/sup T/he University of Minnesota's Scout is a small cylindrical robot capable of rolling and jumping. Models describing the robot's motion are developed. These models can be employed for motion prediction and simulation. The results suggest that the determining factor of the Scout's behavior is the length of the winch cable.

The problem of vision-guided control of miniature mobile robots is investigated. Untethered mobile robots with small physical dimensions of around 10 cm or less do not permit powerful onboard computers because of size and power constraints. These challenges have, in the past, reduced the functionality of such devices to that of a complex remote control vehicle with fancy sensors. With the help of a computationally more powerful entity such as a larger companion robot, the control loop can be closed. Using the miniature robot's video transmission or that of an observer to localize it in the world, control commands can be computed and relayed to the inept robot. The result is a system that exhibits autonomous capabilities. The framework presented here solves the problem of climbing stairs with the miniature Scout robot. The robot's unique locomotion mode, the jump, is employed to hop one step at a time. Methods for externally tracking the Scout are developed. A large number of real-world experiments are conducted and the results discussed.

Classical dynamic contours (snakes) suffer from their inability to properly address the crossover problem. In the closed contour case, a part of the snake inverts and expands without bounds. This paper proposes a novel approach to handle inversions by splitting the contour at the points of self-intersection. Separated parts that are inverted are destroyed while the remaining parts are used to seed new snakes. Collisions of snakes cause them to merge. The probability of crossovers is further reduced by an efficient reparameterization procedure. The method is successfully applied to the challenging task of tracking the globule in a motion lamp.

When designing a mobile robotic team, an engineer is faced with many design choices. This paper discusses the design of a team consisting of two different models of robots with significantly different sensing and control capabilities intended to accomplish a similar task. Two new robotic platforms, the COTS Scout and the MegaScout are described along with their respective design considerations.

To safely and efficiently guide search and rescue operations in disaster areas, gathering of relevant information such as the locations of victims, must occur swiftly. Using the concept of repellent virtual pheromones inspired by insect colony coordination behaviors, miniature robots can be quickly dispersed to survey a disaster site. Assisted by visual servoing, dispersion of the miniature robots can quickly cover an area. An external observer such as another robot or an overhead camera is brought into the control loop to provide each miniature robot estimations of the positions of all the other nearby robots in the robotic team. Each robot can then move away from the other nearby robots, resulting in the robot collective swiftly dispersing through the local area. The technique has been implemented using the miniature scout robots, developed by the Center for Distributed Robotics at the University of Minnesota, which are well-suited to surveillance and reconnaissance missions.

The University of Minnesota's Scout robot is a small cylindrical robot capable of rolling and jumping. In this paper, models describing the robot's motion under its mode of actuation are developed. These models can be employed for Scout motion prediction and simulation. The models suggest that the determining factor of the Scout's behavior is the length of the winch cable. The validity of the models is verified with empirical data.

Presents a method for localizing miniature mobile robots (Scouts) using dynamic contours. An observer robot with a camera follows the miniature robot as it moves and jumps in the workspace. Dynamic contours are very effective in tracking the fast accelerations and decelerations of the Scout robot. We show initial experimental results with particular emphasis on the task of monitoring a Scout during jumps.

Search and rescue operations in large disaster sites require quick gathering of relevant information. Both the knowledge of the location of victims and the environmental/structural conditions must be available to safely and efficiently guide rescue personnel. A major hurdle for robots in such scenarios is stairs. A system for autonomous surmounting of stairs is proposed in which a Scout robot jumps from step to step. The robot's height is only about a quarter step in size. Control of the Scout is accomplished using visual servoing. An external observer such as another robot is brought into the control loop to provide the Scout with an estimation of its pose with respect to the stairs. This cooperation is necessary as the Scout must refrain from ill-fated motions that may lead it back down to where it started its ascend. Initial experimental results are presented along with a discussion of the issues involved.

We have designed and built a set of miniature robots called Scouts and have developed a distributed software system to control them. This paper addresses the fundamental choices we made in the design of the control software, describes experimental results in a surveillance task, and analyzes the factors that affect robot performance. Space and power limitations on the Scouts severely restrict the computational power of their on-board computers, requiring a proxy-processing scheme in which the robots depend on remote computers for their computing needs. While this allows the robots to be autonomous, the fact that robots' behaviors are executed remotely introduces an additional complication-sensor data and motion commands have to be exchanged using wireless communications channels. Communications channels cannot always be shared, thus requiring the robots to obtain exclusive access to them. We present experimental results on a surveillance task in which multiple robots patrol an area and watch for motion. We discuss how the limited communications bandwidth affects robot performance in accomplishing the task, and analyze how performance depends on the number of robots that share the bandwidth.

We describe a distributed software system for controlling a group of miniature robots using a very low capacity communication system. Space and power limitations on the miniature robots drastically restrict the capacity of the communication system and require sharing bandwidth and other resources among the robots. We have developed a process management/scheduling system that dynamically assigns resources to each robot in an attempt to maximize the utilization of the available resources while still maintaining a priori behavior priorities. We describe a surveillance task in which the robots patrol an area and watch for motion, and present experimental results.

Presents a miniature robotic system ("scout") useful for reconnaissance and surveillance missions. A large number of scout robots are deployed and controlled by humans and/or larger "ranger" robots. The specially designed and constructed scouts are extremely small (roughly 116cc volume) yet are readily deployable (by tossing or launching), have multiple mobility modes, have multiple sensing capabilities, can transmit and receive data and instructions, and have a limited capability for autonomous action. The rangers are significantly larger vehicles, based on a commercial-off-the-shelf platform, augmented with scout launchers, radios, and additional sensors. Together, the scouts and rangers form a hierarchical team capable of carrying out complex missions in a wide variety of environments.

A new approach to automatically generate polyhedral convex cones from contact graphs for identification of assembly process states is presented. The state of contact between subassemblies is changing as operation proceeds in manipulative tasks such as part-mating. Measured contact forces and the resulting torques provide information about the contact geometry which is used to guide the assembly operation. In this paper, we present a method to calculate contact graphs for polyhedral subassemblies. The nodes of the contact graph represent contact formations of the subassemblies and the arcs represent neighborhoods of contact formations. This information is used to generate polyhedral convex cones for each contact formation considering friction. These polyhedral convex cones describe static equilibrium for each contact formation and are used to identify the contact state by measuring forces and torques during a part-mating.

Robotic manipulators in contemporary work-cells are often incapable of solving even simple pick-and-place operations. More specifically, most systems require each object to be supplied in the same and pre-defined way. Introducing regrasping to the production cycle relaxes the constraints imposed on supply mechanisms. Regrasping describes the operation that must be performed whenever an object's pick-up grasp is incompatible with its put-down grasp. The paper presents a novel approach to solve the regrasp problem for robots equipped with parallel-jaw end-effecters. The proposed method first evaluates the object's possible grasps and placements. These are subsequently combined to form grasp-placement-grasp triples. A regrasp sequence leading from the pick-up to the put-down grasp is generated by searching through the resulting space of compatible grasp-placement-grasp triples. The algorithm takes kinematic and geometric constraints of both the manipulator and the objects into account. Computational concerns are addressed by subdividing the calculation into an off-line and a fast online phase.