High Reliability MEMS North Seeker

ER-MNS-18 High Reliability MEMS North Seeker

Introduction

ER-MNS-18 is a MEMS north seeker with high cost-effectiveness and reliability. It is composed of a three-axis MEMS gyroscope and a three-axis MEMS accelerometer, and can measure true north. It features high precision, high reliability, and is resistant to harsh environments. It is designed to meet the application requirements of various markets.

Feature

Size:65*51*35.5

Weight:140

Triaxial MEMS gyro and accelerometer

5°C to 55°C temperature compensation

High performance heading accuracy up to 0.5°secψ(1σ)

Low power consumption and wide voltage

Resistant to harsh environment

Application

North seeking in logging tools/gyro tools

Pointing, steering and guiding in advanced mining/drilling equipment

Initial alignment

Direction pointing and tracking in satellite antenna, target tracking system

Guidance and navigation in navigation grade MEMS system

Precision platform attitude measuring and controls

Precision attitude measuring in navigation grade MEMS IMU/INS

North finding in land surveying

Petroleum exploration

Mining

Specification

Model No.	ER-MNS-18AD	ER-MNS-18BD
Azimuth accuracy (1σ,°secψ)	1	0.5
Attitude accuracy(1σ,°)	≤0.3
Azimuth accuracy retaining time	20min
Attitude accuracy retaining time	20min
Azimuth measurement range(°)	0~360
Inclination angle measurement range(°)	-85~85
North seeking time	180s
North seeking method	stationary
Update Rate (Hz)	100
Environment and power
Operating temperature (℃)	5~+55
Storage temperature (℃)	0~+65
Power supply (V)	6~12 DC
Power (W, power supply 6V)	2
Communication interface	RS-422
Physical characteristics
Size (mm×mm×mm)	65*51*35.5
Weight (g)	140g

 

Data protocols

Upper computer receiving protocol

The data update rate is 100Hz, the baud rate is 230400bps, and each frame contains 61 bytes of data, each byte contains 1 start bit (0), 8 data bits, 1 stop bit (1), and no parity. The specific data format is shown in the table below:

Table 1 Receive data frame format

Bytes (60 bytes total)	Data content	supplementary note
1~4	header	EB8055AA
5~8	X Gyro Data	Low then high, dimensionless digital FLOAT
9~12	Y gyro data	Low then high, dimensionless digital FLOAT
13~16	Z Gyro Data	Low then high, dimensionless digital FLOAT
17~20	X ACCL data	Low then high, dimensionless digital FLOAT
21~24	Y ACCL data	Low then high, dimensionless digital FLOAT
25~28	Z ACCL data	Low then high, dimensionless digital FLOAT
29~32	Lon	Low then high, 0.000001°.
33~36	Lat	Low then high, 0.000001°.
37~40	Alt	First low, then high, 0.000001m
41~44	count	Low then high, 10ms
45~46	pit	Low then high, 0.01°
47~48	rol	Low then high, 0.01°
49~50	yaw	Low then high, 0.01°
51~52	North speed	First low then high, 0.01m/s
53~54	up speed	First low then high, 0.01m/s
55~56	east speed	First low then high, 0.01m/s
57	state	0xA1 alignment, 0xB1 hold
58	end of frame	0x00
59	end of frame	0xFF
60	end of frame	0x34
61	matching test	EB 80 and the sum of all bytes other than itself

Host computer sending protocol

Total number of bytes sent down in a single transmission: 21 bytes, baud rate 230400bps, no parity, each byte includes: start bit (0), data bit (8 bits), stop bit (1).

1. Priming

byte symbol	define	note
1	0xEB
2	0x80
3	0x00
4	0xCC
5-8	0x00
9-12	0x00
13-16	0x00
17-21	0x00

2. Send warp and woof height

byte symbol	define	note
1	0xEB
2	0x80
3	0x00
4	0xAA
5-8	lon
9-12	lat
13-16	alt
17	0xAA
18	0xBB
19	0xCC
20	0xDD
21	5~20 heterodyne calibration

 

Determine the definition of the data sent based on byte 4:

1. if control_flag==0xCC: restart work
2. if control_flag==0xAA: send latitude/longitude altitude

Send order: 5-8 bytes: latitude (*1e6 in °)

9-12 bytes: longitude (*1e6 in °)

13-16 bytes: height (*1 in m)

For example, the C code that sends the latitude/longitude instruction (the rest of the bytes are configured arbitrarily), Latitude is "latitude * 1e6", longitude is similar, and altitude scale is 1.

bytSend[0] = 0xeb;

bytSend[1] = 0x80;

bytSend[2] = 0x00;

bytSend[3] = 0xaa;

bytSend[4] = (Latitude>>24) & 0xff;

bytSend[5] = (Latitude>>16) & 0xff;

bytSend[6] = (Latitude>>8) & 0xff;

bytSend[7] = (Latitude) & 0xff.

bytSend[8] = (Longitude>>24) & 0xff;

bytSend[9] = (Longitude>>16) & 0xff;

bytSend[10] = (Longitude>>8) & 0xff;

bytSend[11] = (Longitude) & 0xff.

bytSend[12] = (Altitude>>24) & 0xff;

bytSend[13] = (Altitude>>16) & 0xff;

bytSend[14] = (Altitude>>8) & 0xff;

bytSend[15] = (Altitude) & 0xff;

bytSend[16] = 0xaa;

bytSend[17] = 0xbb;

bytSend[18] = 0xcc;

bytSend[19] = 0xdd;

bytSend[20] = b[4]^b[5]^... .b[19];

Introduction to the software

Click the COMCFG button to set the serial port, baud rate and frequency. The baud rate is 230400 and the frequency CAL is 100HZ.

Click Open to start the test.

Click Initial Align to start the north search, the search time is 300s.The result is displayed at PIT;YAW;ROL.

If you want to change the latitude and longitude, please change them at Lon0 and Lat0, then click Load, and then click Initial Align to re-navigate.

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Application Techniques

1.Applicable to coal mines, tunnels, and exploration! North seeker's strength revealed

2.How important is the North Seeker in the field of oil、mining and drilling?

3.OEM customization, easy integration! The North Seeker helps operations in multiple fields to be more accurate and efficient!

4.Efficient mining, north seeker assists mining drilling operations

5.Accurate orientation, easy to deal with! North seeker helps work more efficiently

6.Not restricted by the environment, MEMS north finders help various fields achieve high-precision orientation

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