F3G40S Three-Axis FOG

F3G40S Three-Axis FOG Performance Parameters

This document specifies the requirements and methods for the use and maintenance of the F3G40S three-axis integrated Fiber Optic Gyroscope (FOG) (hereinafter referred to as "the product").

 

2 Product Description 2.1 Working Principle, Functions, and Scope of Application

2.1.1 Working Principle

The product is an inertial angular rate sensor based on the optical Sagnac effect, used to measure the angular velocity of a vehicle along the product's sensitive axes. The angular velocity sensing unit is a fiber coil. A digital closed-loop detection circuit extracts the optical path difference between clockwise (CW) and counterclockwise (CCW) propagating light induced by external physical angular velocity in the fiber coil, while converting the optical path difference signal into a voltage signal for closed-loop feedback and control, thereby achieving signal modulation and demodulation for high-precision angular velocity detection.

2.1.2 Functions

The product consists of an optical angular velocity sensing unit and a signal detection unit, providing gyro angular increment data and internal temperature information.

2.1.3 Scope of Application

The product is primarily applicable to medium-to-high precision inertial navigation systems (INS), positioning and orientation systems, servo stabilization systems, and similar applications.

2.2 Composition

The main components of the product are as follows:

Optical path unit: includes SLD light source, fiber coil, integrated optical phase modulator (IOPM), fiber coupler, and photodetector;

Electronic circuit unit: light source drive circuit, signal detection and control circuit;

FOG structural components

Reserved mounting positions for accelerometers (MEMS accelerometers or quartz accelerometers).

2.3 Dimensions and Mounting

The outline and mounting dimensions are shown in Figure 1.

Outline dimensions: 71.5 mm ± 0.1 mm × 68 mm ± 0.1 mm × 45.0 mm ± 0.1 mm (length × width × height, including sensor head);

Mounting dimensions: 58.5 mm ± 0.1 mm × 53.0 mm ± 0.1 mm × 52.5 mm ± 0.1 mm × 44.5 mm ± 0.1 mm;

4 mounting holes: Φ3.5.

Figure 1 F3G40S FOG Assembly and Mounting Diagram

 

2.4 Weight

Total product weight: 310 g ± 10 g.

2.5 Main Performance Parameters

The main performance parameters of the product are detailed in Table 1.

Table 1 Main Performance Parameters

No.	Test Item	Specification
1	Start-up Time (s)	3
2	Bias Stability (10 s smoothing, °/h)	≤0.3
3	Bias Repeatability (°/h)	≤0.3
4	Random Walk Coefficient (°/h½)	≤0.01
5	Scale Factor Nonlinearity (ppm)	≤50
6	Scale Factor Repeatability (ppm)	≤50
7	Operating Temperature (°C)	-45~+70
8	Storage Temperature (°C)	-55~+80
9	Dynamic Range (°/s)	±500
10	Supply Voltage (V)	+5V
11	Steady-State Power Consumption (full temp. range, W)	≤8

 

2.6 Mechanical and Electrical Interfaces

2.6.1 Power Supply Requirements

The product is powered by a +5 V DC power supply. The power supply requirements are shown in Table 2:

Table 2 F3G40S FOG Power Supply Requirements

No.	Item	Requirement
1	Power Supply Accuracy	±5%
2	Power Supply Ripple (Vpp)	≤50mV
3	Supply Current	＞2A

 

2.6.2 Electrical Connection Interface

The connector used for external connection is J30JZLN9ZKCA000. The pin definitions are provided in Table 3.

Table 3 J30JZLN9ZKCA000 FOG Connector and Test Point Definitions

Pin No.	Definition	Remarks
1	+5V	Power Input
2	GND	Power Ground
3	Reserved	--
4	RXD+	FOG Differential Strobe Positive
5	TXD+	FOG RS422 Output Positive
6	+5V	Power Input
7	GND	Power Ground
8	RXD-	FOG Differential Strobe Negative
9	TXD-	FOG RS422 Output Negative

Note: When connecting to or handling the product, ESD protection measures shall be taken in accordance with GJB 1649-1993.

 

2.6.3 Communication Protocol

Communication interface: Both RXD and TXD are RS422/485 differential communication interfaces. RXD is used to receive a differential pulse (or square wave) synchronization strobe signal, and TXD is used for serial data signal output.

Communication protocol: The strobe signal frequency shall not exceed 1 kHz. After receiving the falling edge of the strobe signal, the FOG latches the internal angular increment data and begins outputting the gyro data packet via TXD within 1 μs. The baud rate is 460.8 kbps. The data packet contains 23 bytes, each consisting of 1 start bit, 8 data bits, and 1 stop bit, with no parity bit.

The angular increment data represents the accumulated angular displacement of the gyro between two consecutive strobe signals. The average angular velocity over a given time period is obtained by dividing the accumulated angular increment value by the corresponding time interval.

 

The data packet format is as follows:

Table 4 Gyro Data Packet Format

Byte No.	Content
	99 (Hexadecimal)
	66 (Hexadecimal)
	Status Word, normal value: FF (hexadecimal)
	X-axis Gyro Angular Increment 1, LSB
	X-axis Gyro Angular Increment 2
	X-axis Gyro Angular Increment 3
	X-axis Gyro Angular Increment 4, MSB
	Y-axis Gyro Angular Increment 1, LSB
	Y-axis Gyro Angular Increment 2
	Y-axis Gyro Angular Increment 3
	Y-axis Gyro Angular Increment 4, MSB
	Z-axis Gyro Angular Increment 1, LSB
	Z-axis Gyro Angular Increment 2
	Z-axis Gyro Angular Increment 3
	Z-axis Gyro Angular Increment 4, MSB
	Temperature Data 1, LSB
	Temperature Data 1, MSB
	Temperature Data 2, LSB
	Temperature Data 2, MSB
	Temperature Data 3, LSB
	Temperature Data 3, MSB
	Frame Number, increments by 1 on each transmission, cyclic count
	Checksum, cumulative sum of Byte 3 through Byte 22

 

The status word bit definitions are as follows:

Table 5 Gyro Status Word Data Format

bit7	bit6	bit5	bit4	bit3	bit2	bit1	bit0
Reserved	Z-axis Circuit Control Status	Y-axis Circuit Control Status	X-axis Circuit Control Status	Reserved	Z-axis Optical Path Status	Y-axis Optical Path Status	X-axis Optical Path Status

Where: the "Reserved" bits are always 1;

the "Circuit Control Status" bit set to 1 indicates normal FOG circuit control status; set to 0 indicates an abnormal control status;

the "Optical Path Status" bit set to 1 indicates normal FOG optical path operation; set to 0 indicates an abnormal optical path status.

If during FOG operation either of the above two status bits remains 0, accompanied by abnormal gyro data, the FOG shall be returned for repair.

 

3 Product Installation and Removal

Requirement

The user is responsible for installing and removing the product. During this process, the product must not be subjected to impact, striking, or collision, nor shall any mechanical processing be performed on its external surfaces. Exercise caution with the wires and fiber optic sleeves between FOG assemblies, and prevent sharp-angle bending, compression, pulling, and collision.

3.2 Methods and Procedures

a) The flatness of the mounting surface shall be better than 0.02 mm;

b) It is recommended to apply a uniform 0.2–0.5 mm layer of thermal conductive silicone on the bottom of the product during installation;

c) During product testing, it is recommended to place an aluminum plate (larger than the product dimensions) beneath the mounting surface;

d) The magnetic field strength at the product installation location shall not exceed 1 Gauss (G).

3.3 Post-Installation Inspection

Verify that all mounting screws conform to the mounting hole dimensions and are securely fastened.

4 Operating Procedures

4.1 Pre-Use Inspection

Inspect the product for physical damage such as collision marks.

4.2 Product Usage Instructions

Mount the product on the vehicle and correctly connect the cables in accordance with Table 3;

Establish the data connection per the communication protocol specified in Section 2.6.3.

4.3 Precautions

a) The three-axis FOG assembly should not be subjected to frequent power on/off cycling during use, as this may degrade FOG performance and shorten its service life;

b) Before powering on the three-axis FOG assembly, inspect the power supply system to ensure that no short circuits exist between electrical points of the power supply, or between the FOG housing and any electrical points;

c) If the product exhibits abnormal operation, consult the manufacturer. Unauthorized disassembly and repair are strictly prohibited;

d) The three-axis FOG assembly is a precision instrument. Handle with care during use and transportation;

e) Ensure correct connection of product input signal lines, output signal lines, and power supply lines;

f) ESD protection measures shall be taken when handling the product;

g) The optical components in the three-axis FOG assembly are susceptible to moisture. Where feasible, it is recommended that the INS incorporate hermetic sealing;

i) The ambient magnetic field strength at the product location shall be less than 1 Gauss.

5 Maintenance

Prior to installation on the vehicle, the product shall be powered on at least once every 6 months for a duration of 3600 s. Electrical parameter testing is not required during this power-on period;

After installation on the vehicle, the product shall be powered on at least once per year for a duration of 3600 s. Electrical parameter testing is not required during this power-on period.

6 Common Faults and Troubleshooting

The product is in a sealed condition. If any fault occurs at the user site, on-site repair is not possible; the product must be returned to the manufacturer for servicing.

The following lists potential fault phenomena not originating from the product itself, as shown in Table 6. For any other technical issues encountered during use, please contact the manufacturer.

Table 6 Common Faults and Troubleshooting

No.	Fault Symptom	Cause Analysis	Troubleshooting Method
1	Product powered on, +5 V ammeter reading is essentially zero	Product not powered or supply current too low	Check the power supply and supply circuit; restore power to the product
2	Product powered on, +5 V ammeter reading is normal, but computer acquisition program does not work	Test equipment acquisition system malfunction	Check connecting cables and equipment power supply
		Software program conflict	Restart the computer

 

7 Transportation and Storage Requirements

7.1 Transportation Precautions

Place the product according to the orientation indicated on the packaging box;

Transportation is permitted by road, rail, air, and water;

Ensure the packaging box is securely fastened to the carrier to prevent movement during transport.

7.2 Storage Conditions, Shelf Life, and Precautions

Products placed in packaging boxes shall be stored under standard atmospheric pressure conditions in an air-conditioned warehouse. The ambient temperature shall be 25 °C ± 10 °C, relative humidity 30%–70%, and the surrounding magnetic field strength shall be less than 10 Gauss;

The product shelf life is 15 years.

 

8 Unpacking Instructions

Inspect the outer packaging for physical damage such as collision marks;

Verify that the product and all accessories are complete, as detailed in Table 7;

Perform ESD protection procedures when removing the product.

Table 7 Product Delivery Checklist

No.	Item	Quantity
1	F3G40S Fiber Optic Gyroscope	1
2	FOG Assembly Packaging Box	1
3	FOG Assembly Test Report	1
4	J30JZ/XN9TJCAL01 Connector	1
5	Certificate of Conformity	1