Development of a low cost controller and navigation system for unmanned ground vehicle

The objective of this research was to develop an Unmanned Ground Vehicle (UGV) which is capable of autonomously navigating to user specified Global Positioning System (GPS) waypoints. For rapid design and testing of the UGV, it was initially designed in a distributive approach using independent commercial off-the-shelf (COTS) computing modules for control and sensing. Autonomous navigation behavior of the UGV was tested to analyze the strengths and weaknesses of the UGV design, using digital compass for heading and GPS for location measurements. The UGV waypoint navigation has been observed to be consistent for smooth terrains. Uneven terrains, however, posed a challenge for UGV navigation as the underlying terrain induced noise and error into the compass thus making the UGV heading measurements unreliable. The UGV heading estimation was improved by applying a Kalman filter for gyro, GPS, and compass measurements. The heading estimate obtained using this technique has always been observed to be within five degrees of the actual UGV heading. The performance of the UGV electronic control and sensing subsystem has been improved by replacing all the COTS modules with a low cost Freescale 9S12 microcontroller. A circuit board integrating a 9S12 microcontroller and a single axis rate gyro was designed to interface with a host computer. The microcontroller receives instructions over a serial RS-232 connection from the host computer to perform a set of maneuvers and also to monitor the status of the UGV. The hardware design coupled with the estimation technique not only simplified the electronic hardware design and improved the reliability of the system but also brought down the design costs of the UGV