BW SENSING BW-IMU720 Series User manual

Technical Manual
BW-IMU720 Series
Small-size three-axis fiber optic
gyroscope inertial measurement
unit
V3.0

Bewis Sensing Technology LLC www.bwsensing.com Tel：[phone]
BW-IMU720
Small-size three-axis fiber optic
Gyroscope inertial measurement unit
●Unmanned boats and underwater vehicles
●Special robots
●Marine engineering surveying and
mapping
Feature
Application
BW-IMU720 is a small-size high-precision three-axis fiber optic gyroscope inertial
measurement unit developed and produced by Bewis Sensing. It can output acceleration and
angular velocity information without relying on external signal input, which can be calculated
through user-developed algorithms The azimuth angle, roll angle, pitch angle, Euler angle, and
quaternion information of the measured carrier are suitable for inertial attitude measurement
under various states of motion, vibration or static.
BW-IMU720 has a built-in three-axis fiber optic gyroscope and a highly reliable MEMS
accelerometer. The original data deviation is estimated by the 6-state Kalman filter with
appropriate gain, and the measurement accuracy is guaranteed by the algorithm, and the
nonlinear compensation, quadrature compensation, Temperature compensation and drift
compensation, etc., are used to greatly eliminate errors and improve product accuracy. This
product has a digital interface, which can be easily integrated into the system.
●Unmanned vehicles and autonomous
Driving
●Attitude measurement and maintenance
●Unmanned aircraft
Introduction
●Output mode：RS422
●Working temperature：-40℃~+60 ℃
●Weight(without package)：≤450g
●Small size：L70×W65×H51mm
●Gyro bias stability：≤0.4°/h
●Accelerometer bias stability：0.5mg
●Gyro scale factor：≤100ppm
●Accelerometer range：±30g

Bewis Sensing Technology LLC www.bwsensing.com Tel：[phone]
BW-IMU720
Small-size three-axis fiber optic
Gyroscope inertial measurement unit
Fiber optic
gyroscope
Bias stability
≤0.4°/h（10s,1σ)
ARW
≤0.03 °/√h
Bias repeatability
≤0.4°/h（1σ）
Bias stability at full temperature
≤0.04°/h（100s，1σ)
Scale factor nonlinearity
≤100ppm（1σ）
Scale factor repeatability
≤100ppm（1σ）
Bandwidth
≥400Hz
Measurement range
-800~+800°/s
Random walk coefficient
≤0.03 °/√h
Accelerometer
Range：X, Y, Z
±30 g
Bias stability at room temperature
0.4mg（10s,1σ)
Bias stability at full temperature
1mg（10s,1σ)
Scale factor nonlinearity
300ppm（1σ）
Scale factor repeatability
300ppm（1σ）
Other index
Dimension
70×65×51mm
Start-up time
≤1min
Weight
≤450g
Power supply
9-30V DC
Power ripple
≤50mV
Operating temperature
-40~60℃
Storage temperature
-55~75℃
Performance index
Electrical index
Specification

Bewis Sensing Technology LLC www.bwsensing.com Tel：[phone]
BW-IMU720
Small-size three-axis fiber optic
Gyroscope inertial measurement unit
Mechanical properties
Package product size
Product size：L70*W65*H51（mm）
Connector
RS422 communication，J63A-242-015-261-TH
Protection level
IP63(IP67 customized)
Shell material
Magnesium aluminum alloy anodizing
Installation
Four M4 screws

Bewis Sensing Technology LLC www.bwsensing.com Tel：[phone]
BW-IMU720
Small-size three-axis fiber optic
Gyroscope inertial measurement unit
Installation
The user is responsible for the installation and disassembly of the product. During this
process, the product cannot be hit, and the outer surface of the product cannot be
mechanically processed.
The correct installation method can avoid measurement errors. When installing the sensor,
please do the following:
First of all, ensure that the sensor mounting surface is completely close to the surface to be
measured. The surface to be measured should be as level as possible, and there should be
no included angles as shown in Figure A and Figure C. The correct installation method is
shown in Figure B and Figure D.
Secondly, the bottom line of the sensor and the axis of the measured object cannot
have an angle as shown in Figure E. When installing, keep the bottom line of the sensor
parallel or orthogonal to the axis of rotation of the measured object. This product can be
installed horizontally or vertically (vertical installation needs to be customized), and the
correct installation method is shown in Figure F.
Finally, the mounting surface of the sensor and the surface to be measured must be
tightly fixed, smooth in contact, and stable in rotation, and measurement errors due to
acceleration and vibration must be avoided.
the measured surface
uneven surface
generates the
angle
the measured surface
C D
AB
the measured surface the measured surface
uneven surface
generates the
angle
+X

Bewis Sensing Technology LLC www.bwsensing.com Tel：[phone]
BW-IMU720
Small-size three-axis fiber optic
Gyroscope inertial measurement unit
Core point No.
Definition
Annotation
1
GND_IN
Input
2
VIN
Power input
3
VCC_5V
+5V (0.5A) reserve output power
4
P_GND
Keep output
5
A422_R+
Serial port A inertial terminal receiving positive
6
A422_R-
Serial port A used to receive negative
7
A422_T-
Serial port A used to send negative
8
A422_T+
Serial port A habit group terminal sends positive
9
B422_R+
Serial port B inertial terminal receiving positive
10
B422_R-
Serial port B inertia terminal receives negative
11
B422_T+
Serial port B used to send negative
12
B422_T-
The serial port B is used to send positive
13
Hang in the air
14
Hang in the air
15
Hang in the air
Note: When connecting or touching the product, anti-static measures should be
taken in.
accordance with the regulations of GJB 1649-1993.
Electrical connection
Procedure
1. Check before use
Check the appearance of the product for physical damage such as collisions.
2. Instructions on how to use the product
a) The product is installed on the carrier, and the cable is correctly connected as required;
b) Perform data connection in accordance with the communication protocol.
3. Matters needing attention
a) The product should not be frequently switched on and off during use, so as not to damage
the performance of the gyro and reduce the service life of the product;
b) Before powering on the product, check the power supply system to ensure that there is
no short circuit between the electrical points of the power supply, and between the product
shell and the electrical points;
c) If there is any abnormal operation of this product, please consult the manufacturer and
prohibit unauthorized disassembly and maintenance;
d) The optical fiber inertial unit is a precision instrument, which should be handled with care
during use and transportation;；
e) Must ensure the correct connection of product input and output signal lines and power
supply lines;
f) Anti-static measures are required to be taken during the contact with the product;
g) The magnetic field strength around the product location is required to be less than 2
Gauss.

Bewis Sensing Technology LLC www.bwsensing.com Tel：[phone]
BW-IMU720
Small-size three-axis fiber optic
Gyroscope inertial measurement unit
Byte
Name
Value
Transmission
Type
0
Frame header
byte 1
OxAA
uchar
1
Frame header
byte 2
OxAA
uchar
2
Data sent count
1~200
uchar
3
Self-check byte
255
uchar
4~7
X-axis gyro
32bit low in the front, high in the
back
signed int32
8~11
Y-axis gyro
32bit low in the front, high in the
back
signed int32
12~15
Z-axis gyro
32bit low in the front, high in the
back
signed int32
16~19
X-axis
accelerometer
32bit low in the front, high in the
back
float
20~23
Y-axis
accelerometer
32bit low in the front, high in the
back
float
24~27
Z-axis
accelerometer
32bit low in the front, high in the
back
float
28,29
X-axis gyro
temperature
16bit low in the front, high in the
back
1/16
signed int16
30,31
Y-axis gyro
temperature
16bit low in the front, high in the
back
1/16
signed int16
32,33
Z-axis gyro
temperature
16bit low in the front, high in the
back
1/16
signed int16
34,35
X-axis
accelerometer
temperature
16bit low in the front, high in the
back
1/16
signed int16
36,37
Y-axis
accelerometer
temperature
16bit low in the front, high in the
back
1/16
signed int16
38,39
Z-axis
accelerometer
temperature
16bit low in the front, high in the
back
1/16
signed int16
40
Checksum
4~39 byte XOR
uchar
41
Frame end
OxBB
uchar
Protocol
1) Two-way communication, the request signal is 3.3V, LVTTL level, the falling edge is valid
(the falling edge represents the sampling time), the falling edge is input within 50us, and
the serial port signal is sent, which conforms to the RS-422 interface standard;
2) Data refresh rate 200Hz, baud rate 460.8Kbps; (customizable)
3) 8 data bits, 1 stop bit, no parity bit;
4) Data transmission format:

Bewis Sensing Technology LLC www.bwsensing.com Tel：[phone]
BW-IMU720
Small-size three-axis fiber optic
Gyroscope inertial measurement unit
Executive standard
●National Standard for Static Calibration Specifications for Dual-Axis Inclination
Sensors (Draft)
●GB/T 191 SJ 20873-2003 General Specification for Inclinometers and Levels

Wuxi Bewis Sensing Technology LLC
Add：Building 30, NO. 58, Xiuxi Road, Binhu District,
Wuxi City, Jiangsu Province, China
Tel：[phone]
Mail：[e-mail]
Web：www.bwsensing.com
BW-IMU720 Series
Small-size three-axis fiber optic
inertial measurement unit