Getting Started

The 3DM-GQ7 is an advanced navigation system with an extensive feature set. The following list provides a simplified overview of the critical features that are required to properly set up and use the 3DM-GQ7. Use this sequence as a guide to configure the 3DM-GQ7. Not all steps may be necessary for your application.

Please see the Getting Started Video for a quick demo of setting up the GQ7 with SensorConnect™.

 

Overview

(Each step is explained in more detail below.)

  1. Install desired software
  2. Install the 3DM-GQ7
  3. Capture the gyro bias
  4. Select the aiding measurements
  5. Apply kinematic constraints
  6. Configure the output data stream
  7. Configure the RTK input (optional)
  8. Initialize the Navigation Filter
  9. Monitor the Navigation Filter status

 

Install Desired software

There are multiple software offerings for interfacing with the 3DM-GQ7, tailored to various applications and levels of experience with inertial products. These offerings are organized below by increasingly lower levels of device control.

SensorConnect™is not required to use the 3DM-GQ7. However, it provides an intuitive GUI that greatly simplifies the initial configuration and evaluation process. The remaining steps in this section can be easily performed in SensorConnect™. See Software for more details about SensorConnect™.

ROS drivers provide a standardized framework to easily interface with the 3DM-GQ7 . ROS is recommended for applications where ease of integration is prioritized above optimum time synchronization. Examples include waypoint navigation, obstacle avoidance, sensor fusion for SLAM applications, simple embedded startup, etc. See Software for more details about ROS.

MIP SDK is a C and C++ SDK for interfacing with MicroStrain Inertial products at a low level and is the recommend software product for embedded, resource constrained, and time-critical applications. See Software for more details about MIP SDK.

 

Install the 3DM-GQ7

Prior to installation, it is important that users read the instructions on Powering the 3DM-GQ7. In addition, it is critical to correctly configure the mounting transform , navigation coordinate frame , and GNSS antenna offsets . Installation describes this process in more detail.

 

Capture the Gyro Bias

Capturing and removing gyro bias is one of the simplest ways to increase sensor performance. Gyro bias can shift during shipping and installation and should be captured and stored in non-volatile memory after sensor mounting, while the vehicle is stationary (including all motors and moving parts.) Additionally, it may need to be captured and stored periodically throughout the lifetime of the application. Once captured and stored it is automatically applied to the gyro data. See the Capture Gyro Bias (0x0C,0x39) command for details. To ensure this command is persistent through power cycling i.e. stored in non-volatile memory (NVM), use the Device Settings (0x0C,0x30) command to save to NVM.

Instructions for how to perform a gyro bias capture using SensorConnect™ can be found here.

 

Select the Aiding Measurements

The 3DM-GQ7's Navigation Filter can accept a variety of aiding measurements to improve its solution.

Example internal aiding measurements include GNSS position and velocity, dual antenna heading, barometer, and magnetometer.

Example external aiding measurements include GNSS position and velocity, true heading , wheel odometer, and x-axis vehicle velocity.

See Filter Aiding Measurements for more details.

 

Apply Kinematic Constraints

For some applications, various constraints can be applied to the Navigation Filter to improve the navigation solution. See Filter Kinematic Constraints for more detail.

 

Configure the Output Data Stream

Configure the 3DM-GQ7 to output the data quantities required for your application. See Data for a complete list of supported data quantities. This is easily completed through SensorConnect in the "Sampling" tile.

 

Configure the RTK Input (optional)

RTK corrections are not required to get a full navigation solution, but RTK corrections are necessary to get centimeter-level position accuracy. The 3DM-GQ7 supports RTK correction input through the auxiliary port. If using a 3DM-RTK, see 3DM-RTK Integration for details. If using a third party source for correction information, see the specifications for the AUX/RTCM3.

 

Initialize the Navigation Filter

To run in Full Navigation mode, the Navigation Filter requires an initial estimate of attitude, position and velocity. The Navigation Filter can be configured to automatically retrieve these initial estimates from the 3DM-GQ7's internal measurements, or they can be provided manually by the user. The Navigation Filter can also be run in other modes that require fewer initial estimates, but these modes do not provide a full navigation solution. See Filter Initialization for more information.

 

Monitor the Navigation Filter Status

The status of the Navigation Filter can be monitored through the Status (0x82,0x10) data channel. For a full description of this message and the Navigation Filter modes, see Filter Status. Health checks can be performed by monitoring and comparing the Filter Uncertainty Messages with the application specific thresholds. For example, position can be monitored with LLH Position Uncertainty (0x82,0x08), velocity with NED Velocity Uncertainty (0x82,0x09), and attitude can be monitored with Euler Angles Uncertainty (0x82,0x0A).