room and 3 at about 50cm from the ground. The Crazyflie has a LPS deck and ranges in a round-robing fashion with all 6 anchors. The ROS driver pulls the ranging, estimate the Crazyflie position, and calculate a corrected roll/pitch/thrust in order to keep it at the pre-defined setpoint. The Yaw is not controlled externally, it is kept by the Crazyflie internal gyroscope only.

The ROS computer was setup according to the instruction on our wiki, and by launching the pf_hover launch file:

roslaunch bitcraze_lps_estimator dwm_loc_pf_hover.launch uri:=radio://0/110/2M x:=1.5 y:=5 z:=1.2

## 3 comments on “Update on Local Positioning System”

• Really really awesome work there!
Are you planning to solve the yaw? It should theoretically be possible to obtain the heading by fusing position and acceleration measurements, but it would be best to do that on-board of course.

• arnaud says:

Thanks!
Yes the yaw should be solved, it is possible to guess it from pitch/roll and positioning, for example with a Kallman filter.
But until now we could work without: if the Crazyflie is carefully placed before takeoff, we can fly a full battery without the yaw being a problem.

• Alperen Guman says:

Great work! Can’t wait to see the LPS finalized, checking your blog religiously every week for updates about the LPS.