Aceinna INS401 User manual

ACEINNA, Inc.
email: [email protected], website: www.aceinna.com
INS401 USER MANUAL
(Preliminary)
Document Part Number: 7430-4006-02

Date Document
Revision
Firmware
Applicability
Description Author
Aug 19, 2021 -D1 28.00.01 Preliminary Release JN/DW/BL/
CL
Oct 01, 2021 -D2 28.00.02
(maybe
28.01.00)
Update figures to the final
product look and update
content to 28.00.02
CT/KL/DW/
CL
Nov 05, 2021 -D3 28.01 Update contents to reflect FW
28.01
DW
Dec 29, 2021 -D4 28.02 Mounting instructions updated
to reflect FW 28.02
Add more contents for
Firmware Upgrade
AB
WARNING
Aceinna has developed this product exclusively for commercial applications. It has not been tested
for, and Aceinna makes no representation or warranty as to conformance with, any military
specifications or that the product is appropriate for any military application or end-use.
Additionally, any use of this product for nuclear, chemical, biological weapons, or weapons
research, or for any use in missiles, rockets, and/or UAV's of 300km or greater range, or any other
activity prohibited by the Export Administration Regulations, is expressly prohibited without the
written consent of Aceinna and without obtaining appropriate, US export license(s) when required
by US law. Diversion contrary to U.S. law is prohibited.
©2020 Aceinna, Inc. All rights reserved. Information in this document is subject to change
without notice.
Aceinna is a registered trademark of Aceinna Inc. Other product and trade names are trademarks
or registered trademarks of their respective holders.

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Table of Contents
Introduction ........................................................................................................................................... 4
INS401 Overview ........................................................................................................................... 4
INS401 Hardware .................................................................................................................................. 5
Housing and Dimensions ................................................................................................................ 5
Mechanical Interface ...................................................................................................................... 6
RF Connector .......................................................................................................................... 6
Main Connector and Pin Description ...................................................................................... 7
INS401 Installation ................................................................................................................................ 8
Mounting Instructions .................................................................................................................... 8
Antenna Selection and Connection ................................................................................................ 9
Power Requirement ...................................................................................................................... 10
INS401 Operation ................................................................................................................................ 11
Setting Up Communications ......................................................................................................... 11
System Operation and Data Logging ........................................................................................... 11
RTK Corrections .......................................................................................................................... 14
Odometer ...................................................................................................................................... 14
Diagnostic Capabilities ........................................................................................................................ 16
Ethernet Port and Messages ................................................................................................................. 17
Ethernet Data Frame Definition ................................................................................................... 17
Aceinna Binary Packet Format ..................................................................................................... 17
Output Binary Packets .................................................................................................................. 18
GNSS Solution Packet .......................................................................................................... 18
INS navigation solution ......................................................................................................... 18
Diagnostic Message .............................................................................................................. 20
Raw IMU Data ...................................................................................................................... 22
RTCM Data ........................................................................................................................... 22
Output ASCII Messages ............................................................................................................... 22
Input Binary Packets..................................................................................................................... 23
User Commands ........................................................................................................................... 24
Firmware Upgrade ............................................................................................................................... 28
FW Upgrade with AceNav ........................................................................................................... 28
BootLoader Design ....................................................................................................................... 28

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INS401 APP Upgrade ........................................................................................................... 29
INS401 IMU FW Upgrade .................................................................................................... 33
INS401 STA9100 FW Upgrade ............................................................................................ 34
Appendix A: 16-bit CRC Implementation Sample Code ............................................................................ 37
Appendix B: AceNav CLI Software Usage ................................................................................................ 38
System requirement ................................................................................................................................. 38
GNSS/INS operation user settings .......................................................................................................... 38
Commands ............................................................................................................................................... 38
Appendix C: Firmware 28.01 and Earlier IMU Axis Definition ................................................................ 40

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About this Manual
The following annotations have been used to provide additional information.
 NOTE
Note provides additional information about the topic.
 EXAMPLE
Examples are given throughout the manual to help the reader understand the terminology.
 IMPORTANT
This symbol defines items that have significant meaning to the user
WARNING
The user should pay particular attention to this symbol. It means there is a chance that physical
harm could happen to either the person or the equipment.
The following paragraph heading formatting is used in this manual:
1 Heading 1
1.1 Heading 2
1.1.1 Heading 3
1.1.1.1 Heading 4
Normal

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Introduction
INS401 Overview
The Aceinna INS401 is an Inertial Navigation System (INS) with RTK-enabled GNSS
positioning engine and triple-redundant IMU sensors. It is powered by RTK330LA – an ASIL B
certified product of Aceinna. It is designed to work with odometer and RTK corrections for
optimal performance. It is a lightweight and compact enclosure that consists of only two
interfaces – the RF interface, and the power and data communication interface. It is a single-box
solution developed for easy evaluation and flexible deployment for various applications,
including automotive applications and ADAS systems.
The Aceinna INS401 supports multiple constellations – GPS, GLONASS, Galileo, Beidou and
QZSS. It tracks the following satellite signals shown in Table 1.
Table 1. INS401 Frequency Plan
Constellation Satellite Signals
GPS L1 C/A + L2C
GLONASS G1
BeiDou B1I + B2I
Galileo E1 + E5b
QZSS L1C/A + L2C
The INS401 provides the following features:
 Position, velocity, heading and attitude solution at 100Hz
 Multi-constellation and multi-frequency RTK algorithm support for centimeter accurate
positioning
 Integrated and calibrated triple-redundant MEMS IMU with range of ±8 g and 250 °/s
 Automotive ethernet interface
 1 PPS output
 Includes functionality for saving navigation data prior to shutdown to allow faster
initialization

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INS401 Hardware
As described in the overview, the INS401 is a complete Inertial Navigation System contained in
a rugged aluminum housing, qualified for use in industrial and automotive applications. It
contains a dual-band RTK-capable GNSS receiver, a triple redundant IMU which is fully
calibrated for bias, scale factor, linearity, and misalignment, plus an ethernet interface for
external communication. The INS401 is powered directly from 12 V or 24 V battery systems (9
V ~ 32 V input range) and is designed and qualified to withstand the worst-case conditions in
terms of overvoltage, reverse voltage and other fault conditions experienced in these vehicles.
Housing and Dimensions
The INS401 housing is cast aluminum for ruggedness and low manufacturing cost as shown in
Figure 1. There are two connectors on the front panel, and they are permanently installed into the
INS401 housing:
 The small circular connector is the FAKRA-J C type connector for RF connection to the
GNSS antenna
 The large connector is the main electrical connector. It is an automotive grade MX23A
connector that contains the power, communication interfaces to connect with the vehicle
electronic control unit (ECU)
Figure 1 INS401 Housing
The overall dimensions are 130 x 115 x 34.5 mm, as shown in the 2D drawings in Figure 2.

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Figure 2 INS401 Hardware Dimensions
Mechanical Interface
RF Connector
An automotive grade FAKRA-J C type connector, manufactured by Molex, is used for the GNSS
antenna connection. Its manufacturing part number is 734035112. The mating connector has part
number 734036262. The center conductor carries the RF signal into the INS401 receiver and
delivers 5 V DC from the INS401 to the external active antenna.

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Main Connector and Pin Description
The main connector carries all the other power and I/O signals to and from the INS401 module.
This connector is also of automotive grade and is manufactured by JAE Electronics. The male
end which is installed in the INS401 housing has part number MX23A18NF1; the female end,
which is attached to the external wiring harness, has part number MX23A18SF1. Figure 3
illustrates the location of the 18 pins in the male part, as seen facing the connector from outside
the module.
Figure 3 Pin Diagram of the Male End
Table 2 shows the functional description of the 18 pins in the main connector.
Table 2. Pin Description of the Main Connector
Pin
Number
Type Pin Name Pin Function
1
Reserved
N/A
Reserved
2
Reserved
N/A
Reserved
3
I/O
ETH_TRX_N
Ethernet (negative)
4
I/O
ETH_TRX_P
Ethernet (positive)
5
Reserved
N/A
Reserved
6
Reserved
N/A
Reserved
7
Reserved
N/A
Reserved
8
Reserved
N/A
Reserved
9
Power
VCC_IN
9V ~ 32V DC power input
10
Reserved
N/A
Reserved
11
Reserved
N/A
Reserved
12
Reserved
N/A
Reserved
13
Reserved
N/A
Reserved
14
Power
GND
Negative power supply input
15
Power
GND
Negative power supply input
16
O
PPS
1 Pulse per Second output, synchronized to GNSS
17
Power
GND
Negative power supply input
18
Power
GND
Negative power supply input

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INS401 Installation
Mounting Instructions
Use four bolts of 1/4-20 UNC socket head cap screw (ASME B18.3) to fix the INS401 system on
a flat rigid panel on the vehicle, using the mechanical dimension measures shown in Figure 2.
The IMU navigation center and the IMU body frame default coordinate definition is shown in
Figure 4. Align the INS401 system x-axis with the forward driving direction of the vehicle.
By default, the IMU body frame orientation of INS401 is defined as in the figure below, with the
X-axis pointing to the opposite direction of the connectors, Z-axis pointing down, and Y-axis
completing a right-hand coordinate system. (Note in the firmware versions 28.01 and earlier, the
default IMU body frame orientation was different with the X-axis pointing to the same direction
as the connectors, Z-axis pointing down, and Y-axis completing a right-hand coordinate system).
To align with the vehicle frame definition, the INS401 should be mounted on the vehicle with
the connectors facing the tail of the vehicle, i.e. the X-axis of the IMU body frame points to the
forward driving direction of the vehicle.
The “Set User Configuration” command (see Table 11) should be used to re-align the coordinate
system so that X is facing forward, Y is right, and Z is down if the INS401 is mounted in a
different orientation.
Figure 4 IMU Axis Definition and Navigation Center Location
After the INS401 is mounted to the vehicle, measure the IMU to the GNSS antenna lever arm
(translational offset) from the IMU navigation center to the GNSS antenna phase center. The
GNSS antenna is typically installed on top of the vehicle roof. For optimal performance, it is

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required to have the lever arm accuracy of less than 2 cm. For instance, a lever arm measurement
is shown in Figure 5. The translation offset is measured as 1 m in each direction of x, y, z. The
IMU to the GNSS antenna lever arm is [x, y, z] = [1.0, -1.0, -1.0] m. The “Set User
Configuration” command in Table 11 should be used to configure the INS401 with the correct
lever arm.
Figure 5 INS401 IMU to GNSS Antenna Lever Arm Definition and Measurement Demonstration
Antenna Selection and Connection
The INS401 works with a customized external wiring harness to connect to the antenna
connector and the main connector.
 Connect antenna cable to FAKRA-J C type RF terminal
 Connect power supply, Ethernet, PPS signal to main connector MX23A18NF1
 The INS401 will supply power (+5Vdc) to the antenna via the antenna cable
Based on your application, select an GNSS L1&L2 active antenna. A typical antenna LNA gain
between 30 dB and 45 dB is recommended.
When installing the GNSS antenna:
1) Choose an antenna location with a clear view of the sky so each satellite above the horizon
can be tracked without obstruction
2) Mount the antenna on a secure, stable structure capable of safe operation in the specific
environment

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3) Ensure antenna is mounted to a rigid surface to minimize any movement due to vehicle
dynamics.
Power Requirement
Operating voltage: 12V DC
Current requirement: The INS401 consumes 4 W (typical value). It’s recommended to make sure
the supply is capable of at least 600mA from 12V.

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INS401 Operation
The following equipment and items are needed for a testing setup of the INS401 to demo its
operation:
 Active multi-constellation multi-band GNSS antenna
 12 V power adapter (battery)
 100Base-TX (RJ-45 connector) to 100Base-T1 converter
 Testing PC (Windows 10 or Ubuntu 18.04) with internet access
 External harness with MX23A automotive connector and cables
 GNSS RTK correction service account (NTRIP protocol settings)
Setting Up Communications
A typical configuration of the INS401 is shown in Figure 6. The circular RF connector connects
with an active GNSS antenna, and the main MX23A connector contains the connection with the
external power, the ethernet data cable and the other communication port cable if needed. The
primary data port is the automotive grade ethernet port to connect to a vehicle ECU directly or to
a testing computer via a converter. The connection to a vehicle ECU is described in the next
subchapter for system integration. Figure 6 shows a test setup only with a testing PC, which
requires a key unit and the 100Base-TX (with RJ-45 connector) to 100Base-T1 converter, to
connect an automotive-grade ethernet device with an industrial ethernet device typically seen on
a computer.
Figure 6 Typical INS401 Configuration
 NOTE
INS401 does not support power over ethernet.
When ordering the INS401, only the physical module with its integrated connectors is included.
The other components shown in Figure 6 (antenna, cables, mating connectors etc.) must be
purchased separately (INS401 EVK will be available Q1-2022 which include: INS401, antenna,
cables, mating connectors etc.).
System Operation and Data Logging
On the testing computer, only the “AceNav” Command Line Interface (CLI) software, is needed
for the INS401 system to work and to log all the data output from the INS401 system. This CLI

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command line software is open sourced on Aceinna/acenav-cli (github.com). It is recommended
for the user to click here to download the executables of the CLI software. Follow the steps
below to operate the system:
1. Connect with GNSS antenna
2. Connect the main connector with a MX23A female connector (associate cables to the pins
defined in Table 2)
3. Use an ethernet converter to connect with a testing PC via the RJ-45 jack
4. Power on the system
5. Go to the “AceNav” CLI folder, modify the “ins401.json” JSON file inside the
“settings/INS401” subfolder, input the correct NTRIP account information as shown below:
6. Input the lever arm values in the field of “gnss lever arm x”, “gnss lever arm y” and “gnss
lever arm z” (if installed in a vehicle). Note the lever arm is in meters

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7. After running the data logging command below, the information about INS401, the PC
connection, and the NTRIP connection status will be displayed on the console. The NTRIP
status shows “ok” of both [connect] and [request], then the system has connected to a valid
NTRIP server for the GNSS RTK operation
8. Check the output bin files. Every session the “AceNav” CLI has started, a data log
subfolder with the time tag in the folder name is created under “acenav/data”. The data log
subfolder for each data logging session contains four files:
 configuration.json: INS401 configuration file read from the device flash
 rtcm_base_<time_tag>.bin: GNSS RTK correction data in RTCM format
 rtcm_rover_<time_tag>.bin: INS401 GNSS raw data in RTCM format
 user_<time_tag>.bin: high precision positioning solution data, including GNSS
solution, INS solution, and other related variance/status information

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9. Run the data parsing command
10. Check the decoded files for results representation and analysis
 user_<time_tag>_dm.csv: INS401 system diagnostic messages
 user_<time_tag>_gnss.csv: GNSS solution at 1 Hz
 user_<time_tag>_imu.csv: raw IMU data at 100 Hz
 user_<time_tag>_ins.csv: INS solution at 100 Hz
 user_<time_tag>_gnss.kml: GNSS solution trajectory in kml format for Google
Earth presentation
 user_<time_tag>_ins.kml: INS solution trajectory in kml format for Google Earth
presentation
 user_<time_tag>_nmea.text: GNSS solution in NMEA 0183 ASCII strings
 user_<time_tag>_odo.text: vehicle odometer speed data received by INS401
Refer to Appendix B: AceNav CLI Software Usage for a detailed description and the usage of
the “AceNav” CLI.
RTK Corrections
As stated in the overview, for optimal performance, it is necessary to enable RTK corrections.
The performance is related to the distance between the rover and the base station (ideally 20 km
or less). The error increases according to the factor of 1 ppm times the baseline length. Refer to
chapter 6 Ethernet Port and Messages section 6.5 Input Binary Packets for more information
about RTCM messages and Table 7 for base RTCM data packet.
Odometer
As stated in the overview, for optimal performance, it is necessary to provide the odometer input
to the INS401. Refer to chapter 6 Ethernet Port and Messages section 6.5 Input Binary Packets
for more information about the vehicle reference point and Table 8 for vehicle speed data packet.
For optimal performance, it is recommended for the odometer to meet the following requirements:
- Sampling period of 10±3 ms

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- Error standard deviation smaller than 0.1 m/s
- Normalized error autocorrelation at 0.1 s below 0.75 (mean removed before autocorrelation)
- Normalized error autocorrelation at 1 s below 0.70 (mean removed before autocorrelation)
- Error probability density function must be symmetrical (small deviations accepted)
- Maximum delay of 0.1 s
- The vehicular speed must report 0 m/s when the vehicle is not moving
- The vehicular speed must not report 0 m/s when the vehicle is moving
- The vehicular speed must be valid for the entire range of operation of the vehicle, including
negative speeds

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Diagnostic Capabilities
Future section.
Please refer to Table 5 for details on the diagnostic messages.

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Ethernet Port and Messages
The INS401 ethernet interface is defined to have the following functions:
 Data I/O to communicate with the external system control unit
 The firmware upgrade interface via the bootloader
The communication protocol data are defined in section 6.1. An ethernet data frame is first
defined, with two types of messages – Binary packets and ASCII messages described below to
be embedded in the ethernet data frame as effective payload:
 Binary packets: Aceinna proprietary binary data format
 ASCII messages: standard NMEA0183 messages, including GNGGA which is
mandatory to be sent to the NTRIP server to report location and fetch GNSS correction
data from nearby base station
Ethernet Data Frame Definition
The INS401 ethernet TX/RX data frame conforms to IEEE802.3, the format is shown below.
The binary packets and ASCII messages should be filled in user data. Note it is also designed to
contain two packets/messages in the same one data frame. If one packet/message is more than
1500 bytes, it is split into two continuous data frames.
Destination Address Source Address Length User Data Data Frame Checksum
6 bytes 6 bytes 2 bytes 46 to 1500 bytes 4 bytes
 Destination Address: destination MAC address
 Source Address: source MAC address
 Length: length of user data (0~1500), MSB for output message from INS401 to ECU or
the 100Base-TX/100Base-T1 converter, LSB for input message.
 User Data: Min/Max data length is 46/1500. Zero bytes will be filled if less than 46 bytes
 Data Frame Checksum: CRC checksum bytes
Aceinna Binary Packet Format
The Aceinna proprietary binary packet format is defined as below.
Header
(uint16)
Message ID
(uint16)
Length
(uint32) Payload Checksum (uint16)
 Header: packet starts with header bytes 0x5555
 Message ID: the ID of the current message, LSB-first
 Length: the number of bytes in the payload, LSB-first
 Payload: user data contents, LSB-first
 Checksum: CRC16 check. Bytes from the beginning of the “Message ID” to the end of the
“Data content” are included in the checksum calculation, and a sample of the checksum
algorithm C code is shown in Appendix A: 16-bit CRC Implementation Sample Code.
Binary data of CRC is in Little Endian format

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Output Binary Packets
Three types of output data binary packets are defined – GNSS solution, INS solution and
diagnostic message.
GNSS Solution Packet
Table 3 GNSS Solution Packet
Message
GNSS positioning solution data, periodic output at 1 Hz
Message ID
0x0a02
Length
77
Payload Description
：
Byte
Offset
Type Name Unit Description
0
uint16
gps_week
GPS time:
GPS week and seconds in week
2
uint32
gps_millisecs
ms
6 uint8 position_type 0: INVALID
1: Single-point positioning (SPP)
2: Real time differential GNSS (RTD)
4: Real time kinematic (RTK), ambiguity fixed
(RTK_FIXED)
5: RTK with ambiguity float (RTK_FLOAT)
7
double
latitude
deg
Geodetic latitude
15
double
longitude
deg
Geodetic longitude
23
double
height
m
Height above ellipsoid
31
float
latitude_std
m
Latitudinal position accuracy
35
float
longitude_std
m
Longitudinal position accuracy
39
float
height_std
m
Vertical position accuracy
43
uint8
numberOfSVs
N
umber of satellites
44
uint8
numberOfSVs_in_solution
N
umber of satellites in
solution
45
float
hdop
Horizontal Dilution of Precision
49
float
diffage
s
Age of differential GNSS correction
53
float
north_vel
m/s
North velocity
57
float
east_vel
m/s
East velocity
61
float
up_vel
m/s
Up velocity
65
float
north_vel_std
m/s
North velocity accuracy
69
float
east_vel_std
m/s
East velocity accuracy
73
float
up_vel_std
m/s
Up velocity accuracy
INS navigation solution
Table 4 INS Solution Packet
Message
INS navigation solution,
periodic output at 100 Hz
Message ID
0x0a03
Length
108
Payload Description
：
Byte
Offset
Type Name Unit Description