Activity V

Activity V

Objective: RTK fusion of the built-in Xiaomi Mi8 GNSS and IMU observation

Measurement setup:

2 * Xiaomi Mi8 smartphones

1 * commercial MEMS IMU from XSENS (MTi-G-710) à for comparisons reasons

Trimble NetR9 + Trimble Zephyr 2 geodetic antenna à for comparisons reasons

· Reference station, Trimble NetR9

Two smartphones were fixed on a 3D printing platform

For comparison reasons, a commercial XSENS MTi-G-710 was placed immediately under the two smartphones so that the lever-arm can be neglected. In the front of the bus, a geodetic antenna from Trimble was mounted and connected to a high accuracy geodetic receiver from Trimble (NetR9), which builds the ground truth trajectory.

Reference data were collected by means of a static Trimble NetR9 receiver which is located on Building 41 at the UniBWM campus.

The experiment took place at the UnibWM campus for a duration of 15 minutes. The trajectory contains all possible scenarios, eg static, kinematic, fully open sky, signal blockage due to higher building in the campus and foliage / trees

Processing tools

Data logging	ISTA-GNSS logger
Smartphone	2 * Xiaomi MI8
Groundtruth.trajectory	Trimble NetR9 + Trimble Zephyr 2 antenna
RefStation. Receiver	Trimble NetR9
Additional hardware	1 * XSENS (MTi-G-710) (at ~ 400Hz)
	Choke ring
	3D-Printed Platform for 2 Mi8 + Xsens
Evaluation tool / software	Inertial Explorer & MATLAB

Results:

RTK fixing ratio of different GNSS / IMU combinations

IMU

GNSS

MI 8

XSENS

NONE

MI 8

Trimble NetR9

92%

91%

Deviation of the north coordinates from the ground truth solution (Trimble-Xsens)

	δN1 [m]	δN2 [m]	δN3 [m]	δN4 [m]	δN5 [m]
Mean	0.931	-1,302	3,169	0.560	0.446
Max	37,962	23,273	41,928	1,419	1,096
Min	-15,875	-19,432	-24,358	-0.352	-0.168

Deviation of the east coordinates from the ground truth solution (Trimble-Xsens)

	δE1 [m]	δE2 [m]	δE3 [m]	δE4 [m]	δE5 [m]
Mean	-1,922	0.468	-4,595	0.698	0.626
Max	10,743	9,032	15,980	1,400	1,101
Min	-24,219	-14,729	-28,719	-0.657	-0.176

Deviation of the height coordinates from the ground truth solution (Trimble-Xsens)

	δH1 [m]	δH2 [m]	δH3 [m]	δH4 [m]	δH5 [m]
Mean	7.094	0.676	7,974	-0.009	-0.088
Max	38,407	20,223	41,073	0.089	1,695
Min	-3.054	-28,577	-5,909	-0.277	-0.189

Deviation of the north velocity from the ground truth solution (Trimble-Xsens)

	δVN1 [m / s]	δVN2 [m / s]	δVN3 [m / s]	δVN4 [m / s]	δVN5 [m / s]
Mean	0.01	0.04	0.01	0.01	0.06
Max	2.82	6.71	5.64	0.56	22.02
Min	-2.07	-3.34	-3.00	-0.46	-19.12

Deviation of the east velocity from the ground truth solution (Trimble-Xsens)

	δVE1 [m / s]	δVE2 [m / s]	δVE3 [m / s]	δVE4 [m / s]	δVE5 [m / s]
Mean	0.01	0.05	-0.01	0.01	-0.02
Max	1.19	2.57	2.09	0.36	11.59
Min	-1.36	-1.90	-1.48	-0.44	-16.86

Deviation of the heading angles from the ground truth solution (Trimble-Xsens)

	δψ1 [deg]	δψ2 [deg]	δψ3 [deg]	δψ4 [deg]	δψ5 [deg]
Mean	37,805		10,481	10,833
Max	259.769		315,598	341.042
Min	-286,609		-358,539	-312,338

Deviation of the roll angles from the ground truth solution (Trimble-Xsens)

	δΦ1 [deg]	δΦ2 [deg]	δΦ3 [deg]	δΦ4 [deg]	δΦ5 [deg]
Mean	1,662		0.806	1,448
Max	15,376		9,929	12,490
Min	-10,803		-7,843	-10,034

Deviation of the pitch angles from the ground truth solution (Trimble-Xsens)

	δθ1 [deg]	δθ2 [deg]	δθ3 [deg]	δθ4 [deg]	δθ5 [deg]
Mean	-0.393		-0.006	0.713
Max	5,739		7,537	7,662
Min	-8.001		-7,049	-7,182

Computed trajectory using different sensor combinations in ENU-frame, East vs. North (left), height (right)

Computed north (right) and east (left) velocity using different sensor combinations in ENU-frame

Computed up velocity using different sensor combinations in ENU-frame

Computed heading angle (left) and roll angle (right) using different sensor combinations in ENU-frame

Computed pitch angle using different sensor combinations in ENU frame

Log files: Coming Soon.

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