* MarkersSafety barrels guide traffic and serve as a visible barrier between traffic and work crews. These barrels consist of a brightly colored plastic drum (approximately 130cm high and 50cm in diameter) that is attached to a heavy base. The
robotic safety barrel replaces the heavy base with a mobile
robot that transports the safety barrel. The robots work in
teams to provide traffic control.
Independent, autonomous barrel motion has several
advantages. First, the barrels can self-deploy and self-retrieve, eliminating the dangerous task of manually placing barrels.
Second, their positions can be quickly and remotely reconfigured as the work zone changes thus reducing the work
zone size. Finally, barrels could continuously follow work
III. SYSTEM DESIGN
Five barrel robots have been created with two requirements
for both the hardware and software: 1) high reliability and 2) low per-robot cost. The robots must be reliable because a
malfunctioning robot could become a hazard. Cost per robot is critical because multiple (often >100) markers are used and barrels are often destroyed. Specific constraints include
stability in 96 km/h (60 mph) winds, low weight (<12 kg so they can be moved by workers), ability to climb slopes (< 7% grade), travel at 8 km/hr, and traverse small (<8cm)
Mechanically, the robot has two 20 cm diameter wheels that
are independently driven and a passive caster, Fig. 1. This
allows the robot to turn on any radius—including turning in place. Each wheel has an encoder so the robot can determine
its position over short distances. The robot itself stands less than 30 cm tall and raises the barrel height by 7 cm.
Electrically, the robot is powered by a 12-volt lead acid
battery—allowing it to operate continuously for
approximately 20 hours. The barrel robot has three 8-bit
processors: one is used for robot control (RS2000 Rabbit
SemiconductorTM), one to manage communication with the
outside world (PIC), and one to be a watchdog for the RF
heartbeat (PIC). Each robot has an RF transceiver for low
To increase reliability an encoded RF “heartbeat” is
broadcast locally. A loss of this heartbeat causes motor power to be cut through redundant fail-safe electrical relays. Also, each robot’s position is monitored by the robot itself as well as by the lead robot. Discrepancies in these redundant sensors (and processors) will cause either a local (robot) or global (heartbeat) shutdown. All communication between the lead
and barrels uses a 16-bit CRC checksum to prevent erroneous
This paper presents a system that uses mobile robots to
transport safety markers for highway construction and
maintenance. These robots work in teams to provide traffic
control. Independent autonomous barrel robots have several
advantages. First, the barrels can self-deploy and self-retrieve thereby eliminating the dangerous task of manually placing
barrels in busy traffic. The barrel positions can also be quickly and remotely re-configured as the work zone changes. Barrels could continuously follow work crews to maintain proper
placement. The robotic safety barrels are the first elements of a team of robotic safety markers (RSM) that includes signs,
* cones, and possibly barricades and arrestors.
One method to improve work zone safety is to implement a
smart work zone consisting of automated devices that improve * Safety
Safety barrels are placed on the periphery of the work
zone to guide traffic and to serve as a visible barrier between traffic and work crews. These barrels consist of a brightlycolored plastic drum (approximately 130cm high and 50cm in diameter) that is attached to a heavy base. Often, hundreds of barrels are manually placed in a typical work zone. The
Robotic Safety Barrel (RSB) replaces the heavy base of a
typical safety barrel with a mobile...