estimateStates

Estimate states using insCF

Since R2026a

Syntax

estimates = estimateStates(filter,sensorData)

Description

estimates = estimateStates(filter,sensorData) returns the state estimates based on the motion model used in the insCF filter and the sensor data. The function predicts the filter state estimates forward in time based on the row times in sensorData and fuses data from each column of the table one-by-one along each row.

Examples

Estimate Orientation from IMU Data Using insCF

Estimate orientation from recorded IMU data by using a complementary filter, represented by an insCF filter object.

Load the rpy_9axis.mat file into the workspace. The file contains recorded accelerometer, gyroscope, and magnetometer sensor data from a device oscillating in pitch (around the y-axis), yaw (around the z-axis), and roll (around the x-axis). The file also contains the sample rate of the recording. Extract the sensor data and sample rate from the loaded workspace variable.

ld = load("rpy_9axis.mat");
accelerometerData = ld.sensorData.Acceleration;
gyroscopeData = ld.sensorData.AngularVelocity;
magnetometerData = ld.sensorData.MagneticField;
imuSampleRate = ld.Fs; % Hz

Create a timetable from the accelerometer, gyroscope, and magnetometer data.

imuDataTT = timetable(accelerometerData,gyroscopeData,magnetometerData,'SampleRate',imuSampleRate,'StartTime',seconds(1/imuSampleRate),'VariableNames',{'Accelerometer', 'Gyroscope', 'Magnetometer'});

Create an insCF filter object using sensor models for accelerometer, magnetometer, and gyroscope. To model orientation, specify insCFMotionOrientation as the motion model.

acc = insCFAccelerometer;
mag = insCFMagnetometer;
gyro = insCFGyroscope;
motionModel = insCFMotionOrientation;
filter = insCF(acc,mag,gyro,motionModel);

Specify the initial orientation of your sensors. You can obtain the initial orientation by using the ecompass function with the accelerometer and magnetometer data at the first time step.

initialOrientation = [0.006727036930852 -0.131203115007920 -0.058108427699335 -0.989628162602834];
stateparts(filter,"Orientation",initialOrientation)

Specify the sensor gains. The sensor gain value must be between 0 and 1.

gainparts(filter,"Accelerometer",0)
gainparts(filter,"Magnetometer",0.01)

Fuse the accelerometer, gyroscope, and magnetometer data using the insCF filter.

outTT = estimateStates(filter,imuDataTT);

Visualize the estimated orientation.

t = outTT.Properties.RowTimes;
plot(t,eulerd(outTT.Orientation,"ZYX","frame"));
title("Orientation Estimate");
legend("Z-rotation","Y-rotation","X-rotation");
xlabel("Time");
ylabel("Degrees");

Estimate Pose and Velocity Using insCF

Estimate pose (orientation and position) and velocity from IMU and GPS data by using a complementary filter, represented by an insCF filter object.

Load the racetrackINSCFDataset.mat file, which contains a timetable with simulated accelerometer, gyroscope, magnetometer, and GPS sensor data for a racetrack-like trajectory, into the workspace. The file also contains the sample rate of the data.

load("raceTrackINSCFDataset.mat")

Create an insCF filter object that includes the accelerometer, gyroscope, magnetometer, and GPS sensor objects, as well as an insCFMotionPose motion model object for modeling pose.

% Sensor object for predicting orientation
gyro = insCFGyroscope;
% Sensor objects for correcting orientation
accel = insCFAccelerometer;
mag = insCFMagnetometer;
% Sensor object for correcting position
gps = insCFGPS(ReferenceLocation=localOrigin);

% Pose motion model
motModel = insCFMotionPose;

% Filter object
filt = insCF(accel,mag,gyro,gps,motModel);

Specify the initial position, velocity, and orientation from the measurement data.

% Set initial position
stateparts(filt,"Position",initPos)
% Set initial orientation
stateparts(filt,"Orientation",initOrient)
% Set initial velocity
stateparts(filt,"Velocity",initVel)

Specify the sensor gains.

% Set Accelerometer gain
gainparts(filt,"Accelerometer",9.6335e-09)
% Set Magnetometer gain
gainparts(filt,"Magnetometer",0.01)
% Set GPS gain
gainparts(filt,"GPS",0.039246)

Fuse the sensor data using the filter. The filter estimates pose (orientation and position) and velocity. Extract the estimated position.

outTT = estimateStates(filt,sensorData);
estPos = outTT.Position;

Calculate the position RMS error.

posErr = truePos - estPos; 
pRMS = sqrt(mean(posErr.^2));
fprintf("Position RMS Error:\tX: %.3f, Y: %.3f, Z: %.3f (meters) \n", pRMS(1),pRMS(2),pRMS(3))

Position RMS Error:	X: 0.372, Y: 0.493, Z: 0.303 (meters) 

Visualize the estimated pose against the ground truth and GPS data.

figure
plot(truePos(:,1),truePos(:,2),".")
hold on
plot(estPos(:,1),estPos(:,2),"r.-")
gpsLocal = lla2ned(sensorData.GPS,localOrigin,"flat");
plot(gpsLocal(:,1),gpsLocal(:,2),".")

title("Pose Estimate")
legend("Ground Truth","Estimated","GPS")

grid on
xlabel("N (m)")
ylabel("E (m)")
axis equal

Input Arguments

filter — Complementary filter

insCF object

Complementary filter, specified as an insCF object.

sensorData — Sensor Data

timetable

Sensor data, specified as a timetable. The variable names of the timetable and the names specified in the SensorNames property of the filter input argument must have one-to-one correspondence. Each entry in the table specifies the measurement from the corresponding sensor at the specified row time.

If a sensor does not produce measurements at a row time, specify the corresponding entry as NaN.

Example: estimateStates(filter,timetable(accelerometerData,gyroscopeData,magnetometerData,'SampleRate',imuSampleRate)) specifies the sensor data as a timetable with imuSampleRate sample rate.

Example: estimateStates(filter,timetable(accelerometerData,gyroscopeData,magnetometerData,'TimeStep',dt)) specifies the sensor data as a timetable with dt length of time between consecutive row times.

Output Arguments

estimates — State estimates

timetable

State estimates, returned as a timetable. The name of each variable in the table represents a state. The format of each state estimate depends on the state.

State	Estimate Format
Orientation	quaternion object
Position	[x y z], where each position element is in meters
Velocity	[vx vy vz], where each element is in meters per second

Extended Capabilities

C/C++ Code Generation
Generate C and C++ code using MATLAB® Coder™.

Version History

Introduced in R2026a