The key to utilizing the potential of multirobot systems is cooperation. How can we achieve cooperation in systems composed of failure-prone autonomous robots operating in noisy, dynamic environments? In this paper, we present a novel method of dynamic task allocation for groups of such robots. We implemented and tested an auction-based task allocation system which we call MURDOCH, built upon a principled, resource centric, publish /subscribe communication model. A variant of the Contract Net Protocol, MURDOCH produces a distributed approximation to a global optimum of resource usage. We validated MURDOCH in two very different domains: a tightly coupled multirobot physical manipulation task and a loosely coupled multirobot experiment in long-term autonomy. The primary contribution of this paper is to show empirically that distributed negotiation mechanisms such as MURDOCH are viable and effective for coordinating physical multirobot systems.

Abstract—This paper presents a behavior-based approach to formation maneuvers for groups of mobile robots. Complex formation maneuvers are decomposed into a sequence of maneuvers between formation patterns. The paper presents three formation control strategies. The first strategy uses relative position information configured in a bidirectional ring topology to maintain the formation. The second strategy injects interrobot damping via passivity techniques. The third strategy accounts for actuator saturation. Hardware results demonstrate the effectiveness of the proposed control strategies. Index Terms—Behavioral methods, coordinated control, formations, mobile robots, passivity.

This paper presents the coupled dynamics approach to executing Elementary Formation Maneuvers (EFM) for Hilare-type mobile robots. The concept of an EFM is presented. It is then shown that each of these EFMs posses a common mathematical structure and thus may be executed by the same type of robot control. We present three different EFM controls in this paper. The first puts feedback on the relative motion and the global motion of each robot. The second control adds inter-robot damping. And the third control uses saturated inputs on the relative motion and the global motion of each robot. We present simulation and hardware results for each of these controls. I. Introduction Cooperative robots can often be used to perform tasks that are too difficult for a single robot to perform alone. For example a group of robots can be used for moving large awkward objects [1], [2] or for moving a large number of objects [3]. In addition groups of robots can be used for terrain model acquisition [3]...

We present a distributed planar object manipulation algorithm inspired by human behavior. The system, which we call pusher-watcher, enables the cooperative manipulation of large objects by teams of autonomous mobile robots. The robots are not equipped with gripping devices, but instead move objects by pushing against them. The pusher robots have no global positioning information, and cannot see over the object; thus a watcher robot has the responsibility for leading the team (and object) to the goal, which only it can perceive. The system is entirely distributed, with each robot under local control. Through the use of Murdoch, an auction-based resource-centric general purpose task-allocation framework, roles in the team are automatically assigned in an efficient manner. Further, robot failures are easily tolerated and, when possible, automatically recovered. We present results and analysis from a battery of experiments with pusher-watcher implemented on a group of Pioneer 2 mobile robots.

This paper proposes a new architecture for tightly coupled multi-robot cooperation. At all times, a robot is identified as a leader, while the others are designated as followers. The assignment of roles and the coordination between the robots is guaranteed by communication protocols and control algorithms. The key feature is the flexibility that allows changes in leadership and assignment of roles during the execution of a task. We describe the experimental implementation and demonstration in a cooperative transportation task, in which two and three heterogeneous robots cooperate to carry a large object in an environment containing static and dynamic obstacles.

A Large-Scale Minimalist Multi-Robot System (LMMS) is one composed of a group of robots each with limited capabilities in terms of sensing, computation, and communication. Such systems have received increased attention due to their empirically demonstrated performance and beneficial characteristics, such as their robustness to environmental perturbations and individual robot failure and their scalability to large numbers of robots. However, little work has been done in investigating ways to endow such a LMMS with the capability to achieve a desired division of labor over a set of dynamically evolving concurrent tasks, important in many task-achieving LMMS. Such a capability can help to increase the efficiency and robustness of overall task performance as well as open new domains in which LMMS can be seen as a viable alternative to more complex control solutions. In this paper we present a method for achieving a desired division of labor in a LMMS, experimentally validate it in a realistic simulation, and demonstrate its potential to scale to large numbers of robots and its ability to adapt to environmental perturbations.

This paper describes a novel action selection method for multiple mobile robots box-pushing in a dynamic environment. The robots are designed to need no explicit communication, and be adaptive to a dynamic environments by changing modules of behaviors. Though it is a significant problem to deal with adaptive action selection for multiple mobile-robots in a dynamic environment, few studies have been done. Decentralized control of robots without explicit communication is also practical and important for robustness. Thus we propose adaptive action selection without explicit communication for multi-robot boxpushing, which changes an available behavior set depending on a situation. First four situations are defined with two parameters: existence of other robots and task di#culty. Next we design a set of behaviors for each situations, and mobile robots are programmed to act with behavior-based approach. We fully implement our method on four real mobile robots, and make experiments in dynamic...

Does coherent behaviour require an explicit mechanism of cooperation? In this dissertation, the relationship between local perception and global action in a system of multiple mobile robots was examined for a collective box-pushing task. The problem investigated was how local sensing could be used to coordinate the individual motor responses of a system of robots in a coherent manner, using only implicit communication through the task. The task was to move a large box from an initially unknown position to a specified goal location. The central thesis put forward, is that for the box-pushing task a coherent behaviour is possible, without an explicit mechanism of cooperation, by using the mass effect of a system of redundant robots. Preliminary work in collective robotics appeared to lend weight to the hypothesis that collective tasks, by multi-robot systems, are possible without centralized control or explicit inter-robot communications, two common control mechanisms used for cooperati...

Swarm Robotics (SR) is closely related to Swarm Intelligence, and both were initially inspired by studies of social insects. Their guiding principles are based on their biological inspiration and take the form of an emphasis on decentralised local control and communication. Earlier studies went a step further in emphasising the use of simple reactive robots that only communicate indirectly through the environment. More recently SR studies have moved beyond these constraints to explore the use of non-reactive robots that communicate directly, and that can learn and represent their environment. There is no clear agreement in the literature about how far such extensions of the original principles could go. Should there be any limitations on the individual abilities of the robots used in SR studies? Should knowledge of the capabilities of social insects lead to constraints on the capabilities of individual robots in SR studies? There is a lack of explicit discussion of such questions and researchers have adopted a variety of constraints for a variety of reasons. A simple taxonomy of swarm robotics is presented here with the aim of addressing and clarifying these questions. The taxonomy distinguishes sub-areas of SR based on the emphases and justifications for minimalism and individual simplicity.

system, TerminatorBot, a novel, centimeter-scale crawling robot has been developed to address applications in surveillance, search-and-rescue, and planetary exploration. Its two 3 degreeof-freedom arms, which stow inside the cylindrical body for ballistic deployment and protected transport, comprise a dualuse mechanism for manipulation and locomotion. The intended applications require a small, rugged, and lightweight robot, hence the desire for dual-use. TerminatorBot’s unique mechanism provides mobility and fine manipulation on a scale currently unavailable. To facilitate manipulation, we have also developed a specialized force/torque sensor. This new sensor design has a biased distribution of flexures, which equalizes force and torque sensitivities at the operational point. This paper describes the mechanism and design of TerminatorBot, the specialized force/torque sensor, and the mechanism-specific gaits. Index Terms — robotics, mobile manipulation, force sensor, TerminatorBot