June 22, 2008
June 22, 2008
June 25, 2008
Computers in Education
13.1241.1 - 13.1241.8
The Inertial Navigation Unit: Teaching Navigation Principles using a Custom Designed Sensor Package
This paper describes the application and design of a small, inexpensive inertial navigation unit (INU) created to introduce systems engineering students at the United States Naval Academy (USNA) to the principles of navigation systems and to act as a navigation sensor for robotic and autonomous vehicle projects. The INU has been used in place of a multitude of standard navigation sensors such as an inertial measurement unit (IMU), magnetic compass module, and Global Positioning System (GPS) receiver. Its integrated design simplifies mechanical mounting, reduces navigation system weight and size, simplifies data interfacing with a control computer, and provides great flexibility for reconfiguring to meet a variety of engineering education objectives. The INU is capable of firmware upgrades and algorithm enhancements in the field via in-circuit programming, enhancing its longevity as a useful educational tool. In addition, a variety of controllers or a personal computer (PC) can communicate with the INU board through a standard RS-232C serial interface. This compact unit provides good system performance at a reasonable cost compared to most commercially available units. These features enable hands-on education techniques in the navigation aspects of robotics, examples of which are presented.
A significant amount of work in robotics is done in the USNA Systems Engineering Department, with autonomous vehicles in particular. Such ABET accredited engineering programs require a “capstone” design project for graduation, and each year there are numerous student projects to build autonomous vehicles of various types. Several student independent research projects are also completed each year. Supporting these projects is a senior-level elective course in autonomous vehicles in which students are exposed to the principles of vehicle navigation and provided hands-on experience with navigation system components. Navigation systems commonly include an IMU, a combination of accelerometers and gyros to sense vehicle translational and rotational motions without external reference. Other navigation components commonly found on autonomous vehicles include a magnetic compass as a heading reference and a GPS receiver for position and velocity measurement. The need for small and inexpensive, yet capable, navigation systems in this department are therefore necessary.
To meet this need, a navigation sensor package was developed and built “in house”. A printed circuit board was manufactured locally and populated with readily available components to produce a compact, low-cost inertial sensor module that meets these requirements in all but a few of the most demanding applications. The INU is based on Microchip’s dsPIC30F4013 digital signal processor1 and commercially available sensors. The INU is less than 2” x 3” x 1.3”, weighs less than 1.6oz, costs under $300 for parts, and has an update rate of 80Hz. The system provides 6-axes of inertial sensor data, GPS, a real time clock (RTC) for data stamping, magnetic compass, and temperature sensing, making it an ideal circuit board for embedded applications.
Bradshaw, J., & Nicholson, J. (2008, June), The Inertial Navigation Unit: Teaching Navigation Principles Using A Custom Designed Sensor Package Paper presented at 2008 Annual Conference & Exposition, Pittsburgh, Pennsylvania. https://peer.asee.org/3480
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