# Switching State Estimators
This page shows you which state estimators are available and how you can switch between them.
TIP
EKF2 is highly recommended on vehicles with a GNSS/GPS. The Q-Estimator is recommended if you don't have GPS, and is commonly used in multicopter racers.
# Available Estimators
The available estimators are:
EKF2 attitude, position and wind states estimator (recommended) - An extended Kalman filter estimating attitude, 3D position / velocity and wind states.
LPE position estimator (deprecated) - An extended Kalman filter for 3D position and velocity states.
WARNING
LPE is deprecated. It works (at time of writing, in PX4 v1.14) but is no longer supported or maintained.
Q attitude estimator - A very simple, quaternion based complementary filter for attitude. It does not require a GPS, magnetometer, or barometer.
# How to Enable Different Estimators
For multirotors and VTOL use the parameter SYS_MC_EST_GROUP to choose between the following configurations (LPE is not supported for Fixed-wing).
| SYS_MC_EST_GROUP | Q Estimator | LPE | EKF2 |
|---|---|---|---|
| 1 | enabled | enabled | |
| 2 | enabled | ||
| 3 | enabled |
Note
For FMU-v2 (only) you will also need to build PX4 to specifically include required estimator (e.g. EKF2: make px4_fmu-v2, LPE: make px4_fmu-v2_lpe).
This is required because FMU-v2 is too resource constrained to include both estimators.
Other Pixhawk FMU versions include both.