ROBART II became the center of focus for the next several years in Bart Everett's basement workshop in Springfield, VA. The system basically performed the same functions as its predecessor but employed a multiprocessor architecture to enable parallel real-time operations. Optimization of performance was addressed through significantly increased sensor capability, distributed processing, and precise vehicle motion control. Upon his transfer in 1986 to the Naval Ocean Systems Center (our predecessor), the prototype was made available to the Navy for use as a test bed in support of mobile robotics research. The initial development effort focused on two specific technology areas.
The first of these addressed the navigational concerns that were hindering successful implementation of a number of robotic applications requiring mobility (Gilbreath & Everett, 1988). Simply put, an autonomous vehicle must be able to determine its position and orientation in the workspace, plan a path to its intended destination, and then execute that path without running into any obstructions. Numerous proximity and ranging sensors were incorporated on the robot to support map generation, position estimation, collision avoidance, navigational planning, and terrain assessment, enabling successful traversal of congested environments with no human intervention.
The second thrust was aimed at producing a robust automated security system exhibiting a high probability of detection with the ability to distinguish between actual and nuisance alarms. ROBART II was therefore also equipped with a multitude of intrusion and environmental sensors in support of its role as an intelligent sentry. These sensors monitor both system and room temperature, relative humidity, barometric pressure, ambient light and noise levels, toxic gas, smoke, and fire. Intrusion detection is addressed through the use of infrared, optical, ultrasonic, microwave, and video motion detection, as well as vibration monitoring and discriminatory hearing.
All high-level planning and assessment software runs on a desktop IBM-PC/AT computer connected to the robot via a 1200-baud Repco RF modem (Everett, et al., 1990). Robot position as well as sensor monitoring are represented graphically for the operator. The security assessment software package (Smurlo & Everett, 1993) displays time-stamped sensor status as well as environmental conditions, and can be overlaid on live video transmitted from a camera on-board the robot.
The scope of involvement was broadened in 1988 to include enhancements to the world-modeling scheme to incorporate fixed-installation security sensors (thereby allowing a mobile robot to operate in a secure area already protected by installed motion sensors) and inventory monitoring capability (allowing the robot to detect missing objects). In addition, a reflexive teleoperated control capability was added in 1989 to free the operator from the lower-level concerns associated with direct teleoperation. Speed of the vehicle and direction of motion are servo-controlled by an onboard processor in response to local sensor inputs, but under the high-level supervisory control of the remote operator (Laird & Everett, 1990). The robot's rich array of collision-avoidance sensors, originally intended to provide an envelope of protection during autonomous transit, were called into play during manual operation as well to greatly minimize the possibility of operator error. The commanded speed and direction of the platform was suitably altered as needed by the onboard processors to keep the robot from running into obstructions.
In spite of having been built at home from hobbyist-grade components, ROBART II has proven to be an amazingly reliable piece of equipment, with only four documented cases of hardware failure since officially coming to life in early 1983. This record is somewhat noteworthy, considering the workout given the system over its 20-year lifetime; records indicate the robot performed in 53 live demonstrations for visiting students, faculty, scientists, and government officials in 1987 alone. ROBART II was continuously on line without a power interruption from 1988 to 2002, when someone accidentally disconnected it's recharging station over a weekend.